[v2,2/6] hwtracing: Add trace function support for HiSilicon PCIe Tune and Trace device

HiSilicon PCIe tune and trace device(PTT) is a PCIe Root Complex
integrated Endpoint(RCiEP) device, providing the capability
to dynamically monitor and tune the PCIe traffic(tune),
and trace the TLP headers(trace).

Add the driver for the device to enable the trace function. The driver
will create PMU device for each PTT device, and users can start trace
through perf command.

Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
---
 drivers/Makefile                       |    1 +
 drivers/hwtracing/Kconfig              |    2 +
 drivers/hwtracing/hisilicon/Kconfig    |    8 +
 drivers/hwtracing/hisilicon/Makefile   |    2 +
 drivers/hwtracing/hisilicon/hisi_ptt.c | 1146 ++++++++++++++++++++++++
 5 files changed, 1159 insertions(+)
 create mode 100644 drivers/hwtracing/hisilicon/Kconfig
 create mode 100644 drivers/hwtracing/hisilicon/Makefile
 create mode 100644 drivers/hwtracing/hisilicon/hisi_ptt.c

On 2021-11-16 09:06, Yicong Yang via iommu wrote:
[...]
> +/*
> + * Get RMR address if provided by the firmware.
> + * Return 0 if the IOMMU doesn't present or the policy of the
> + * IOMMU domain is passthrough or we get a usable RMR region.
> + * Otherwise a negative value is returned.
> + */
> +static int hisi_ptt_get_rmr(struct hisi_ptt *hisi_ptt)
> +{
> +	struct pci_dev *pdev = hisi_ptt->pdev;
> +	struct iommu_domain *iommu_domain;
> +	struct iommu_resv_region *region;
> +	LIST_HEAD(list);
> +
> +	/*
> +	 * Use direct DMA if IOMMU does not present or the policy of the
> +	 * IOMMU domain is passthrough.
> +	 */
> +	iommu_domain = iommu_get_domain_for_dev(&pdev->dev);
> +	if (!iommu_domain || iommu_domain->type == IOMMU_DOMAIN_IDENTITY)
> +		return 0;
> +
> +	iommu_get_resv_regions(&pdev->dev, &list);
> +	list_for_each_entry(region, &list, list)
> +		if (region->type == IOMMU_RESV_DIRECT &&
> +		    region->length >= HISI_PTT_TRACE_BUFFER_SIZE) {
> +			hisi_ptt->trace_ctrl.has_rmr = true;
> +			hisi_ptt->trace_ctrl.rmr_addr = region->start;
> +			hisi_ptt->trace_ctrl.rmr_length = region->length;
> +			break;
> +		}
> +
> +	iommu_put_resv_regions(&pdev->dev, &list);
> +	return hisi_ptt->trace_ctrl.has_rmr ? 0 : -ENOMEM;
> +}

No.

The whole point of RMRs is for devices that are already configured to 
access the given address range in a manner beyond the kernel's control. 
If you can do this, it proves that you should not have an RMR in the 
first place.

The notion of a kernel driver explicitly configuring its device to DMA 
into any random RMR that looks big enough is so egregiously wrong that 
I'm almost lost for words...

Robin.

On 2021/11/16 18:56, Robin Murphy wrote:
> On 2021-11-16 09:06, Yicong Yang via iommu wrote:
> [...]
>> +/*
>> + * Get RMR address if provided by the firmware.
>> + * Return 0 if the IOMMU doesn't present or the policy of the
>> + * IOMMU domain is passthrough or we get a usable RMR region.
>> + * Otherwise a negative value is returned.
>> + */
>> +static int hisi_ptt_get_rmr(struct hisi_ptt *hisi_ptt)
>> +{
>> +    struct pci_dev *pdev = hisi_ptt->pdev;
>> +    struct iommu_domain *iommu_domain;
>> +    struct iommu_resv_region *region;
>> +    LIST_HEAD(list);
>> +
>> +    /*
>> +     * Use direct DMA if IOMMU does not present or the policy of the
>> +     * IOMMU domain is passthrough.
>> +     */
>> +    iommu_domain = iommu_get_domain_for_dev(&pdev->dev);
>> +    if (!iommu_domain || iommu_domain->type == IOMMU_DOMAIN_IDENTITY)
>> +        return 0;
>> +
>> +    iommu_get_resv_regions(&pdev->dev, &list);
>> +    list_for_each_entry(region, &list, list)
>> +        if (region->type == IOMMU_RESV_DIRECT &&
>> +            region->length >= HISI_PTT_TRACE_BUFFER_SIZE) {
>> +            hisi_ptt->trace_ctrl.has_rmr = true;
>> +            hisi_ptt->trace_ctrl.rmr_addr = region->start;
>> +            hisi_ptt->trace_ctrl.rmr_length = region->length;
>> +            break;
>> +        }
>> +
>> +    iommu_put_resv_regions(&pdev->dev, &list);
>> +    return hisi_ptt->trace_ctrl.has_rmr ? 0 : -ENOMEM;
>> +}
> 
> No.
> 
> The whole point of RMRs is for devices that are already configured to access the given address range in a manner beyond the kernel's control. If you can do this, it proves that you should not have an RMR in the first place.
> 
> The notion of a kernel driver explicitly configuring its device to DMA into any random RMR that looks big enough is so egregiously wrong that I'm almost lost for words...
> 

our bios will reserve such a region and reported it through iort. the device will write to the region and in the driver we need to access the region
to get the traced data. the region is reserved exclusively and will not be accessed by kernel or other devices.

is it ok to let bios configure the address to the device and from CPU side we just read it?

Thanks,
Yicong

Hi Robin,

On 2021/11/16 19:37, Yicong Yang wrote:
> On 2021/11/16 18:56, Robin Murphy wrote:
>> On 2021-11-16 09:06, Yicong Yang via iommu wrote:
>> [...]
>>> +/*
>>> + * Get RMR address if provided by the firmware.
>>> + * Return 0 if the IOMMU doesn't present or the policy of the
>>> + * IOMMU domain is passthrough or we get a usable RMR region.
>>> + * Otherwise a negative value is returned.
>>> + */
>>> +static int hisi_ptt_get_rmr(struct hisi_ptt *hisi_ptt)
>>> +{
>>> +    struct pci_dev *pdev = hisi_ptt->pdev;
>>> +    struct iommu_domain *iommu_domain;
>>> +    struct iommu_resv_region *region;
>>> +    LIST_HEAD(list);
>>> +
>>> +    /*
>>> +     * Use direct DMA if IOMMU does not present or the policy of the
>>> +     * IOMMU domain is passthrough.
>>> +     */
>>> +    iommu_domain = iommu_get_domain_for_dev(&pdev->dev);
>>> +    if (!iommu_domain || iommu_domain->type == IOMMU_DOMAIN_IDENTITY)
>>> +        return 0;
>>> +
>>> +    iommu_get_resv_regions(&pdev->dev, &list);
>>> +    list_for_each_entry(region, &list, list)
>>> +        if (region->type == IOMMU_RESV_DIRECT &&
>>> +            region->length >= HISI_PTT_TRACE_BUFFER_SIZE) {
>>> +            hisi_ptt->trace_ctrl.has_rmr = true;
>>> +            hisi_ptt->trace_ctrl.rmr_addr = region->start;
>>> +            hisi_ptt->trace_ctrl.rmr_length = region->length;
>>> +            break;
>>> +        }
>>> +
>>> +    iommu_put_resv_regions(&pdev->dev, &list);
>>> +    return hisi_ptt->trace_ctrl.has_rmr ? 0 : -ENOMEM;
>>> +}
>>
>> No.
>>
>> The whole point of RMRs is for devices that are already configured to access the given address range in a manner beyond the kernel's control. If you can do this, it proves that you should not have an RMR in the first place.
>>
>> The notion of a kernel driver explicitly configuring its device to DMA into any random RMR that looks big enough is so egregiously wrong that I'm almost lost for words...
>>
> 
> our bios will reserve such a region and reported it through iort. the device will write to the region and in the driver we need to access the region
> to get the traced data. the region is reserved exclusively and will not be accessed by kernel or other devices.
> 
> is it ok to let bios configure the address to the device and from CPU side we just read it?
> 

Any suggestion?  Is this still an issue you concern if we move the configuration of the device address to BIOS and just read from the CPU side?

> 
> 
> .
>

Hi Yicong,

On Tue, Nov 16, 2021 at 05:06:21PM +0800, Yicong Yang wrote:
> HiSilicon PCIe tune and trace device(PTT) is a PCIe Root Complex
> integrated Endpoint(RCiEP) device, providing the capability
> to dynamically monitor and tune the PCIe traffic(tune),
> and trace the TLP headers(trace).
>

Is there a reason to put "tune" and "trace" are whithin parentheses?  

> Add the driver for the device to enable the trace function. The driver
> will create PMU device for each PTT device, and users can start trace
> through perf command.
> 
> Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
> ---
>  drivers/Makefile                       |    1 +
>  drivers/hwtracing/Kconfig              |    2 +
>  drivers/hwtracing/hisilicon/Kconfig    |    8 +
>  drivers/hwtracing/hisilicon/Makefile   |    2 +
>  drivers/hwtracing/hisilicon/hisi_ptt.c | 1146 ++++++++++++++++++++++++

Not sure about the "hisilicon" directory.  Right now we have "coresight",
"intel_th" and "stm" - they concentrate on the technology rather than the
vendor.  I think "ptt" would be just fine: 

drivers/hwtracing/ptt/Kconfig 
drivers/hwtracing/ptt/Makefile
drivers/hwtracing/ptt/hisi_ptt.c

That way if other vendors want to introduce support for the same kind of
technology we can simply put them under "drivers/hwtracing/ptt/" and things are
still accurate.


>  5 files changed, 1159 insertions(+)
>  create mode 100644 drivers/hwtracing/hisilicon/Kconfig
>  create mode 100644 drivers/hwtracing/hisilicon/Makefile
>  create mode 100644 drivers/hwtracing/hisilicon/hisi_ptt.c
> 
> diff --git a/drivers/Makefile b/drivers/Makefile
> index be5d40ae1488..bb0dc9b55ea2 100644
> --- a/drivers/Makefile
> +++ b/drivers/Makefile
> @@ -176,6 +176,7 @@ obj-$(CONFIG_USB4)		+= thunderbolt/
>  obj-$(CONFIG_CORESIGHT)		+= hwtracing/coresight/
>  obj-y				+= hwtracing/intel_th/
>  obj-$(CONFIG_STM)		+= hwtracing/stm/
> +obj-$(CONFIG_HISI_PTT)         += hwtracing/hisilicon/
>  obj-$(CONFIG_ANDROID)		+= android/
>  obj-$(CONFIG_NVMEM)		+= nvmem/
>  obj-$(CONFIG_FPGA)		+= fpga/
> diff --git a/drivers/hwtracing/Kconfig b/drivers/hwtracing/Kconfig
> index 13085835a636..e3796b17541a 100644
> --- a/drivers/hwtracing/Kconfig
> +++ b/drivers/hwtracing/Kconfig
> @@ -5,4 +5,6 @@ source "drivers/hwtracing/stm/Kconfig"
>  
>  source "drivers/hwtracing/intel_th/Kconfig"
>  
> +source "drivers/hwtracing/hisilicon/Kconfig"
> +
>  endmenu
> diff --git a/drivers/hwtracing/hisilicon/Kconfig b/drivers/hwtracing/hisilicon/Kconfig
> new file mode 100644
> index 000000000000..9c3ab80d99fe
> --- /dev/null
> +++ b/drivers/hwtracing/hisilicon/Kconfig
> @@ -0,0 +1,8 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +config HISI_PTT
> +	tristate "HiSilicon PCIe Tune and Trace Device"
> +	depends on PCI && HAS_DMA && HAS_IOMEM

What Arm architecture are you aiming this for?  Can it be found on both armv7
and armv8?

> +	help
> +	  HiSilicon PCIe Tune and Trace Device exist as a PCIe RCiEP
> +	  device, provides support for PCIe traffic tuning and
> +	  tracing TLP headers to the memory.

Please indicate what the name of the driver will be when compiled as a module.

> diff --git a/drivers/hwtracing/hisilicon/Makefile b/drivers/hwtracing/hisilicon/Makefile
> new file mode 100644
> index 000000000000..908c09a98161
> --- /dev/null
> +++ b/drivers/hwtracing/hisilicon/Makefile
> @@ -0,0 +1,2 @@
> +# SPDX-License-Identifier: GPL-2.0
> +obj-$(CONFIG_HISI_PTT) += hisi_ptt.o
> diff --git a/drivers/hwtracing/hisilicon/hisi_ptt.c b/drivers/hwtracing/hisilicon/hisi_ptt.c
> new file mode 100644
> index 000000000000..e11e9b6cc2a8
> --- /dev/null
> +++ b/drivers/hwtracing/hisilicon/hisi_ptt.c
> @@ -0,0 +1,1146 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Driver for HiSilicon PCIe tune and trace device
> + *
> + * Copyright (c) 2021 HiSilicon Limited.
> + */
> +
> +#include <linux/bitfield.h>
> +#include <linux/bitops.h>
> +#include <linux/delay.h>
> +#include <linux/dma-iommu.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/interrupt.h>
> +#include <linux/io.h>
> +#include <linux/iommu.h>
> +#include <linux/iopoll.h>
> +#include <linux/kfifo.h>
> +#include <linux/module.h>
> +#include <linux/notifier.h>
> +#include <linux/pci.h>
> +#include <linux/perf_event.h>
> +#include <linux/sizes.h>
> +#include <linux/sysfs.h>
> +#include <linux/vmalloc.h>
> +#include <linux/workqueue.h>
> +
> +#define HISI_PTT_TRACE_ADDR_SIZE	0x0800
> +#define HISI_PTT_TRACE_ADDR_BASE_LO_0	0x0810
> +#define HISI_PTT_TRACE_ADDR_BASE_HI_0	0x0814
> +#define HISI_PTT_TRACE_ADDR_STRIDE	0x8
> +#define HISI_PTT_TRACE_CTRL		0x0850
> +#define   HISI_PTT_TRACE_CTRL_EN	BIT(0)
> +#define   HISI_PTT_TRACE_CTRL_RST	BIT(1)
> +#define   HISI_PTT_TRACE_CTRL_RXTX_SEL	GENMASK(3, 2)
> +#define   HISI_PTT_TRACE_CTRL_TYPE_SEL	GENMASK(7, 4)
> +#define   HISI_PTT_TRACE_CTRL_DATA_FORMAT	BIT(14)
> +#define   HISI_PTT_TRACE_CTRL_FILTER_MODE	BIT(15)
> +#define   HISI_PTT_TRACE_CTRL_TARGET_SEL	GENMASK(31, 16)
> +#define HISI_PTT_TRACE_INT_STAT		0x0890
> +#define   HISI_PTT_TRACE_INT_STAT_MASK	GENMASK(3, 0)
> +#define HISI_PTT_TRACE_INT_MASK		0x0894
> +#define HISI_PTT_TRACE_WR_STS		0x08a0
> +#define   HISI_PTT_TRACE_WR_STS_WRITE	GENMASK(27, 0)
> +#define   HISI_PTT_TRACE_WR_STS_BUFFER	GENMASK(29, 28)
> +#define HISI_PTT_TRACE_STS		0x08b0
> +#define   HISI_PTT_TRACE_IDLE		BIT(0)
> +#define HISI_PTT_DEVICE_RANGE		0x0fe0
> +#define HISI_PTT_LOCATION		0x0fe8
> +#define   HISI_PTT_CORE_ID		GENMASK(15, 0)
> +#define   HISI_PTT_SICL_ID		GENMASK(31, 16)

Extra spaces between #define and the literals.  Please align the values with
that of HISI_PTT_TRACE_DMA_IRQ below.

> +
> +#define HISI_PTT_TRACE_DMA_IRQ			0
> +#define HISI_PTT_TRACE_BUFLETS_CNT		4
> +#define HISI_PTT_TRACE_BUFLET_SIZE		SZ_4M
> +#define HISI_PTT_TRACE_BUFFER_SIZE		(HISI_PTT_TRACE_BUFLET_SIZE * \
> +						 HISI_PTT_TRACE_BUFLETS_CNT)
> +#define HISI_PTT_FILTER_UPDATE_FIFO_SIZE	16
> +
> +/* Delay time for filter updating work */
> +#define HISI_PTT_WORK_DELAY_MS		100UL
> +/* Wait time for DMA hardware to reset */
> +#define HISI_PTT_RESET_WAIT_MS		1000UL
> +/* Poll timeout and interval for waiting hardware work to finish */
> +#define HISI_PTT_WAIT_TIMEOUT_US	1000000UL
> +#define HISI_PTT_WAIT_POLL_INTERVAL_US	100UL
> +
> +#define HISI_PCIE_CORE_PORT_ID(devfn)	(PCI_FUNC(devfn) << 1)
> +
> +enum hisi_ptt_trace_status {
> +	HISI_PTT_TRACE_STATUS_OFF = 0,
> +	HISI_PTT_TRACE_STATUS_ON,
> +};
> +
> +struct hisi_ptt_dma_buflet {

I'm not sure what a "buflet" is...  Probably best to just call this
hisi_ptt_dma_buffer" if it pertains to a buffer.  On that note it is hard to
know due to the lack of proper structure documentation.  Please have a look at
how "coresight_device" is documented.  The same applies to the rest of the
structures declared below.

> +	struct list_head list;
> +	unsigned int size;
> +	dma_addr_t dma;
> +
> +	/*
> +	 * The address of the buflet holding the trace data.
> +	 * See Documentation/trace/hisi-ptt.rst for the details

As of this writing, hisi-ptt.rst doesn't exist.

> +	 * of the data format.
> +	 */
> +	void *addr;
> +	int index;
> +};
> +
> +struct hisi_ptt_trace_ctrl {
> +	enum hisi_ptt_trace_status status;
> +	struct perf_output_handle handle;
> +	struct list_head trace_buf;
> +	/*
> +	 * The index of the buffer which trace data
> +	 * currently is writing to.
> +	 */
> +	u32 buf_index;
> +
> +	int default_cpu;
> +	u32 buflet_size;
> +	bool is_port;
> +	u32 format:1;		/* Format of the traced TLP headers */
> +	u32 type:4;		/* Type of the TLP headers to trace */
> +	u32 direction:2;	/* Direction of the TLP headers to trace */
> +	u32 filter:16;		/* Root port or Requester to filter the TLP headers */
> +
> +	phys_addr_t rmr_addr;
> +	size_t rmr_length;
> +	bool has_rmr;
> +};
> +
> +struct hisi_ptt_filter_desc {
> +	struct list_head list;
> +	struct pci_dev *pdev;
> +	u16 val;
> +};
> +
> +struct hisi_ptt_pmu_buf {
> +	size_t length;
> +	int nr_pages;
> +	void *base;
> +	long pos;
> +};
> +
> +/* Structure containing the information for filter updating */
> +struct hisi_ptt_filter_update_info {
> +	struct pci_dev *pdev;
> +	u32 port_devid;
> +	bool is_port;
> +	bool is_add;
> +	u16 val;
> +};
> +
> +struct hisi_ptt {
> +	struct hisi_ptt_trace_ctrl trace_ctrl;
> +	struct notifier_block hisi_ptt_nb;
> +	struct pmu hisi_ptt_pmu;
> +	void __iomem *iobase;
> +	struct pci_dev *pdev;
> +	/*
> +	 * Use the mutex to protect the filter list and
> +	 * serialize the perf process.
> +	 */
> +	struct mutex mutex;
> +	const char *name;
> +	u16 core_id;
> +	u16 sicl_id;
> +	/* PCI device range managed by the PTT device */
> +	u32 upper;
> +	u32 lower;
> +	u8 busnr;
> +
> +	/*
> +	 * The trace TLP headers can either be filtered by certain
> +	 * root port, or by the requester ID. Organize the filters
> +	 * by @port_filters and @req_filters here. The mask of all
> +	 * the valid ports is also cached for doing sanity check
> +	 * of user input.
> +	 */
> +	struct list_head port_filters;
> +	struct list_head req_filters;
> +	u16 port_mask;
> +
> +	/*
> +	 * We use a delayed work here to avoid indefinitely waiting for
> +	 * the hisi_ptt->mutex which protecting the filter list. The
> +	 * work will be delayed only if the mutex can not be held,
> +	 * otherwise no delay will be applied.
> +	 */
> +	struct delayed_work work;
> +	spinlock_t filter_update_lock;
> +	DECLARE_KFIFO(filter_update_kfifo, struct hisi_ptt_filter_update_info,
> +		      HISI_PTT_FILTER_UPDATE_FIFO_SIZE);
> +};

It might be a good idea to spinoff a hisi_ptt.h for the above declarations.

> +
> +static inline struct hisi_ptt *to_hisi_ptt(struct pmu *pmu)
> +{
> +	return container_of(pmu, struct hisi_ptt, hisi_ptt_pmu);
> +}

I'm not sure there is any value to this inline function.  I suggest to simply
call container_of() whenever it is needed.

> +
> +static u16 hisi_ptt_get_filter_val(struct pci_dev *pdev)
> +{
> +	if (pci_pcie_type(pdev) == PCI_EXP_TYPE_ROOT_PORT)
> +		return BIT(HISI_PCIE_CORE_PORT_ID(PCI_SLOT(pdev->devfn)));
> +
> +	return PCI_DEVID(pdev->bus->number, pdev->devfn);
> +}
> +
> +static int hisi_ptt_wait_trace_hw_idle(struct hisi_ptt *hisi_ptt)
> +{
> +	u32 val;
> +
> +	return readl_poll_timeout(hisi_ptt->iobase + HISI_PTT_TRACE_STS, val,
> +				  val & HISI_PTT_TRACE_IDLE,
> +				  HISI_PTT_WAIT_POLL_INTERVAL_US,
> +				  HISI_PTT_WAIT_TIMEOUT_US);
> +}
> +
> +static void hisi_ptt_free_trace_buf(struct hisi_ptt *hisi_ptt)
> +{
> +	struct hisi_ptt_trace_ctrl *ctrl = &hisi_ptt->trace_ctrl;
> +	struct device *dev = &hisi_ptt->pdev->dev;
> +	struct hisi_ptt_dma_buflet *buflet, *tbuflet;
> +
> +	list_for_each_entry_safe(buflet, tbuflet, &ctrl->trace_buf, list) {
> +		list_del(&buflet->list);
> +
> +		if (ctrl->has_rmr)
> +			memunmap(buflet->addr);
> +		else
> +			dma_free_coherent(dev, buflet->size, buflet->addr,
> +					  buflet->dma);
> +
> +		kfree(buflet);
> +	}
> +}
> +
> +static int hisi_ptt_alloc_trace_buf(struct hisi_ptt *hisi_ptt)
> +{
> +	struct hisi_ptt_trace_ctrl *ctrl = &hisi_ptt->trace_ctrl;
> +	struct device *dev = &hisi_ptt->pdev->dev;
> +	struct hisi_ptt_dma_buflet *buflet;
> +	int i, ret;
> +
> +	hisi_ptt->trace_ctrl.buf_index = 0;
> +
> +	/* Make sure the trace buffer is empty before allocating */
> +	if (!list_empty(&ctrl->trace_buf)) {
> +		list_for_each_entry(buflet, &ctrl->trace_buf, list)
> +			memset(buflet->addr, 0, buflet->size);
> +		return 0;
> +	}
> +
> +	for (i = 0; i < HISI_PTT_TRACE_BUFLETS_CNT; ++i) {
> +		buflet = kzalloc(sizeof(*buflet), GFP_KERNEL);
> +		if (!buflet) {
> +			ret = -ENOMEM;
> +			goto err;
> +		}
> +
> +		if (ctrl->has_rmr) {
> +			phys_addr_t base = ctrl->rmr_addr + i * ctrl->buflet_size;
> +
> +			buflet->dma = base;
> +			buflet->addr = memremap(base, ctrl->buflet_size, MEMREMAP_WB);
> +		} else {
> +			buflet->addr = dma_alloc_coherent(dev, ctrl->buflet_size,
> +							  &buflet->dma, GFP_KERNEL);
> +		}
> +
> +		if (!buflet->addr) {
> +			kfree(buflet);
> +			ret = -ENOMEM;
> +			goto err;
> +		}
> +
> +		memset(buflet->addr, 0, buflet->size);
> +
> +		buflet->index = i;
> +		buflet->size = ctrl->buflet_size;
> +		list_add_tail(&buflet->list, &ctrl->trace_buf);
> +	}
> +
> +	return 0;
> +err:
> +	hisi_ptt_free_trace_buf(hisi_ptt);
> +	return ret;
> +}
> +
> +static void hisi_ptt_trace_end(struct hisi_ptt *hisi_ptt)
> +{
> +	writel(0, hisi_ptt->iobase + HISI_PTT_TRACE_CTRL);
> +	hisi_ptt->trace_ctrl.status = HISI_PTT_TRACE_STATUS_OFF;
> +}
> +
> +static int hisi_ptt_trace_start(struct hisi_ptt *hisi_ptt)
> +{
> +	struct hisi_ptt_trace_ctrl *ctrl = &hisi_ptt->trace_ctrl;
> +	struct hisi_ptt_dma_buflet *cur;
> +	u32 val;
> +
> +	/* Check device idle before start trace */
> +	if (hisi_ptt_wait_trace_hw_idle(hisi_ptt)) {
> +		pci_err(hisi_ptt->pdev, "Failed to start trace, the device is still busy.\n");
> +		return -EBUSY;
> +	}
> +
> +	/* Reset the DMA before start tracing */
> +	val = readl(hisi_ptt->iobase + HISI_PTT_TRACE_CTRL);
> +	val |= HISI_PTT_TRACE_CTRL_RST;
> +	writel(val, hisi_ptt->iobase + HISI_PTT_TRACE_CTRL);
> +
> +	/*
> +	 * We'll be in the perf context where preemption is disabled,
> +	 * so use busy loop here.
> +	 */
> +	mdelay(HISI_PTT_RESET_WAIT_MS);
> +
> +	val = readl(hisi_ptt->iobase + HISI_PTT_TRACE_CTRL);
> +	val &= ~HISI_PTT_TRACE_CTRL_RST;
> +	writel(val, hisi_ptt->iobase + HISI_PTT_TRACE_CTRL);
> +
> +	/* clear the interrupt status */
> +	writel(HISI_PTT_TRACE_INT_STAT_MASK, hisi_ptt->iobase + HISI_PTT_TRACE_INT_STAT);
> +	writel(0, hisi_ptt->iobase + HISI_PTT_TRACE_INT_MASK);
> +
> +	list_for_each_entry(cur, &ctrl->trace_buf, list) {
> +		writel(lower_32_bits(cur->dma),
> +		       hisi_ptt->iobase + HISI_PTT_TRACE_ADDR_BASE_LO_0 +
> +		       cur->index * HISI_PTT_TRACE_ADDR_STRIDE);
> +		writel(upper_32_bits(cur->dma),
> +		       hisi_ptt->iobase + HISI_PTT_TRACE_ADDR_BASE_HI_0 +
> +		       cur->index * HISI_PTT_TRACE_ADDR_STRIDE);
> +	}
> +	writel(ctrl->buflet_size, hisi_ptt->iobase + HISI_PTT_TRACE_ADDR_SIZE);
> +
> +	/* set the trace control register */
> +	val = FIELD_PREP(HISI_PTT_TRACE_CTRL_TYPE_SEL, ctrl->type);
> +	val |= FIELD_PREP(HISI_PTT_TRACE_CTRL_RXTX_SEL, ctrl->direction);
> +	val |= FIELD_PREP(HISI_PTT_TRACE_CTRL_DATA_FORMAT, ctrl->format);
> +	val |= FIELD_PREP(HISI_PTT_TRACE_CTRL_TARGET_SEL, hisi_ptt->trace_ctrl.filter);
> +	if (!hisi_ptt->trace_ctrl.is_port)
> +		val |= HISI_PTT_TRACE_CTRL_FILTER_MODE;
> +
> +	val |= HISI_PTT_TRACE_CTRL_EN;
> +	writel(val, hisi_ptt->iobase + HISI_PTT_TRACE_CTRL);
> +
> +	ctrl->status = HISI_PTT_TRACE_STATUS_ON;
> +
> +	return 0;
> +}
> +
> +static int hisi_ptt_update_aux(struct hisi_ptt *hisi_ptt, int index, bool stop)
> +{
> +	struct perf_output_handle *handle = &hisi_ptt->trace_ctrl.handle;
> +	struct perf_event *event = handle->event;
> +	struct hisi_ptt_dma_buflet *cur;
> +	struct hisi_ptt_pmu_buf *buf;
> +
> +	buf = perf_get_aux(handle);
> +	if (!buf || !handle->size)
> +		return -EINVAL;
> +
> +	list_for_each_entry(cur, &hisi_ptt->trace_ctrl.trace_buf, list)
> +		if (cur->index == index)
> +			break;
> +
> +	memcpy(buf->base + buf->pos, cur->addr, cur->size);
> +	memset(cur->addr, 0, cur->size);
> +	buf->pos += cur->size;
> +
> +	if (stop) {
> +		perf_aux_output_end(handle, buf->pos);
> +	} else if (buf->length - buf->pos < cur->size) {
> +		perf_aux_output_skip(handle, buf->length - buf->pos);
> +		perf_aux_output_end(handle, buf->pos);
> +
> +		buf = perf_aux_output_begin(handle, event);
> +		if (!buf)
> +			return -EINVAL;
> +
> +		buf->pos = handle->head % buf->length;
> +		if (buf->length - buf->pos < cur->size) {
> +			perf_aux_output_end(handle, 0);
> +			return -EINVAL;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +static irqreturn_t hisi_ptt_isr(int irq, void *context)
> +{
> +	struct hisi_ptt *hisi_ptt = context;
> +	u32 status, buf_idx;
> +
> +	status = readl(hisi_ptt->iobase + HISI_PTT_TRACE_INT_STAT);
> +	buf_idx = ffs(status) - 1;
> +
> +	/* Clear the interrupt status of buflet @buf_idx */
> +	writel(status, hisi_ptt->iobase + HISI_PTT_TRACE_INT_STAT);
> +
> +	/*
> +	 * Update the AUX buffer and cache the current buflet index,
> +	 * as we need to know this and save the data when the trace
> +	 * is ended out of the interrupt handler. End the trace
> +	 * if the updating fails.
> +	 */
> +	if (hisi_ptt_update_aux(hisi_ptt, buf_idx, false))
> +		hisi_ptt_trace_end(hisi_ptt);
> +	else
> +		hisi_ptt->trace_ctrl.buf_index = (buf_idx + 1) % HISI_PTT_TRACE_BUFLETS_CNT;
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static irqreturn_t hisi_ptt_irq(int irq, void *context)
> +{
> +	struct hisi_ptt *hisi_ptt = context;
> +	u32 status;
> +
> +	status = readl(hisi_ptt->iobase + HISI_PTT_TRACE_INT_STAT);
> +	if (!(status & HISI_PTT_TRACE_INT_STAT_MASK))
> +		return IRQ_NONE;
> +
> +	return IRQ_WAKE_THREAD;
> +}
> +
> +static void hisi_ptt_irq_free_vectors(void *pdev)
> +{
> +	pci_free_irq_vectors(pdev);
> +}
> +
> +static int hisi_ptt_register_irq(struct hisi_ptt *hisi_ptt)
> +{
> +	struct pci_dev *pdev = hisi_ptt->pdev;
> +	int ret;
> +
> +	ret = pci_alloc_irq_vectors(pdev, 1, 1, PCI_IRQ_MSI);
> +	if (ret < 0) {
> +		pci_err(pdev, "failed to allocate irq vector, ret = %d.\n", ret);
> +		return ret;
> +	}
> +
> +	ret = devm_add_action_or_reset(&pdev->dev, hisi_ptt_irq_free_vectors, pdev);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = devm_request_threaded_irq(&pdev->dev,
> +					pci_irq_vector(pdev, HISI_PTT_TRACE_DMA_IRQ),
> +					hisi_ptt_irq, hisi_ptt_isr, 0,
> +					"hisi-ptt", hisi_ptt);
> +	if (ret) {
> +		pci_err(pdev, "failed to request irq %d, ret = %d.\n",
> +			pci_irq_vector(pdev, HISI_PTT_TRACE_DMA_IRQ), ret);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static void hisi_ptt_update_filters(struct work_struct *work)
> +{
> +	struct delayed_work *delayed_work = to_delayed_work(work);
> +	struct hisi_ptt_filter_update_info info;
> +	struct hisi_ptt_filter_desc *filter;
> +	struct list_head *target_list;
> +	struct hisi_ptt *hisi_ptt;
> +
> +	hisi_ptt = container_of(delayed_work, struct hisi_ptt, work);
> +
> +	if (!mutex_trylock(&hisi_ptt->mutex)) {
> +		schedule_delayed_work(&hisi_ptt->work, HISI_PTT_WORK_DELAY_MS);
> +		return;
> +	}
> +
> +	while (kfifo_get(&hisi_ptt->filter_update_kfifo, &info)) {
> +		target_list = info.is_port ? &hisi_ptt->port_filters :
> +			      &hisi_ptt->req_filters;
> +
> +		if (info.is_add) {
> +			filter = kzalloc(sizeof(*filter), GFP_KERNEL);
> +			if (!filter)
> +				continue;
> +
> +			filter->pdev = info.pdev;
> +			filter->val = info.val;
> +
> +			list_add_tail(&filter->list, target_list);
> +		} else {
> +			list_for_each_entry(filter, target_list, list)
> +				if (filter->val == info.val) {
> +					list_del(&filter->list);
> +					kfree(filter);
> +					break;
> +				}
> +		}
> +
> +		/* Update the available port mask */
> +		if (!info.is_port)
> +			continue;
> +
> +		if (info.is_add)
> +			hisi_ptt->port_mask |= info.val;
> +		else
> +			hisi_ptt->port_mask &= ~info.val;
> +	}
> +
> +	mutex_unlock(&hisi_ptt->mutex);
> +}
> +
> +static void hisi_ptt_update_fifo_in(struct hisi_ptt *hisi_ptt,
> +				    struct hisi_ptt_filter_update_info *info)
> +{
> +	struct pci_dev *root_port = pcie_find_root_port(info->pdev);
> +
> +	if (!root_port)
> +		return;
> +
> +	info->port_devid = PCI_DEVID(root_port->bus->number, root_port->devfn);
> +	if (info->port_devid < hisi_ptt->lower ||
> +	    info->port_devid > hisi_ptt->upper)
> +		return;
> +
> +	info->is_port = pci_pcie_type(info->pdev) == PCI_EXP_TYPE_ROOT_PORT;
> +	info->val = hisi_ptt_get_filter_val(info->pdev);
> +
> +	if (kfifo_in_spinlocked(&hisi_ptt->filter_update_kfifo, info, 1,
> +				&hisi_ptt->filter_update_lock))
> +		schedule_delayed_work(&hisi_ptt->work, 0);
> +	else
> +		pci_warn(hisi_ptt->pdev,
> +			 "filter update fifo overflow for target %s\n",
> +			 pci_name(info->pdev));
> +}
> +
> +/*
> + * A PCI bus notifier is used here for dynamically updating the filter
> + * list.
> + */
> +static int hisi_ptt_notifier_call(struct notifier_block *nb, unsigned long action,
> +				  void *data)
> +{
> +	struct hisi_ptt *hisi_ptt = container_of(nb, struct hisi_ptt, hisi_ptt_nb);
> +	struct hisi_ptt_filter_update_info info;
> +	struct device *dev = data;
> +	struct pci_dev *pdev = to_pci_dev(dev);
> +
> +	info.pdev = pdev;
> +
> +	switch (action) {
> +	case BUS_NOTIFY_ADD_DEVICE:
> +		info.is_add = true;
> +		break;
> +	case BUS_NOTIFY_DEL_DEVICE:
> +		info.is_add = false;
> +		break;
> +	default:
> +		return 0;
> +	}
> +
> +	hisi_ptt_update_fifo_in(hisi_ptt, &info);
> +
> +	return 0;
> +}
> +
> +static int hisi_ptt_init_filters(struct pci_dev *pdev, void *data)
> +{
> +	struct hisi_ptt_filter_update_info info = {
> +		.pdev = pdev,
> +		.is_add = true,
> +	};
> +	struct hisi_ptt *hisi_ptt = data;
> +
> +	hisi_ptt_update_fifo_in(hisi_ptt, &info);
> +
> +	return 0;
> +}
> +
> +static void hisi_ptt_release_filters(struct hisi_ptt *hisi_ptt)
> +{
> +	struct hisi_ptt_filter_desc *filter, *tfilter;
> +
> +	list_for_each_entry_safe(filter, tfilter, &hisi_ptt->req_filters, list) {
> +		list_del(&filter->list);
> +		kfree(filter);
> +	}
> +
> +	list_for_each_entry_safe(filter, tfilter, &hisi_ptt->port_filters, list) {
> +		list_del(&filter->list);
> +		kfree(filter);
> +	}
> +}
> +
> +static void hisi_ptt_init_ctrls(struct hisi_ptt *hisi_ptt)
> +{
> +	struct pci_dev *pdev = hisi_ptt->pdev;
> +	struct pci_bus *bus;
> +	u32 reg;
> +
> +	INIT_DELAYED_WORK(&hisi_ptt->work, hisi_ptt_update_filters);
> +	spin_lock_init(&hisi_ptt->filter_update_lock);
> +	INIT_KFIFO(hisi_ptt->filter_update_kfifo);
> +	INIT_LIST_HEAD(&hisi_ptt->port_filters);
> +	INIT_LIST_HEAD(&hisi_ptt->req_filters);
> +
> +	/*
> +	 * The device range register provides the information about the
> +	 * root ports which the RCiEP can control and trace. The RCiEP
> +	 * and the root ports it support are on the same PCIe core, with
> +	 * same domain number but maybe different bus number. The device
> +	 * range register will tell us which root ports we can support,
> +	 * Bit[31:16] indicates the upper BDF numbers of the root port,
> +	 * while Bit[15:0] indicates the lower.
> +	 */
> +	reg = readl(hisi_ptt->iobase + HISI_PTT_DEVICE_RANGE);
> +	hisi_ptt->upper = reg >> 16;
> +	hisi_ptt->lower = reg & 0xffff;
> +	hisi_ptt->busnr = PCI_BUS_NUM(hisi_ptt->upper);
> +
> +	reg = readl(hisi_ptt->iobase + HISI_PTT_LOCATION);
> +	hisi_ptt->core_id = FIELD_GET(HISI_PTT_CORE_ID, reg);
> +	hisi_ptt->sicl_id = FIELD_GET(HISI_PTT_SICL_ID, reg);
> +
> +	bus = pci_find_bus(pci_domain_nr(pdev->bus), hisi_ptt->busnr);
> +	if (bus)
> +		pci_walk_bus(bus, hisi_ptt_init_filters, hisi_ptt);

What happens if bus is NULL?  Should this be reported to the caller and cause
hisi_ptt_probe() to fail?  Please add a comment that describes the scenario.

> +
> +	/* Initialize trace controls */
> +	INIT_LIST_HEAD(&hisi_ptt->trace_ctrl.trace_buf);
> +	hisi_ptt->trace_ctrl.buflet_size = HISI_PTT_TRACE_BUFLET_SIZE;
> +	hisi_ptt->trace_ctrl.default_cpu = cpumask_first(cpumask_of_node(dev_to_node(&pdev->dev)));
> +}
> +
> +#define HISI_PTT_PMU_FILTER_IS_PORT	BIT(19)
> +#define HISI_PTT_PMU_FILTER_VAL_MASK	GENMASK(15, 0)
> +#define HISI_PTT_PMU_DIRECTION_MASK	GENMASK(23, 20)
> +#define HISI_PTT_PMU_TYPE_MASK		GENMASK(31, 24)
> +#define HISI_PTT_PMU_FORMAT_MASK	GENMASK(35, 32)
> +
> +static ssize_t available_filters_show(struct device *dev,
> +				      struct device_attribute *attr,
> +				      char *buf)
> +{
> +	struct hisi_ptt *hisi_ptt = to_hisi_ptt(dev_get_drvdata(dev));
> +	struct hisi_ptt_filter_desc *filter;
> +	int pos = 0;
> +
> +	if (list_empty(&hisi_ptt->port_filters))
> +		return sysfs_emit(buf, "#### No available filter ####\n");
> +
> +	mutex_lock(&hisi_ptt->mutex);
> +	pos += sysfs_emit_at(buf, pos, "#### Root Ports ####\n");
> +	list_for_each_entry(filter, &hisi_ptt->port_filters, list)
> +		pos += sysfs_emit_at(buf, pos, "%s	0x%05lx\n",
> +				     pci_name(filter->pdev),
> +				     hisi_ptt_get_filter_val(filter->pdev) |
> +				     HISI_PTT_PMU_FILTER_IS_PORT);
> +
> +	pos += sysfs_emit_at(buf, pos, "#### Requesters ####\n");
> +	list_for_each_entry(filter, &hisi_ptt->req_filters, list)
> +		pos += sysfs_emit_at(buf, pos, "%s	0x%05x\n",
> +				     pci_name(filter->pdev),
> +				     hisi_ptt_get_filter_val(filter->pdev));
> +
> +	mutex_unlock(&hisi_ptt->mutex);
> +	return pos;
> +}
> +static DEVICE_ATTR_ADMIN_RO(available_filters);
> +
> +PMU_FORMAT_ATTR(filter,		"config:0-19");
> +PMU_FORMAT_ATTR(direction,	"config:20-23");
> +PMU_FORMAT_ATTR(type,		"config:24-31");
> +PMU_FORMAT_ATTR(format,		"config:32-35");
> +
> +static struct attribute *hisi_ptt_pmu_format_attrs[] = {
> +	&format_attr_filter.attr,
> +	&format_attr_direction.attr,
> +	&format_attr_type.attr,
> +	&format_attr_format.attr,
> +	NULL
> +};
> +
> +static struct attribute_group hisi_ptt_pmu_format_group = {
> +	.name = "format",
> +	.attrs = hisi_ptt_pmu_format_attrs,
> +};
> +
> +static struct attribute *hisi_ptt_pmu_filter_attrs[] = {
> +	&dev_attr_available_filters.attr,
> +	NULL
> +};
> +
> +static struct attribute_group hisi_ptt_pmu_filter_group = {
> +	.attrs = hisi_ptt_pmu_filter_attrs,
> +};
> +
> +static const struct attribute_group *hisi_ptt_pmu_groups[] = {
> +	&hisi_ptt_pmu_format_group,
> +	&hisi_ptt_pmu_filter_group,
> +	NULL
> +};
> +
> +/*
> + * The supported value of the direction parameter. See hisi_ptt.rst
> + * documentation for more details.
> + */
> +static u32 hisi_ptt_trace_available_direction[] = {
> +	0,
> +	1,
> +	2,
> +	3,
> +};
> +
> +/* Different types can be set simultaneously */
> +static u32 hisi_ptt_trace_available_type[] = {
> +	1,	/* posted_request */
> +	2,	/* non-posted_request */
> +	4,	/* completion */
> +};
> +
> +static u32 hisi_ptt_trace_availble_format[] = {
> +	0,	/* 4DW */
> +	1,	/* 8DW */
> +};
> +
> +/*
> + * Check whether the config is valid or not. Some configs are multi-selectable
> + * and can be set simultaneously, while some are single selectable (onehot).
> + * Use this function to check the non-onehot configs while
> + * hisi_ptt_trace_valid_config_onehot() for the onehot ones.
> + */
> +static int hisi_ptt_trace_valid_config(u32 val, u32 *available_list, u32 list_size)
> +{
> +	int i;
> +
> +	/*
> +	 * The non-onehot configs cannot be 0. Walk the available
> +	 * list and clear the valid bits of the config. If there
> +	 * is any resident bit after the walk then the config is
> +	 * invalid.
> +	 */
> +	for (i = 0; i < list_size; i++)
> +		val &= ~available_list[i];
> +
> +	return val ? -EINVAL : 0;
> +}
> +
> +static int hisi_ptt_trace_valid_config_onehot(u32 val, u32 *available_list, u32 list_size)
> +{
> +	int i, ret = -EINVAL;
> +
> +	for (i = 0; i < list_size; i++)
> +		if (val == available_list[i]) {
> +			ret = 0;
> +			break;
> +		}
> +
> +	return ret;
> +}
> +
> +static int hisi_ptt_trace_init_filter(struct hisi_ptt *hisi_ptt, u64 config)
> +{
> +	unsigned long val, port_mask = hisi_ptt->port_mask;
> +	struct hisi_ptt_filter_desc *filter;
> +	int ret = -EINVAL;
> +
> +	hisi_ptt->trace_ctrl.is_port = FIELD_GET(HISI_PTT_PMU_FILTER_IS_PORT, config);
> +	val = FIELD_GET(HISI_PTT_PMU_FILTER_VAL_MASK, config);
> +
> +	/*
> +	 * Port filters are defined as bit mask. For port filters, check
> +	 * the bits in the @val are within the range of hisi_ptt->port_mask
> +	 * and whether it's empty or not, otherwise user has specified
> +	 * some unsupported root ports.
> +	 *
> +	 * For Requester ID filters, walk the available filter list to see
> +	 * whether we have one matched.
> +	 */
> +	if (hisi_ptt->trace_ctrl.is_port &&
> +	    bitmap_subset(&val, &port_mask, BITS_PER_LONG)) {
> +		ret = 0;
> +	} else {
> +		list_for_each_entry(filter, &hisi_ptt->req_filters, list)
> +			if (filter->val == val) {
> +				ret = 0;
> +				break;
> +			}
> +	}
> +
> +	if (ret)
> +		return ret;
> +
> +	hisi_ptt->trace_ctrl.filter = val;
> +	return 0;
> +}
> +
> +static int hisi_ptt_pmu_event_init(struct perf_event *event)
> +{
> +	struct hisi_ptt *hisi_ptt = to_hisi_ptt(event->pmu);
> +	struct hisi_ptt_trace_ctrl *ctrl = &hisi_ptt->trace_ctrl;
> +	int ret;
> +	u32 val;
> +
> +	if (event->attr.type != hisi_ptt->hisi_ptt_pmu.type)
> +		return -ENOENT;
> +
> +	mutex_lock(&hisi_ptt->mutex);
> +
> +	ret = hisi_ptt_trace_init_filter(hisi_ptt, event->attr.config);
> +	if (ret < 0)
> +		goto out;
> +
> +	val = FIELD_GET(HISI_PTT_PMU_DIRECTION_MASK, event->attr.config);
> +	ret = hisi_ptt_trace_valid_config_onehot(val, hisi_ptt_trace_available_direction,
> +						 ARRAY_SIZE(hisi_ptt_trace_available_direction));
> +	if (ret < 0)
> +		goto out;
> +	ctrl->direction = val;
> +
> +	val = FIELD_GET(HISI_PTT_PMU_TYPE_MASK, event->attr.config);
> +
> +	ret = hisi_ptt_trace_valid_config(val, hisi_ptt_trace_available_type,
> +					  ARRAY_SIZE(hisi_ptt_trace_available_type));
> +	if (ret < 0)
> +		goto out;
> +	ctrl->type = val;
> +
> +	val = FIELD_GET(HISI_PTT_PMU_FORMAT_MASK, event->attr.config);
> +	ret = hisi_ptt_trace_valid_config_onehot(val, hisi_ptt_trace_availble_format,
> +						 ARRAY_SIZE(hisi_ptt_trace_availble_format));
> +	if (ret < 0)
> +		goto out;
> +	ctrl->format = val;
> +
> +out:
> +	mutex_unlock(&hisi_ptt->mutex);
> +	return ret;
> +}
> +
> +static void *hisi_ptt_pmu_setup_aux(struct perf_event *event, void **pages,
> +				    int nr_pages, bool overwrite)
> +{
> +	struct hisi_ptt_pmu_buf *buf;
> +	struct page **pagelist;
> +	int i;
> +
> +	if (overwrite) {
> +		dev_warn(event->pmu->dev, "Overwrite mode is not supported\n");
> +		return NULL;
> +	}
> +
> +	/* If the pages size less than buflets, we cannot start trace */
> +	if (nr_pages < HISI_PTT_TRACE_BUFFER_SIZE / PAGE_SIZE)
> +		return NULL;
> +
> +	buf = kzalloc(sizeof(*buf), GFP_KERNEL);
> +	if (!buf)
> +		return NULL;
> +
> +	pagelist = kcalloc(nr_pages, sizeof(*pagelist), GFP_KERNEL);
> +	if (!pagelist) {
> +		kfree(buf);
> +		return NULL;
> +	}
> +
> +	for (i = 0; i < nr_pages; i++)
> +		pagelist[i] = virt_to_page(pages[i]);
> +
> +	buf->base = vmap(pagelist, nr_pages, VM_MAP, PAGE_KERNEL);
> +	if (!buf->base) {
> +		kfree(pagelist);
> +		kfree(buf);
> +		return NULL;
> +	}
> +
> +	buf->nr_pages = nr_pages;
> +	buf->length = nr_pages * PAGE_SIZE;
> +	buf->pos = 0;
> +
> +	kfree(pagelist);
> +	return buf;
> +}
> +
> +static void hisi_ptt_pmu_free_aux(void *aux)
> +{
> +	struct hisi_ptt_pmu_buf *buf = aux;
> +
> +	vunmap(buf->base);
> +	kfree(buf);
> +}
> +
> +static void hisi_ptt_pmu_start(struct perf_event *event, int flags)
> +{
> +	struct hisi_ptt *hisi_ptt = to_hisi_ptt(event->pmu);
> +	struct perf_output_handle *handle = &hisi_ptt->trace_ctrl.handle;
> +	struct hw_perf_event *hwc = &event->hw;
> +	struct hisi_ptt_pmu_buf *buf;
> +	int cpu = event->cpu;
> +	int ret;
> +
> +	hwc->state = 0;
> +	mutex_lock(&hisi_ptt->mutex);
> +	if (hisi_ptt->trace_ctrl.status == HISI_PTT_TRACE_STATUS_ON) {
> +		pci_dbg(hisi_ptt->pdev, "trace has already started\n");
> +		goto stop;
> +	}
> +
> +	if (cpu == -1)
> +		cpu = hisi_ptt->trace_ctrl.default_cpu;
> +
> +	/*
> +	 * Handle the interrupt on the same cpu which starts the trace to avoid
> +	 * context mismatch. Otherwise we'll trigger the WARN from the perf
> +	 * core in event_function_local().
> +	 */
> +	WARN_ON(irq_set_affinity(pci_irq_vector(hisi_ptt->pdev, HISI_PTT_TRACE_DMA_IRQ),
> +				 cpumask_of(cpu)));
> +
> +	ret = hisi_ptt_alloc_trace_buf(hisi_ptt);
> +	if (ret) {
> +		pci_dbg(hisi_ptt->pdev, "alloc trace buf failed, ret = %d\n", ret);
> +		goto stop;
> +	}
> +
> +	buf = perf_aux_output_begin(handle, event);
> +	if (!buf) {
> +		pci_dbg(hisi_ptt->pdev, "aux output begin failed\n");
> +		goto stop;
> +	}
> +
> +	buf->pos = handle->head % buf->length;
> +
> +	ret = hisi_ptt_trace_start(hisi_ptt);
> +	if (ret) {
> +		pci_dbg(hisi_ptt->pdev, "trace start failed, ret = %d\n", ret);
> +		perf_aux_output_end(handle, 0);
> +		goto stop;
> +	}
> +
> +	mutex_unlock(&hisi_ptt->mutex);
> +	return;
> +stop:
> +	event->hw.state |= PERF_HES_STOPPED;
> +	mutex_unlock(&hisi_ptt->mutex);
> +}
> +
> +static void hisi_ptt_pmu_stop(struct perf_event *event, int flags)
> +{
> +	struct hisi_ptt *hisi_ptt = to_hisi_ptt(event->pmu);
> +	struct hw_perf_event *hwc = &event->hw;
> +
> +	if (hwc->state & PERF_HES_STOPPED)
> +		return;
> +
> +	mutex_lock(&hisi_ptt->mutex);
> +	if (hisi_ptt->trace_ctrl.status == HISI_PTT_TRACE_STATUS_ON) {
> +		hisi_ptt_trace_end(hisi_ptt);
> +		WARN(hisi_ptt_wait_trace_hw_idle(hisi_ptt), "Device is still busy");
> +		hisi_ptt_update_aux(hisi_ptt, hisi_ptt->trace_ctrl.buf_index, true);
> +	}
> +	mutex_unlock(&hisi_ptt->mutex);
> +
> +	hwc->state |= PERF_HES_STOPPED;
> +	perf_event_update_userpage(event);
> +	hwc->state |= PERF_HES_UPTODATE;
> +}
> +
> +static int hisi_ptt_pmu_add(struct perf_event *event, int flags)
> +{
> +	struct hisi_ptt *hisi_ptt = to_hisi_ptt(event->pmu);
> +	struct hw_perf_event *hwc = &event->hw;
> +	int cpu = event->cpu;
> +
> +	if (cpu == -1 && smp_processor_id() != hisi_ptt->trace_ctrl.default_cpu)
> +		return 0;
> +
> +	hwc->state = PERF_HES_STOPPED | PERF_HES_UPTODATE;
> +
> +	if (flags & PERF_EF_START) {
> +		hisi_ptt_pmu_start(event, PERF_EF_RELOAD);
> +		if (hwc->state & PERF_HES_STOPPED)
> +			return -EINVAL;
> +	}
> +
> +	return 0;
> +}
> +
> +static void hisi_ptt_pmu_del(struct perf_event *event, int flags)
> +{
> +	hisi_ptt_pmu_stop(event, PERF_EF_UPDATE);
> +}
> +
> +static void hisi_ptt_unregister_pmu(void *priv)
> +{
> +	perf_pmu_unregister(priv);
> +}
> +
> +static int hisi_ptt_register_pmu(struct hisi_ptt *hisi_ptt)
> +{
> +	char *pmu_name;
> +	int ret;
> +
> +	hisi_ptt->hisi_ptt_pmu = (struct pmu) {
> +		.module		= THIS_MODULE,
> +		.capabilities	= PERF_PMU_CAP_EXCLUSIVE | PERF_PMU_CAP_ITRACE,
> +		.task_ctx_nr	= perf_sw_context,
> +		.attr_groups	= hisi_ptt_pmu_groups,
> +		.event_init	= hisi_ptt_pmu_event_init,
> +		.setup_aux	= hisi_ptt_pmu_setup_aux,
> +		.free_aux	= hisi_ptt_pmu_free_aux,
> +		.start		= hisi_ptt_pmu_start,
> +		.stop		= hisi_ptt_pmu_stop,
> +		.add		= hisi_ptt_pmu_add,
> +		.del		= hisi_ptt_pmu_del,
> +	};
> +
> +	pmu_name = devm_kasprintf(&hisi_ptt->pdev->dev, GFP_KERNEL, "hisi_ptt%u_%u",
> +				  hisi_ptt->sicl_id, hisi_ptt->core_id);
> +	if (!pmu_name)
> +		return -ENOMEM;
> +
> +	ret = perf_pmu_register(&hisi_ptt->hisi_ptt_pmu, pmu_name, -1);
> +	if (ret)
> +		return ret;
> +
> +	return devm_add_action_or_reset(&hisi_ptt->pdev->dev,
> +					hisi_ptt_unregister_pmu,
> +					&hisi_ptt->hisi_ptt_pmu);
> +}
> +
> +/*
> + * Get RMR address if provided by the firmware.
> + * Return 0 if the IOMMU doesn't present or the policy of the
> + * IOMMU domain is passthrough or we get a usable RMR region.
> + * Otherwise a negative value is returned.
> + */
> +static int hisi_ptt_get_rmr(struct hisi_ptt *hisi_ptt)
> +{
> +	struct pci_dev *pdev = hisi_ptt->pdev;
> +	struct iommu_domain *iommu_domain;
> +	struct iommu_resv_region *region;
> +	LIST_HEAD(list);
> +
> +	/*
> +	 * Use direct DMA if IOMMU does not present or the policy of the
> +	 * IOMMU domain is passthrough.
> +	 */
> +	iommu_domain = iommu_get_domain_for_dev(&pdev->dev);
> +	if (!iommu_domain || iommu_domain->type == IOMMU_DOMAIN_IDENTITY)
> +		return 0;
> +
> +	iommu_get_resv_regions(&pdev->dev, &list);
> +	list_for_each_entry(region, &list, list)
> +		if (region->type == IOMMU_RESV_DIRECT &&
> +		    region->length >= HISI_PTT_TRACE_BUFFER_SIZE) {
> +			hisi_ptt->trace_ctrl.has_rmr = true;
> +			hisi_ptt->trace_ctrl.rmr_addr = region->start;
> +			hisi_ptt->trace_ctrl.rmr_length = region->length;
> +			break;
> +		}
> +
> +	iommu_put_resv_regions(&pdev->dev, &list);
> +	return hisi_ptt->trace_ctrl.has_rmr ? 0 : -ENOMEM;
> +}
> +
> +static int hisi_ptt_probe(struct pci_dev *pdev,
> +			  const struct pci_device_id *id)
> +{
> +	struct hisi_ptt *hisi_ptt;
> +	int ret;
> +
> +	hisi_ptt = devm_kzalloc(&pdev->dev, sizeof(*hisi_ptt), GFP_KERNEL);
> +	if (!hisi_ptt)
> +		return -ENOMEM;
> +
> +	mutex_init(&hisi_ptt->mutex);
> +	hisi_ptt->pdev = pdev;
> +
> +	/*
> +	 * Lifetime of pci_dev is longer than hisi_ptt,
> +	 * so directly reference to the pci name string.
> +	 */
> +	hisi_ptt->name = pci_name(hisi_ptt->pdev);
> +	pci_set_drvdata(pdev, hisi_ptt);
> +
> +	ret = pcim_enable_device(pdev);
> +	if (ret) {
> +		pci_err(pdev, "failed to enable device, ret = %d.\n", ret);
> +		return ret;
> +	}
> +
> +	ret = pcim_iomap_regions(pdev, BIT(2), hisi_ptt->name);
> +	if (ret) {
> +		pci_err(pdev, "failed to remap io memory, ret = %d.\n", ret);
> +		return ret;
> +	}
> +
> +	hisi_ptt->iobase = pcim_iomap_table(pdev)[2];
> +
> +	ret = dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(64));
> +	if (ret) {
> +		pci_err(pdev, "failed to set 64 bit dma mask, ret = %d.\n", ret);
> +		return ret;
> +	}
> +	pci_set_master(pdev);
> +
> +	ret = hisi_ptt_register_irq(hisi_ptt);
> +	if (ret)
> +		return ret;
> +
> +	hisi_ptt_init_ctrls(hisi_ptt);
> +
> +	ret = hisi_ptt_register_pmu(hisi_ptt);
> +	if (ret) {
> +		pci_err(pdev, "failed to register pmu device, ret = %d", ret);
> +		return ret;
> +	}

If this fails the pci_free_irq_vectors() is not called.

I am out of time for today - I will continue tomorrow.

Thanks,
Mathieu

> +
> +	ret = hisi_ptt_get_rmr(hisi_ptt);
> +	if (ret) {
> +		pci_err(pdev, "failed to get RMR region, ret = %d", ret);
> +		return ret;
> +	}
> +
> +	/* Register the bus notifier for dynamically updating the filter list */
> +	hisi_ptt->hisi_ptt_nb.notifier_call = hisi_ptt_notifier_call;
> +	ret = bus_register_notifier(&pci_bus_type, &hisi_ptt->hisi_ptt_nb);
> +	if (ret)
> +		pci_warn(pdev, "failed to register filter update notifier, ret = %d", ret);
> +
> +	return 0;
> +}
> +
> +void hisi_ptt_remove(struct pci_dev *pdev)
> +{
> +	struct hisi_ptt *hisi_ptt = pci_get_drvdata(pdev);
> +
> +	bus_unregister_notifier(&pci_bus_type, &hisi_ptt->hisi_ptt_nb);
> +
> +	/* Cancel any work that has been queued */
> +	cancel_delayed_work_sync(&hisi_ptt->work);
> +
> +	if (hisi_ptt->trace_ctrl.status == HISI_PTT_TRACE_STATUS_ON)
> +		hisi_ptt_trace_end(hisi_ptt);
> +
> +	hisi_ptt_free_trace_buf(hisi_ptt);
> +	hisi_ptt_release_filters(hisi_ptt);
> +}
> +
> +static const struct pci_device_id hisi_ptt_id_tbl[] = {
> +	{ PCI_DEVICE(PCI_VENDOR_ID_HUAWEI, 0xa12e) },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(pci, hisi_ptt_id_tbl);
> +
> +static struct pci_driver hisi_ptt_driver = {
> +	.name = "hisi_ptt",
> +	.id_table = hisi_ptt_id_tbl,
> +	.probe = hisi_ptt_probe,
> +	.remove = hisi_ptt_remove,
> +};
> +module_pci_driver(hisi_ptt_driver);
> +
> +MODULE_LICENSE("GPL v2");
> +MODULE_AUTHOR("Yicong Yang <yangyicong@hisilicon.com>");
> +MODULE_DESCRIPTION("Driver for HiSilicon PCIe tune and trace device");
> -- 
> 2.33.0
>

Hi Mathieu,

Thanks for the comments! Replies inline.

On 2021/11/25 2:51, Mathieu Poirier wrote:
> Hi Yicong,
> 
> On Tue, Nov 16, 2021 at 05:06:21PM +0800, Yicong Yang wrote:
>> HiSilicon PCIe tune and trace device(PTT) is a PCIe Root Complex
>> integrated Endpoint(RCiEP) device, providing the capability
>> to dynamically monitor and tune the PCIe traffic(tune),
>> and trace the TLP headers(trace).
>>
> 
> Is there a reason to put "tune" and "trace" are whithin parentheses?  
> 

yeah. I want to use these single word to denote the related function, and
place them in the parantheses near the function's description to make sure
readers can match them.

>> Add the driver for the device to enable the trace function. The driver
>> will create PMU device for each PTT device, and users can start trace
>> through perf command.
>>
>> Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
>> ---
>>  drivers/Makefile                       |    1 +
>>  drivers/hwtracing/Kconfig              |    2 +
>>  drivers/hwtracing/hisilicon/Kconfig    |    8 +
>>  drivers/hwtracing/hisilicon/Makefile   |    2 +
>>  drivers/hwtracing/hisilicon/hisi_ptt.c | 1146 ++++++++++++++++++++++++
> 
> Not sure about the "hisilicon" directory.  Right now we have "coresight",
> "intel_th" and "stm" - they concentrate on the technology rather than the
> vendor.  I think "ptt" would be just fine: 
> 
> drivers/hwtracing/ptt/Kconfig 
> drivers/hwtracing/ptt/Makefile
> drivers/hwtracing/ptt/hisi_ptt.c
> 
> That way if other vendors want to introduce support for the same kind of
> technology we can simply put them under "drivers/hwtracing/ptt/" and things are
> still accurate.
> 

sure. sounds sensible. will rename the directory to "ptt" if no objection.

> 
>>  5 files changed, 1159 insertions(+)
>>  create mode 100644 drivers/hwtracing/hisilicon/Kconfig
>>  create mode 100644 drivers/hwtracing/hisilicon/Makefile
>>  create mode 100644 drivers/hwtracing/hisilicon/hisi_ptt.c
>>
>> diff --git a/drivers/Makefile b/drivers/Makefile
>> index be5d40ae1488..bb0dc9b55ea2 100644
>> --- a/drivers/Makefile
>> +++ b/drivers/Makefile
>> @@ -176,6 +176,7 @@ obj-$(CONFIG_USB4)		+= thunderbolt/
>>  obj-$(CONFIG_CORESIGHT)		+= hwtracing/coresight/
>>  obj-y				+= hwtracing/intel_th/
>>  obj-$(CONFIG_STM)		+= hwtracing/stm/
>> +obj-$(CONFIG_HISI_PTT)         += hwtracing/hisilicon/
>>  obj-$(CONFIG_ANDROID)		+= android/
>>  obj-$(CONFIG_NVMEM)		+= nvmem/
>>  obj-$(CONFIG_FPGA)		+= fpga/
>> diff --git a/drivers/hwtracing/Kconfig b/drivers/hwtracing/Kconfig
>> index 13085835a636..e3796b17541a 100644
>> --- a/drivers/hwtracing/Kconfig
>> +++ b/drivers/hwtracing/Kconfig
>> @@ -5,4 +5,6 @@ source "drivers/hwtracing/stm/Kconfig"
>>  
>>  source "drivers/hwtracing/intel_th/Kconfig"
>>  
>> +source "drivers/hwtracing/hisilicon/Kconfig"
>> +
>>  endmenu
>> diff --git a/drivers/hwtracing/hisilicon/Kconfig b/drivers/hwtracing/hisilicon/Kconfig
>> new file mode 100644
>> index 000000000000..9c3ab80d99fe
>> --- /dev/null
>> +++ b/drivers/hwtracing/hisilicon/Kconfig
>> @@ -0,0 +1,8 @@
>> +# SPDX-License-Identifier: GPL-2.0-only
>> +config HISI_PTT
>> +	tristate "HiSilicon PCIe Tune and Trace Device"
>> +	depends on PCI && HAS_DMA && HAS_IOMEM
> 
> What Arm architecture are you aiming this for?  Can it be found on both armv7
> and armv8?
> 

currently the device will appear on Kunpeng 930, which is armv8.

>> +	help
>> +	  HiSilicon PCIe Tune and Trace Device exist as a PCIe RCiEP
>> +	  device, provides support for PCIe traffic tuning and
>> +	  tracing TLP headers to the memory.
> 
> Please indicate what the name of the driver will be when compiled as a module.
> 

sure. will add the module's name here.

>> diff --git a/drivers/hwtracing/hisilicon/Makefile b/drivers/hwtracing/hisilicon/Makefile
>> new file mode 100644
>> index 000000000000..908c09a98161
>> --- /dev/null
>> +++ b/drivers/hwtracing/hisilicon/Makefile
>> @@ -0,0 +1,2 @@
>> +# SPDX-License-Identifier: GPL-2.0
>> +obj-$(CONFIG_HISI_PTT) += hisi_ptt.o
>> diff --git a/drivers/hwtracing/hisilicon/hisi_ptt.c b/drivers/hwtracing/hisilicon/hisi_ptt.c
>> new file mode 100644
>> index 000000000000..e11e9b6cc2a8
>> --- /dev/null
>> +++ b/drivers/hwtracing/hisilicon/hisi_ptt.c
>> @@ -0,0 +1,1146 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Driver for HiSilicon PCIe tune and trace device
>> + *
>> + * Copyright (c) 2021 HiSilicon Limited.
>> + */
>> +
>> +#include <linux/bitfield.h>
>> +#include <linux/bitops.h>
>> +#include <linux/delay.h>
>> +#include <linux/dma-iommu.h>
>> +#include <linux/dma-mapping.h>
>> +#include <linux/interrupt.h>
>> +#include <linux/io.h>
>> +#include <linux/iommu.h>
>> +#include <linux/iopoll.h>
>> +#include <linux/kfifo.h>
>> +#include <linux/module.h>
>> +#include <linux/notifier.h>
>> +#include <linux/pci.h>
>> +#include <linux/perf_event.h>
>> +#include <linux/sizes.h>
>> +#include <linux/sysfs.h>
>> +#include <linux/vmalloc.h>
>> +#include <linux/workqueue.h>
>> +
>> +#define HISI_PTT_TRACE_ADDR_SIZE	0x0800
>> +#define HISI_PTT_TRACE_ADDR_BASE_LO_0	0x0810
>> +#define HISI_PTT_TRACE_ADDR_BASE_HI_0	0x0814
>> +#define HISI_PTT_TRACE_ADDR_STRIDE	0x8
>> +#define HISI_PTT_TRACE_CTRL		0x0850
>> +#define   HISI_PTT_TRACE_CTRL_EN	BIT(0)
>> +#define   HISI_PTT_TRACE_CTRL_RST	BIT(1)
>> +#define   HISI_PTT_TRACE_CTRL_RXTX_SEL	GENMASK(3, 2)
>> +#define   HISI_PTT_TRACE_CTRL_TYPE_SEL	GENMASK(7, 4)
>> +#define   HISI_PTT_TRACE_CTRL_DATA_FORMAT	BIT(14)
>> +#define   HISI_PTT_TRACE_CTRL_FILTER_MODE	BIT(15)
>> +#define   HISI_PTT_TRACE_CTRL_TARGET_SEL	GENMASK(31, 16)
>> +#define HISI_PTT_TRACE_INT_STAT		0x0890
>> +#define   HISI_PTT_TRACE_INT_STAT_MASK	GENMASK(3, 0)
>> +#define HISI_PTT_TRACE_INT_MASK		0x0894
>> +#define HISI_PTT_TRACE_WR_STS		0x08a0
>> +#define   HISI_PTT_TRACE_WR_STS_WRITE	GENMASK(27, 0)
>> +#define   HISI_PTT_TRACE_WR_STS_BUFFER	GENMASK(29, 28)
>> +#define HISI_PTT_TRACE_STS		0x08b0
>> +#define   HISI_PTT_TRACE_IDLE		BIT(0)
>> +#define HISI_PTT_DEVICE_RANGE		0x0fe0
>> +#define HISI_PTT_LOCATION		0x0fe8
>> +#define   HISI_PTT_CORE_ID		GENMASK(15, 0)
>> +#define   HISI_PTT_SICL_ID		GENMASK(31, 16)
> 
> Extra spaces between #define and the literals.  Please align the values with
> that of HISI_PTT_TRACE_DMA_IRQ below.
> 

Spaces are intended to distinguish the definition of the register offset and
related register fields. also used in include/uapi/linux/pci_regs.h.

HISI_PTT_TRACE_DMA_IRQ is well aligned with tab but seems with problem display
in the mail text, maybe because the tab is not 8 characters when display.

>> +
>> +#define HISI_PTT_TRACE_DMA_IRQ			0
>> +#define HISI_PTT_TRACE_BUFLETS_CNT		4
>> +#define HISI_PTT_TRACE_BUFLET_SIZE		SZ_4M
>> +#define HISI_PTT_TRACE_BUFFER_SIZE		(HISI_PTT_TRACE_BUFLET_SIZE * \
>> +						 HISI_PTT_TRACE_BUFLETS_CNT)
>> +#define HISI_PTT_FILTER_UPDATE_FIFO_SIZE	16
>> +
>> +/* Delay time for filter updating work */
>> +#define HISI_PTT_WORK_DELAY_MS		100UL
>> +/* Wait time for DMA hardware to reset */
>> +#define HISI_PTT_RESET_WAIT_MS		1000UL
>> +/* Poll timeout and interval for waiting hardware work to finish */
>> +#define HISI_PTT_WAIT_TIMEOUT_US	1000000UL
>> +#define HISI_PTT_WAIT_POLL_INTERVAL_US	100UL
>> +
>> +#define HISI_PCIE_CORE_PORT_ID(devfn)	(PCI_FUNC(devfn) << 1)
>> +
>> +enum hisi_ptt_trace_status {
>> +	HISI_PTT_TRACE_STATUS_OFF = 0,
>> +	HISI_PTT_TRACE_STATUS_ON,
>> +};
>> +
>> +struct hisi_ptt_dma_buflet {
> 
> I'm not sure what a "buflet" is...  Probably best to just call this
> hisi_ptt_dma_buffer" if it pertains to a buffer.  On that note it is hard to
> know due to the lack of proper structure documentation.  Please have a look at
> how "coresight_device" is documented.  The same applies to the rest of the
> structures declared below.
> 

It's mentioned in section 5 of hisi_ptt.rst as "Driver will allocate each DMA buffer
(we call it buflet) of 4MiB ...".

The total DMA buffer of PTT device is divided into 4 parts, and each part is called
a 'buflet', which means a small buffer (there exists other words with similiar
format: droplet, wavelet, ...).

The device is designed like this to make sure we won't lose any data when we have to change
the buffer address, the device can continue to write to the next buflet and don't
neet to pause.

>> +	struct list_head list;
>> +	unsigned int size;
>> +	dma_addr_t dma;
>> +
>> +	/*
>> +	 * The address of the buflet holding the trace data.
>> +	 * See Documentation/trace/hisi-ptt.rst for the details
> 
> As of this writing, hisi-ptt.rst doesn't exist.
> 

The comment intends to direct the user to the documentation if the user
want to know details about the data format. The data format is decribed
in the section 4 of the doc.

>> +	 * of the data format.
>> +	 */
>> +	void *addr;
>> +	int index;
>> +};
>> +
>> +struct hisi_ptt_trace_ctrl {
>> +	enum hisi_ptt_trace_status status;
>> +	struct perf_output_handle handle;
>> +	struct list_head trace_buf;
>> +	/*
>> +	 * The index of the buffer which trace data
>> +	 * currently is writing to.
>> +	 */
>> +	u32 buf_index;
>> +
>> +	int default_cpu;
>> +	u32 buflet_size;
>> +	bool is_port;
>> +	u32 format:1;		/* Format of the traced TLP headers */
>> +	u32 type:4;		/* Type of the TLP headers to trace */
>> +	u32 direction:2;	/* Direction of the TLP headers to trace */
>> +	u32 filter:16;		/* Root port or Requester to filter the TLP headers */
>> +
>> +	phys_addr_t rmr_addr;
>> +	size_t rmr_length;
>> +	bool has_rmr;
>> +};
>> +
>> +struct hisi_ptt_filter_desc {
>> +	struct list_head list;
>> +	struct pci_dev *pdev;
>> +	u16 val;
>> +};
>> +
>> +struct hisi_ptt_pmu_buf {
>> +	size_t length;
>> +	int nr_pages;
>> +	void *base;
>> +	long pos;
>> +};
>> +
>> +/* Structure containing the information for filter updating */
>> +struct hisi_ptt_filter_update_info {
>> +	struct pci_dev *pdev;
>> +	u32 port_devid;
>> +	bool is_port;
>> +	bool is_add;
>> +	u16 val;
>> +};
>> +
>> +struct hisi_ptt {
>> +	struct hisi_ptt_trace_ctrl trace_ctrl;
>> +	struct notifier_block hisi_ptt_nb;
>> +	struct pmu hisi_ptt_pmu;
>> +	void __iomem *iobase;
>> +	struct pci_dev *pdev;
>> +	/*
>> +	 * Use the mutex to protect the filter list and
>> +	 * serialize the perf process.
>> +	 */
>> +	struct mutex mutex;
>> +	const char *name;
>> +	u16 core_id;
>> +	u16 sicl_id;
>> +	/* PCI device range managed by the PTT device */
>> +	u32 upper;
>> +	u32 lower;
>> +	u8 busnr;
>> +
>> +	/*
>> +	 * The trace TLP headers can either be filtered by certain
>> +	 * root port, or by the requester ID. Organize the filters
>> +	 * by @port_filters and @req_filters here. The mask of all
>> +	 * the valid ports is also cached for doing sanity check
>> +	 * of user input.
>> +	 */
>> +	struct list_head port_filters;
>> +	struct list_head req_filters;
>> +	u16 port_mask;
>> +
>> +	/*
>> +	 * We use a delayed work here to avoid indefinitely waiting for
>> +	 * the hisi_ptt->mutex which protecting the filter list. The
>> +	 * work will be delayed only if the mutex can not be held,
>> +	 * otherwise no delay will be applied.
>> +	 */
>> +	struct delayed_work work;
>> +	spinlock_t filter_update_lock;
>> +	DECLARE_KFIFO(filter_update_kfifo, struct hisi_ptt_filter_update_info,
>> +		      HISI_PTT_FILTER_UPDATE_FIFO_SIZE);
>> +};
> 
> It might be a good idea to spinoff a hisi_ptt.h for the above declarations.
> 

I'm not sure whether it is common or permitted to provide a header which is only used by
this driver with a single file.

>> +
>> +static inline struct hisi_ptt *to_hisi_ptt(struct pmu *pmu)
>> +{
>> +	return container_of(pmu, struct hisi_ptt, hisi_ptt_pmu);
>> +}
> 
> I'm not sure there is any value to this inline function.  I suggest to simply
> call container_of() whenever it is needed.
> 

ok.

>> +
>> +static u16 hisi_ptt_get_filter_val(struct pci_dev *pdev)
>> +{
>> +	if (pci_pcie_type(pdev) == PCI_EXP_TYPE_ROOT_PORT)
>> +		return BIT(HISI_PCIE_CORE_PORT_ID(PCI_SLOT(pdev->devfn)));
>> +
>> +	return PCI_DEVID(pdev->bus->number, pdev->devfn);
>> +}
>> +
>> +static int hisi_ptt_wait_trace_hw_idle(struct hisi_ptt *hisi_ptt)
>> +{
>> +	u32 val;
>> +
>> +	return readl_poll_timeout(hisi_ptt->iobase + HISI_PTT_TRACE_STS, val,
>> +				  val & HISI_PTT_TRACE_IDLE,
>> +				  HISI_PTT_WAIT_POLL_INTERVAL_US,
>> +				  HISI_PTT_WAIT_TIMEOUT_US);
>> +}
>> +
>> +static void hisi_ptt_free_trace_buf(struct hisi_ptt *hisi_ptt)
>> +{
>> +	struct hisi_ptt_trace_ctrl *ctrl = &hisi_ptt->trace_ctrl;
>> +	struct device *dev = &hisi_ptt->pdev->dev;
>> +	struct hisi_ptt_dma_buflet *buflet, *tbuflet;
>> +
>> +	list_for_each_entry_safe(buflet, tbuflet, &ctrl->trace_buf, list) {
>> +		list_del(&buflet->list);
>> +
>> +		if (ctrl->has_rmr)
>> +			memunmap(buflet->addr);
>> +		else
>> +			dma_free_coherent(dev, buflet->size, buflet->addr,
>> +					  buflet->dma);
>> +
>> +		kfree(buflet);
>> +	}
>> +}
>> +
>> +static int hisi_ptt_alloc_trace_buf(struct hisi_ptt *hisi_ptt)
>> +{
>> +	struct hisi_ptt_trace_ctrl *ctrl = &hisi_ptt->trace_ctrl;
>> +	struct device *dev = &hisi_ptt->pdev->dev;
>> +	struct hisi_ptt_dma_buflet *buflet;
>> +	int i, ret;
>> +
>> +	hisi_ptt->trace_ctrl.buf_index = 0;
>> +
>> +	/* Make sure the trace buffer is empty before allocating */
>> +	if (!list_empty(&ctrl->trace_buf)) {
>> +		list_for_each_entry(buflet, &ctrl->trace_buf, list)
>> +			memset(buflet->addr, 0, buflet->size);
>> +		return 0;
>> +	}
>> +
>> +	for (i = 0; i < HISI_PTT_TRACE_BUFLETS_CNT; ++i) {
>> +		buflet = kzalloc(sizeof(*buflet), GFP_KERNEL);
>> +		if (!buflet) {
>> +			ret = -ENOMEM;
>> +			goto err;
>> +		}
>> +
>> +		if (ctrl->has_rmr) {
>> +			phys_addr_t base = ctrl->rmr_addr + i * ctrl->buflet_size;
>> +
>> +			buflet->dma = base;
>> +			buflet->addr = memremap(base, ctrl->buflet_size, MEMREMAP_WB);
>> +		} else {
>> +			buflet->addr = dma_alloc_coherent(dev, ctrl->buflet_size,
>> +							  &buflet->dma, GFP_KERNEL);
>> +		}
>> +
>> +		if (!buflet->addr) {
>> +			kfree(buflet);
>> +			ret = -ENOMEM;
>> +			goto err;
>> +		}
>> +
>> +		memset(buflet->addr, 0, buflet->size);
>> +
>> +		buflet->index = i;
>> +		buflet->size = ctrl->buflet_size;
>> +		list_add_tail(&buflet->list, &ctrl->trace_buf);
>> +	}
>> +
>> +	return 0;
>> +err:
>> +	hisi_ptt_free_trace_buf(hisi_ptt);
>> +	return ret;
>> +}
>> +
>> +static void hisi_ptt_trace_end(struct hisi_ptt *hisi_ptt)
>> +{
>> +	writel(0, hisi_ptt->iobase + HISI_PTT_TRACE_CTRL);
>> +	hisi_ptt->trace_ctrl.status = HISI_PTT_TRACE_STATUS_OFF;
>> +}
>> +
>> +static int hisi_ptt_trace_start(struct hisi_ptt *hisi_ptt)
>> +{
>> +	struct hisi_ptt_trace_ctrl *ctrl = &hisi_ptt->trace_ctrl;
>> +	struct hisi_ptt_dma_buflet *cur;
>> +	u32 val;
>> +
>> +	/* Check device idle before start trace */
>> +	if (hisi_ptt_wait_trace_hw_idle(hisi_ptt)) {
>> +		pci_err(hisi_ptt->pdev, "Failed to start trace, the device is still busy.\n");
>> +		return -EBUSY;
>> +	}
>> +
>> +	/* Reset the DMA before start tracing */
>> +	val = readl(hisi_ptt->iobase + HISI_PTT_TRACE_CTRL);
>> +	val |= HISI_PTT_TRACE_CTRL_RST;
>> +	writel(val, hisi_ptt->iobase + HISI_PTT_TRACE_CTRL);
>> +
>> +	/*
>> +	 * We'll be in the perf context where preemption is disabled,
>> +	 * so use busy loop here.
>> +	 */
>> +	mdelay(HISI_PTT_RESET_WAIT_MS);
>> +
>> +	val = readl(hisi_ptt->iobase + HISI_PTT_TRACE_CTRL);
>> +	val &= ~HISI_PTT_TRACE_CTRL_RST;
>> +	writel(val, hisi_ptt->iobase + HISI_PTT_TRACE_CTRL);
>> +
>> +	/* clear the interrupt status */
>> +	writel(HISI_PTT_TRACE_INT_STAT_MASK, hisi_ptt->iobase + HISI_PTT_TRACE_INT_STAT);
>> +	writel(0, hisi_ptt->iobase + HISI_PTT_TRACE_INT_MASK);
>> +
>> +	list_for_each_entry(cur, &ctrl->trace_buf, list) {
>> +		writel(lower_32_bits(cur->dma),
>> +		       hisi_ptt->iobase + HISI_PTT_TRACE_ADDR_BASE_LO_0 +
>> +		       cur->index * HISI_PTT_TRACE_ADDR_STRIDE);
>> +		writel(upper_32_bits(cur->dma),
>> +		       hisi_ptt->iobase + HISI_PTT_TRACE_ADDR_BASE_HI_0 +
>> +		       cur->index * HISI_PTT_TRACE_ADDR_STRIDE);
>> +	}
>> +	writel(ctrl->buflet_size, hisi_ptt->iobase + HISI_PTT_TRACE_ADDR_SIZE);
>> +
>> +	/* set the trace control register */
>> +	val = FIELD_PREP(HISI_PTT_TRACE_CTRL_TYPE_SEL, ctrl->type);
>> +	val |= FIELD_PREP(HISI_PTT_TRACE_CTRL_RXTX_SEL, ctrl->direction);
>> +	val |= FIELD_PREP(HISI_PTT_TRACE_CTRL_DATA_FORMAT, ctrl->format);
>> +	val |= FIELD_PREP(HISI_PTT_TRACE_CTRL_TARGET_SEL, hisi_ptt->trace_ctrl.filter);
>> +	if (!hisi_ptt->trace_ctrl.is_port)
>> +		val |= HISI_PTT_TRACE_CTRL_FILTER_MODE;
>> +
>> +	val |= HISI_PTT_TRACE_CTRL_EN;
>> +	writel(val, hisi_ptt->iobase + HISI_PTT_TRACE_CTRL);
>> +
>> +	ctrl->status = HISI_PTT_TRACE_STATUS_ON;
>> +
>> +	return 0;
>> +}
>> +
>> +static int hisi_ptt_update_aux(struct hisi_ptt *hisi_ptt, int index, bool stop)
>> +{
>> +	struct perf_output_handle *handle = &hisi_ptt->trace_ctrl.handle;
>> +	struct perf_event *event = handle->event;
>> +	struct hisi_ptt_dma_buflet *cur;
>> +	struct hisi_ptt_pmu_buf *buf;
>> +
>> +	buf = perf_get_aux(handle);
>> +	if (!buf || !handle->size)
>> +		return -EINVAL;
>> +
>> +	list_for_each_entry(cur, &hisi_ptt->trace_ctrl.trace_buf, list)
>> +		if (cur->index == index)
>> +			break;
>> +
>> +	memcpy(buf->base + buf->pos, cur->addr, cur->size);
>> +	memset(cur->addr, 0, cur->size);
>> +	buf->pos += cur->size;
>> +
>> +	if (stop) {
>> +		perf_aux_output_end(handle, buf->pos);
>> +	} else if (buf->length - buf->pos < cur->size) {
>> +		perf_aux_output_skip(handle, buf->length - buf->pos);
>> +		perf_aux_output_end(handle, buf->pos);
>> +
>> +		buf = perf_aux_output_begin(handle, event);
>> +		if (!buf)
>> +			return -EINVAL;
>> +
>> +		buf->pos = handle->head % buf->length;
>> +		if (buf->length - buf->pos < cur->size) {
>> +			perf_aux_output_end(handle, 0);
>> +			return -EINVAL;
>> +		}
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static irqreturn_t hisi_ptt_isr(int irq, void *context)
>> +{
>> +	struct hisi_ptt *hisi_ptt = context;
>> +	u32 status, buf_idx;
>> +
>> +	status = readl(hisi_ptt->iobase + HISI_PTT_TRACE_INT_STAT);
>> +	buf_idx = ffs(status) - 1;
>> +
>> +	/* Clear the interrupt status of buflet @buf_idx */
>> +	writel(status, hisi_ptt->iobase + HISI_PTT_TRACE_INT_STAT);
>> +
>> +	/*
>> +	 * Update the AUX buffer and cache the current buflet index,
>> +	 * as we need to know this and save the data when the trace
>> +	 * is ended out of the interrupt handler. End the trace
>> +	 * if the updating fails.
>> +	 */
>> +	if (hisi_ptt_update_aux(hisi_ptt, buf_idx, false))
>> +		hisi_ptt_trace_end(hisi_ptt);
>> +	else
>> +		hisi_ptt->trace_ctrl.buf_index = (buf_idx + 1) % HISI_PTT_TRACE_BUFLETS_CNT;
>> +
>> +	return IRQ_HANDLED;
>> +}
>> +
>> +static irqreturn_t hisi_ptt_irq(int irq, void *context)
>> +{
>> +	struct hisi_ptt *hisi_ptt = context;
>> +	u32 status;
>> +
>> +	status = readl(hisi_ptt->iobase + HISI_PTT_TRACE_INT_STAT);
>> +	if (!(status & HISI_PTT_TRACE_INT_STAT_MASK))
>> +		return IRQ_NONE;
>> +
>> +	return IRQ_WAKE_THREAD;
>> +}
>> +
>> +static void hisi_ptt_irq_free_vectors(void *pdev)
>> +{
>> +	pci_free_irq_vectors(pdev);
>> +}
>> +
>> +static int hisi_ptt_register_irq(struct hisi_ptt *hisi_ptt)
>> +{
>> +	struct pci_dev *pdev = hisi_ptt->pdev;
>> +	int ret;
>> +
>> +	ret = pci_alloc_irq_vectors(pdev, 1, 1, PCI_IRQ_MSI);
>> +	if (ret < 0) {
>> +		pci_err(pdev, "failed to allocate irq vector, ret = %d.\n", ret);
>> +		return ret;
>> +	}
>> +
>> +	ret = devm_add_action_or_reset(&pdev->dev, hisi_ptt_irq_free_vectors, pdev);
>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	ret = devm_request_threaded_irq(&pdev->dev,
>> +					pci_irq_vector(pdev, HISI_PTT_TRACE_DMA_IRQ),
>> +					hisi_ptt_irq, hisi_ptt_isr, 0,
>> +					"hisi-ptt", hisi_ptt);
>> +	if (ret) {
>> +		pci_err(pdev, "failed to request irq %d, ret = %d.\n",
>> +			pci_irq_vector(pdev, HISI_PTT_TRACE_DMA_IRQ), ret);
>> +		return ret;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static void hisi_ptt_update_filters(struct work_struct *work)
>> +{
>> +	struct delayed_work *delayed_work = to_delayed_work(work);
>> +	struct hisi_ptt_filter_update_info info;
>> +	struct hisi_ptt_filter_desc *filter;
>> +	struct list_head *target_list;
>> +	struct hisi_ptt *hisi_ptt;
>> +
>> +	hisi_ptt = container_of(delayed_work, struct hisi_ptt, work);
>> +
>> +	if (!mutex_trylock(&hisi_ptt->mutex)) {
>> +		schedule_delayed_work(&hisi_ptt->work, HISI_PTT_WORK_DELAY_MS);
>> +		return;
>> +	}
>> +
>> +	while (kfifo_get(&hisi_ptt->filter_update_kfifo, &info)) {
>> +		target_list = info.is_port ? &hisi_ptt->port_filters :
>> +			      &hisi_ptt->req_filters;
>> +
>> +		if (info.is_add) {
>> +			filter = kzalloc(sizeof(*filter), GFP_KERNEL);
>> +			if (!filter)
>> +				continue;
>> +
>> +			filter->pdev = info.pdev;
>> +			filter->val = info.val;
>> +
>> +			list_add_tail(&filter->list, target_list);
>> +		} else {
>> +			list_for_each_entry(filter, target_list, list)
>> +				if (filter->val == info.val) {
>> +					list_del(&filter->list);
>> +					kfree(filter);
>> +					break;
>> +				}
>> +		}
>> +
>> +		/* Update the available port mask */
>> +		if (!info.is_port)
>> +			continue;
>> +
>> +		if (info.is_add)
>> +			hisi_ptt->port_mask |= info.val;
>> +		else
>> +			hisi_ptt->port_mask &= ~info.val;
>> +	}
>> +
>> +	mutex_unlock(&hisi_ptt->mutex);
>> +}
>> +
>> +static void hisi_ptt_update_fifo_in(struct hisi_ptt *hisi_ptt,
>> +				    struct hisi_ptt_filter_update_info *info)
>> +{
>> +	struct pci_dev *root_port = pcie_find_root_port(info->pdev);
>> +
>> +	if (!root_port)
>> +		return;
>> +
>> +	info->port_devid = PCI_DEVID(root_port->bus->number, root_port->devfn);
>> +	if (info->port_devid < hisi_ptt->lower ||
>> +	    info->port_devid > hisi_ptt->upper)
>> +		return;
>> +
>> +	info->is_port = pci_pcie_type(info->pdev) == PCI_EXP_TYPE_ROOT_PORT;
>> +	info->val = hisi_ptt_get_filter_val(info->pdev);
>> +
>> +	if (kfifo_in_spinlocked(&hisi_ptt->filter_update_kfifo, info, 1,
>> +				&hisi_ptt->filter_update_lock))
>> +		schedule_delayed_work(&hisi_ptt->work, 0);
>> +	else
>> +		pci_warn(hisi_ptt->pdev,
>> +			 "filter update fifo overflow for target %s\n",
>> +			 pci_name(info->pdev));
>> +}
>> +
>> +/*
>> + * A PCI bus notifier is used here for dynamically updating the filter
>> + * list.
>> + */
>> +static int hisi_ptt_notifier_call(struct notifier_block *nb, unsigned long action,
>> +				  void *data)
>> +{
>> +	struct hisi_ptt *hisi_ptt = container_of(nb, struct hisi_ptt, hisi_ptt_nb);
>> +	struct hisi_ptt_filter_update_info info;
>> +	struct device *dev = data;
>> +	struct pci_dev *pdev = to_pci_dev(dev);
>> +
>> +	info.pdev = pdev;
>> +
>> +	switch (action) {
>> +	case BUS_NOTIFY_ADD_DEVICE:
>> +		info.is_add = true;
>> +		break;
>> +	case BUS_NOTIFY_DEL_DEVICE:
>> +		info.is_add = false;
>> +		break;
>> +	default:
>> +		return 0;
>> +	}
>> +
>> +	hisi_ptt_update_fifo_in(hisi_ptt, &info);
>> +
>> +	return 0;
>> +}
>> +
>> +static int hisi_ptt_init_filters(struct pci_dev *pdev, void *data)
>> +{
>> +	struct hisi_ptt_filter_update_info info = {
>> +		.pdev = pdev,
>> +		.is_add = true,
>> +	};
>> +	struct hisi_ptt *hisi_ptt = data;
>> +
>> +	hisi_ptt_update_fifo_in(hisi_ptt, &info);
>> +
>> +	return 0;
>> +}
>> +
>> +static void hisi_ptt_release_filters(struct hisi_ptt *hisi_ptt)
>> +{
>> +	struct hisi_ptt_filter_desc *filter, *tfilter;
>> +
>> +	list_for_each_entry_safe(filter, tfilter, &hisi_ptt->req_filters, list) {
>> +		list_del(&filter->list);
>> +		kfree(filter);
>> +	}
>> +
>> +	list_for_each_entry_safe(filter, tfilter, &hisi_ptt->port_filters, list) {
>> +		list_del(&filter->list);
>> +		kfree(filter);
>> +	}
>> +}
>> +
>> +static void hisi_ptt_init_ctrls(struct hisi_ptt *hisi_ptt)
>> +{
>> +	struct pci_dev *pdev = hisi_ptt->pdev;
>> +	struct pci_bus *bus;
>> +	u32 reg;
>> +
>> +	INIT_DELAYED_WORK(&hisi_ptt->work, hisi_ptt_update_filters);
>> +	spin_lock_init(&hisi_ptt->filter_update_lock);
>> +	INIT_KFIFO(hisi_ptt->filter_update_kfifo);
>> +	INIT_LIST_HEAD(&hisi_ptt->port_filters);
>> +	INIT_LIST_HEAD(&hisi_ptt->req_filters);
>> +
>> +	/*
>> +	 * The device range register provides the information about the
>> +	 * root ports which the RCiEP can control and trace. The RCiEP
>> +	 * and the root ports it support are on the same PCIe core, with
>> +	 * same domain number but maybe different bus number. The device
>> +	 * range register will tell us which root ports we can support,
>> +	 * Bit[31:16] indicates the upper BDF numbers of the root port,
>> +	 * while Bit[15:0] indicates the lower.
>> +	 */
>> +	reg = readl(hisi_ptt->iobase + HISI_PTT_DEVICE_RANGE);
>> +	hisi_ptt->upper = reg >> 16;
>> +	hisi_ptt->lower = reg & 0xffff;
>> +	hisi_ptt->busnr = PCI_BUS_NUM(hisi_ptt->upper);
>> +
>> +	reg = readl(hisi_ptt->iobase + HISI_PTT_LOCATION);
>> +	hisi_ptt->core_id = FIELD_GET(HISI_PTT_CORE_ID, reg);
>> +	hisi_ptt->sicl_id = FIELD_GET(HISI_PTT_SICL_ID, reg);
>> +
>> +	bus = pci_find_bus(pci_domain_nr(pdev->bus), hisi_ptt->busnr);
>> +	if (bus)
>> +		pci_walk_bus(bus, hisi_ptt_init_filters, hisi_ptt);
> 
> What happens if bus is NULL?  Should this be reported to the caller and cause
> hisi_ptt_probe() to fail?  Please add a comment that describes the scenario.
> 

It's ok if the list is NULL in the probe process,
as the device maybe hotplugged after the PTT driver probe, in which case
we can detect the event and update the list as we register a bus notifier.

>> +
>> +	/* Initialize trace controls */
>> +	INIT_LIST_HEAD(&hisi_ptt->trace_ctrl.trace_buf);
>> +	hisi_ptt->trace_ctrl.buflet_size = HISI_PTT_TRACE_BUFLET_SIZE;
>> +	hisi_ptt->trace_ctrl.default_cpu = cpumask_first(cpumask_of_node(dev_to_node(&pdev->dev)));
>> +}
>> +
>> +#define HISI_PTT_PMU_FILTER_IS_PORT	BIT(19)
>> +#define HISI_PTT_PMU_FILTER_VAL_MASK	GENMASK(15, 0)
>> +#define HISI_PTT_PMU_DIRECTION_MASK	GENMASK(23, 20)
>> +#define HISI_PTT_PMU_TYPE_MASK		GENMASK(31, 24)
>> +#define HISI_PTT_PMU_FORMAT_MASK	GENMASK(35, 32)
>> +
>> +static ssize_t available_filters_show(struct device *dev,
>> +				      struct device_attribute *attr,
>> +				      char *buf)
>> +{
>> +	struct hisi_ptt *hisi_ptt = to_hisi_ptt(dev_get_drvdata(dev));
>> +	struct hisi_ptt_filter_desc *filter;
>> +	int pos = 0;
>> +
>> +	if (list_empty(&hisi_ptt->port_filters))
>> +		return sysfs_emit(buf, "#### No available filter ####\n");
>> +
>> +	mutex_lock(&hisi_ptt->mutex);
>> +	pos += sysfs_emit_at(buf, pos, "#### Root Ports ####\n");
>> +	list_for_each_entry(filter, &hisi_ptt->port_filters, list)
>> +		pos += sysfs_emit_at(buf, pos, "%s	0x%05lx\n",
>> +				     pci_name(filter->pdev),
>> +				     hisi_ptt_get_filter_val(filter->pdev) |
>> +				     HISI_PTT_PMU_FILTER_IS_PORT);
>> +
>> +	pos += sysfs_emit_at(buf, pos, "#### Requesters ####\n");
>> +	list_for_each_entry(filter, &hisi_ptt->req_filters, list)
>> +		pos += sysfs_emit_at(buf, pos, "%s	0x%05x\n",
>> +				     pci_name(filter->pdev),
>> +				     hisi_ptt_get_filter_val(filter->pdev));
>> +
>> +	mutex_unlock(&hisi_ptt->mutex);
>> +	return pos;
>> +}
>> +static DEVICE_ATTR_ADMIN_RO(available_filters);
>> +
>> +PMU_FORMAT_ATTR(filter,		"config:0-19");
>> +PMU_FORMAT_ATTR(direction,	"config:20-23");
>> +PMU_FORMAT_ATTR(type,		"config:24-31");
>> +PMU_FORMAT_ATTR(format,		"config:32-35");
>> +
>> +static struct attribute *hisi_ptt_pmu_format_attrs[] = {
>> +	&format_attr_filter.attr,
>> +	&format_attr_direction.attr,
>> +	&format_attr_type.attr,
>> +	&format_attr_format.attr,
>> +	NULL
>> +};
>> +
>> +static struct attribute_group hisi_ptt_pmu_format_group = {
>> +	.name = "format",
>> +	.attrs = hisi_ptt_pmu_format_attrs,
>> +};
>> +
>> +static struct attribute *hisi_ptt_pmu_filter_attrs[] = {
>> +	&dev_attr_available_filters.attr,
>> +	NULL
>> +};
>> +
>> +static struct attribute_group hisi_ptt_pmu_filter_group = {
>> +	.attrs = hisi_ptt_pmu_filter_attrs,
>> +};
>> +
>> +static const struct attribute_group *hisi_ptt_pmu_groups[] = {
>> +	&hisi_ptt_pmu_format_group,
>> +	&hisi_ptt_pmu_filter_group,
>> +	NULL
>> +};
>> +
>> +/*
>> + * The supported value of the direction parameter. See hisi_ptt.rst
>> + * documentation for more details.
>> + */
>> +static u32 hisi_ptt_trace_available_direction[] = {
>> +	0,
>> +	1,
>> +	2,
>> +	3,
>> +};
>> +
>> +/* Different types can be set simultaneously */
>> +static u32 hisi_ptt_trace_available_type[] = {
>> +	1,	/* posted_request */
>> +	2,	/* non-posted_request */
>> +	4,	/* completion */
>> +};
>> +
>> +static u32 hisi_ptt_trace_availble_format[] = {
>> +	0,	/* 4DW */
>> +	1,	/* 8DW */
>> +};
>> +
>> +/*
>> + * Check whether the config is valid or not. Some configs are multi-selectable
>> + * and can be set simultaneously, while some are single selectable (onehot).
>> + * Use this function to check the non-onehot configs while
>> + * hisi_ptt_trace_valid_config_onehot() for the onehot ones.
>> + */
>> +static int hisi_ptt_trace_valid_config(u32 val, u32 *available_list, u32 list_size)
>> +{
>> +	int i;
>> +
>> +	/*
>> +	 * The non-onehot configs cannot be 0. Walk the available
>> +	 * list and clear the valid bits of the config. If there
>> +	 * is any resident bit after the walk then the config is
>> +	 * invalid.
>> +	 */
>> +	for (i = 0; i < list_size; i++)
>> +		val &= ~available_list[i];
>> +
>> +	return val ? -EINVAL : 0;
>> +}
>> +
>> +static int hisi_ptt_trace_valid_config_onehot(u32 val, u32 *available_list, u32 list_size)
>> +{
>> +	int i, ret = -EINVAL;
>> +
>> +	for (i = 0; i < list_size; i++)
>> +		if (val == available_list[i]) {
>> +			ret = 0;
>> +			break;
>> +		}
>> +
>> +	return ret;
>> +}
>> +
>> +static int hisi_ptt_trace_init_filter(struct hisi_ptt *hisi_ptt, u64 config)
>> +{
>> +	unsigned long val, port_mask = hisi_ptt->port_mask;
>> +	struct hisi_ptt_filter_desc *filter;
>> +	int ret = -EINVAL;
>> +
>> +	hisi_ptt->trace_ctrl.is_port = FIELD_GET(HISI_PTT_PMU_FILTER_IS_PORT, config);
>> +	val = FIELD_GET(HISI_PTT_PMU_FILTER_VAL_MASK, config);
>> +
>> +	/*
>> +	 * Port filters are defined as bit mask. For port filters, check
>> +	 * the bits in the @val are within the range of hisi_ptt->port_mask
>> +	 * and whether it's empty or not, otherwise user has specified
>> +	 * some unsupported root ports.
>> +	 *
>> +	 * For Requester ID filters, walk the available filter list to see
>> +	 * whether we have one matched.
>> +	 */
>> +	if (hisi_ptt->trace_ctrl.is_port &&
>> +	    bitmap_subset(&val, &port_mask, BITS_PER_LONG)) {
>> +		ret = 0;
>> +	} else {
>> +		list_for_each_entry(filter, &hisi_ptt->req_filters, list)
>> +			if (filter->val == val) {
>> +				ret = 0;
>> +				break;
>> +			}
>> +	}
>> +
>> +	if (ret)
>> +		return ret;
>> +
>> +	hisi_ptt->trace_ctrl.filter = val;
>> +	return 0;
>> +}
>> +
>> +static int hisi_ptt_pmu_event_init(struct perf_event *event)
>> +{
>> +	struct hisi_ptt *hisi_ptt = to_hisi_ptt(event->pmu);
>> +	struct hisi_ptt_trace_ctrl *ctrl = &hisi_ptt->trace_ctrl;
>> +	int ret;
>> +	u32 val;
>> +
>> +	if (event->attr.type != hisi_ptt->hisi_ptt_pmu.type)
>> +		return -ENOENT;
>> +
>> +	mutex_lock(&hisi_ptt->mutex);
>> +
>> +	ret = hisi_ptt_trace_init_filter(hisi_ptt, event->attr.config);
>> +	if (ret < 0)
>> +		goto out;
>> +
>> +	val = FIELD_GET(HISI_PTT_PMU_DIRECTION_MASK, event->attr.config);
>> +	ret = hisi_ptt_trace_valid_config_onehot(val, hisi_ptt_trace_available_direction,
>> +						 ARRAY_SIZE(hisi_ptt_trace_available_direction));
>> +	if (ret < 0)
>> +		goto out;
>> +	ctrl->direction = val;
>> +
>> +	val = FIELD_GET(HISI_PTT_PMU_TYPE_MASK, event->attr.config);
>> +
>> +	ret = hisi_ptt_trace_valid_config(val, hisi_ptt_trace_available_type,
>> +					  ARRAY_SIZE(hisi_ptt_trace_available_type));
>> +	if (ret < 0)
>> +		goto out;
>> +	ctrl->type = val;
>> +
>> +	val = FIELD_GET(HISI_PTT_PMU_FORMAT_MASK, event->attr.config);
>> +	ret = hisi_ptt_trace_valid_config_onehot(val, hisi_ptt_trace_availble_format,
>> +						 ARRAY_SIZE(hisi_ptt_trace_availble_format));
>> +	if (ret < 0)
>> +		goto out;
>> +	ctrl->format = val;
>> +
>> +out:
>> +	mutex_unlock(&hisi_ptt->mutex);
>> +	return ret;
>> +}
>> +
>> +static void *hisi_ptt_pmu_setup_aux(struct perf_event *event, void **pages,
>> +				    int nr_pages, bool overwrite)
>> +{
>> +	struct hisi_ptt_pmu_buf *buf;
>> +	struct page **pagelist;
>> +	int i;
>> +
>> +	if (overwrite) {
>> +		dev_warn(event->pmu->dev, "Overwrite mode is not supported\n");
>> +		return NULL;
>> +	}
>> +
>> +	/* If the pages size less than buflets, we cannot start trace */
>> +	if (nr_pages < HISI_PTT_TRACE_BUFFER_SIZE / PAGE_SIZE)
>> +		return NULL;
>> +
>> +	buf = kzalloc(sizeof(*buf), GFP_KERNEL);
>> +	if (!buf)
>> +		return NULL;
>> +
>> +	pagelist = kcalloc(nr_pages, sizeof(*pagelist), GFP_KERNEL);
>> +	if (!pagelist) {
>> +		kfree(buf);
>> +		return NULL;
>> +	}
>> +
>> +	for (i = 0; i < nr_pages; i++)
>> +		pagelist[i] = virt_to_page(pages[i]);
>> +
>> +	buf->base = vmap(pagelist, nr_pages, VM_MAP, PAGE_KERNEL);
>> +	if (!buf->base) {
>> +		kfree(pagelist);
>> +		kfree(buf);
>> +		return NULL;
>> +	}
>> +
>> +	buf->nr_pages = nr_pages;
>> +	buf->length = nr_pages * PAGE_SIZE;
>> +	buf->pos = 0;
>> +
>> +	kfree(pagelist);
>> +	return buf;
>> +}
>> +
>> +static void hisi_ptt_pmu_free_aux(void *aux)
>> +{
>> +	struct hisi_ptt_pmu_buf *buf = aux;
>> +
>> +	vunmap(buf->base);
>> +	kfree(buf);
>> +}
>> +
>> +static void hisi_ptt_pmu_start(struct perf_event *event, int flags)
>> +{
>> +	struct hisi_ptt *hisi_ptt = to_hisi_ptt(event->pmu);
>> +	struct perf_output_handle *handle = &hisi_ptt->trace_ctrl.handle;
>> +	struct hw_perf_event *hwc = &event->hw;
>> +	struct hisi_ptt_pmu_buf *buf;
>> +	int cpu = event->cpu;
>> +	int ret;
>> +
>> +	hwc->state = 0;
>> +	mutex_lock(&hisi_ptt->mutex);
>> +	if (hisi_ptt->trace_ctrl.status == HISI_PTT_TRACE_STATUS_ON) {
>> +		pci_dbg(hisi_ptt->pdev, "trace has already started\n");
>> +		goto stop;
>> +	}
>> +
>> +	if (cpu == -1)
>> +		cpu = hisi_ptt->trace_ctrl.default_cpu;
>> +
>> +	/*
>> +	 * Handle the interrupt on the same cpu which starts the trace to avoid
>> +	 * context mismatch. Otherwise we'll trigger the WARN from the perf
>> +	 * core in event_function_local().
>> +	 */
>> +	WARN_ON(irq_set_affinity(pci_irq_vector(hisi_ptt->pdev, HISI_PTT_TRACE_DMA_IRQ),
>> +				 cpumask_of(cpu)));
>> +
>> +	ret = hisi_ptt_alloc_trace_buf(hisi_ptt);
>> +	if (ret) {
>> +		pci_dbg(hisi_ptt->pdev, "alloc trace buf failed, ret = %d\n", ret);
>> +		goto stop;
>> +	}
>> +
>> +	buf = perf_aux_output_begin(handle, event);
>> +	if (!buf) {
>> +		pci_dbg(hisi_ptt->pdev, "aux output begin failed\n");
>> +		goto stop;
>> +	}
>> +
>> +	buf->pos = handle->head % buf->length;
>> +
>> +	ret = hisi_ptt_trace_start(hisi_ptt);
>> +	if (ret) {
>> +		pci_dbg(hisi_ptt->pdev, "trace start failed, ret = %d\n", ret);
>> +		perf_aux_output_end(handle, 0);
>> +		goto stop;
>> +	}
>> +
>> +	mutex_unlock(&hisi_ptt->mutex);
>> +	return;
>> +stop:
>> +	event->hw.state |= PERF_HES_STOPPED;
>> +	mutex_unlock(&hisi_ptt->mutex);
>> +}
>> +
>> +static void hisi_ptt_pmu_stop(struct perf_event *event, int flags)
>> +{
>> +	struct hisi_ptt *hisi_ptt = to_hisi_ptt(event->pmu);
>> +	struct hw_perf_event *hwc = &event->hw;
>> +
>> +	if (hwc->state & PERF_HES_STOPPED)
>> +		return;
>> +
>> +	mutex_lock(&hisi_ptt->mutex);
>> +	if (hisi_ptt->trace_ctrl.status == HISI_PTT_TRACE_STATUS_ON) {
>> +		hisi_ptt_trace_end(hisi_ptt);
>> +		WARN(hisi_ptt_wait_trace_hw_idle(hisi_ptt), "Device is still busy");
>> +		hisi_ptt_update_aux(hisi_ptt, hisi_ptt->trace_ctrl.buf_index, true);
>> +	}
>> +	mutex_unlock(&hisi_ptt->mutex);
>> +
>> +	hwc->state |= PERF_HES_STOPPED;
>> +	perf_event_update_userpage(event);
>> +	hwc->state |= PERF_HES_UPTODATE;
>> +}
>> +
>> +static int hisi_ptt_pmu_add(struct perf_event *event, int flags)
>> +{
>> +	struct hisi_ptt *hisi_ptt = to_hisi_ptt(event->pmu);
>> +	struct hw_perf_event *hwc = &event->hw;
>> +	int cpu = event->cpu;
>> +
>> +	if (cpu == -1 && smp_processor_id() != hisi_ptt->trace_ctrl.default_cpu)
>> +		return 0;
>> +
>> +	hwc->state = PERF_HES_STOPPED | PERF_HES_UPTODATE;
>> +
>> +	if (flags & PERF_EF_START) {
>> +		hisi_ptt_pmu_start(event, PERF_EF_RELOAD);
>> +		if (hwc->state & PERF_HES_STOPPED)
>> +			return -EINVAL;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static void hisi_ptt_pmu_del(struct perf_event *event, int flags)
>> +{
>> +	hisi_ptt_pmu_stop(event, PERF_EF_UPDATE);
>> +}
>> +
>> +static void hisi_ptt_unregister_pmu(void *priv)
>> +{
>> +	perf_pmu_unregister(priv);
>> +}
>> +
>> +static int hisi_ptt_register_pmu(struct hisi_ptt *hisi_ptt)
>> +{
>> +	char *pmu_name;
>> +	int ret;
>> +
>> +	hisi_ptt->hisi_ptt_pmu = (struct pmu) {
>> +		.module		= THIS_MODULE,
>> +		.capabilities	= PERF_PMU_CAP_EXCLUSIVE | PERF_PMU_CAP_ITRACE,
>> +		.task_ctx_nr	= perf_sw_context,
>> +		.attr_groups	= hisi_ptt_pmu_groups,
>> +		.event_init	= hisi_ptt_pmu_event_init,
>> +		.setup_aux	= hisi_ptt_pmu_setup_aux,
>> +		.free_aux	= hisi_ptt_pmu_free_aux,
>> +		.start		= hisi_ptt_pmu_start,
>> +		.stop		= hisi_ptt_pmu_stop,
>> +		.add		= hisi_ptt_pmu_add,
>> +		.del		= hisi_ptt_pmu_del,
>> +	};
>> +
>> +	pmu_name = devm_kasprintf(&hisi_ptt->pdev->dev, GFP_KERNEL, "hisi_ptt%u_%u",
>> +				  hisi_ptt->sicl_id, hisi_ptt->core_id);
>> +	if (!pmu_name)
>> +		return -ENOMEM;
>> +
>> +	ret = perf_pmu_register(&hisi_ptt->hisi_ptt_pmu, pmu_name, -1);
>> +	if (ret)
>> +		return ret;
>> +
>> +	return devm_add_action_or_reset(&hisi_ptt->pdev->dev,
>> +					hisi_ptt_unregister_pmu,
>> +					&hisi_ptt->hisi_ptt_pmu);
>> +}
>> +
>> +/*
>> + * Get RMR address if provided by the firmware.
>> + * Return 0 if the IOMMU doesn't present or the policy of the
>> + * IOMMU domain is passthrough or we get a usable RMR region.
>> + * Otherwise a negative value is returned.
>> + */
>> +static int hisi_ptt_get_rmr(struct hisi_ptt *hisi_ptt)
>> +{
>> +	struct pci_dev *pdev = hisi_ptt->pdev;
>> +	struct iommu_domain *iommu_domain;
>> +	struct iommu_resv_region *region;
>> +	LIST_HEAD(list);
>> +
>> +	/*
>> +	 * Use direct DMA if IOMMU does not present or the policy of the
>> +	 * IOMMU domain is passthrough.
>> +	 */
>> +	iommu_domain = iommu_get_domain_for_dev(&pdev->dev);
>> +	if (!iommu_domain || iommu_domain->type == IOMMU_DOMAIN_IDENTITY)
>> +		return 0;
>> +
>> +	iommu_get_resv_regions(&pdev->dev, &list);
>> +	list_for_each_entry(region, &list, list)
>> +		if (region->type == IOMMU_RESV_DIRECT &&
>> +		    region->length >= HISI_PTT_TRACE_BUFFER_SIZE) {
>> +			hisi_ptt->trace_ctrl.has_rmr = true;
>> +			hisi_ptt->trace_ctrl.rmr_addr = region->start;
>> +			hisi_ptt->trace_ctrl.rmr_length = region->length;
>> +			break;
>> +		}
>> +
>> +	iommu_put_resv_regions(&pdev->dev, &list);
>> +	return hisi_ptt->trace_ctrl.has_rmr ? 0 : -ENOMEM;
>> +}
>> +
>> +static int hisi_ptt_probe(struct pci_dev *pdev,
>> +			  const struct pci_device_id *id)
>> +{
>> +	struct hisi_ptt *hisi_ptt;
>> +	int ret;
>> +
>> +	hisi_ptt = devm_kzalloc(&pdev->dev, sizeof(*hisi_ptt), GFP_KERNEL);
>> +	if (!hisi_ptt)
>> +		return -ENOMEM;
>> +
>> +	mutex_init(&hisi_ptt->mutex);
>> +	hisi_ptt->pdev = pdev;
>> +
>> +	/*
>> +	 * Lifetime of pci_dev is longer than hisi_ptt,
>> +	 * so directly reference to the pci name string.
>> +	 */
>> +	hisi_ptt->name = pci_name(hisi_ptt->pdev);
>> +	pci_set_drvdata(pdev, hisi_ptt);
>> +
>> +	ret = pcim_enable_device(pdev);
>> +	if (ret) {
>> +		pci_err(pdev, "failed to enable device, ret = %d.\n", ret);
>> +		return ret;
>> +	}
>> +
>> +	ret = pcim_iomap_regions(pdev, BIT(2), hisi_ptt->name);
>> +	if (ret) {
>> +		pci_err(pdev, "failed to remap io memory, ret = %d.\n", ret);
>> +		return ret;
>> +	}
>> +
>> +	hisi_ptt->iobase = pcim_iomap_table(pdev)[2];
>> +
>> +	ret = dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(64));
>> +	if (ret) {
>> +		pci_err(pdev, "failed to set 64 bit dma mask, ret = %d.\n", ret);
>> +		return ret;
>> +	}
>> +	pci_set_master(pdev);
>> +
>> +	ret = hisi_ptt_register_irq(hisi_ptt);
>> +	if (ret)
>> +		return ret;
>> +
>> +	hisi_ptt_init_ctrls(hisi_ptt);
>> +
>> +	ret = hisi_ptt_register_pmu(hisi_ptt);
>> +	if (ret) {
>> +		pci_err(pdev, "failed to register pmu device, ret = %d", ret);
>> +		return ret;
>> +	}
> 
> If this fails the pci_free_irq_vectors() is not called.
> 

It'll be called as we've registered a devm callback when
allocating the irq vector. See hisi_ptt_register_irq().

> I am out of time for today - I will continue tomorrow.
> 

Sure. Thanks!
Yicong

> Thanks,
> Mathieu
> 
>> +
>> +	ret = hisi_ptt_get_rmr(hisi_ptt);
>> +	if (ret) {
>> +		pci_err(pdev, "failed to get RMR region, ret = %d", ret);
>> +		return ret;
>> +	}
>> +
>> +	/* Register the bus notifier for dynamically updating the filter list */
>> +	hisi_ptt->hisi_ptt_nb.notifier_call = hisi_ptt_notifier_call;
>> +	ret = bus_register_notifier(&pci_bus_type, &hisi_ptt->hisi_ptt_nb);
>> +	if (ret)
>> +		pci_warn(pdev, "failed to register filter update notifier, ret = %d", ret);
>> +
>> +	return 0;
>> +}
>> +
>> +void hisi_ptt_remove(struct pci_dev *pdev)
>> +{
>> +	struct hisi_ptt *hisi_ptt = pci_get_drvdata(pdev);
>> +
>> +	bus_unregister_notifier(&pci_bus_type, &hisi_ptt->hisi_ptt_nb);
>> +
>> +	/* Cancel any work that has been queued */
>> +	cancel_delayed_work_sync(&hisi_ptt->work);
>> +
>> +	if (hisi_ptt->trace_ctrl.status == HISI_PTT_TRACE_STATUS_ON)
>> +		hisi_ptt_trace_end(hisi_ptt);
>> +
>> +	hisi_ptt_free_trace_buf(hisi_ptt);
>> +	hisi_ptt_release_filters(hisi_ptt);
>> +}
>> +
>> +static const struct pci_device_id hisi_ptt_id_tbl[] = {
>> +	{ PCI_DEVICE(PCI_VENDOR_ID_HUAWEI, 0xa12e) },
>> +	{ }
>> +};
>> +MODULE_DEVICE_TABLE(pci, hisi_ptt_id_tbl);
>> +
>> +static struct pci_driver hisi_ptt_driver = {
>> +	.name = "hisi_ptt",
>> +	.id_table = hisi_ptt_id_tbl,
>> +	.probe = hisi_ptt_probe,
>> +	.remove = hisi_ptt_remove,
>> +};
>> +module_pci_driver(hisi_ptt_driver);
>> +
>> +MODULE_LICENSE("GPL v2");
>> +MODULE_AUTHOR("Yicong Yang <yangyicong@hisilicon.com>");
>> +MODULE_DESCRIPTION("Driver for HiSilicon PCIe tune and trace device");
>> -- 
>> 2.33.0
>>
> .
>

On 2021-11-18 09:01, Yicong Yang via iommu wrote:
> Hi Robin,
> 
> On 2021/11/16 19:37, Yicong Yang wrote:
>> On 2021/11/16 18:56, Robin Murphy wrote:
>>> On 2021-11-16 09:06, Yicong Yang via iommu wrote:
>>> [...]
>>>> +/*
>>>> + * Get RMR address if provided by the firmware.
>>>> + * Return 0 if the IOMMU doesn't present or the policy of the
>>>> + * IOMMU domain is passthrough or we get a usable RMR region.
>>>> + * Otherwise a negative value is returned.
>>>> + */
>>>> +static int hisi_ptt_get_rmr(struct hisi_ptt *hisi_ptt)
>>>> +{
>>>> +    struct pci_dev *pdev = hisi_ptt->pdev;
>>>> +    struct iommu_domain *iommu_domain;
>>>> +    struct iommu_resv_region *region;
>>>> +    LIST_HEAD(list);
>>>> +
>>>> +    /*
>>>> +     * Use direct DMA if IOMMU does not present or the policy of the
>>>> +     * IOMMU domain is passthrough.
>>>> +     */
>>>> +    iommu_domain = iommu_get_domain_for_dev(&pdev->dev);
>>>> +    if (!iommu_domain || iommu_domain->type == IOMMU_DOMAIN_IDENTITY)
>>>> +        return 0;
>>>> +
>>>> +    iommu_get_resv_regions(&pdev->dev, &list);
>>>> +    list_for_each_entry(region, &list, list)
>>>> +        if (region->type == IOMMU_RESV_DIRECT &&
>>>> +            region->length >= HISI_PTT_TRACE_BUFFER_SIZE) {
>>>> +            hisi_ptt->trace_ctrl.has_rmr = true;
>>>> +            hisi_ptt->trace_ctrl.rmr_addr = region->start;
>>>> +            hisi_ptt->trace_ctrl.rmr_length = region->length;
>>>> +            break;
>>>> +        }
>>>> +
>>>> +    iommu_put_resv_regions(&pdev->dev, &list);
>>>> +    return hisi_ptt->trace_ctrl.has_rmr ? 0 : -ENOMEM;
>>>> +}
>>>
>>> No.
>>>
>>> The whole point of RMRs is for devices that are already configured to access the given address range in a manner beyond the kernel's control. If you can do this, it proves that you should not have an RMR in the first place.
>>>
>>> The notion of a kernel driver explicitly configuring its device to DMA into any random RMR that looks big enough is so egregiously wrong that I'm almost lost for words...
>>>
>>
>> our bios will reserve such a region and reported it through iort. the device will write to the region and in the driver we need to access the region
>> to get the traced data. the region is reserved exclusively and will not be accessed by kernel or other devices.
>>
>> is it ok to let bios configure the address to the device and from CPU side we just read it?
>>
> 
> Any suggestion?  Is this still an issue you concern if we move the configuration of the device address to BIOS and just read from the CPU side?

If the firmware configures the device so that it's actively tracing and 
writing out to memory while the kernel boots, then that is a valid 
reason to have an RMR. However what you're doing in the driver is still 
complete nonsense. As far as I can follow, the way it's working is this:

- At probe time, the initial state of the hardware is entirely ignored. 
If it *is* already active, there appears to be a fun chance of crashing 
if TRACE_INT_MASK is clear and an interrupt happens to fire before 
anyone has got round to calling perf_aux_output_begin() to make 
trace_ctrl.handle.rb non-NULL.

- Later, once the user starts a tracing session, a buffer is set up 
*either* as a completely normal DMA allocation, or by memremap()ing some 
random IOVA carveout which may or may not be whatever memory the 
firmware was tracing to.

- The hardware is then reset and completely reprogrammed to use the new 
buffer, again without any consideration of its previous state (other 
than possibly timing out and failing if it's already running and that 
means it never goes idle).

Therefore the driver does not seem to respect any prior configuration of 
the device by firmware, does not seem to expect it to be running at boot 
time, does not seem to have any way to preserve and export any trace 
data captured in an RMR if it *was* running at boot time, and thus 
without loss of generality could simply use the dma_alloc_coherent() 
path all the time. Am I missing anything?

As things stand, RMRs are not yet supported upstream (FYI we're still 
working on fixing the spec...), so the code above is at best dead, and 
at worst actively wrong. Furthermore, if the expected usage model *is* 
that the kernel driver completely resets and reprograms the hardware, 
then even if there is an RMR for boot-time tracing I would rather expect 
it to be flagged as remappable, and thus potentially end up as an 
IOMMU_RESV_DIRECT_RELAXABLE reservation which you wouldn't match anyway.

And after all that, if you really do have a genuine need to respect and 
preserve prior firmware configuration of the device, then I would surely 
expect to see the driver actually doing exactly that. Presumably: at 
probe time, look at TRACE_CTRL; if the device is already configured, 
read out that configuration - especially including TRACE_ADDR_* - and 
make sure to reuse it. Not go off on a tangent blindly poking into 
internal IOMMU API abstractions in the vain hope that the first thing 
you find happens to be sort-of-related to the information that you 
actually care about.

Thanks,
Robin.

On Thu, Nov 25, 2021 at 04:39:46PM +0800, Yicong Yang wrote:
> Hi Mathieu,
> 
> Thanks for the comments! Replies inline.
> 
> On 2021/11/25 2:51, Mathieu Poirier wrote:
> > Hi Yicong,
> > 
> > On Tue, Nov 16, 2021 at 05:06:21PM +0800, Yicong Yang wrote:
> >> HiSilicon PCIe tune and trace device(PTT) is a PCIe Root Complex
> >> integrated Endpoint(RCiEP) device, providing the capability
> >> to dynamically monitor and tune the PCIe traffic(tune),
> >> and trace the TLP headers(trace).
> >>
> > 
> > Is there a reason to put "tune" and "trace" are whithin parentheses?  
> > 
> 
> yeah. I want to use these single word to denote the related function, and
> place them in the parantheses near the function's description to make sure
> readers can match them.
> 

Probably a better idea to simply write "TLP headers" and "PCIe traffic" when
referring to them.  Otherwise it is very confusing because the reader doesn't
know if you mean the acronym or the real definition of "tune" and "trace".

> >> Add the driver for the device to enable the trace function. The driver
> >> will create PMU device for each PTT device, and users can start trace
> >> through perf command.
> >>
> >> Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
> >> ---
> >>  drivers/Makefile                       |    1 +
> >>  drivers/hwtracing/Kconfig              |    2 +
> >>  drivers/hwtracing/hisilicon/Kconfig    |    8 +
> >>  drivers/hwtracing/hisilicon/Makefile   |    2 +
> >>  drivers/hwtracing/hisilicon/hisi_ptt.c | 1146 ++++++++++++++++++++++++
> > 
> > Not sure about the "hisilicon" directory.  Right now we have "coresight",
> > "intel_th" and "stm" - they concentrate on the technology rather than the
> > vendor.  I think "ptt" would be just fine: 
> > 
> > drivers/hwtracing/ptt/Kconfig 
> > drivers/hwtracing/ptt/Makefile
> > drivers/hwtracing/ptt/hisi_ptt.c
> > 
> > That way if other vendors want to introduce support for the same kind of
> > technology we can simply put them under "drivers/hwtracing/ptt/" and things are
> > still accurate.
> > 
> 
> sure. sounds sensible. will rename the directory to "ptt" if no objection.
> 
> > 
> >>  5 files changed, 1159 insertions(+)
> >>  create mode 100644 drivers/hwtracing/hisilicon/Kconfig
> >>  create mode 100644 drivers/hwtracing/hisilicon/Makefile
> >>  create mode 100644 drivers/hwtracing/hisilicon/hisi_ptt.c
> >>
> >> diff --git a/drivers/Makefile b/drivers/Makefile
> >> index be5d40ae1488..bb0dc9b55ea2 100644
> >> --- a/drivers/Makefile
> >> +++ b/drivers/Makefile
> >> @@ -176,6 +176,7 @@ obj-$(CONFIG_USB4)		+= thunderbolt/
> >>  obj-$(CONFIG_CORESIGHT)		+= hwtracing/coresight/
> >>  obj-y				+= hwtracing/intel_th/
> >>  obj-$(CONFIG_STM)		+= hwtracing/stm/
> >> +obj-$(CONFIG_HISI_PTT)         += hwtracing/hisilicon/
> >>  obj-$(CONFIG_ANDROID)		+= android/
> >>  obj-$(CONFIG_NVMEM)		+= nvmem/
> >>  obj-$(CONFIG_FPGA)		+= fpga/
> >> diff --git a/drivers/hwtracing/Kconfig b/drivers/hwtracing/Kconfig
> >> index 13085835a636..e3796b17541a 100644
> >> --- a/drivers/hwtracing/Kconfig
> >> +++ b/drivers/hwtracing/Kconfig
> >> @@ -5,4 +5,6 @@ source "drivers/hwtracing/stm/Kconfig"
> >>  
> >>  source "drivers/hwtracing/intel_th/Kconfig"
> >>  
> >> +source "drivers/hwtracing/hisilicon/Kconfig"
> >> +
> >>  endmenu
> >> diff --git a/drivers/hwtracing/hisilicon/Kconfig b/drivers/hwtracing/hisilicon/Kconfig
> >> new file mode 100644
> >> index 000000000000..9c3ab80d99fe
> >> --- /dev/null
> >> +++ b/drivers/hwtracing/hisilicon/Kconfig
> >> @@ -0,0 +1,8 @@
> >> +# SPDX-License-Identifier: GPL-2.0-only
> >> +config HISI_PTT
> >> +	tristate "HiSilicon PCIe Tune and Trace Device"
> >> +	depends on PCI && HAS_DMA && HAS_IOMEM
> > 
> > What Arm architecture are you aiming this for?  Can it be found on both armv7
> > and armv8?
> > 
> 
> currently the device will appear on Kunpeng 930, which is armv8.

Ok, then please make it dependent on armv8.

> 
> >> +	help
> >> +	  HiSilicon PCIe Tune and Trace Device exist as a PCIe RCiEP
> >> +	  device, provides support for PCIe traffic tuning and
> >> +	  tracing TLP headers to the memory.
> > 
> > Please indicate what the name of the driver will be when compiled as a module.
> > 
> 
> sure. will add the module's name here.
> 
> >> diff --git a/drivers/hwtracing/hisilicon/Makefile b/drivers/hwtracing/hisilicon/Makefile
> >> new file mode 100644
> >> index 000000000000..908c09a98161
> >> --- /dev/null
> >> +++ b/drivers/hwtracing/hisilicon/Makefile
> >> @@ -0,0 +1,2 @@
> >> +# SPDX-License-Identifier: GPL-2.0
> >> +obj-$(CONFIG_HISI_PTT) += hisi_ptt.o
> >> diff --git a/drivers/hwtracing/hisilicon/hisi_ptt.c b/drivers/hwtracing/hisilicon/hisi_ptt.c
> >> new file mode 100644
> >> index 000000000000..e11e9b6cc2a8
> >> --- /dev/null
> >> +++ b/drivers/hwtracing/hisilicon/hisi_ptt.c
> >> @@ -0,0 +1,1146 @@
> >> +// SPDX-License-Identifier: GPL-2.0
> >> +/*
> >> + * Driver for HiSilicon PCIe tune and trace device
> >> + *
> >> + * Copyright (c) 2021 HiSilicon Limited.
> >> + */
> >> +
> >> +#include <linux/bitfield.h>
> >> +#include <linux/bitops.h>
> >> +#include <linux/delay.h>
> >> +#include <linux/dma-iommu.h>
> >> +#include <linux/dma-mapping.h>
> >> +#include <linux/interrupt.h>
> >> +#include <linux/io.h>
> >> +#include <linux/iommu.h>
> >> +#include <linux/iopoll.h>
> >> +#include <linux/kfifo.h>
> >> +#include <linux/module.h>
> >> +#include <linux/notifier.h>
> >> +#include <linux/pci.h>
> >> +#include <linux/perf_event.h>
> >> +#include <linux/sizes.h>
> >> +#include <linux/sysfs.h>
> >> +#include <linux/vmalloc.h>
> >> +#include <linux/workqueue.h>
> >> +
> >> +#define HISI_PTT_TRACE_ADDR_SIZE	0x0800
> >> +#define HISI_PTT_TRACE_ADDR_BASE_LO_0	0x0810
> >> +#define HISI_PTT_TRACE_ADDR_BASE_HI_0	0x0814
> >> +#define HISI_PTT_TRACE_ADDR_STRIDE	0x8
> >> +#define HISI_PTT_TRACE_CTRL		0x0850
> >> +#define   HISI_PTT_TRACE_CTRL_EN	BIT(0)
> >> +#define   HISI_PTT_TRACE_CTRL_RST	BIT(1)
> >> +#define   HISI_PTT_TRACE_CTRL_RXTX_SEL	GENMASK(3, 2)
> >> +#define   HISI_PTT_TRACE_CTRL_TYPE_SEL	GENMASK(7, 4)
> >> +#define   HISI_PTT_TRACE_CTRL_DATA_FORMAT	BIT(14)
> >> +#define   HISI_PTT_TRACE_CTRL_FILTER_MODE	BIT(15)
> >> +#define   HISI_PTT_TRACE_CTRL_TARGET_SEL	GENMASK(31, 16)
> >> +#define HISI_PTT_TRACE_INT_STAT		0x0890
> >> +#define   HISI_PTT_TRACE_INT_STAT_MASK	GENMASK(3, 0)
> >> +#define HISI_PTT_TRACE_INT_MASK		0x0894
> >> +#define HISI_PTT_TRACE_WR_STS		0x08a0
> >> +#define   HISI_PTT_TRACE_WR_STS_WRITE	GENMASK(27, 0)
> >> +#define   HISI_PTT_TRACE_WR_STS_BUFFER	GENMASK(29, 28)
> >> +#define HISI_PTT_TRACE_STS		0x08b0
> >> +#define   HISI_PTT_TRACE_IDLE		BIT(0)
> >> +#define HISI_PTT_DEVICE_RANGE		0x0fe0
> >> +#define HISI_PTT_LOCATION		0x0fe8
> >> +#define   HISI_PTT_CORE_ID		GENMASK(15, 0)
> >> +#define   HISI_PTT_SICL_ID		GENMASK(31, 16)
> > 
> > Extra spaces between #define and the literals.  Please align the values with
> > that of HISI_PTT_TRACE_DMA_IRQ below.
> > 
> 
> Spaces are intended to distinguish the definition of the register offset and
> related register fields. also used in include/uapi/linux/pci_regs.h.
>

Interesting and definitely not the norm...

> HISI_PTT_TRACE_DMA_IRQ is well aligned with tab but seems with problem display
> in the mail text, maybe because the tab is not 8 characters when display.
> 

In my VI terminal the '0' of HISI_PTT_TRACE_DMA_IRQ is align with the '3' in
GENMASK(31, 16) and I suspect it is the same for other people.

> >> +
> >> +#define HISI_PTT_TRACE_DMA_IRQ			0
> >> +#define HISI_PTT_TRACE_BUFLETS_CNT		4
> >> +#define HISI_PTT_TRACE_BUFLET_SIZE		SZ_4M
> >> +#define HISI_PTT_TRACE_BUFFER_SIZE		(HISI_PTT_TRACE_BUFLET_SIZE * \
> >> +						 HISI_PTT_TRACE_BUFLETS_CNT)
> >> +#define HISI_PTT_FILTER_UPDATE_FIFO_SIZE	16
> >> +
> >> +/* Delay time for filter updating work */
> >> +#define HISI_PTT_WORK_DELAY_MS		100UL
> >> +/* Wait time for DMA hardware to reset */
> >> +#define HISI_PTT_RESET_WAIT_MS		1000UL
> >> +/* Poll timeout and interval for waiting hardware work to finish */
> >> +#define HISI_PTT_WAIT_TIMEOUT_US	1000000UL
> >> +#define HISI_PTT_WAIT_POLL_INTERVAL_US	100UL
> >> +
> >> +#define HISI_PCIE_CORE_PORT_ID(devfn)	(PCI_FUNC(devfn) << 1)
> >> +
> >> +enum hisi_ptt_trace_status {
> >> +	HISI_PTT_TRACE_STATUS_OFF = 0,
> >> +	HISI_PTT_TRACE_STATUS_ON,
> >> +};
> >> +
> >> +struct hisi_ptt_dma_buflet {
> > 
> > I'm not sure what a "buflet" is...  Probably best to just call this
> > hisi_ptt_dma_buffer" if it pertains to a buffer.  On that note it is hard to
> > know due to the lack of proper structure documentation.  Please have a look at
> > how "coresight_device" is documented.  The same applies to the rest of the
> > structures declared below.
> > 
> 
> It's mentioned in section 5 of hisi_ptt.rst as "Driver will allocate each DMA buffer
> (we call it buflet) of 4MiB ...".

I just noticed the documentation in patch 5 - I will read it before continuing
with this set.

> 
> The total DMA buffer of PTT device is divided into 4 parts, and each part is called
> a 'buflet', which means a small buffer (there exists other words with similiar
> format: droplet, wavelet, ...).
> 
> The device is designed like this to make sure we won't lose any data when we have to change
> the buffer address, the device can continue to write to the next buflet and don't
> neet to pause.
> 
> >> +	struct list_head list;
> >> +	unsigned int size;
> >> +	dma_addr_t dma;
> >> +
> >> +	/*
> >> +	 * The address of the buflet holding the trace data.
> >> +	 * See Documentation/trace/hisi-ptt.rst for the details
> > 
> > As of this writing, hisi-ptt.rst doesn't exist.
> > 
> 
> The comment intends to direct the user to the documentation if the user
> want to know details about the data format. The data format is decribed
> in the section 4 of the doc.
> 
> >> +	 * of the data format.
> >> +	 */
> >> +	void *addr;
> >> +	int index;
> >> +};
> >> +
> >> +struct hisi_ptt_trace_ctrl {
> >> +	enum hisi_ptt_trace_status status;
> >> +	struct perf_output_handle handle;
> >> +	struct list_head trace_buf;
> >> +	/*
> >> +	 * The index of the buffer which trace data
> >> +	 * currently is writing to.
> >> +	 */
> >> +	u32 buf_index;
> >> +
> >> +	int default_cpu;
> >> +	u32 buflet_size;
> >> +	bool is_port;
> >> +	u32 format:1;		/* Format of the traced TLP headers */
> >> +	u32 type:4;		/* Type of the TLP headers to trace */
> >> +	u32 direction:2;	/* Direction of the TLP headers to trace */
> >> +	u32 filter:16;		/* Root port or Requester to filter the TLP headers */
> >> +
> >> +	phys_addr_t rmr_addr;
> >> +	size_t rmr_length;
> >> +	bool has_rmr;
> >> +};
> >> +
> >> +struct hisi_ptt_filter_desc {
> >> +	struct list_head list;
> >> +	struct pci_dev *pdev;
> >> +	u16 val;
> >> +};
> >> +
> >> +struct hisi_ptt_pmu_buf {
> >> +	size_t length;
> >> +	int nr_pages;
> >> +	void *base;
> >> +	long pos;
> >> +};
> >> +
> >> +/* Structure containing the information for filter updating */
> >> +struct hisi_ptt_filter_update_info {
> >> +	struct pci_dev *pdev;
> >> +	u32 port_devid;
> >> +	bool is_port;
> >> +	bool is_add;
> >> +	u16 val;
> >> +};
> >> +
> >> +struct hisi_ptt {
> >> +	struct hisi_ptt_trace_ctrl trace_ctrl;
> >> +	struct notifier_block hisi_ptt_nb;
> >> +	struct pmu hisi_ptt_pmu;
> >> +	void __iomem *iobase;
> >> +	struct pci_dev *pdev;
> >> +	/*
> >> +	 * Use the mutex to protect the filter list and
> >> +	 * serialize the perf process.
> >> +	 */
> >> +	struct mutex mutex;
> >> +	const char *name;
> >> +	u16 core_id;
> >> +	u16 sicl_id;
> >> +	/* PCI device range managed by the PTT device */
> >> +	u32 upper;
> >> +	u32 lower;
> >> +	u8 busnr;
> >> +
> >> +	/*
> >> +	 * The trace TLP headers can either be filtered by certain
> >> +	 * root port, or by the requester ID. Organize the filters
> >> +	 * by @port_filters and @req_filters here. The mask of all
> >> +	 * the valid ports is also cached for doing sanity check
> >> +	 * of user input.
> >> +	 */
> >> +	struct list_head port_filters;
> >> +	struct list_head req_filters;
> >> +	u16 port_mask;
> >> +
> >> +	/*
> >> +	 * We use a delayed work here to avoid indefinitely waiting for
> >> +	 * the hisi_ptt->mutex which protecting the filter list. The
> >> +	 * work will be delayed only if the mutex can not be held,
> >> +	 * otherwise no delay will be applied.
> >> +	 */
> >> +	struct delayed_work work;
> >> +	spinlock_t filter_update_lock;
> >> +	DECLARE_KFIFO(filter_update_kfifo, struct hisi_ptt_filter_update_info,
> >> +		      HISI_PTT_FILTER_UPDATE_FIFO_SIZE);
> >> +};
> > 
> > It might be a good idea to spinoff a hisi_ptt.h for the above declarations.
> > 
> 
> I'm not sure whether it is common or permitted to provide a header which is only used by
> this driver with a single file.

I've seen it done many times.

> 
> >> +
> >> +static inline struct hisi_ptt *to_hisi_ptt(struct pmu *pmu)
> >> +{
> >> +	return container_of(pmu, struct hisi_ptt, hisi_ptt_pmu);
> >> +}
> > 
> > I'm not sure there is any value to this inline function.  I suggest to simply
> > call container_of() whenever it is needed.
> > 
> 
> ok.
> 
> >> +
> >> +static u16 hisi_ptt_get_filter_val(struct pci_dev *pdev)
> >> +{
> >> +	if (pci_pcie_type(pdev) == PCI_EXP_TYPE_ROOT_PORT)
> >> +		return BIT(HISI_PCIE_CORE_PORT_ID(PCI_SLOT(pdev->devfn)));
> >> +
> >> +	return PCI_DEVID(pdev->bus->number, pdev->devfn);
> >> +}
> >> +
> >> +static int hisi_ptt_wait_trace_hw_idle(struct hisi_ptt *hisi_ptt)
> >> +{
> >> +	u32 val;
> >> +
> >> +	return readl_poll_timeout(hisi_ptt->iobase + HISI_PTT_TRACE_STS, val,
> >> +				  val & HISI_PTT_TRACE_IDLE,
> >> +				  HISI_PTT_WAIT_POLL_INTERVAL_US,
> >> +				  HISI_PTT_WAIT_TIMEOUT_US);
> >> +}
> >> +
> >> +static void hisi_ptt_free_trace_buf(struct hisi_ptt *hisi_ptt)
> >> +{
> >> +	struct hisi_ptt_trace_ctrl *ctrl = &hisi_ptt->trace_ctrl;
> >> +	struct device *dev = &hisi_ptt->pdev->dev;
> >> +	struct hisi_ptt_dma_buflet *buflet, *tbuflet;
> >> +
> >> +	list_for_each_entry_safe(buflet, tbuflet, &ctrl->trace_buf, list) {
> >> +		list_del(&buflet->list);
> >> +
> >> +		if (ctrl->has_rmr)
> >> +			memunmap(buflet->addr);
> >> +		else
> >> +			dma_free_coherent(dev, buflet->size, buflet->addr,
> >> +					  buflet->dma);
> >> +
> >> +		kfree(buflet);
> >> +	}
> >> +}
> >> +
> >> +static int hisi_ptt_alloc_trace_buf(struct hisi_ptt *hisi_ptt)
> >> +{
> >> +	struct hisi_ptt_trace_ctrl *ctrl = &hisi_ptt->trace_ctrl;
> >> +	struct device *dev = &hisi_ptt->pdev->dev;
> >> +	struct hisi_ptt_dma_buflet *buflet;
> >> +	int i, ret;
> >> +
> >> +	hisi_ptt->trace_ctrl.buf_index = 0;
> >> +
> >> +	/* Make sure the trace buffer is empty before allocating */
> >> +	if (!list_empty(&ctrl->trace_buf)) {
> >> +		list_for_each_entry(buflet, &ctrl->trace_buf, list)
> >> +			memset(buflet->addr, 0, buflet->size);
> >> +		return 0;
> >> +	}
> >> +
> >> +	for (i = 0; i < HISI_PTT_TRACE_BUFLETS_CNT; ++i) {
> >> +		buflet = kzalloc(sizeof(*buflet), GFP_KERNEL);
> >> +		if (!buflet) {
> >> +			ret = -ENOMEM;
> >> +			goto err;
> >> +		}
> >> +
> >> +		if (ctrl->has_rmr) {
> >> +			phys_addr_t base = ctrl->rmr_addr + i * ctrl->buflet_size;
> >> +
> >> +			buflet->dma = base;
> >> +			buflet->addr = memremap(base, ctrl->buflet_size, MEMREMAP_WB);
> >> +		} else {
> >> +			buflet->addr = dma_alloc_coherent(dev, ctrl->buflet_size,
> >> +							  &buflet->dma, GFP_KERNEL);
> >> +		}
> >> +
> >> +		if (!buflet->addr) {
> >> +			kfree(buflet);
> >> +			ret = -ENOMEM;
> >> +			goto err;
> >> +		}
> >> +
> >> +		memset(buflet->addr, 0, buflet->size);
> >> +
> >> +		buflet->index = i;
> >> +		buflet->size = ctrl->buflet_size;
> >> +		list_add_tail(&buflet->list, &ctrl->trace_buf);
> >> +	}
> >> +
> >> +	return 0;
> >> +err:
> >> +	hisi_ptt_free_trace_buf(hisi_ptt);
> >> +	return ret;
> >> +}
> >> +
> >> +static void hisi_ptt_trace_end(struct hisi_ptt *hisi_ptt)
> >> +{
> >> +	writel(0, hisi_ptt->iobase + HISI_PTT_TRACE_CTRL);
> >> +	hisi_ptt->trace_ctrl.status = HISI_PTT_TRACE_STATUS_OFF;
> >> +}
> >> +
> >> +static int hisi_ptt_trace_start(struct hisi_ptt *hisi_ptt)
> >> +{
> >> +	struct hisi_ptt_trace_ctrl *ctrl = &hisi_ptt->trace_ctrl;
> >> +	struct hisi_ptt_dma_buflet *cur;
> >> +	u32 val;
> >> +
> >> +	/* Check device idle before start trace */
> >> +	if (hisi_ptt_wait_trace_hw_idle(hisi_ptt)) {
> >> +		pci_err(hisi_ptt->pdev, "Failed to start trace, the device is still busy.\n");
> >> +		return -EBUSY;
> >> +	}
> >> +
> >> +	/* Reset the DMA before start tracing */
> >> +	val = readl(hisi_ptt->iobase + HISI_PTT_TRACE_CTRL);
> >> +	val |= HISI_PTT_TRACE_CTRL_RST;
> >> +	writel(val, hisi_ptt->iobase + HISI_PTT_TRACE_CTRL);
> >> +
> >> +	/*
> >> +	 * We'll be in the perf context where preemption is disabled,
> >> +	 * so use busy loop here.
> >> +	 */
> >> +	mdelay(HISI_PTT_RESET_WAIT_MS);
> >> +
> >> +	val = readl(hisi_ptt->iobase + HISI_PTT_TRACE_CTRL);
> >> +	val &= ~HISI_PTT_TRACE_CTRL_RST;
> >> +	writel(val, hisi_ptt->iobase + HISI_PTT_TRACE_CTRL);
> >> +
> >> +	/* clear the interrupt status */
> >> +	writel(HISI_PTT_TRACE_INT_STAT_MASK, hisi_ptt->iobase + HISI_PTT_TRACE_INT_STAT);
> >> +	writel(0, hisi_ptt->iobase + HISI_PTT_TRACE_INT_MASK);
> >> +
> >> +	list_for_each_entry(cur, &ctrl->trace_buf, list) {
> >> +		writel(lower_32_bits(cur->dma),
> >> +		       hisi_ptt->iobase + HISI_PTT_TRACE_ADDR_BASE_LO_0 +
> >> +		       cur->index * HISI_PTT_TRACE_ADDR_STRIDE);
> >> +		writel(upper_32_bits(cur->dma),
> >> +		       hisi_ptt->iobase + HISI_PTT_TRACE_ADDR_BASE_HI_0 +
> >> +		       cur->index * HISI_PTT_TRACE_ADDR_STRIDE);
> >> +	}
> >> +	writel(ctrl->buflet_size, hisi_ptt->iobase + HISI_PTT_TRACE_ADDR_SIZE);
> >> +
> >> +	/* set the trace control register */
> >> +	val = FIELD_PREP(HISI_PTT_TRACE_CTRL_TYPE_SEL, ctrl->type);
> >> +	val |= FIELD_PREP(HISI_PTT_TRACE_CTRL_RXTX_SEL, ctrl->direction);
> >> +	val |= FIELD_PREP(HISI_PTT_TRACE_CTRL_DATA_FORMAT, ctrl->format);
> >> +	val |= FIELD_PREP(HISI_PTT_TRACE_CTRL_TARGET_SEL, hisi_ptt->trace_ctrl.filter);
> >> +	if (!hisi_ptt->trace_ctrl.is_port)
> >> +		val |= HISI_PTT_TRACE_CTRL_FILTER_MODE;
> >> +
> >> +	val |= HISI_PTT_TRACE_CTRL_EN;
> >> +	writel(val, hisi_ptt->iobase + HISI_PTT_TRACE_CTRL);
> >> +
> >> +	ctrl->status = HISI_PTT_TRACE_STATUS_ON;
> >> +
> >> +	return 0;
> >> +}
> >> +
> >> +static int hisi_ptt_update_aux(struct hisi_ptt *hisi_ptt, int index, bool stop)
> >> +{
> >> +	struct perf_output_handle *handle = &hisi_ptt->trace_ctrl.handle;
> >> +	struct perf_event *event = handle->event;
> >> +	struct hisi_ptt_dma_buflet *cur;
> >> +	struct hisi_ptt_pmu_buf *buf;
> >> +
> >> +	buf = perf_get_aux(handle);
> >> +	if (!buf || !handle->size)
> >> +		return -EINVAL;
> >> +
> >> +	list_for_each_entry(cur, &hisi_ptt->trace_ctrl.trace_buf, list)
> >> +		if (cur->index == index)
> >> +			break;
> >> +
> >> +	memcpy(buf->base + buf->pos, cur->addr, cur->size);
> >> +	memset(cur->addr, 0, cur->size);
> >> +	buf->pos += cur->size;
> >> +
> >> +	if (stop) {
> >> +		perf_aux_output_end(handle, buf->pos);
> >> +	} else if (buf->length - buf->pos < cur->size) {
> >> +		perf_aux_output_skip(handle, buf->length - buf->pos);
> >> +		perf_aux_output_end(handle, buf->pos);
> >> +
> >> +		buf = perf_aux_output_begin(handle, event);
> >> +		if (!buf)
> >> +			return -EINVAL;
> >> +
> >> +		buf->pos = handle->head % buf->length;
> >> +		if (buf->length - buf->pos < cur->size) {
> >> +			perf_aux_output_end(handle, 0);
> >> +			return -EINVAL;
> >> +		}
> >> +	}
> >> +
> >> +	return 0;
> >> +}
> >> +
> >> +static irqreturn_t hisi_ptt_isr(int irq, void *context)
> >> +{
> >> +	struct hisi_ptt *hisi_ptt = context;
> >> +	u32 status, buf_idx;
> >> +
> >> +	status = readl(hisi_ptt->iobase + HISI_PTT_TRACE_INT_STAT);
> >> +	buf_idx = ffs(status) - 1;
> >> +
> >> +	/* Clear the interrupt status of buflet @buf_idx */
> >> +	writel(status, hisi_ptt->iobase + HISI_PTT_TRACE_INT_STAT);
> >> +
> >> +	/*
> >> +	 * Update the AUX buffer and cache the current buflet index,
> >> +	 * as we need to know this and save the data when the trace
> >> +	 * is ended out of the interrupt handler. End the trace
> >> +	 * if the updating fails.
> >> +	 */
> >> +	if (hisi_ptt_update_aux(hisi_ptt, buf_idx, false))
> >> +		hisi_ptt_trace_end(hisi_ptt);
> >> +	else
> >> +		hisi_ptt->trace_ctrl.buf_index = (buf_idx + 1) % HISI_PTT_TRACE_BUFLETS_CNT;
> >> +
> >> +	return IRQ_HANDLED;
> >> +}
> >> +
> >> +static irqreturn_t hisi_ptt_irq(int irq, void *context)
> >> +{
> >> +	struct hisi_ptt *hisi_ptt = context;
> >> +	u32 status;
> >> +
> >> +	status = readl(hisi_ptt->iobase + HISI_PTT_TRACE_INT_STAT);
> >> +	if (!(status & HISI_PTT_TRACE_INT_STAT_MASK))
> >> +		return IRQ_NONE;
> >> +
> >> +	return IRQ_WAKE_THREAD;
> >> +}
> >> +
> >> +static void hisi_ptt_irq_free_vectors(void *pdev)
> >> +{
> >> +	pci_free_irq_vectors(pdev);
> >> +}
> >> +
> >> +static int hisi_ptt_register_irq(struct hisi_ptt *hisi_ptt)
> >> +{
> >> +	struct pci_dev *pdev = hisi_ptt->pdev;
> >> +	int ret;
> >> +
> >> +	ret = pci_alloc_irq_vectors(pdev, 1, 1, PCI_IRQ_MSI);
> >> +	if (ret < 0) {
> >> +		pci_err(pdev, "failed to allocate irq vector, ret = %d.\n", ret);
> >> +		return ret;
> >> +	}
> >> +
> >> +	ret = devm_add_action_or_reset(&pdev->dev, hisi_ptt_irq_free_vectors, pdev);
> >> +	if (ret < 0)
> >> +		return ret;
> >> +
> >> +	ret = devm_request_threaded_irq(&pdev->dev,
> >> +					pci_irq_vector(pdev, HISI_PTT_TRACE_DMA_IRQ),
> >> +					hisi_ptt_irq, hisi_ptt_isr, 0,
> >> +					"hisi-ptt", hisi_ptt);
> >> +	if (ret) {
> >> +		pci_err(pdev, "failed to request irq %d, ret = %d.\n",
> >> +			pci_irq_vector(pdev, HISI_PTT_TRACE_DMA_IRQ), ret);
> >> +		return ret;
> >> +	}
> >> +
> >> +	return 0;
> >> +}
> >> +
> >> +static void hisi_ptt_update_filters(struct work_struct *work)
> >> +{
> >> +	struct delayed_work *delayed_work = to_delayed_work(work);
> >> +	struct hisi_ptt_filter_update_info info;
> >> +	struct hisi_ptt_filter_desc *filter;
> >> +	struct list_head *target_list;
> >> +	struct hisi_ptt *hisi_ptt;
> >> +
> >> +	hisi_ptt = container_of(delayed_work, struct hisi_ptt, work);
> >> +
> >> +	if (!mutex_trylock(&hisi_ptt->mutex)) {
> >> +		schedule_delayed_work(&hisi_ptt->work, HISI_PTT_WORK_DELAY_MS);
> >> +		return;
> >> +	}
> >> +
> >> +	while (kfifo_get(&hisi_ptt->filter_update_kfifo, &info)) {
> >> +		target_list = info.is_port ? &hisi_ptt->port_filters :
> >> +			      &hisi_ptt->req_filters;
> >> +
> >> +		if (info.is_add) {
> >> +			filter = kzalloc(sizeof(*filter), GFP_KERNEL);
> >> +			if (!filter)
> >> +				continue;
> >> +
> >> +			filter->pdev = info.pdev;
> >> +			filter->val = info.val;
> >> +
> >> +			list_add_tail(&filter->list, target_list);
> >> +		} else {
> >> +			list_for_each_entry(filter, target_list, list)
> >> +				if (filter->val == info.val) {
> >> +					list_del(&filter->list);
> >> +					kfree(filter);
> >> +					break;
> >> +				}
> >> +		}
> >> +
> >> +		/* Update the available port mask */
> >> +		if (!info.is_port)
> >> +			continue;
> >> +
> >> +		if (info.is_add)
> >> +			hisi_ptt->port_mask |= info.val;
> >> +		else
> >> +			hisi_ptt->port_mask &= ~info.val;
> >> +	}
> >> +
> >> +	mutex_unlock(&hisi_ptt->mutex);
> >> +}
> >> +
> >> +static void hisi_ptt_update_fifo_in(struct hisi_ptt *hisi_ptt,
> >> +				    struct hisi_ptt_filter_update_info *info)
> >> +{
> >> +	struct pci_dev *root_port = pcie_find_root_port(info->pdev);
> >> +
> >> +	if (!root_port)
> >> +		return;
> >> +
> >> +	info->port_devid = PCI_DEVID(root_port->bus->number, root_port->devfn);
> >> +	if (info->port_devid < hisi_ptt->lower ||
> >> +	    info->port_devid > hisi_ptt->upper)
> >> +		return;
> >> +
> >> +	info->is_port = pci_pcie_type(info->pdev) == PCI_EXP_TYPE_ROOT_PORT;
> >> +	info->val = hisi_ptt_get_filter_val(info->pdev);
> >> +
> >> +	if (kfifo_in_spinlocked(&hisi_ptt->filter_update_kfifo, info, 1,
> >> +				&hisi_ptt->filter_update_lock))
> >> +		schedule_delayed_work(&hisi_ptt->work, 0);
> >> +	else
> >> +		pci_warn(hisi_ptt->pdev,
> >> +			 "filter update fifo overflow for target %s\n",
> >> +			 pci_name(info->pdev));
> >> +}
> >> +
> >> +/*
> >> + * A PCI bus notifier is used here for dynamically updating the filter
> >> + * list.
> >> + */
> >> +static int hisi_ptt_notifier_call(struct notifier_block *nb, unsigned long action,
> >> +				  void *data)
> >> +{
> >> +	struct hisi_ptt *hisi_ptt = container_of(nb, struct hisi_ptt, hisi_ptt_nb);
> >> +	struct hisi_ptt_filter_update_info info;
> >> +	struct device *dev = data;
> >> +	struct pci_dev *pdev = to_pci_dev(dev);
> >> +
> >> +	info.pdev = pdev;
> >> +
> >> +	switch (action) {
> >> +	case BUS_NOTIFY_ADD_DEVICE:
> >> +		info.is_add = true;
> >> +		break;
> >> +	case BUS_NOTIFY_DEL_DEVICE:
> >> +		info.is_add = false;
> >> +		break;
> >> +	default:
> >> +		return 0;
> >> +	}
> >> +
> >> +	hisi_ptt_update_fifo_in(hisi_ptt, &info);
> >> +
> >> +	return 0;
> >> +}
> >> +
> >> +static int hisi_ptt_init_filters(struct pci_dev *pdev, void *data)
> >> +{
> >> +	struct hisi_ptt_filter_update_info info = {
> >> +		.pdev = pdev,
> >> +		.is_add = true,
> >> +	};
> >> +	struct hisi_ptt *hisi_ptt = data;
> >> +
> >> +	hisi_ptt_update_fifo_in(hisi_ptt, &info);
> >> +
> >> +	return 0;
> >> +}
> >> +
> >> +static void hisi_ptt_release_filters(struct hisi_ptt *hisi_ptt)
> >> +{
> >> +	struct hisi_ptt_filter_desc *filter, *tfilter;
> >> +
> >> +	list_for_each_entry_safe(filter, tfilter, &hisi_ptt->req_filters, list) {
> >> +		list_del(&filter->list);
> >> +		kfree(filter);
> >> +	}
> >> +
> >> +	list_for_each_entry_safe(filter, tfilter, &hisi_ptt->port_filters, list) {
> >> +		list_del(&filter->list);
> >> +		kfree(filter);
> >> +	}
> >> +}
> >> +
> >> +static void hisi_ptt_init_ctrls(struct hisi_ptt *hisi_ptt)
> >> +{
> >> +	struct pci_dev *pdev = hisi_ptt->pdev;
> >> +	struct pci_bus *bus;
> >> +	u32 reg;
> >> +
> >> +	INIT_DELAYED_WORK(&hisi_ptt->work, hisi_ptt_update_filters);
> >> +	spin_lock_init(&hisi_ptt->filter_update_lock);
> >> +	INIT_KFIFO(hisi_ptt->filter_update_kfifo);
> >> +	INIT_LIST_HEAD(&hisi_ptt->port_filters);
> >> +	INIT_LIST_HEAD(&hisi_ptt->req_filters);
> >> +
> >> +	/*
> >> +	 * The device range register provides the information about the
> >> +	 * root ports which the RCiEP can control and trace. The RCiEP
> >> +	 * and the root ports it support are on the same PCIe core, with
> >> +	 * same domain number but maybe different bus number. The device
> >> +	 * range register will tell us which root ports we can support,
> >> +	 * Bit[31:16] indicates the upper BDF numbers of the root port,
> >> +	 * while Bit[15:0] indicates the lower.
> >> +	 */
> >> +	reg = readl(hisi_ptt->iobase + HISI_PTT_DEVICE_RANGE);
> >> +	hisi_ptt->upper = reg >> 16;
> >> +	hisi_ptt->lower = reg & 0xffff;
> >> +	hisi_ptt->busnr = PCI_BUS_NUM(hisi_ptt->upper);
> >> +
> >> +	reg = readl(hisi_ptt->iobase + HISI_PTT_LOCATION);
> >> +	hisi_ptt->core_id = FIELD_GET(HISI_PTT_CORE_ID, reg);
> >> +	hisi_ptt->sicl_id = FIELD_GET(HISI_PTT_SICL_ID, reg);
> >> +
> >> +	bus = pci_find_bus(pci_domain_nr(pdev->bus), hisi_ptt->busnr);
> >> +	if (bus)
> >> +		pci_walk_bus(bus, hisi_ptt_init_filters, hisi_ptt);
> > 
> > What happens if bus is NULL?  Should this be reported to the caller and cause
> > hisi_ptt_probe() to fail?  Please add a comment that describes the scenario.
> > 
> 
> It's ok if the list is NULL in the probe process,
> as the device maybe hotplugged after the PTT driver probe, in which case
> we can detect the event and update the list as we register a bus notifier.
> 

Please add the above as a comment in the code.


> >> +
> >> +	/* Initialize trace controls */
> >> +	INIT_LIST_HEAD(&hisi_ptt->trace_ctrl.trace_buf);
> >> +	hisi_ptt->trace_ctrl.buflet_size = HISI_PTT_TRACE_BUFLET_SIZE;
> >> +	hisi_ptt->trace_ctrl.default_cpu = cpumask_first(cpumask_of_node(dev_to_node(&pdev->dev)));
> >> +}
> >> +
> >> +#define HISI_PTT_PMU_FILTER_IS_PORT	BIT(19)
> >> +#define HISI_PTT_PMU_FILTER_VAL_MASK	GENMASK(15, 0)
> >> +#define HISI_PTT_PMU_DIRECTION_MASK	GENMASK(23, 20)
> >> +#define HISI_PTT_PMU_TYPE_MASK		GENMASK(31, 24)
> >> +#define HISI_PTT_PMU_FORMAT_MASK	GENMASK(35, 32)
> >> +
> >> +static ssize_t available_filters_show(struct device *dev,
> >> +				      struct device_attribute *attr,
> >> +				      char *buf)
> >> +{
> >> +	struct hisi_ptt *hisi_ptt = to_hisi_ptt(dev_get_drvdata(dev));
> >> +	struct hisi_ptt_filter_desc *filter;
> >> +	int pos = 0;
> >> +
> >> +	if (list_empty(&hisi_ptt->port_filters))
> >> +		return sysfs_emit(buf, "#### No available filter ####\n");
> >> +
> >> +	mutex_lock(&hisi_ptt->mutex);
> >> +	pos += sysfs_emit_at(buf, pos, "#### Root Ports ####\n");
> >> +	list_for_each_entry(filter, &hisi_ptt->port_filters, list)
> >> +		pos += sysfs_emit_at(buf, pos, "%s	0x%05lx\n",
> >> +				     pci_name(filter->pdev),
> >> +				     hisi_ptt_get_filter_val(filter->pdev) |
> >> +				     HISI_PTT_PMU_FILTER_IS_PORT);
> >> +
> >> +	pos += sysfs_emit_at(buf, pos, "#### Requesters ####\n");
> >> +	list_for_each_entry(filter, &hisi_ptt->req_filters, list)
> >> +		pos += sysfs_emit_at(buf, pos, "%s	0x%05x\n",
> >> +				     pci_name(filter->pdev),
> >> +				     hisi_ptt_get_filter_val(filter->pdev));
> >> +
> >> +	mutex_unlock(&hisi_ptt->mutex);
> >> +	return pos;
> >> +}
> >> +static DEVICE_ATTR_ADMIN_RO(available_filters);
> >> +
> >> +PMU_FORMAT_ATTR(filter,		"config:0-19");
> >> +PMU_FORMAT_ATTR(direction,	"config:20-23");
> >> +PMU_FORMAT_ATTR(type,		"config:24-31");
> >> +PMU_FORMAT_ATTR(format,		"config:32-35");
> >> +
> >> +static struct attribute *hisi_ptt_pmu_format_attrs[] = {
> >> +	&format_attr_filter.attr,
> >> +	&format_attr_direction.attr,
> >> +	&format_attr_type.attr,
> >> +	&format_attr_format.attr,
> >> +	NULL
> >> +};
> >> +
> >> +static struct attribute_group hisi_ptt_pmu_format_group = {
> >> +	.name = "format",
> >> +	.attrs = hisi_ptt_pmu_format_attrs,
> >> +};
> >> +
> >> +static struct attribute *hisi_ptt_pmu_filter_attrs[] = {
> >> +	&dev_attr_available_filters.attr,
> >> +	NULL
> >> +};
> >> +
> >> +static struct attribute_group hisi_ptt_pmu_filter_group = {
> >> +	.attrs = hisi_ptt_pmu_filter_attrs,
> >> +};
> >> +
> >> +static const struct attribute_group *hisi_ptt_pmu_groups[] = {
> >> +	&hisi_ptt_pmu_format_group,
> >> +	&hisi_ptt_pmu_filter_group,
> >> +	NULL
> >> +};
> >> +
> >> +/*
> >> + * The supported value of the direction parameter. See hisi_ptt.rst
> >> + * documentation for more details.
> >> + */
> >> +static u32 hisi_ptt_trace_available_direction[] = {
> >> +	0,
> >> +	1,
> >> +	2,
> >> +	3,
> >> +};
> >> +
> >> +/* Different types can be set simultaneously */
> >> +static u32 hisi_ptt_trace_available_type[] = {
> >> +	1,	/* posted_request */
> >> +	2,	/* non-posted_request */
> >> +	4,	/* completion */
> >> +};
> >> +
> >> +static u32 hisi_ptt_trace_availble_format[] = {
> >> +	0,	/* 4DW */
> >> +	1,	/* 8DW */
> >> +};
> >> +
> >> +/*
> >> + * Check whether the config is valid or not. Some configs are multi-selectable
> >> + * and can be set simultaneously, while some are single selectable (onehot).
> >> + * Use this function to check the non-onehot configs while
> >> + * hisi_ptt_trace_valid_config_onehot() for the onehot ones.
> >> + */
> >> +static int hisi_ptt_trace_valid_config(u32 val, u32 *available_list, u32 list_size)
> >> +{
> >> +	int i;
> >> +
> >> +	/*
> >> +	 * The non-onehot configs cannot be 0. Walk the available
> >> +	 * list and clear the valid bits of the config. If there
> >> +	 * is any resident bit after the walk then the config is
> >> +	 * invalid.
> >> +	 */
> >> +	for (i = 0; i < list_size; i++)
> >> +		val &= ~available_list[i];
> >> +
> >> +	return val ? -EINVAL : 0;
> >> +}
> >> +
> >> +static int hisi_ptt_trace_valid_config_onehot(u32 val, u32 *available_list, u32 list_size)
> >> +{
> >> +	int i, ret = -EINVAL;
> >> +
> >> +	for (i = 0; i < list_size; i++)
> >> +		if (val == available_list[i]) {
> >> +			ret = 0;
> >> +			break;
> >> +		}
> >> +
> >> +	return ret;
> >> +}
> >> +
> >> +static int hisi_ptt_trace_init_filter(struct hisi_ptt *hisi_ptt, u64 config)
> >> +{
> >> +	unsigned long val, port_mask = hisi_ptt->port_mask;
> >> +	struct hisi_ptt_filter_desc *filter;
> >> +	int ret = -EINVAL;
> >> +
> >> +	hisi_ptt->trace_ctrl.is_port = FIELD_GET(HISI_PTT_PMU_FILTER_IS_PORT, config);
> >> +	val = FIELD_GET(HISI_PTT_PMU_FILTER_VAL_MASK, config);
> >> +
> >> +	/*
> >> +	 * Port filters are defined as bit mask. For port filters, check
> >> +	 * the bits in the @val are within the range of hisi_ptt->port_mask
> >> +	 * and whether it's empty or not, otherwise user has specified
> >> +	 * some unsupported root ports.
> >> +	 *
> >> +	 * For Requester ID filters, walk the available filter list to see
> >> +	 * whether we have one matched.
> >> +	 */
> >> +	if (hisi_ptt->trace_ctrl.is_port &&
> >> +	    bitmap_subset(&val, &port_mask, BITS_PER_LONG)) {
> >> +		ret = 0;
> >> +	} else {
> >> +		list_for_each_entry(filter, &hisi_ptt->req_filters, list)
> >> +			if (filter->val == val) {
> >> +				ret = 0;
> >> +				break;
> >> +			}
> >> +	}
> >> +
> >> +	if (ret)
> >> +		return ret;
> >> +
> >> +	hisi_ptt->trace_ctrl.filter = val;
> >> +	return 0;
> >> +}
> >> +
> >> +static int hisi_ptt_pmu_event_init(struct perf_event *event)
> >> +{
> >> +	struct hisi_ptt *hisi_ptt = to_hisi_ptt(event->pmu);
> >> +	struct hisi_ptt_trace_ctrl *ctrl = &hisi_ptt->trace_ctrl;
> >> +	int ret;
> >> +	u32 val;
> >> +
> >> +	if (event->attr.type != hisi_ptt->hisi_ptt_pmu.type)
> >> +		return -ENOENT;
> >> +
> >> +	mutex_lock(&hisi_ptt->mutex);
> >> +
> >> +	ret = hisi_ptt_trace_init_filter(hisi_ptt, event->attr.config);
> >> +	if (ret < 0)
> >> +		goto out;
> >> +
> >> +	val = FIELD_GET(HISI_PTT_PMU_DIRECTION_MASK, event->attr.config);
> >> +	ret = hisi_ptt_trace_valid_config_onehot(val, hisi_ptt_trace_available_direction,
> >> +						 ARRAY_SIZE(hisi_ptt_trace_available_direction));
> >> +	if (ret < 0)
> >> +		goto out;
> >> +	ctrl->direction = val;
> >> +
> >> +	val = FIELD_GET(HISI_PTT_PMU_TYPE_MASK, event->attr.config);
> >> +
> >> +	ret = hisi_ptt_trace_valid_config(val, hisi_ptt_trace_available_type,
> >> +					  ARRAY_SIZE(hisi_ptt_trace_available_type));
> >> +	if (ret < 0)
> >> +		goto out;
> >> +	ctrl->type = val;
> >> +
> >> +	val = FIELD_GET(HISI_PTT_PMU_FORMAT_MASK, event->attr.config);
> >> +	ret = hisi_ptt_trace_valid_config_onehot(val, hisi_ptt_trace_availble_format,
> >> +						 ARRAY_SIZE(hisi_ptt_trace_availble_format));
> >> +	if (ret < 0)
> >> +		goto out;
> >> +	ctrl->format = val;
> >> +
> >> +out:
> >> +	mutex_unlock(&hisi_ptt->mutex);
> >> +	return ret;
> >> +}
> >> +
> >> +static void *hisi_ptt_pmu_setup_aux(struct perf_event *event, void **pages,
> >> +				    int nr_pages, bool overwrite)
> >> +{
> >> +	struct hisi_ptt_pmu_buf *buf;
> >> +	struct page **pagelist;
> >> +	int i;
> >> +
> >> +	if (overwrite) {
> >> +		dev_warn(event->pmu->dev, "Overwrite mode is not supported\n");
> >> +		return NULL;
> >> +	}
> >> +
> >> +	/* If the pages size less than buflets, we cannot start trace */
> >> +	if (nr_pages < HISI_PTT_TRACE_BUFFER_SIZE / PAGE_SIZE)
> >> +		return NULL;
> >> +
> >> +	buf = kzalloc(sizeof(*buf), GFP_KERNEL);
> >> +	if (!buf)
> >> +		return NULL;
> >> +
> >> +	pagelist = kcalloc(nr_pages, sizeof(*pagelist), GFP_KERNEL);
> >> +	if (!pagelist) {
> >> +		kfree(buf);
> >> +		return NULL;
> >> +	}
> >> +
> >> +	for (i = 0; i < nr_pages; i++)
> >> +		pagelist[i] = virt_to_page(pages[i]);
> >> +
> >> +	buf->base = vmap(pagelist, nr_pages, VM_MAP, PAGE_KERNEL);
> >> +	if (!buf->base) {
> >> +		kfree(pagelist);
> >> +		kfree(buf);
> >> +		return NULL;
> >> +	}
> >> +
> >> +	buf->nr_pages = nr_pages;
> >> +	buf->length = nr_pages * PAGE_SIZE;
> >> +	buf->pos = 0;
> >> +
> >> +	kfree(pagelist);
> >> +	return buf;
> >> +}
> >> +
> >> +static void hisi_ptt_pmu_free_aux(void *aux)
> >> +{
> >> +	struct hisi_ptt_pmu_buf *buf = aux;
> >> +
> >> +	vunmap(buf->base);
> >> +	kfree(buf);
> >> +}
> >> +
> >> +static void hisi_ptt_pmu_start(struct perf_event *event, int flags)
> >> +{
> >> +	struct hisi_ptt *hisi_ptt = to_hisi_ptt(event->pmu);
> >> +	struct perf_output_handle *handle = &hisi_ptt->trace_ctrl.handle;
> >> +	struct hw_perf_event *hwc = &event->hw;
> >> +	struct hisi_ptt_pmu_buf *buf;
> >> +	int cpu = event->cpu;
> >> +	int ret;
> >> +
> >> +	hwc->state = 0;
> >> +	mutex_lock(&hisi_ptt->mutex);
> >> +	if (hisi_ptt->trace_ctrl.status == HISI_PTT_TRACE_STATUS_ON) {
> >> +		pci_dbg(hisi_ptt->pdev, "trace has already started\n");
> >> +		goto stop;
> >> +	}
> >> +
> >> +	if (cpu == -1)
> >> +		cpu = hisi_ptt->trace_ctrl.default_cpu;
> >> +
> >> +	/*
> >> +	 * Handle the interrupt on the same cpu which starts the trace to avoid
> >> +	 * context mismatch. Otherwise we'll trigger the WARN from the perf
> >> +	 * core in event_function_local().
> >> +	 */
> >> +	WARN_ON(irq_set_affinity(pci_irq_vector(hisi_ptt->pdev, HISI_PTT_TRACE_DMA_IRQ),
> >> +				 cpumask_of(cpu)));
> >> +
> >> +	ret = hisi_ptt_alloc_trace_buf(hisi_ptt);
> >> +	if (ret) {
> >> +		pci_dbg(hisi_ptt->pdev, "alloc trace buf failed, ret = %d\n", ret);
> >> +		goto stop;
> >> +	}
> >> +
> >> +	buf = perf_aux_output_begin(handle, event);
> >> +	if (!buf) {
> >> +		pci_dbg(hisi_ptt->pdev, "aux output begin failed\n");
> >> +		goto stop;
> >> +	}
> >> +
> >> +	buf->pos = handle->head % buf->length;
> >> +
> >> +	ret = hisi_ptt_trace_start(hisi_ptt);
> >> +	if (ret) {
> >> +		pci_dbg(hisi_ptt->pdev, "trace start failed, ret = %d\n", ret);
> >> +		perf_aux_output_end(handle, 0);
> >> +		goto stop;
> >> +	}
> >> +
> >> +	mutex_unlock(&hisi_ptt->mutex);
> >> +	return;
> >> +stop:
> >> +	event->hw.state |= PERF_HES_STOPPED;
> >> +	mutex_unlock(&hisi_ptt->mutex);
> >> +}
> >> +
> >> +static void hisi_ptt_pmu_stop(struct perf_event *event, int flags)
> >> +{
> >> +	struct hisi_ptt *hisi_ptt = to_hisi_ptt(event->pmu);
> >> +	struct hw_perf_event *hwc = &event->hw;
> >> +
> >> +	if (hwc->state & PERF_HES_STOPPED)
> >> +		return;
> >> +
> >> +	mutex_lock(&hisi_ptt->mutex);
> >> +	if (hisi_ptt->trace_ctrl.status == HISI_PTT_TRACE_STATUS_ON) {
> >> +		hisi_ptt_trace_end(hisi_ptt);
> >> +		WARN(hisi_ptt_wait_trace_hw_idle(hisi_ptt), "Device is still busy");
> >> +		hisi_ptt_update_aux(hisi_ptt, hisi_ptt->trace_ctrl.buf_index, true);
> >> +	}
> >> +	mutex_unlock(&hisi_ptt->mutex);
> >> +
> >> +	hwc->state |= PERF_HES_STOPPED;
> >> +	perf_event_update_userpage(event);
> >> +	hwc->state |= PERF_HES_UPTODATE;
> >> +}
> >> +
> >> +static int hisi_ptt_pmu_add(struct perf_event *event, int flags)
> >> +{
> >> +	struct hisi_ptt *hisi_ptt = to_hisi_ptt(event->pmu);
> >> +	struct hw_perf_event *hwc = &event->hw;
> >> +	int cpu = event->cpu;
> >> +
> >> +	if (cpu == -1 && smp_processor_id() != hisi_ptt->trace_ctrl.default_cpu)
> >> +		return 0;
> >> +
> >> +	hwc->state = PERF_HES_STOPPED | PERF_HES_UPTODATE;
> >> +
> >> +	if (flags & PERF_EF_START) {
> >> +		hisi_ptt_pmu_start(event, PERF_EF_RELOAD);
> >> +		if (hwc->state & PERF_HES_STOPPED)
> >> +			return -EINVAL;
> >> +	}
> >> +
> >> +	return 0;
> >> +}
> >> +
> >> +static void hisi_ptt_pmu_del(struct perf_event *event, int flags)
> >> +{
> >> +	hisi_ptt_pmu_stop(event, PERF_EF_UPDATE);
> >> +}
> >> +
> >> +static void hisi_ptt_unregister_pmu(void *priv)
> >> +{
> >> +	perf_pmu_unregister(priv);
> >> +}
> >> +
> >> +static int hisi_ptt_register_pmu(struct hisi_ptt *hisi_ptt)
> >> +{
> >> +	char *pmu_name;
> >> +	int ret;
> >> +
> >> +	hisi_ptt->hisi_ptt_pmu = (struct pmu) {
> >> +		.module		= THIS_MODULE,
> >> +		.capabilities	= PERF_PMU_CAP_EXCLUSIVE | PERF_PMU_CAP_ITRACE,
> >> +		.task_ctx_nr	= perf_sw_context,
> >> +		.attr_groups	= hisi_ptt_pmu_groups,
> >> +		.event_init	= hisi_ptt_pmu_event_init,
> >> +		.setup_aux	= hisi_ptt_pmu_setup_aux,
> >> +		.free_aux	= hisi_ptt_pmu_free_aux,
> >> +		.start		= hisi_ptt_pmu_start,
> >> +		.stop		= hisi_ptt_pmu_stop,
> >> +		.add		= hisi_ptt_pmu_add,
> >> +		.del		= hisi_ptt_pmu_del,
> >> +	};
> >> +
> >> +	pmu_name = devm_kasprintf(&hisi_ptt->pdev->dev, GFP_KERNEL, "hisi_ptt%u_%u",
> >> +				  hisi_ptt->sicl_id, hisi_ptt->core_id);
> >> +	if (!pmu_name)
> >> +		return -ENOMEM;
> >> +
> >> +	ret = perf_pmu_register(&hisi_ptt->hisi_ptt_pmu, pmu_name, -1);
> >> +	if (ret)
> >> +		return ret;
> >> +
> >> +	return devm_add_action_or_reset(&hisi_ptt->pdev->dev,
> >> +					hisi_ptt_unregister_pmu,
> >> +					&hisi_ptt->hisi_ptt_pmu);
> >> +}
> >> +
> >> +/*
> >> + * Get RMR address if provided by the firmware.
> >> + * Return 0 if the IOMMU doesn't present or the policy of the
> >> + * IOMMU domain is passthrough or we get a usable RMR region.
> >> + * Otherwise a negative value is returned.
> >> + */
> >> +static int hisi_ptt_get_rmr(struct hisi_ptt *hisi_ptt)
> >> +{
> >> +	struct pci_dev *pdev = hisi_ptt->pdev;
> >> +	struct iommu_domain *iommu_domain;
> >> +	struct iommu_resv_region *region;
> >> +	LIST_HEAD(list);
> >> +
> >> +	/*
> >> +	 * Use direct DMA if IOMMU does not present or the policy of the
> >> +	 * IOMMU domain is passthrough.
> >> +	 */
> >> +	iommu_domain = iommu_get_domain_for_dev(&pdev->dev);
> >> +	if (!iommu_domain || iommu_domain->type == IOMMU_DOMAIN_IDENTITY)
> >> +		return 0;
> >> +
> >> +	iommu_get_resv_regions(&pdev->dev, &list);
> >> +	list_for_each_entry(region, &list, list)
> >> +		if (region->type == IOMMU_RESV_DIRECT &&
> >> +		    region->length >= HISI_PTT_TRACE_BUFFER_SIZE) {
> >> +			hisi_ptt->trace_ctrl.has_rmr = true;
> >> +			hisi_ptt->trace_ctrl.rmr_addr = region->start;
> >> +			hisi_ptt->trace_ctrl.rmr_length = region->length;
> >> +			break;
> >> +		}
> >> +
> >> +	iommu_put_resv_regions(&pdev->dev, &list);
> >> +	return hisi_ptt->trace_ctrl.has_rmr ? 0 : -ENOMEM;
> >> +}
> >> +
> >> +static int hisi_ptt_probe(struct pci_dev *pdev,
> >> +			  const struct pci_device_id *id)
> >> +{
> >> +	struct hisi_ptt *hisi_ptt;
> >> +	int ret;
> >> +
> >> +	hisi_ptt = devm_kzalloc(&pdev->dev, sizeof(*hisi_ptt), GFP_KERNEL);
> >> +	if (!hisi_ptt)
> >> +		return -ENOMEM;
> >> +
> >> +	mutex_init(&hisi_ptt->mutex);
> >> +	hisi_ptt->pdev = pdev;
> >> +
> >> +	/*
> >> +	 * Lifetime of pci_dev is longer than hisi_ptt,
> >> +	 * so directly reference to the pci name string.
> >> +	 */
> >> +	hisi_ptt->name = pci_name(hisi_ptt->pdev);
> >> +	pci_set_drvdata(pdev, hisi_ptt);
> >> +
> >> +	ret = pcim_enable_device(pdev);
> >> +	if (ret) {
> >> +		pci_err(pdev, "failed to enable device, ret = %d.\n", ret);
> >> +		return ret;
> >> +	}
> >> +
> >> +	ret = pcim_iomap_regions(pdev, BIT(2), hisi_ptt->name);
> >> +	if (ret) {
> >> +		pci_err(pdev, "failed to remap io memory, ret = %d.\n", ret);
> >> +		return ret;
> >> +	}
> >> +
> >> +	hisi_ptt->iobase = pcim_iomap_table(pdev)[2];
> >> +
> >> +	ret = dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(64));
> >> +	if (ret) {
> >> +		pci_err(pdev, "failed to set 64 bit dma mask, ret = %d.\n", ret);
> >> +		return ret;
> >> +	}
> >> +	pci_set_master(pdev);
> >> +
> >> +	ret = hisi_ptt_register_irq(hisi_ptt);
> >> +	if (ret)
> >> +		return ret;
> >> +
> >> +	hisi_ptt_init_ctrls(hisi_ptt);
> >> +
> >> +	ret = hisi_ptt_register_pmu(hisi_ptt);
> >> +	if (ret) {
> >> +		pci_err(pdev, "failed to register pmu device, ret = %d", ret);
> >> +		return ret;
> >> +	}
> > 
> > If this fails the pci_free_irq_vectors() is not called.
> > 
> 
> It'll be called as we've registered a devm callback when
> allocating the irq vector. See hisi_ptt_register_irq().

Ah yes - thanks for pointing that out.

> 
> > I am out of time for today - I will continue tomorrow.
> > 
> 
> Sure. Thanks!
> Yicong
> 
> > Thanks,
> > Mathieu
> > 
> >> +
> >> +	ret = hisi_ptt_get_rmr(hisi_ptt);
> >> +	if (ret) {
> >> +		pci_err(pdev, "failed to get RMR region, ret = %d", ret);
> >> +		return ret;
> >> +	}
> >> +
> >> +	/* Register the bus notifier for dynamically updating the filter list */
> >> +	hisi_ptt->hisi_ptt_nb.notifier_call = hisi_ptt_notifier_call;
> >> +	ret = bus_register_notifier(&pci_bus_type, &hisi_ptt->hisi_ptt_nb);
> >> +	if (ret)
> >> +		pci_warn(pdev, "failed to register filter update notifier, ret = %d", ret);
> >> +
> >> +	return 0;
> >> +}
> >> +
> >> +void hisi_ptt_remove(struct pci_dev *pdev)
> >> +{
> >> +	struct hisi_ptt *hisi_ptt = pci_get_drvdata(pdev);
> >> +
> >> +	bus_unregister_notifier(&pci_bus_type, &hisi_ptt->hisi_ptt_nb);
> >> +
> >> +	/* Cancel any work that has been queued */
> >> +	cancel_delayed_work_sync(&hisi_ptt->work);
> >> +
> >> +	if (hisi_ptt->trace_ctrl.status == HISI_PTT_TRACE_STATUS_ON)
> >> +		hisi_ptt_trace_end(hisi_ptt);
> >> +
> >> +	hisi_ptt_free_trace_buf(hisi_ptt);
> >> +	hisi_ptt_release_filters(hisi_ptt);
> >> +}
> >> +
> >> +static const struct pci_device_id hisi_ptt_id_tbl[] = {
> >> +	{ PCI_DEVICE(PCI_VENDOR_ID_HUAWEI, 0xa12e) },
> >> +	{ }
> >> +};
> >> +MODULE_DEVICE_TABLE(pci, hisi_ptt_id_tbl);
> >> +
> >> +static struct pci_driver hisi_ptt_driver = {
> >> +	.name = "hisi_ptt",
> >> +	.id_table = hisi_ptt_id_tbl,
> >> +	.probe = hisi_ptt_probe,
> >> +	.remove = hisi_ptt_remove,
> >> +};
> >> +module_pci_driver(hisi_ptt_driver);
> >> +
> >> +MODULE_LICENSE("GPL v2");
> >> +MODULE_AUTHOR("Yicong Yang <yangyicong@hisilicon.com>");
> >> +MODULE_DESCRIPTION("Driver for HiSilicon PCIe tune and trace device");
> >> -- 
> >> 2.33.0
> >>
> > .
> >

[...]

> 
> > >> +
> > >> +#define HISI_PTT_TRACE_DMA_IRQ			0
> > >> +#define HISI_PTT_TRACE_BUFLETS_CNT		4
> > >> +#define HISI_PTT_TRACE_BUFLET_SIZE		SZ_4M
> > >> +#define HISI_PTT_TRACE_BUFFER_SIZE		(HISI_PTT_TRACE_BUFLET_SIZE * \
> > >> +						 HISI_PTT_TRACE_BUFLETS_CNT)
> > >> +#define HISI_PTT_FILTER_UPDATE_FIFO_SIZE	16
> > >> +
> > >> +/* Delay time for filter updating work */
> > >> +#define HISI_PTT_WORK_DELAY_MS		100UL
> > >> +/* Wait time for DMA hardware to reset */
> > >> +#define HISI_PTT_RESET_WAIT_MS		1000UL
> > >> +/* Poll timeout and interval for waiting hardware work to finish */
> > >> +#define HISI_PTT_WAIT_TIMEOUT_US	1000000UL
> > >> +#define HISI_PTT_WAIT_POLL_INTERVAL_US	100UL
> > >> +
> > >> +#define HISI_PCIE_CORE_PORT_ID(devfn)	(PCI_FUNC(devfn) << 1)
> > >> +
> > >> +enum hisi_ptt_trace_status {
> > >> +	HISI_PTT_TRACE_STATUS_OFF = 0,
> > >> +	HISI_PTT_TRACE_STATUS_ON,
> > >> +};
> > >> +
> > >> +struct hisi_ptt_dma_buflet {
> > > 
> > > I'm not sure what a "buflet" is...  Probably best to just call this
> > > hisi_ptt_dma_buffer" if it pertains to a buffer.  On that note it is hard to
> > > know due to the lack of proper structure documentation.  Please have a look at
> > > how "coresight_device" is documented.  The same applies to the rest of the
> > > structures declared below.
> > > 
> > 
> > It's mentioned in section 5 of hisi_ptt.rst as "Driver will allocate each DMA buffer
> > (we call it buflet) of 4MiB ...".
> 
> I just noticed the documentation in patch 5 - I will read it before continuing
> with this set.
>

As promised I read the documentation and it didn't do much to alliviate my
concern about the terminology.  If a "buflet" is a DMA buffer than simply call
it a DMA buffer, regardless of the size.  

The size of this patchset makes it hard enough to review as it is... On top
of things reviewers have to remember that PTT means "PCIe tune and trace
device", tune means "PCIe link's events" and trace means "TLP headers".

But we also have to keep in mind that a buflet is really just a DMA buffer...

I will not continue reviewing this set.  Please fix the terminology and spin
another revision.  Doing so I suggest you trim down the submission to the
absolute minimum feature set this driver should provide - enhancements can be
made later when a foundation has been laid out.

Robin has pointed out what seems to be serious problems with the
implemenation.  That will also have to be sorted out for the next iteration.

Regards,
Mathieu


> > 
> > The total DMA buffer of PTT device is divided into 4 parts, and each part is called
> > a 'buflet', which means a small buffer (there exists other words with similiar
> > format: droplet, wavelet, ...).
> > 
> > The device is designed like this to make sure we won't lose any data when we have to change
> > the buffer address, the device can continue to write to the next buflet and don't
> > neet to pause.
> > 
> > >> +	struct list_head list;
> > >> +	unsigned int size;
> > >> +	dma_addr_t dma;
> > >> +
> > >> +	/*
> > >> +	 * The address of the buflet holding the trace data.
> > >> +	 * See Documentation/trace/hisi-ptt.rst for the details
> > > 
> > > As of this writing, hisi-ptt.rst doesn't exist.
> > > 
> > 
> > The comment intends to direct the user to the documentation if the user
> > want to know details about the data format. The data format is decribed
> > in the section 4 of the doc.
> > 
> > >> +	 * of the data format.
> > >> +	 */
> > >> +	void *addr;
> > >> +	int index;
> > >> +};
> > >> +
> > >> +struct hisi_ptt_trace_ctrl {
> > >> +	enum hisi_ptt_trace_status status;
> > >> +	struct perf_output_handle handle;
> > >> +	struct list_head trace_buf;
> > >> +	/*
> > >> +	 * The index of the buffer which trace data
> > >> +	 * currently is writing to.
> > >> +	 */
> > >> +	u32 buf_index;
> > >> +
> > >> +	int default_cpu;
> > >> +	u32 buflet_size;
> > >> +	bool is_port;
> > >> +	u32 format:1;		/* Format of the traced TLP headers */
> > >> +	u32 type:4;		/* Type of the TLP headers to trace */
> > >> +	u32 direction:2;	/* Direction of the TLP headers to trace */
> > >> +	u32 filter:16;		/* Root port or Requester to filter the TLP headers */
> > >> +
> > >> +	phys_addr_t rmr_addr;
> > >> +	size_t rmr_length;
> > >> +	bool has_rmr;
> > >> +};
> > >> +
> > >> +struct hisi_ptt_filter_desc {
> > >> +	struct list_head list;
> > >> +	struct pci_dev *pdev;
> > >> +	u16 val;
> > >> +};
> > >> +
> > >> +struct hisi_ptt_pmu_buf {
> > >> +	size_t length;
> > >> +	int nr_pages;
> > >> +	void *base;
> > >> +	long pos;
> > >> +};
> > >> +
> > >> +/* Structure containing the information for filter updating */
> > >> +struct hisi_ptt_filter_update_info {
> > >> +	struct pci_dev *pdev;
> > >> +	u32 port_devid;
> > >> +	bool is_port;
> > >> +	bool is_add;
> > >> +	u16 val;
> > >> +};
> > >> +
> > >> +struct hisi_ptt {
> > >> +	struct hisi_ptt_trace_ctrl trace_ctrl;
> > >> +	struct notifier_block hisi_ptt_nb;
> > >> +	struct pmu hisi_ptt_pmu;
> > >> +	void __iomem *iobase;
> > >> +	struct pci_dev *pdev;
> > >> +	/*
> > >> +	 * Use the mutex to protect the filter list and
> > >> +	 * serialize the perf process.
> > >> +	 */
> > >> +	struct mutex mutex;
> > >> +	const char *name;
> > >> +	u16 core_id;
> > >> +	u16 sicl_id;
> > >> +	/* PCI device range managed by the PTT device */
> > >> +	u32 upper;
> > >> +	u32 lower;
> > >> +	u8 busnr;
> > >> +
> > >> +	/*
> > >> +	 * The trace TLP headers can either be filtered by certain
> > >> +	 * root port, or by the requester ID. Organize the filters
> > >> +	 * by @port_filters and @req_filters here. The mask of all
> > >> +	 * the valid ports is also cached for doing sanity check
> > >> +	 * of user input.
> > >> +	 */
> > >> +	struct list_head port_filters;
> > >> +	struct list_head req_filters;
> > >> +	u16 port_mask;
> > >> +
> > >> +	/*
> > >> +	 * We use a delayed work here to avoid indefinitely waiting for
> > >> +	 * the hisi_ptt->mutex which protecting the filter list. The
> > >> +	 * work will be delayed only if the mutex can not be held,
> > >> +	 * otherwise no delay will be applied.
> > >> +	 */
> > >> +	struct delayed_work work;
> > >> +	spinlock_t filter_update_lock;
> > >> +	DECLARE_KFIFO(filter_update_kfifo, struct hisi_ptt_filter_update_info,
> > >> +		      HISI_PTT_FILTER_UPDATE_FIFO_SIZE);
> > >> +};
> > > 
> > > It might be a good idea to spinoff a hisi_ptt.h for the above declarations.
> > > 
> > 
> > I'm not sure whether it is common or permitted to provide a header which is only used by
> > this driver with a single file.
> 
> I've seen it done many times.
> 
> > 
> > >> +
> > >> +static inline struct hisi_ptt *to_hisi_ptt(struct pmu *pmu)
> > >> +{
> > >> +	return container_of(pmu, struct hisi_ptt, hisi_ptt_pmu);
> > >> +}
> > > 
> > > I'm not sure there is any value to this inline function.  I suggest to simply
> > > call container_of() whenever it is needed.
> > > 
> > 
> > ok.
> > 
> > >> +
> > >> +static u16 hisi_ptt_get_filter_val(struct pci_dev *pdev)
> > >> +{
> > >> +	if (pci_pcie_type(pdev) == PCI_EXP_TYPE_ROOT_PORT)
> > >> +		return BIT(HISI_PCIE_CORE_PORT_ID(PCI_SLOT(pdev->devfn)));
> > >> +
> > >> +	return PCI_DEVID(pdev->bus->number, pdev->devfn);
> > >> +}
> > >> +
> > >> +static int hisi_ptt_wait_trace_hw_idle(struct hisi_ptt *hisi_ptt)
> > >> +{
> > >> +	u32 val;
> > >> +
> > >> +	return readl_poll_timeout(hisi_ptt->iobase + HISI_PTT_TRACE_STS, val,
> > >> +				  val & HISI_PTT_TRACE_IDLE,
> > >> +				  HISI_PTT_WAIT_POLL_INTERVAL_US,
> > >> +				  HISI_PTT_WAIT_TIMEOUT_US);
> > >> +}
> > >> +
> > >> +static void hisi_ptt_free_trace_buf(struct hisi_ptt *hisi_ptt)
> > >> +{
> > >> +	struct hisi_ptt_trace_ctrl *ctrl = &hisi_ptt->trace_ctrl;
> > >> +	struct device *dev = &hisi_ptt->pdev->dev;
> > >> +	struct hisi_ptt_dma_buflet *buflet, *tbuflet;
> > >> +
> > >> +	list_for_each_entry_safe(buflet, tbuflet, &ctrl->trace_buf, list) {
> > >> +		list_del(&buflet->list);
> > >> +
> > >> +		if (ctrl->has_rmr)
> > >> +			memunmap(buflet->addr);
> > >> +		else
> > >> +			dma_free_coherent(dev, buflet->size, buflet->addr,
> > >> +					  buflet->dma);
> > >> +
> > >> +		kfree(buflet);
> > >> +	}
> > >> +}
> > >> +
> > >> +static int hisi_ptt_alloc_trace_buf(struct hisi_ptt *hisi_ptt)
> > >> +{
> > >> +	struct hisi_ptt_trace_ctrl *ctrl = &hisi_ptt->trace_ctrl;
> > >> +	struct device *dev = &hisi_ptt->pdev->dev;
> > >> +	struct hisi_ptt_dma_buflet *buflet;
> > >> +	int i, ret;
> > >> +
> > >> +	hisi_ptt->trace_ctrl.buf_index = 0;
> > >> +
> > >> +	/* Make sure the trace buffer is empty before allocating */
> > >> +	if (!list_empty(&ctrl->trace_buf)) {
> > >> +		list_for_each_entry(buflet, &ctrl->trace_buf, list)
> > >> +			memset(buflet->addr, 0, buflet->size);
> > >> +		return 0;
> > >> +	}
> > >> +
> > >> +	for (i = 0; i < HISI_PTT_TRACE_BUFLETS_CNT; ++i) {
> > >> +		buflet = kzalloc(sizeof(*buflet), GFP_KERNEL);
> > >> +		if (!buflet) {
> > >> +			ret = -ENOMEM;
> > >> +			goto err;
> > >> +		}
> > >> +
> > >> +		if (ctrl->has_rmr) {
> > >> +			phys_addr_t base = ctrl->rmr_addr + i * ctrl->buflet_size;
> > >> +
> > >> +			buflet->dma = base;
> > >> +			buflet->addr = memremap(base, ctrl->buflet_size, MEMREMAP_WB);
> > >> +		} else {
> > >> +			buflet->addr = dma_alloc_coherent(dev, ctrl->buflet_size,
> > >> +							  &buflet->dma, GFP_KERNEL);
> > >> +		}
> > >> +
> > >> +		if (!buflet->addr) {
> > >> +			kfree(buflet);
> > >> +			ret = -ENOMEM;
> > >> +			goto err;
> > >> +		}
> > >> +
> > >> +		memset(buflet->addr, 0, buflet->size);
> > >> +
> > >> +		buflet->index = i;
> > >> +		buflet->size = ctrl->buflet_size;
> > >> +		list_add_tail(&buflet->list, &ctrl->trace_buf);
> > >> +	}
> > >> +
> > >> +	return 0;
> > >> +err:
> > >> +	hisi_ptt_free_trace_buf(hisi_ptt);
> > >> +	return ret;
> > >> +}
> > >> +
> > >> +static void hisi_ptt_trace_end(struct hisi_ptt *hisi_ptt)
> > >> +{
> > >> +	writel(0, hisi_ptt->iobase + HISI_PTT_TRACE_CTRL);
> > >> +	hisi_ptt->trace_ctrl.status = HISI_PTT_TRACE_STATUS_OFF;
> > >> +}
> > >> +
> > >> +static int hisi_ptt_trace_start(struct hisi_ptt *hisi_ptt)
> > >> +{
> > >> +	struct hisi_ptt_trace_ctrl *ctrl = &hisi_ptt->trace_ctrl;
> > >> +	struct hisi_ptt_dma_buflet *cur;
> > >> +	u32 val;
> > >> +
> > >> +	/* Check device idle before start trace */
> > >> +	if (hisi_ptt_wait_trace_hw_idle(hisi_ptt)) {
> > >> +		pci_err(hisi_ptt->pdev, "Failed to start trace, the device is still busy.\n");
> > >> +		return -EBUSY;
> > >> +	}
> > >> +
> > >> +	/* Reset the DMA before start tracing */
> > >> +	val = readl(hisi_ptt->iobase + HISI_PTT_TRACE_CTRL);
> > >> +	val |= HISI_PTT_TRACE_CTRL_RST;
> > >> +	writel(val, hisi_ptt->iobase + HISI_PTT_TRACE_CTRL);
> > >> +
> > >> +	/*
> > >> +	 * We'll be in the perf context where preemption is disabled,
> > >> +	 * so use busy loop here.
> > >> +	 */
> > >> +	mdelay(HISI_PTT_RESET_WAIT_MS);
> > >> +
> > >> +	val = readl(hisi_ptt->iobase + HISI_PTT_TRACE_CTRL);
> > >> +	val &= ~HISI_PTT_TRACE_CTRL_RST;
> > >> +	writel(val, hisi_ptt->iobase + HISI_PTT_TRACE_CTRL);
> > >> +
> > >> +	/* clear the interrupt status */
> > >> +	writel(HISI_PTT_TRACE_INT_STAT_MASK, hisi_ptt->iobase + HISI_PTT_TRACE_INT_STAT);
> > >> +	writel(0, hisi_ptt->iobase + HISI_PTT_TRACE_INT_MASK);
> > >> +
> > >> +	list_for_each_entry(cur, &ctrl->trace_buf, list) {
> > >> +		writel(lower_32_bits(cur->dma),
> > >> +		       hisi_ptt->iobase + HISI_PTT_TRACE_ADDR_BASE_LO_0 +
> > >> +		       cur->index * HISI_PTT_TRACE_ADDR_STRIDE);
> > >> +		writel(upper_32_bits(cur->dma),
> > >> +		       hisi_ptt->iobase + HISI_PTT_TRACE_ADDR_BASE_HI_0 +
> > >> +		       cur->index * HISI_PTT_TRACE_ADDR_STRIDE);
> > >> +	}
> > >> +	writel(ctrl->buflet_size, hisi_ptt->iobase + HISI_PTT_TRACE_ADDR_SIZE);
> > >> +
> > >> +	/* set the trace control register */
> > >> +	val = FIELD_PREP(HISI_PTT_TRACE_CTRL_TYPE_SEL, ctrl->type);
> > >> +	val |= FIELD_PREP(HISI_PTT_TRACE_CTRL_RXTX_SEL, ctrl->direction);
> > >> +	val |= FIELD_PREP(HISI_PTT_TRACE_CTRL_DATA_FORMAT, ctrl->format);
> > >> +	val |= FIELD_PREP(HISI_PTT_TRACE_CTRL_TARGET_SEL, hisi_ptt->trace_ctrl.filter);
> > >> +	if (!hisi_ptt->trace_ctrl.is_port)
> > >> +		val |= HISI_PTT_TRACE_CTRL_FILTER_MODE;
> > >> +
> > >> +	val |= HISI_PTT_TRACE_CTRL_EN;
> > >> +	writel(val, hisi_ptt->iobase + HISI_PTT_TRACE_CTRL);
> > >> +
> > >> +	ctrl->status = HISI_PTT_TRACE_STATUS_ON;
> > >> +
> > >> +	return 0;
> > >> +}
> > >> +
> > >> +static int hisi_ptt_update_aux(struct hisi_ptt *hisi_ptt, int index, bool stop)
> > >> +{
> > >> +	struct perf_output_handle *handle = &hisi_ptt->trace_ctrl.handle;
> > >> +	struct perf_event *event = handle->event;
> > >> +	struct hisi_ptt_dma_buflet *cur;
> > >> +	struct hisi_ptt_pmu_buf *buf;
> > >> +
> > >> +	buf = perf_get_aux(handle);
> > >> +	if (!buf || !handle->size)
> > >> +		return -EINVAL;
> > >> +
> > >> +	list_for_each_entry(cur, &hisi_ptt->trace_ctrl.trace_buf, list)
> > >> +		if (cur->index == index)
> > >> +			break;
> > >> +
> > >> +	memcpy(buf->base + buf->pos, cur->addr, cur->size);
> > >> +	memset(cur->addr, 0, cur->size);
> > >> +	buf->pos += cur->size;
> > >> +
> > >> +	if (stop) {
> > >> +		perf_aux_output_end(handle, buf->pos);
> > >> +	} else if (buf->length - buf->pos < cur->size) {
> > >> +		perf_aux_output_skip(handle, buf->length - buf->pos);
> > >> +		perf_aux_output_end(handle, buf->pos);
> > >> +
> > >> +		buf = perf_aux_output_begin(handle, event);
> > >> +		if (!buf)
> > >> +			return -EINVAL;
> > >> +
> > >> +		buf->pos = handle->head % buf->length;
> > >> +		if (buf->length - buf->pos < cur->size) {
> > >> +			perf_aux_output_end(handle, 0);
> > >> +			return -EINVAL;
> > >> +		}
> > >> +	}
> > >> +
> > >> +	return 0;
> > >> +}
> > >> +
> > >> +static irqreturn_t hisi_ptt_isr(int irq, void *context)
> > >> +{
> > >> +	struct hisi_ptt *hisi_ptt = context;
> > >> +	u32 status, buf_idx;
> > >> +
> > >> +	status = readl(hisi_ptt->iobase + HISI_PTT_TRACE_INT_STAT);
> > >> +	buf_idx = ffs(status) - 1;
> > >> +
> > >> +	/* Clear the interrupt status of buflet @buf_idx */
> > >> +	writel(status, hisi_ptt->iobase + HISI_PTT_TRACE_INT_STAT);
> > >> +
> > >> +	/*
> > >> +	 * Update the AUX buffer and cache the current buflet index,
> > >> +	 * as we need to know this and save the data when the trace
> > >> +	 * is ended out of the interrupt handler. End the trace
> > >> +	 * if the updating fails.
> > >> +	 */
> > >> +	if (hisi_ptt_update_aux(hisi_ptt, buf_idx, false))
> > >> +		hisi_ptt_trace_end(hisi_ptt);
> > >> +	else
> > >> +		hisi_ptt->trace_ctrl.buf_index = (buf_idx + 1) % HISI_PTT_TRACE_BUFLETS_CNT;
> > >> +
> > >> +	return IRQ_HANDLED;
> > >> +}
> > >> +
> > >> +static irqreturn_t hisi_ptt_irq(int irq, void *context)
> > >> +{
> > >> +	struct hisi_ptt *hisi_ptt = context;
> > >> +	u32 status;
> > >> +
> > >> +	status = readl(hisi_ptt->iobase + HISI_PTT_TRACE_INT_STAT);
> > >> +	if (!(status & HISI_PTT_TRACE_INT_STAT_MASK))
> > >> +		return IRQ_NONE;
> > >> +
> > >> +	return IRQ_WAKE_THREAD;
> > >> +}
> > >> +
> > >> +static void hisi_ptt_irq_free_vectors(void *pdev)
> > >> +{
> > >> +	pci_free_irq_vectors(pdev);
> > >> +}
> > >> +
> > >> +static int hisi_ptt_register_irq(struct hisi_ptt *hisi_ptt)
> > >> +{
> > >> +	struct pci_dev *pdev = hisi_ptt->pdev;
> > >> +	int ret;
> > >> +
> > >> +	ret = pci_alloc_irq_vectors(pdev, 1, 1, PCI_IRQ_MSI);
> > >> +	if (ret < 0) {
> > >> +		pci_err(pdev, "failed to allocate irq vector, ret = %d.\n", ret);
> > >> +		return ret;
> > >> +	}
> > >> +
> > >> +	ret = devm_add_action_or_reset(&pdev->dev, hisi_ptt_irq_free_vectors, pdev);
> > >> +	if (ret < 0)
> > >> +		return ret;
> > >> +
> > >> +	ret = devm_request_threaded_irq(&pdev->dev,
> > >> +					pci_irq_vector(pdev, HISI_PTT_TRACE_DMA_IRQ),
> > >> +					hisi_ptt_irq, hisi_ptt_isr, 0,
> > >> +					"hisi-ptt", hisi_ptt);
> > >> +	if (ret) {
> > >> +		pci_err(pdev, "failed to request irq %d, ret = %d.\n",
> > >> +			pci_irq_vector(pdev, HISI_PTT_TRACE_DMA_IRQ), ret);
> > >> +		return ret;
> > >> +	}
> > >> +
> > >> +	return 0;
> > >> +}
> > >> +
> > >> +static void hisi_ptt_update_filters(struct work_struct *work)
> > >> +{
> > >> +	struct delayed_work *delayed_work = to_delayed_work(work);
> > >> +	struct hisi_ptt_filter_update_info info;
> > >> +	struct hisi_ptt_filter_desc *filter;
> > >> +	struct list_head *target_list;
> > >> +	struct hisi_ptt *hisi_ptt;
> > >> +
> > >> +	hisi_ptt = container_of(delayed_work, struct hisi_ptt, work);
> > >> +
> > >> +	if (!mutex_trylock(&hisi_ptt->mutex)) {
> > >> +		schedule_delayed_work(&hisi_ptt->work, HISI_PTT_WORK_DELAY_MS);
> > >> +		return;
> > >> +	}
> > >> +
> > >> +	while (kfifo_get(&hisi_ptt->filter_update_kfifo, &info)) {
> > >> +		target_list = info.is_port ? &hisi_ptt->port_filters :
> > >> +			      &hisi_ptt->req_filters;
> > >> +
> > >> +		if (info.is_add) {
> > >> +			filter = kzalloc(sizeof(*filter), GFP_KERNEL);
> > >> +			if (!filter)
> > >> +				continue;
> > >> +
> > >> +			filter->pdev = info.pdev;
> > >> +			filter->val = info.val;
> > >> +
> > >> +			list_add_tail(&filter->list, target_list);
> > >> +		} else {
> > >> +			list_for_each_entry(filter, target_list, list)
> > >> +				if (filter->val == info.val) {
> > >> +					list_del(&filter->list);
> > >> +					kfree(filter);
> > >> +					break;
> > >> +				}
> > >> +		}
> > >> +
> > >> +		/* Update the available port mask */
> > >> +		if (!info.is_port)
> > >> +			continue;
> > >> +
> > >> +		if (info.is_add)
> > >> +			hisi_ptt->port_mask |= info.val;
> > >> +		else
> > >> +			hisi_ptt->port_mask &= ~info.val;
> > >> +	}
> > >> +
> > >> +	mutex_unlock(&hisi_ptt->mutex);
> > >> +}
> > >> +
> > >> +static void hisi_ptt_update_fifo_in(struct hisi_ptt *hisi_ptt,
> > >> +				    struct hisi_ptt_filter_update_info *info)
> > >> +{
> > >> +	struct pci_dev *root_port = pcie_find_root_port(info->pdev);
> > >> +
> > >> +	if (!root_port)
> > >> +		return;
> > >> +
> > >> +	info->port_devid = PCI_DEVID(root_port->bus->number, root_port->devfn);
> > >> +	if (info->port_devid < hisi_ptt->lower ||
> > >> +	    info->port_devid > hisi_ptt->upper)
> > >> +		return;
> > >> +
> > >> +	info->is_port = pci_pcie_type(info->pdev) == PCI_EXP_TYPE_ROOT_PORT;
> > >> +	info->val = hisi_ptt_get_filter_val(info->pdev);
> > >> +
> > >> +	if (kfifo_in_spinlocked(&hisi_ptt->filter_update_kfifo, info, 1,
> > >> +				&hisi_ptt->filter_update_lock))
> > >> +		schedule_delayed_work(&hisi_ptt->work, 0);
> > >> +	else
> > >> +		pci_warn(hisi_ptt->pdev,
> > >> +			 "filter update fifo overflow for target %s\n",
> > >> +			 pci_name(info->pdev));
> > >> +}
> > >> +
> > >> +/*
> > >> + * A PCI bus notifier is used here for dynamically updating the filter
> > >> + * list.
> > >> + */
> > >> +static int hisi_ptt_notifier_call(struct notifier_block *nb, unsigned long action,
> > >> +				  void *data)
> > >> +{
> > >> +	struct hisi_ptt *hisi_ptt = container_of(nb, struct hisi_ptt, hisi_ptt_nb);
> > >> +	struct hisi_ptt_filter_update_info info;
> > >> +	struct device *dev = data;
> > >> +	struct pci_dev *pdev = to_pci_dev(dev);
> > >> +
> > >> +	info.pdev = pdev;
> > >> +
> > >> +	switch (action) {
> > >> +	case BUS_NOTIFY_ADD_DEVICE:
> > >> +		info.is_add = true;
> > >> +		break;
> > >> +	case BUS_NOTIFY_DEL_DEVICE:
> > >> +		info.is_add = false;
> > >> +		break;
> > >> +	default:
> > >> +		return 0;
> > >> +	}
> > >> +
> > >> +	hisi_ptt_update_fifo_in(hisi_ptt, &info);
> > >> +
> > >> +	return 0;
> > >> +}
> > >> +
> > >> +static int hisi_ptt_init_filters(struct pci_dev *pdev, void *data)
> > >> +{
> > >> +	struct hisi_ptt_filter_update_info info = {
> > >> +		.pdev = pdev,
> > >> +		.is_add = true,
> > >> +	};
> > >> +	struct hisi_ptt *hisi_ptt = data;
> > >> +
> > >> +	hisi_ptt_update_fifo_in(hisi_ptt, &info);
> > >> +
> > >> +	return 0;
> > >> +}
> > >> +
> > >> +static void hisi_ptt_release_filters(struct hisi_ptt *hisi_ptt)
> > >> +{
> > >> +	struct hisi_ptt_filter_desc *filter, *tfilter;
> > >> +
> > >> +	list_for_each_entry_safe(filter, tfilter, &hisi_ptt->req_filters, list) {
> > >> +		list_del(&filter->list);
> > >> +		kfree(filter);
> > >> +	}
> > >> +
> > >> +	list_for_each_entry_safe(filter, tfilter, &hisi_ptt->port_filters, list) {
> > >> +		list_del(&filter->list);
> > >> +		kfree(filter);
> > >> +	}
> > >> +}
> > >> +
> > >> +static void hisi_ptt_init_ctrls(struct hisi_ptt *hisi_ptt)
> > >> +{
> > >> +	struct pci_dev *pdev = hisi_ptt->pdev;
> > >> +	struct pci_bus *bus;
> > >> +	u32 reg;
> > >> +
> > >> +	INIT_DELAYED_WORK(&hisi_ptt->work, hisi_ptt_update_filters);
> > >> +	spin_lock_init(&hisi_ptt->filter_update_lock);
> > >> +	INIT_KFIFO(hisi_ptt->filter_update_kfifo);
> > >> +	INIT_LIST_HEAD(&hisi_ptt->port_filters);
> > >> +	INIT_LIST_HEAD(&hisi_ptt->req_filters);
> > >> +
> > >> +	/*
> > >> +	 * The device range register provides the information about the
> > >> +	 * root ports which the RCiEP can control and trace. The RCiEP
> > >> +	 * and the root ports it support are on the same PCIe core, with
> > >> +	 * same domain number but maybe different bus number. The device
> > >> +	 * range register will tell us which root ports we can support,
> > >> +	 * Bit[31:16] indicates the upper BDF numbers of the root port,
> > >> +	 * while Bit[15:0] indicates the lower.
> > >> +	 */
> > >> +	reg = readl(hisi_ptt->iobase + HISI_PTT_DEVICE_RANGE);
> > >> +	hisi_ptt->upper = reg >> 16;
> > >> +	hisi_ptt->lower = reg & 0xffff;
> > >> +	hisi_ptt->busnr = PCI_BUS_NUM(hisi_ptt->upper);
> > >> +
> > >> +	reg = readl(hisi_ptt->iobase + HISI_PTT_LOCATION);
> > >> +	hisi_ptt->core_id = FIELD_GET(HISI_PTT_CORE_ID, reg);
> > >> +	hisi_ptt->sicl_id = FIELD_GET(HISI_PTT_SICL_ID, reg);
> > >> +
> > >> +	bus = pci_find_bus(pci_domain_nr(pdev->bus), hisi_ptt->busnr);
> > >> +	if (bus)
> > >> +		pci_walk_bus(bus, hisi_ptt_init_filters, hisi_ptt);
> > > 
> > > What happens if bus is NULL?  Should this be reported to the caller and cause
> > > hisi_ptt_probe() to fail?  Please add a comment that describes the scenario.
> > > 
> > 
> > It's ok if the list is NULL in the probe process,
> > as the device maybe hotplugged after the PTT driver probe, in which case
> > we can detect the event and update the list as we register a bus notifier.
> > 
> 
> Please add the above as a comment in the code.
> 
> 
> > >> +
> > >> +	/* Initialize trace controls */
> > >> +	INIT_LIST_HEAD(&hisi_ptt->trace_ctrl.trace_buf);
> > >> +	hisi_ptt->trace_ctrl.buflet_size = HISI_PTT_TRACE_BUFLET_SIZE;
> > >> +	hisi_ptt->trace_ctrl.default_cpu = cpumask_first(cpumask_of_node(dev_to_node(&pdev->dev)));
> > >> +}
> > >> +
> > >> +#define HISI_PTT_PMU_FILTER_IS_PORT	BIT(19)
> > >> +#define HISI_PTT_PMU_FILTER_VAL_MASK	GENMASK(15, 0)
> > >> +#define HISI_PTT_PMU_DIRECTION_MASK	GENMASK(23, 20)
> > >> +#define HISI_PTT_PMU_TYPE_MASK		GENMASK(31, 24)
> > >> +#define HISI_PTT_PMU_FORMAT_MASK	GENMASK(35, 32)
> > >> +
> > >> +static ssize_t available_filters_show(struct device *dev,
> > >> +				      struct device_attribute *attr,
> > >> +				      char *buf)
> > >> +{
> > >> +	struct hisi_ptt *hisi_ptt = to_hisi_ptt(dev_get_drvdata(dev));
> > >> +	struct hisi_ptt_filter_desc *filter;
> > >> +	int pos = 0;
> > >> +
> > >> +	if (list_empty(&hisi_ptt->port_filters))
> > >> +		return sysfs_emit(buf, "#### No available filter ####\n");
> > >> +
> > >> +	mutex_lock(&hisi_ptt->mutex);
> > >> +	pos += sysfs_emit_at(buf, pos, "#### Root Ports ####\n");
> > >> +	list_for_each_entry(filter, &hisi_ptt->port_filters, list)
> > >> +		pos += sysfs_emit_at(buf, pos, "%s	0x%05lx\n",
> > >> +				     pci_name(filter->pdev),
> > >> +				     hisi_ptt_get_filter_val(filter->pdev) |
> > >> +				     HISI_PTT_PMU_FILTER_IS_PORT);
> > >> +
> > >> +	pos += sysfs_emit_at(buf, pos, "#### Requesters ####\n");
> > >> +	list_for_each_entry(filter, &hisi_ptt->req_filters, list)
> > >> +		pos += sysfs_emit_at(buf, pos, "%s	0x%05x\n",
> > >> +				     pci_name(filter->pdev),
> > >> +				     hisi_ptt_get_filter_val(filter->pdev));
> > >> +
> > >> +	mutex_unlock(&hisi_ptt->mutex);
> > >> +	return pos;
> > >> +}
> > >> +static DEVICE_ATTR_ADMIN_RO(available_filters);
> > >> +
> > >> +PMU_FORMAT_ATTR(filter,		"config:0-19");
> > >> +PMU_FORMAT_ATTR(direction,	"config:20-23");
> > >> +PMU_FORMAT_ATTR(type,		"config:24-31");
> > >> +PMU_FORMAT_ATTR(format,		"config:32-35");
> > >> +
> > >> +static struct attribute *hisi_ptt_pmu_format_attrs[] = {
> > >> +	&format_attr_filter.attr,
> > >> +	&format_attr_direction.attr,
> > >> +	&format_attr_type.attr,
> > >> +	&format_attr_format.attr,
> > >> +	NULL
> > >> +};
> > >> +
> > >> +static struct attribute_group hisi_ptt_pmu_format_group = {
> > >> +	.name = "format",
> > >> +	.attrs = hisi_ptt_pmu_format_attrs,
> > >> +};
> > >> +
> > >> +static struct attribute *hisi_ptt_pmu_filter_attrs[] = {
> > >> +	&dev_attr_available_filters.attr,
> > >> +	NULL
> > >> +};
> > >> +
> > >> +static struct attribute_group hisi_ptt_pmu_filter_group = {
> > >> +	.attrs = hisi_ptt_pmu_filter_attrs,
> > >> +};
> > >> +
> > >> +static const struct attribute_group *hisi_ptt_pmu_groups[] = {
> > >> +	&hisi_ptt_pmu_format_group,
> > >> +	&hisi_ptt_pmu_filter_group,
> > >> +	NULL
> > >> +};
> > >> +
> > >> +/*
> > >> + * The supported value of the direction parameter. See hisi_ptt.rst
> > >> + * documentation for more details.
> > >> + */
> > >> +static u32 hisi_ptt_trace_available_direction[] = {
> > >> +	0,
> > >> +	1,
> > >> +	2,
> > >> +	3,
> > >> +};
> > >> +
> > >> +/* Different types can be set simultaneously */
> > >> +static u32 hisi_ptt_trace_available_type[] = {
> > >> +	1,	/* posted_request */
> > >> +	2,	/* non-posted_request */
> > >> +	4,	/* completion */
> > >> +};
> > >> +
> > >> +static u32 hisi_ptt_trace_availble_format[] = {
> > >> +	0,	/* 4DW */
> > >> +	1,	/* 8DW */
> > >> +};
> > >> +
> > >> +/*
> > >> + * Check whether the config is valid or not. Some configs are multi-selectable
> > >> + * and can be set simultaneously, while some are single selectable (onehot).
> > >> + * Use this function to check the non-onehot configs while
> > >> + * hisi_ptt_trace_valid_config_onehot() for the onehot ones.
> > >> + */
> > >> +static int hisi_ptt_trace_valid_config(u32 val, u32 *available_list, u32 list_size)
> > >> +{
> > >> +	int i;
> > >> +
> > >> +	/*
> > >> +	 * The non-onehot configs cannot be 0. Walk the available
> > >> +	 * list and clear the valid bits of the config. If there
> > >> +	 * is any resident bit after the walk then the config is
> > >> +	 * invalid.
> > >> +	 */
> > >> +	for (i = 0; i < list_size; i++)
> > >> +		val &= ~available_list[i];
> > >> +
> > >> +	return val ? -EINVAL : 0;
> > >> +}
> > >> +
> > >> +static int hisi_ptt_trace_valid_config_onehot(u32 val, u32 *available_list, u32 list_size)
> > >> +{
> > >> +	int i, ret = -EINVAL;
> > >> +
> > >> +	for (i = 0; i < list_size; i++)
> > >> +		if (val == available_list[i]) {
> > >> +			ret = 0;
> > >> +			break;
> > >> +		}
> > >> +
> > >> +	return ret;
> > >> +}
> > >> +
> > >> +static int hisi_ptt_trace_init_filter(struct hisi_ptt *hisi_ptt, u64 config)
> > >> +{
> > >> +	unsigned long val, port_mask = hisi_ptt->port_mask;
> > >> +	struct hisi_ptt_filter_desc *filter;
> > >> +	int ret = -EINVAL;
> > >> +
> > >> +	hisi_ptt->trace_ctrl.is_port = FIELD_GET(HISI_PTT_PMU_FILTER_IS_PORT, config);
> > >> +	val = FIELD_GET(HISI_PTT_PMU_FILTER_VAL_MASK, config);
> > >> +
> > >> +	/*
> > >> +	 * Port filters are defined as bit mask. For port filters, check
> > >> +	 * the bits in the @val are within the range of hisi_ptt->port_mask
> > >> +	 * and whether it's empty or not, otherwise user has specified
> > >> +	 * some unsupported root ports.
> > >> +	 *
> > >> +	 * For Requester ID filters, walk the available filter list to see
> > >> +	 * whether we have one matched.
> > >> +	 */
> > >> +	if (hisi_ptt->trace_ctrl.is_port &&
> > >> +	    bitmap_subset(&val, &port_mask, BITS_PER_LONG)) {
> > >> +		ret = 0;
> > >> +	} else {
> > >> +		list_for_each_entry(filter, &hisi_ptt->req_filters, list)
> > >> +			if (filter->val == val) {
> > >> +				ret = 0;
> > >> +				break;
> > >> +			}
> > >> +	}
> > >> +
> > >> +	if (ret)
> > >> +		return ret;
> > >> +
> > >> +	hisi_ptt->trace_ctrl.filter = val;
> > >> +	return 0;
> > >> +}
> > >> +
> > >> +static int hisi_ptt_pmu_event_init(struct perf_event *event)
> > >> +{
> > >> +	struct hisi_ptt *hisi_ptt = to_hisi_ptt(event->pmu);
> > >> +	struct hisi_ptt_trace_ctrl *ctrl = &hisi_ptt->trace_ctrl;
> > >> +	int ret;
> > >> +	u32 val;
> > >> +
> > >> +	if (event->attr.type != hisi_ptt->hisi_ptt_pmu.type)
> > >> +		return -ENOENT;
> > >> +
> > >> +	mutex_lock(&hisi_ptt->mutex);
> > >> +
> > >> +	ret = hisi_ptt_trace_init_filter(hisi_ptt, event->attr.config);
> > >> +	if (ret < 0)
> > >> +		goto out;
> > >> +
> > >> +	val = FIELD_GET(HISI_PTT_PMU_DIRECTION_MASK, event->attr.config);
> > >> +	ret = hisi_ptt_trace_valid_config_onehot(val, hisi_ptt_trace_available_direction,
> > >> +						 ARRAY_SIZE(hisi_ptt_trace_available_direction));
> > >> +	if (ret < 0)
> > >> +		goto out;
> > >> +	ctrl->direction = val;
> > >> +
> > >> +	val = FIELD_GET(HISI_PTT_PMU_TYPE_MASK, event->attr.config);
> > >> +
> > >> +	ret = hisi_ptt_trace_valid_config(val, hisi_ptt_trace_available_type,
> > >> +					  ARRAY_SIZE(hisi_ptt_trace_available_type));
> > >> +	if (ret < 0)
> > >> +		goto out;
> > >> +	ctrl->type = val;
> > >> +
> > >> +	val = FIELD_GET(HISI_PTT_PMU_FORMAT_MASK, event->attr.config);
> > >> +	ret = hisi_ptt_trace_valid_config_onehot(val, hisi_ptt_trace_availble_format,
> > >> +						 ARRAY_SIZE(hisi_ptt_trace_availble_format));
> > >> +	if (ret < 0)
> > >> +		goto out;
> > >> +	ctrl->format = val;
> > >> +
> > >> +out:
> > >> +	mutex_unlock(&hisi_ptt->mutex);
> > >> +	return ret;
> > >> +}
> > >> +
> > >> +static void *hisi_ptt_pmu_setup_aux(struct perf_event *event, void **pages,
> > >> +				    int nr_pages, bool overwrite)
> > >> +{
> > >> +	struct hisi_ptt_pmu_buf *buf;
> > >> +	struct page **pagelist;
> > >> +	int i;
> > >> +
> > >> +	if (overwrite) {
> > >> +		dev_warn(event->pmu->dev, "Overwrite mode is not supported\n");
> > >> +		return NULL;
> > >> +	}
> > >> +
> > >> +	/* If the pages size less than buflets, we cannot start trace */
> > >> +	if (nr_pages < HISI_PTT_TRACE_BUFFER_SIZE / PAGE_SIZE)
> > >> +		return NULL;
> > >> +
> > >> +	buf = kzalloc(sizeof(*buf), GFP_KERNEL);
> > >> +	if (!buf)
> > >> +		return NULL;
> > >> +
> > >> +	pagelist = kcalloc(nr_pages, sizeof(*pagelist), GFP_KERNEL);
> > >> +	if (!pagelist) {
> > >> +		kfree(buf);
> > >> +		return NULL;
> > >> +	}
> > >> +
> > >> +	for (i = 0; i < nr_pages; i++)
> > >> +		pagelist[i] = virt_to_page(pages[i]);
> > >> +
> > >> +	buf->base = vmap(pagelist, nr_pages, VM_MAP, PAGE_KERNEL);
> > >> +	if (!buf->base) {
> > >> +		kfree(pagelist);
> > >> +		kfree(buf);
> > >> +		return NULL;
> > >> +	}
> > >> +
> > >> +	buf->nr_pages = nr_pages;
> > >> +	buf->length = nr_pages * PAGE_SIZE;
> > >> +	buf->pos = 0;
> > >> +
> > >> +	kfree(pagelist);
> > >> +	return buf;
> > >> +}
> > >> +
> > >> +static void hisi_ptt_pmu_free_aux(void *aux)
> > >> +{
> > >> +	struct hisi_ptt_pmu_buf *buf = aux;
> > >> +
> > >> +	vunmap(buf->base);
> > >> +	kfree(buf);
> > >> +}
> > >> +
> > >> +static void hisi_ptt_pmu_start(struct perf_event *event, int flags)
> > >> +{
> > >> +	struct hisi_ptt *hisi_ptt = to_hisi_ptt(event->pmu);
> > >> +	struct perf_output_handle *handle = &hisi_ptt->trace_ctrl.handle;
> > >> +	struct hw_perf_event *hwc = &event->hw;
> > >> +	struct hisi_ptt_pmu_buf *buf;
> > >> +	int cpu = event->cpu;
> > >> +	int ret;
> > >> +
> > >> +	hwc->state = 0;
> > >> +	mutex_lock(&hisi_ptt->mutex);
> > >> +	if (hisi_ptt->trace_ctrl.status == HISI_PTT_TRACE_STATUS_ON) {
> > >> +		pci_dbg(hisi_ptt->pdev, "trace has already started\n");
> > >> +		goto stop;
> > >> +	}
> > >> +
> > >> +	if (cpu == -1)
> > >> +		cpu = hisi_ptt->trace_ctrl.default_cpu;
> > >> +
> > >> +	/*
> > >> +	 * Handle the interrupt on the same cpu which starts the trace to avoid
> > >> +	 * context mismatch. Otherwise we'll trigger the WARN from the perf
> > >> +	 * core in event_function_local().
> > >> +	 */
> > >> +	WARN_ON(irq_set_affinity(pci_irq_vector(hisi_ptt->pdev, HISI_PTT_TRACE_DMA_IRQ),
> > >> +				 cpumask_of(cpu)));
> > >> +
> > >> +	ret = hisi_ptt_alloc_trace_buf(hisi_ptt);
> > >> +	if (ret) {
> > >> +		pci_dbg(hisi_ptt->pdev, "alloc trace buf failed, ret = %d\n", ret);
> > >> +		goto stop;
> > >> +	}
> > >> +
> > >> +	buf = perf_aux_output_begin(handle, event);
> > >> +	if (!buf) {
> > >> +		pci_dbg(hisi_ptt->pdev, "aux output begin failed\n");
> > >> +		goto stop;
> > >> +	}
> > >> +
> > >> +	buf->pos = handle->head % buf->length;
> > >> +
> > >> +	ret = hisi_ptt_trace_start(hisi_ptt);
> > >> +	if (ret) {
> > >> +		pci_dbg(hisi_ptt->pdev, "trace start failed, ret = %d\n", ret);
> > >> +		perf_aux_output_end(handle, 0);
> > >> +		goto stop;
> > >> +	}
> > >> +
> > >> +	mutex_unlock(&hisi_ptt->mutex);
> > >> +	return;
> > >> +stop:
> > >> +	event->hw.state |= PERF_HES_STOPPED;
> > >> +	mutex_unlock(&hisi_ptt->mutex);
> > >> +}
> > >> +
> > >> +static void hisi_ptt_pmu_stop(struct perf_event *event, int flags)
> > >> +{
> > >> +	struct hisi_ptt *hisi_ptt = to_hisi_ptt(event->pmu);
> > >> +	struct hw_perf_event *hwc = &event->hw;
> > >> +
> > >> +	if (hwc->state & PERF_HES_STOPPED)
> > >> +		return;
> > >> +
> > >> +	mutex_lock(&hisi_ptt->mutex);
> > >> +	if (hisi_ptt->trace_ctrl.status == HISI_PTT_TRACE_STATUS_ON) {
> > >> +		hisi_ptt_trace_end(hisi_ptt);
> > >> +		WARN(hisi_ptt_wait_trace_hw_idle(hisi_ptt), "Device is still busy");
> > >> +		hisi_ptt_update_aux(hisi_ptt, hisi_ptt->trace_ctrl.buf_index, true);
> > >> +	}
> > >> +	mutex_unlock(&hisi_ptt->mutex);
> > >> +
> > >> +	hwc->state |= PERF_HES_STOPPED;
> > >> +	perf_event_update_userpage(event);
> > >> +	hwc->state |= PERF_HES_UPTODATE;
> > >> +}
> > >> +
> > >> +static int hisi_ptt_pmu_add(struct perf_event *event, int flags)
> > >> +{
> > >> +	struct hisi_ptt *hisi_ptt = to_hisi_ptt(event->pmu);
> > >> +	struct hw_perf_event *hwc = &event->hw;
> > >> +	int cpu = event->cpu;
> > >> +
> > >> +	if (cpu == -1 && smp_processor_id() != hisi_ptt->trace_ctrl.default_cpu)
> > >> +		return 0;
> > >> +
> > >> +	hwc->state = PERF_HES_STOPPED | PERF_HES_UPTODATE;
> > >> +
> > >> +	if (flags & PERF_EF_START) {
> > >> +		hisi_ptt_pmu_start(event, PERF_EF_RELOAD);
> > >> +		if (hwc->state & PERF_HES_STOPPED)
> > >> +			return -EINVAL;
> > >> +	}
> > >> +
> > >> +	return 0;
> > >> +}
> > >> +
> > >> +static void hisi_ptt_pmu_del(struct perf_event *event, int flags)
> > >> +{
> > >> +	hisi_ptt_pmu_stop(event, PERF_EF_UPDATE);
> > >> +}
> > >> +
> > >> +static void hisi_ptt_unregister_pmu(void *priv)
> > >> +{
> > >> +	perf_pmu_unregister(priv);
> > >> +}
> > >> +
> > >> +static int hisi_ptt_register_pmu(struct hisi_ptt *hisi_ptt)
> > >> +{
> > >> +	char *pmu_name;
> > >> +	int ret;
> > >> +
> > >> +	hisi_ptt->hisi_ptt_pmu = (struct pmu) {
> > >> +		.module		= THIS_MODULE,
> > >> +		.capabilities	= PERF_PMU_CAP_EXCLUSIVE | PERF_PMU_CAP_ITRACE,
> > >> +		.task_ctx_nr	= perf_sw_context,
> > >> +		.attr_groups	= hisi_ptt_pmu_groups,
> > >> +		.event_init	= hisi_ptt_pmu_event_init,
> > >> +		.setup_aux	= hisi_ptt_pmu_setup_aux,
> > >> +		.free_aux	= hisi_ptt_pmu_free_aux,
> > >> +		.start		= hisi_ptt_pmu_start,
> > >> +		.stop		= hisi_ptt_pmu_stop,
> > >> +		.add		= hisi_ptt_pmu_add,
> > >> +		.del		= hisi_ptt_pmu_del,
> > >> +	};
> > >> +
> > >> +	pmu_name = devm_kasprintf(&hisi_ptt->pdev->dev, GFP_KERNEL, "hisi_ptt%u_%u",
> > >> +				  hisi_ptt->sicl_id, hisi_ptt->core_id);
> > >> +	if (!pmu_name)
> > >> +		return -ENOMEM;
> > >> +
> > >> +	ret = perf_pmu_register(&hisi_ptt->hisi_ptt_pmu, pmu_name, -1);
> > >> +	if (ret)
> > >> +		return ret;
> > >> +
> > >> +	return devm_add_action_or_reset(&hisi_ptt->pdev->dev,
> > >> +					hisi_ptt_unregister_pmu,
> > >> +					&hisi_ptt->hisi_ptt_pmu);
> > >> +}
> > >> +
> > >> +/*
> > >> + * Get RMR address if provided by the firmware.
> > >> + * Return 0 if the IOMMU doesn't present or the policy of the
> > >> + * IOMMU domain is passthrough or we get a usable RMR region.
> > >> + * Otherwise a negative value is returned.
> > >> + */
> > >> +static int hisi_ptt_get_rmr(struct hisi_ptt *hisi_ptt)
> > >> +{
> > >> +	struct pci_dev *pdev = hisi_ptt->pdev;
> > >> +	struct iommu_domain *iommu_domain;
> > >> +	struct iommu_resv_region *region;
> > >> +	LIST_HEAD(list);
> > >> +
> > >> +	/*
> > >> +	 * Use direct DMA if IOMMU does not present or the policy of the
> > >> +	 * IOMMU domain is passthrough.
> > >> +	 */
> > >> +	iommu_domain = iommu_get_domain_for_dev(&pdev->dev);
> > >> +	if (!iommu_domain || iommu_domain->type == IOMMU_DOMAIN_IDENTITY)
> > >> +		return 0;
> > >> +
> > >> +	iommu_get_resv_regions(&pdev->dev, &list);
> > >> +	list_for_each_entry(region, &list, list)
> > >> +		if (region->type == IOMMU_RESV_DIRECT &&
> > >> +		    region->length >= HISI_PTT_TRACE_BUFFER_SIZE) {
> > >> +			hisi_ptt->trace_ctrl.has_rmr = true;
> > >> +			hisi_ptt->trace_ctrl.rmr_addr = region->start;
> > >> +			hisi_ptt->trace_ctrl.rmr_length = region->length;
> > >> +			break;
> > >> +		}
> > >> +
> > >> +	iommu_put_resv_regions(&pdev->dev, &list);
> > >> +	return hisi_ptt->trace_ctrl.has_rmr ? 0 : -ENOMEM;
> > >> +}
> > >> +
> > >> +static int hisi_ptt_probe(struct pci_dev *pdev,
> > >> +			  const struct pci_device_id *id)
> > >> +{
> > >> +	struct hisi_ptt *hisi_ptt;
> > >> +	int ret;
> > >> +
> > >> +	hisi_ptt = devm_kzalloc(&pdev->dev, sizeof(*hisi_ptt), GFP_KERNEL);
> > >> +	if (!hisi_ptt)
> > >> +		return -ENOMEM;
> > >> +
> > >> +	mutex_init(&hisi_ptt->mutex);
> > >> +	hisi_ptt->pdev = pdev;
> > >> +
> > >> +	/*
> > >> +	 * Lifetime of pci_dev is longer than hisi_ptt,
> > >> +	 * so directly reference to the pci name string.
> > >> +	 */
> > >> +	hisi_ptt->name = pci_name(hisi_ptt->pdev);
> > >> +	pci_set_drvdata(pdev, hisi_ptt);
> > >> +
> > >> +	ret = pcim_enable_device(pdev);
> > >> +	if (ret) {
> > >> +		pci_err(pdev, "failed to enable device, ret = %d.\n", ret);
> > >> +		return ret;
> > >> +	}
> > >> +
> > >> +	ret = pcim_iomap_regions(pdev, BIT(2), hisi_ptt->name);
> > >> +	if (ret) {
> > >> +		pci_err(pdev, "failed to remap io memory, ret = %d.\n", ret);
> > >> +		return ret;
> > >> +	}
> > >> +
> > >> +	hisi_ptt->iobase = pcim_iomap_table(pdev)[2];
> > >> +
> > >> +	ret = dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(64));
> > >> +	if (ret) {
> > >> +		pci_err(pdev, "failed to set 64 bit dma mask, ret = %d.\n", ret);
> > >> +		return ret;
> > >> +	}
> > >> +	pci_set_master(pdev);
> > >> +
> > >> +	ret = hisi_ptt_register_irq(hisi_ptt);
> > >> +	if (ret)
> > >> +		return ret;
> > >> +
> > >> +	hisi_ptt_init_ctrls(hisi_ptt);
> > >> +
> > >> +	ret = hisi_ptt_register_pmu(hisi_ptt);
> > >> +	if (ret) {
> > >> +		pci_err(pdev, "failed to register pmu device, ret = %d", ret);
> > >> +		return ret;
> > >> +	}
> > > 
> > > If this fails the pci_free_irq_vectors() is not called.
> > > 
> > 
> > It'll be called as we've registered a devm callback when
> > allocating the irq vector. See hisi_ptt_register_irq().
> 
> Ah yes - thanks for pointing that out.
> 
> > 
> > > I am out of time for today - I will continue tomorrow.
> > > 
> > 
> > Sure. Thanks!
> > Yicong
> > 
> > > Thanks,
> > > Mathieu
> > > 
> > >> +
> > >> +	ret = hisi_ptt_get_rmr(hisi_ptt);
> > >> +	if (ret) {
> > >> +		pci_err(pdev, "failed to get RMR region, ret = %d", ret);
> > >> +		return ret;
> > >> +	}
> > >> +
> > >> +	/* Register the bus notifier for dynamically updating the filter list */
> > >> +	hisi_ptt->hisi_ptt_nb.notifier_call = hisi_ptt_notifier_call;
> > >> +	ret = bus_register_notifier(&pci_bus_type, &hisi_ptt->hisi_ptt_nb);
> > >> +	if (ret)
> > >> +		pci_warn(pdev, "failed to register filter update notifier, ret = %d", ret);
> > >> +
> > >> +	return 0;
> > >> +}
> > >> +
> > >> +void hisi_ptt_remove(struct pci_dev *pdev)
> > >> +{
> > >> +	struct hisi_ptt *hisi_ptt = pci_get_drvdata(pdev);
> > >> +
> > >> +	bus_unregister_notifier(&pci_bus_type, &hisi_ptt->hisi_ptt_nb);
> > >> +
> > >> +	/* Cancel any work that has been queued */
> > >> +	cancel_delayed_work_sync(&hisi_ptt->work);
> > >> +
> > >> +	if (hisi_ptt->trace_ctrl.status == HISI_PTT_TRACE_STATUS_ON)
> > >> +		hisi_ptt_trace_end(hisi_ptt);
> > >> +
> > >> +	hisi_ptt_free_trace_buf(hisi_ptt);
> > >> +	hisi_ptt_release_filters(hisi_ptt);
> > >> +}
> > >> +
> > >> +static const struct pci_device_id hisi_ptt_id_tbl[] = {
> > >> +	{ PCI_DEVICE(PCI_VENDOR_ID_HUAWEI, 0xa12e) },
> > >> +	{ }
> > >> +};
> > >> +MODULE_DEVICE_TABLE(pci, hisi_ptt_id_tbl);
> > >> +
> > >> +static struct pci_driver hisi_ptt_driver = {
> > >> +	.name = "hisi_ptt",
> > >> +	.id_table = hisi_ptt_id_tbl,
> > >> +	.probe = hisi_ptt_probe,
> > >> +	.remove = hisi_ptt_remove,
> > >> +};
> > >> +module_pci_driver(hisi_ptt_driver);
> > >> +
> > >> +MODULE_LICENSE("GPL v2");
> > >> +MODULE_AUTHOR("Yicong Yang <yangyicong@hisilicon.com>");
> > >> +MODULE_DESCRIPTION("Driver for HiSilicon PCIe tune and trace device");
> > >> -- 
> > >> 2.33.0
> > >>
> > > .
> > >

On 2021/11/25 23:49, Robin Murphy wrote:
> On 2021-11-18 09:01, Yicong Yang via iommu wrote:
>> Hi Robin,
>>
>> On 2021/11/16 19:37, Yicong Yang wrote:
>>> On 2021/11/16 18:56, Robin Murphy wrote:
>>>> On 2021-11-16 09:06, Yicong Yang via iommu wrote:
>>>> [...]
>>>>> +/*
>>>>> + * Get RMR address if provided by the firmware.
>>>>> + * Return 0 if the IOMMU doesn't present or the policy of the
>>>>> + * IOMMU domain is passthrough or we get a usable RMR region.
>>>>> + * Otherwise a negative value is returned.
>>>>> + */
>>>>> +static int hisi_ptt_get_rmr(struct hisi_ptt *hisi_ptt)
>>>>> +{
>>>>> +    struct pci_dev *pdev = hisi_ptt->pdev;
>>>>> +    struct iommu_domain *iommu_domain;
>>>>> +    struct iommu_resv_region *region;
>>>>> +    LIST_HEAD(list);
>>>>> +
>>>>> +    /*
>>>>> +     * Use direct DMA if IOMMU does not present or the policy of the
>>>>> +     * IOMMU domain is passthrough.
>>>>> +     */
>>>>> +    iommu_domain = iommu_get_domain_for_dev(&pdev->dev);
>>>>> +    if (!iommu_domain || iommu_domain->type == IOMMU_DOMAIN_IDENTITY)
>>>>> +        return 0;
>>>>> +
>>>>> +    iommu_get_resv_regions(&pdev->dev, &list);
>>>>> +    list_for_each_entry(region, &list, list)
>>>>> +        if (region->type == IOMMU_RESV_DIRECT &&
>>>>> +            region->length >= HISI_PTT_TRACE_BUFFER_SIZE) {
>>>>> +            hisi_ptt->trace_ctrl.has_rmr = true;
>>>>> +            hisi_ptt->trace_ctrl.rmr_addr = region->start;
>>>>> +            hisi_ptt->trace_ctrl.rmr_length = region->length;
>>>>> +            break;
>>>>> +        }
>>>>> +
>>>>> +    iommu_put_resv_regions(&pdev->dev, &list);
>>>>> +    return hisi_ptt->trace_ctrl.has_rmr ? 0 : -ENOMEM;
>>>>> +}
>>>>
>>>> No.
>>>>
>>>> The whole point of RMRs is for devices that are already configured to access the given address range in a manner beyond the kernel's control. If you can do this, it proves that you should not have an RMR in the first place.
>>>>
>>>> The notion of a kernel driver explicitly configuring its device to DMA into any random RMR that looks big enough is so egregiously wrong that I'm almost lost for words...
>>>>
>>>
>>> our bios will reserve such a region and reported it through iort. the device will write to the region and in the driver we need to access the region
>>> to get the traced data. the region is reserved exclusively and will not be accessed by kernel or other devices.
>>>
>>> is it ok to let bios configure the address to the device and from CPU side we just read it?
>>>
>>
>> Any suggestion?  Is this still an issue you concern if we move the configuration of the device address to BIOS and just read from the CPU side?
> 
> If the firmware configures the device so that it's actively tracing and writing out to memory while the kernel boots, then that is a valid reason to have an RMR. However what you're doing in the driver is still complete nonsense. As far as I can follow, the way it's working is this:
> 
> - At probe time, the initial state of the hardware is entirely ignored. If it *is* already active, there appears to be a fun chance of crashing if TRACE_INT_MASK is clear and an interrupt happens to fire before anyone has got round to calling perf_aux_output_begin() to make trace_ctrl.handle.rb non-NULL.
> 
> - Later, once the user starts a tracing session, a buffer is set up *either* as a completely normal DMA allocation, or by memremap()ing some random IOVA carveout which may or may not be whatever memory the firmware was tracing to.
> 
> - The hardware is then reset and completely reprogrammed to use the new buffer, again without any consideration of its previous state (other than possibly timing out and failing if it's already running and that means it never goes idle).
> 
> Therefore the driver does not seem to respect any prior configuration of the device by firmware, does not seem to expect it to be running at boot time, does not seem to have any way to preserve and export any trace data captured in an RMR if it *was* running at boot time, and thus without loss of generality could simply use the dma_alloc_coherent() path all the time. Am I missing anything?
> 

Thanks for the further explanation and I think I understand your concerns more clearer.

The trace is not supposed to begin by the firmware at boot time. Due to some hardware restriction, the device cannot trace with non-identical mapping.
So we'd like to use RMR to make the device work when the dma mapping is non-identical. Thus we check here to decide whether to use RMR or not: if the iommu
is not presented or in the passthrough mode, we can use direct DMA by dma_alloc_coherent(); if the iommu is present and the mode is not passthrough, we try
to retrieve RMR or we fail the probe. The firmware is expected to reserve a range of memory and reports it to the driver and is not expected to configure
the trace and do boot time tracing.

> As things stand, RMRs are not yet supported upstream (FYI we're still working on fixing the spec...), so the code above is at best dead, and at worst actively wrong. Furthermore, if the expected usage model *is* that the kernel driver completely resets and reprograms the hardware, then even if there is an RMR for boot-time tracing I would rather expect it to be flagged as remappable, and thus potentially end up as an IOMMU_RESV_DIRECT_RELAXABLE reservation which you wouldn't match anyway.
> 

Yes the firmware is not expected to start the trace. Will change the desired flag to IOMMU_RESV_DIRECT_RELAXABLE and have a test.

> And after all that, if you really do have a genuine need to respect and preserve prior firmware configuration of the device, then I would surely expect to see the driver actually doing exactly that. Presumably: at probe time, look at TRACE_CTRL; if the device is already configured, read out that configuration - especially including TRACE_ADDR_* - and make sure to reuse it. Not go off on a tangent blindly poking into internal IOMMU API abstractions in the vain hope that the first thing you find happens to be sort-of-related to the information that you actually care about.
> 

Yes, we do need RMR to make the device work at situation where the mapping is non-identical.

We're certain that the bios won't start and configure the trace in this device's usage, is it still necessary to make
firmware configure the TRACE_ADDR_* to the device?

As suggested, I think I'll need to modify the RMR codes like

- check TRACE_CTRL, and stop it if it's started. (won't happen but check for sanity)
- if smmu is not presented, use direct DMA
- try to retrieve RMR address with flag IOMMU_RESV_DIRECT_RELAXABLE , if presented set hisi_ptt->has_rmr. in this case we won't use direct DMA
- check if the TRACE_ADDR_* has been configured. if so don't reconfigure it when trace
- if no rmr but smmu works in passthrough mode, use direct DMA
- otherwise fails the probe

If I miss something please point it out.

Thanks,
Yicong

On 2021/11/26 2:50, Mathieu Poirier wrote:
> On Thu, Nov 25, 2021 at 04:39:46PM +0800, Yicong Yang wrote:
>> Hi Mathieu,
>>
>> Thanks for the comments! Replies inline.
>>
>> On 2021/11/25 2:51, Mathieu Poirier wrote:
>>> Hi Yicong,
>>>
>>> On Tue, Nov 16, 2021 at 05:06:21PM +0800, Yicong Yang wrote:
>>>> HiSilicon PCIe tune and trace device(PTT) is a PCIe Root Complex
>>>> integrated Endpoint(RCiEP) device, providing the capability
>>>> to dynamically monitor and tune the PCIe traffic(tune),
>>>> and trace the TLP headers(trace).
>>>>
>>>
>>> Is there a reason to put "tune" and "trace" are whithin parentheses?  
>>>
>>
>> yeah. I want to use these single word to denote the related function, and
>> place them in the parantheses near the function's description to make sure
>> readers can match them.
>>
> 
> Probably a better idea to simply write "TLP headers" and "PCIe traffic" when
> referring to them.  Otherwise it is very confusing because the reader doesn't
> know if you mean the acronym or the real definition of "tune" and "trace".
> 

ok I reread the commit and seems reader will know the acronym as it's mentioned
as "*tune* the PCIe traffic" and "*trace* the TLP headers". I think the
contents in the parantheses can be simply dropped.

>>>> Add the driver for the device to enable the trace function. The driver
>>>> will create PMU device for each PTT device, and users can start trace
>>>> through perf command.
>>>>
>>>> Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
>>>> ---
>>>>  drivers/Makefile                       |    1 +
>>>>  drivers/hwtracing/Kconfig              |    2 +
>>>>  drivers/hwtracing/hisilicon/Kconfig    |    8 +
>>>>  drivers/hwtracing/hisilicon/Makefile   |    2 +
>>>>  drivers/hwtracing/hisilicon/hisi_ptt.c | 1146 ++++++++++++++++++++++++
>>>
>>> Not sure about the "hisilicon" directory.  Right now we have "coresight",
>>> "intel_th" and "stm" - they concentrate on the technology rather than the
>>> vendor.  I think "ptt" would be just fine: 
>>>
>>> drivers/hwtracing/ptt/Kconfig 
>>> drivers/hwtracing/ptt/Makefile
>>> drivers/hwtracing/ptt/hisi_ptt.c
>>>
>>> That way if other vendors want to introduce support for the same kind of
>>> technology we can simply put them under "drivers/hwtracing/ptt/" and things are
>>> still accurate.
>>>
>>
>> sure. sounds sensible. will rename the directory to "ptt" if no objection.
>>
>>>
>>>>  5 files changed, 1159 insertions(+)
>>>>  create mode 100644 drivers/hwtracing/hisilicon/Kconfig
>>>>  create mode 100644 drivers/hwtracing/hisilicon/Makefile
>>>>  create mode 100644 drivers/hwtracing/hisilicon/hisi_ptt.c
>>>>
>>>> diff --git a/drivers/Makefile b/drivers/Makefile
>>>> index be5d40ae1488..bb0dc9b55ea2 100644
>>>> --- a/drivers/Makefile
>>>> +++ b/drivers/Makefile
>>>> @@ -176,6 +176,7 @@ obj-$(CONFIG_USB4)		+= thunderbolt/
>>>>  obj-$(CONFIG_CORESIGHT)		+= hwtracing/coresight/
>>>>  obj-y				+= hwtracing/intel_th/
>>>>  obj-$(CONFIG_STM)		+= hwtracing/stm/
>>>> +obj-$(CONFIG_HISI_PTT)         += hwtracing/hisilicon/
>>>>  obj-$(CONFIG_ANDROID)		+= android/
>>>>  obj-$(CONFIG_NVMEM)		+= nvmem/
>>>>  obj-$(CONFIG_FPGA)		+= fpga/
>>>> diff --git a/drivers/hwtracing/Kconfig b/drivers/hwtracing/Kconfig
>>>> index 13085835a636..e3796b17541a 100644
>>>> --- a/drivers/hwtracing/Kconfig
>>>> +++ b/drivers/hwtracing/Kconfig
>>>> @@ -5,4 +5,6 @@ source "drivers/hwtracing/stm/Kconfig"
>>>>  
>>>>  source "drivers/hwtracing/intel_th/Kconfig"
>>>>  
>>>> +source "drivers/hwtracing/hisilicon/Kconfig"
>>>> +
>>>>  endmenu
>>>> diff --git a/drivers/hwtracing/hisilicon/Kconfig b/drivers/hwtracing/hisilicon/Kconfig
>>>> new file mode 100644
>>>> index 000000000000..9c3ab80d99fe
>>>> --- /dev/null
>>>> +++ b/drivers/hwtracing/hisilicon/Kconfig
>>>> @@ -0,0 +1,8 @@
>>>> +# SPDX-License-Identifier: GPL-2.0-only
>>>> +config HISI_PTT
>>>> +	tristate "HiSilicon PCIe Tune and Trace Device"
>>>> +	depends on PCI && HAS_DMA && HAS_IOMEM
>>>
>>> What Arm architecture are you aiming this for?  Can it be found on both armv7
>>> and armv8?
>>>
>>
>> currently the device will appear on Kunpeng 930, which is armv8.
> 
> Ok, then please make it dependent on armv8.
> 

sure.

>>
>>>> +	help
>>>> +	  HiSilicon PCIe Tune and Trace Device exist as a PCIe RCiEP
>>>> +	  device, provides support for PCIe traffic tuning and
>>>> +	  tracing TLP headers to the memory.
>>>
>>> Please indicate what the name of the driver will be when compiled as a module.
>>>
>>
>> sure. will add the module's name here.
>>
>>>> diff --git a/drivers/hwtracing/hisilicon/Makefile b/drivers/hwtracing/hisilicon/Makefile
>>>> new file mode 100644
>>>> index 000000000000..908c09a98161
>>>> --- /dev/null
>>>> +++ b/drivers/hwtracing/hisilicon/Makefile
>>>> @@ -0,0 +1,2 @@
>>>> +# SPDX-License-Identifier: GPL-2.0
>>>> +obj-$(CONFIG_HISI_PTT) += hisi_ptt.o
>>>> diff --git a/drivers/hwtracing/hisilicon/hisi_ptt.c b/drivers/hwtracing/hisilicon/hisi_ptt.c
>>>> new file mode 100644
>>>> index 000000000000..e11e9b6cc2a8
>>>> --- /dev/null
>>>> +++ b/drivers/hwtracing/hisilicon/hisi_ptt.c
>>>> @@ -0,0 +1,1146 @@
>>>> +// SPDX-License-Identifier: GPL-2.0
>>>> +/*
>>>> + * Driver for HiSilicon PCIe tune and trace device
>>>> + *
>>>> + * Copyright (c) 2021 HiSilicon Limited.
>>>> + */
>>>> +
>>>> +#include <linux/bitfield.h>
>>>> +#include <linux/bitops.h>
>>>> +#include <linux/delay.h>
>>>> +#include <linux/dma-iommu.h>
>>>> +#include <linux/dma-mapping.h>
>>>> +#include <linux/interrupt.h>
>>>> +#include <linux/io.h>
>>>> +#include <linux/iommu.h>
>>>> +#include <linux/iopoll.h>
>>>> +#include <linux/kfifo.h>
>>>> +#include <linux/module.h>
>>>> +#include <linux/notifier.h>
>>>> +#include <linux/pci.h>
>>>> +#include <linux/perf_event.h>
>>>> +#include <linux/sizes.h>
>>>> +#include <linux/sysfs.h>
>>>> +#include <linux/vmalloc.h>
>>>> +#include <linux/workqueue.h>
>>>> +
>>>> +#define HISI_PTT_TRACE_ADDR_SIZE	0x0800
>>>> +#define HISI_PTT_TRACE_ADDR_BASE_LO_0	0x0810
>>>> +#define HISI_PTT_TRACE_ADDR_BASE_HI_0	0x0814
>>>> +#define HISI_PTT_TRACE_ADDR_STRIDE	0x8
>>>> +#define HISI_PTT_TRACE_CTRL		0x0850
>>>> +#define   HISI_PTT_TRACE_CTRL_EN	BIT(0)
>>>> +#define   HISI_PTT_TRACE_CTRL_RST	BIT(1)
>>>> +#define   HISI_PTT_TRACE_CTRL_RXTX_SEL	GENMASK(3, 2)
>>>> +#define   HISI_PTT_TRACE_CTRL_TYPE_SEL	GENMASK(7, 4)
>>>> +#define   HISI_PTT_TRACE_CTRL_DATA_FORMAT	BIT(14)
>>>> +#define   HISI_PTT_TRACE_CTRL_FILTER_MODE	BIT(15)
>>>> +#define   HISI_PTT_TRACE_CTRL_TARGET_SEL	GENMASK(31, 16)
>>>> +#define HISI_PTT_TRACE_INT_STAT		0x0890
>>>> +#define   HISI_PTT_TRACE_INT_STAT_MASK	GENMASK(3, 0)
>>>> +#define HISI_PTT_TRACE_INT_MASK		0x0894
>>>> +#define HISI_PTT_TRACE_WR_STS		0x08a0
>>>> +#define   HISI_PTT_TRACE_WR_STS_WRITE	GENMASK(27, 0)
>>>> +#define   HISI_PTT_TRACE_WR_STS_BUFFER	GENMASK(29, 28)
>>>> +#define HISI_PTT_TRACE_STS		0x08b0
>>>> +#define   HISI_PTT_TRACE_IDLE		BIT(0)
>>>> +#define HISI_PTT_DEVICE_RANGE		0x0fe0
>>>> +#define HISI_PTT_LOCATION		0x0fe8
>>>> +#define   HISI_PTT_CORE_ID		GENMASK(15, 0)
>>>> +#define   HISI_PTT_SICL_ID		GENMASK(31, 16)
>>>
>>> Extra spaces between #define and the literals.  Please align the values with
>>> that of HISI_PTT_TRACE_DMA_IRQ below.
>>>
>>
>> Spaces are intended to distinguish the definition of the register offset and
>> related register fields. also used in include/uapi/linux/pci_regs.h.
>>
> 
> Interesting and definitely not the norm...
> 
>> HISI_PTT_TRACE_DMA_IRQ is well aligned with tab but seems with problem display
>> in the mail text, maybe because the tab is not 8 characters when display.
>>
> 
> In my VI terminal the '0' of HISI_PTT_TRACE_DMA_IRQ is align with the '3' in
> GENMASK(31, 16) and I suspect it is the same for other people.
> 

not sure what happens, with tab=8char it's aligned on my vim and vscode. and yes
it's also aligned with '3' in GENMASK(31,16).

#define HISI_PTT_TRACE_DMA_IRQ\t\t\t0
#define HISI_PTT_TRACE_BUFLETS_CNT\t\t4

>>>> +
>>>> +#define HISI_PTT_TRACE_DMA_IRQ			0
>>>> +#define HISI_PTT_TRACE_BUFLETS_CNT		4
>>>> +#define HISI_PTT_TRACE_BUFLET_SIZE		SZ_4M
>>>> +#define HISI_PTT_TRACE_BUFFER_SIZE		(HISI_PTT_TRACE_BUFLET_SIZE * \
>>>> +						 HISI_PTT_TRACE_BUFLETS_CNT)
>>>> +#define HISI_PTT_FILTER_UPDATE_FIFO_SIZE	16
>>>> +
>>>> +/* Delay time for filter updating work */
>>>> +#define HISI_PTT_WORK_DELAY_MS		100UL
>>>> +/* Wait time for DMA hardware to reset */
>>>> +#define HISI_PTT_RESET_WAIT_MS		1000UL
>>>> +/* Poll timeout and interval for waiting hardware work to finish */
>>>> +#define HISI_PTT_WAIT_TIMEOUT_US	1000000UL
>>>> +#define HISI_PTT_WAIT_POLL_INTERVAL_US	100UL
>>>> +
>>>> +#define HISI_PCIE_CORE_PORT_ID(devfn)	(PCI_FUNC(devfn) << 1)
>>>> +
>>>> +enum hisi_ptt_trace_status {
>>>> +	HISI_PTT_TRACE_STATUS_OFF = 0,
>>>> +	HISI_PTT_TRACE_STATUS_ON,
>>>> +};
>>>> +
>>>> +struct hisi_ptt_dma_buflet {
>>>
>>> I'm not sure what a "buflet" is...  Probably best to just call this
>>> hisi_ptt_dma_buffer" if it pertains to a buffer.  On that note it is hard to
>>> know due to the lack of proper structure documentation.  Please have a look at
>>> how "coresight_device" is documented.  The same applies to the rest of the
>>> structures declared below.
>>>
>>
>> It's mentioned in section 5 of hisi_ptt.rst as "Driver will allocate each DMA buffer
>> (we call it buflet) of 4MiB ...".
> 
> I just noticed the documentation in patch 5 - I will read it before continuing
> with this set.
> 
>>
>> The total DMA buffer of PTT device is divided into 4 parts, and each part is called
>> a 'buflet', which means a small buffer (there exists other words with similiar
>> format: droplet, wavelet, ...).
>>
>> The device is designed like this to make sure we won't lose any data when we have to change
>> the buffer address, the device can continue to write to the next buflet and don't
>> neet to pause.
>>
>>>> +	struct list_head list;
>>>> +	unsigned int size;
>>>> +	dma_addr_t dma;
>>>> +
>>>> +	/*
>>>> +	 * The address of the buflet holding the trace data.
>>>> +	 * See Documentation/trace/hisi-ptt.rst for the details
>>>
>>> As of this writing, hisi-ptt.rst doesn't exist.
>>>
>>
>> The comment intends to direct the user to the documentation if the user
>> want to know details about the data format. The data format is decribed
>> in the section 4 of the doc.
>>
>>>> +	 * of the data format.
>>>> +	 */
>>>> +	void *addr;
>>>> +	int index;
>>>> +};
>>>> +
>>>> +struct hisi_ptt_trace_ctrl {
>>>> +	enum hisi_ptt_trace_status status;
>>>> +	struct perf_output_handle handle;
>>>> +	struct list_head trace_buf;
>>>> +	/*
>>>> +	 * The index of the buffer which trace data
>>>> +	 * currently is writing to.
>>>> +	 */
>>>> +	u32 buf_index;
>>>> +
>>>> +	int default_cpu;
>>>> +	u32 buflet_size;
>>>> +	bool is_port;
>>>> +	u32 format:1;		/* Format of the traced TLP headers */
>>>> +	u32 type:4;		/* Type of the TLP headers to trace */
>>>> +	u32 direction:2;	/* Direction of the TLP headers to trace */
>>>> +	u32 filter:16;		/* Root port or Requester to filter the TLP headers */
>>>> +
>>>> +	phys_addr_t rmr_addr;
>>>> +	size_t rmr_length;
>>>> +	bool has_rmr;
>>>> +};
>>>> +
>>>> +struct hisi_ptt_filter_desc {
>>>> +	struct list_head list;
>>>> +	struct pci_dev *pdev;
>>>> +	u16 val;
>>>> +};
>>>> +
>>>> +struct hisi_ptt_pmu_buf {
>>>> +	size_t length;
>>>> +	int nr_pages;
>>>> +	void *base;
>>>> +	long pos;
>>>> +};
>>>> +
>>>> +/* Structure containing the information for filter updating */
>>>> +struct hisi_ptt_filter_update_info {
>>>> +	struct pci_dev *pdev;
>>>> +	u32 port_devid;
>>>> +	bool is_port;
>>>> +	bool is_add;
>>>> +	u16 val;
>>>> +};
>>>> +
>>>> +struct hisi_ptt {
>>>> +	struct hisi_ptt_trace_ctrl trace_ctrl;
>>>> +	struct notifier_block hisi_ptt_nb;
>>>> +	struct pmu hisi_ptt_pmu;
>>>> +	void __iomem *iobase;
>>>> +	struct pci_dev *pdev;
>>>> +	/*
>>>> +	 * Use the mutex to protect the filter list and
>>>> +	 * serialize the perf process.
>>>> +	 */
>>>> +	struct mutex mutex;
>>>> +	const char *name;
>>>> +	u16 core_id;
>>>> +	u16 sicl_id;
>>>> +	/* PCI device range managed by the PTT device */
>>>> +	u32 upper;
>>>> +	u32 lower;
>>>> +	u8 busnr;
>>>> +
>>>> +	/*
>>>> +	 * The trace TLP headers can either be filtered by certain
>>>> +	 * root port, or by the requester ID. Organize the filters
>>>> +	 * by @port_filters and @req_filters here. The mask of all
>>>> +	 * the valid ports is also cached for doing sanity check
>>>> +	 * of user input.
>>>> +	 */
>>>> +	struct list_head port_filters;
>>>> +	struct list_head req_filters;
>>>> +	u16 port_mask;
>>>> +
>>>> +	/*
>>>> +	 * We use a delayed work here to avoid indefinitely waiting for
>>>> +	 * the hisi_ptt->mutex which protecting the filter list. The
>>>> +	 * work will be delayed only if the mutex can not be held,
>>>> +	 * otherwise no delay will be applied.
>>>> +	 */
>>>> +	struct delayed_work work;
>>>> +	spinlock_t filter_update_lock;
>>>> +	DECLARE_KFIFO(filter_update_kfifo, struct hisi_ptt_filter_update_info,
>>>> +		      HISI_PTT_FILTER_UPDATE_FIFO_SIZE);
>>>> +};
>>>
>>> It might be a good idea to spinoff a hisi_ptt.h for the above declarations.
>>>
>>
>> I'm not sure whether it is common or permitted to provide a header which is only used by
>> this driver with a single file.
> 
> I've seen it done many times.
> 

will split a header file for the driver.

>>
>>>> +
>>>> +static inline struct hisi_ptt *to_hisi_ptt(struct pmu *pmu)
>>>> +{
>>>> +	return container_of(pmu, struct hisi_ptt, hisi_ptt_pmu);
>>>> +}
>>>
>>> I'm not sure there is any value to this inline function.  I suggest to simply
>>> call container_of() whenever it is needed.
>>>
>>
>> ok.
>>
>>>> +
>>>> +static u16 hisi_ptt_get_filter_val(struct pci_dev *pdev)
>>>> +{
>>>> +	if (pci_pcie_type(pdev) == PCI_EXP_TYPE_ROOT_PORT)
>>>> +		return BIT(HISI_PCIE_CORE_PORT_ID(PCI_SLOT(pdev->devfn)));
>>>> +
>>>> +	return PCI_DEVID(pdev->bus->number, pdev->devfn);
>>>> +}
>>>> +
>>>> +static int hisi_ptt_wait_trace_hw_idle(struct hisi_ptt *hisi_ptt)
>>>> +{
>>>> +	u32 val;
>>>> +
>>>> +	return readl_poll_timeout(hisi_ptt->iobase + HISI_PTT_TRACE_STS, val,
>>>> +				  val & HISI_PTT_TRACE_IDLE,
>>>> +				  HISI_PTT_WAIT_POLL_INTERVAL_US,
>>>> +				  HISI_PTT_WAIT_TIMEOUT_US);
>>>> +}
>>>> +
>>>> +static void hisi_ptt_free_trace_buf(struct hisi_ptt *hisi_ptt)
>>>> +{
>>>> +	struct hisi_ptt_trace_ctrl *ctrl = &hisi_ptt->trace_ctrl;
>>>> +	struct device *dev = &hisi_ptt->pdev->dev;
>>>> +	struct hisi_ptt_dma_buflet *buflet, *tbuflet;
>>>> +
>>>> +	list_for_each_entry_safe(buflet, tbuflet, &ctrl->trace_buf, list) {
>>>> +		list_del(&buflet->list);
>>>> +
>>>> +		if (ctrl->has_rmr)
>>>> +			memunmap(buflet->addr);
>>>> +		else
>>>> +			dma_free_coherent(dev, buflet->size, buflet->addr,
>>>> +					  buflet->dma);
>>>> +
>>>> +		kfree(buflet);
>>>> +	}
>>>> +}
>>>> +
>>>> +static int hisi_ptt_alloc_trace_buf(struct hisi_ptt *hisi_ptt)
>>>> +{
>>>> +	struct hisi_ptt_trace_ctrl *ctrl = &hisi_ptt->trace_ctrl;
>>>> +	struct device *dev = &hisi_ptt->pdev->dev;
>>>> +	struct hisi_ptt_dma_buflet *buflet;
>>>> +	int i, ret;
>>>> +
>>>> +	hisi_ptt->trace_ctrl.buf_index = 0;
>>>> +
>>>> +	/* Make sure the trace buffer is empty before allocating */
>>>> +	if (!list_empty(&ctrl->trace_buf)) {
>>>> +		list_for_each_entry(buflet, &ctrl->trace_buf, list)
>>>> +			memset(buflet->addr, 0, buflet->size);
>>>> +		return 0;
>>>> +	}
>>>> +
>>>> +	for (i = 0; i < HISI_PTT_TRACE_BUFLETS_CNT; ++i) {
>>>> +		buflet = kzalloc(sizeof(*buflet), GFP_KERNEL);
>>>> +		if (!buflet) {
>>>> +			ret = -ENOMEM;
>>>> +			goto err;
>>>> +		}
>>>> +
>>>> +		if (ctrl->has_rmr) {
>>>> +			phys_addr_t base = ctrl->rmr_addr + i * ctrl->buflet_size;
>>>> +
>>>> +			buflet->dma = base;
>>>> +			buflet->addr = memremap(base, ctrl->buflet_size, MEMREMAP_WB);
>>>> +		} else {
>>>> +			buflet->addr = dma_alloc_coherent(dev, ctrl->buflet_size,
>>>> +							  &buflet->dma, GFP_KERNEL);
>>>> +		}
>>>> +
>>>> +		if (!buflet->addr) {
>>>> +			kfree(buflet);
>>>> +			ret = -ENOMEM;
>>>> +			goto err;
>>>> +		}
>>>> +
>>>> +		memset(buflet->addr, 0, buflet->size);
>>>> +
>>>> +		buflet->index = i;
>>>> +		buflet->size = ctrl->buflet_size;
>>>> +		list_add_tail(&buflet->list, &ctrl->trace_buf);
>>>> +	}
>>>> +
>>>> +	return 0;
>>>> +err:
>>>> +	hisi_ptt_free_trace_buf(hisi_ptt);
>>>> +	return ret;
>>>> +}
>>>> +
>>>> +static void hisi_ptt_trace_end(struct hisi_ptt *hisi_ptt)
>>>> +{
>>>> +	writel(0, hisi_ptt->iobase + HISI_PTT_TRACE_CTRL);
>>>> +	hisi_ptt->trace_ctrl.status = HISI_PTT_TRACE_STATUS_OFF;
>>>> +}
>>>> +
>>>> +static int hisi_ptt_trace_start(struct hisi_ptt *hisi_ptt)
>>>> +{
>>>> +	struct hisi_ptt_trace_ctrl *ctrl = &hisi_ptt->trace_ctrl;
>>>> +	struct hisi_ptt_dma_buflet *cur;
>>>> +	u32 val;
>>>> +
>>>> +	/* Check device idle before start trace */
>>>> +	if (hisi_ptt_wait_trace_hw_idle(hisi_ptt)) {
>>>> +		pci_err(hisi_ptt->pdev, "Failed to start trace, the device is still busy.\n");
>>>> +		return -EBUSY;
>>>> +	}
>>>> +
>>>> +	/* Reset the DMA before start tracing */
>>>> +	val = readl(hisi_ptt->iobase + HISI_PTT_TRACE_CTRL);
>>>> +	val |= HISI_PTT_TRACE_CTRL_RST;
>>>> +	writel(val, hisi_ptt->iobase + HISI_PTT_TRACE_CTRL);
>>>> +
>>>> +	/*
>>>> +	 * We'll be in the perf context where preemption is disabled,
>>>> +	 * so use busy loop here.
>>>> +	 */
>>>> +	mdelay(HISI_PTT_RESET_WAIT_MS);
>>>> +
>>>> +	val = readl(hisi_ptt->iobase + HISI_PTT_TRACE_CTRL);
>>>> +	val &= ~HISI_PTT_TRACE_CTRL_RST;
>>>> +	writel(val, hisi_ptt->iobase + HISI_PTT_TRACE_CTRL);
>>>> +
>>>> +	/* clear the interrupt status */
>>>> +	writel(HISI_PTT_TRACE_INT_STAT_MASK, hisi_ptt->iobase + HISI_PTT_TRACE_INT_STAT);
>>>> +	writel(0, hisi_ptt->iobase + HISI_PTT_TRACE_INT_MASK);
>>>> +
>>>> +	list_for_each_entry(cur, &ctrl->trace_buf, list) {
>>>> +		writel(lower_32_bits(cur->dma),
>>>> +		       hisi_ptt->iobase + HISI_PTT_TRACE_ADDR_BASE_LO_0 +
>>>> +		       cur->index * HISI_PTT_TRACE_ADDR_STRIDE);
>>>> +		writel(upper_32_bits(cur->dma),
>>>> +		       hisi_ptt->iobase + HISI_PTT_TRACE_ADDR_BASE_HI_0 +
>>>> +		       cur->index * HISI_PTT_TRACE_ADDR_STRIDE);
>>>> +	}
>>>> +	writel(ctrl->buflet_size, hisi_ptt->iobase + HISI_PTT_TRACE_ADDR_SIZE);
>>>> +
>>>> +	/* set the trace control register */
>>>> +	val = FIELD_PREP(HISI_PTT_TRACE_CTRL_TYPE_SEL, ctrl->type);
>>>> +	val |= FIELD_PREP(HISI_PTT_TRACE_CTRL_RXTX_SEL, ctrl->direction);
>>>> +	val |= FIELD_PREP(HISI_PTT_TRACE_CTRL_DATA_FORMAT, ctrl->format);
>>>> +	val |= FIELD_PREP(HISI_PTT_TRACE_CTRL_TARGET_SEL, hisi_ptt->trace_ctrl.filter);
>>>> +	if (!hisi_ptt->trace_ctrl.is_port)
>>>> +		val |= HISI_PTT_TRACE_CTRL_FILTER_MODE;
>>>> +
>>>> +	val |= HISI_PTT_TRACE_CTRL_EN;
>>>> +	writel(val, hisi_ptt->iobase + HISI_PTT_TRACE_CTRL);
>>>> +
>>>> +	ctrl->status = HISI_PTT_TRACE_STATUS_ON;
>>>> +
>>>> +	return 0;
>>>> +}
>>>> +
>>>> +static int hisi_ptt_update_aux(struct hisi_ptt *hisi_ptt, int index, bool stop)
>>>> +{
>>>> +	struct perf_output_handle *handle = &hisi_ptt->trace_ctrl.handle;
>>>> +	struct perf_event *event = handle->event;
>>>> +	struct hisi_ptt_dma_buflet *cur;
>>>> +	struct hisi_ptt_pmu_buf *buf;
>>>> +
>>>> +	buf = perf_get_aux(handle);
>>>> +	if (!buf || !handle->size)
>>>> +		return -EINVAL;
>>>> +
>>>> +	list_for_each_entry(cur, &hisi_ptt->trace_ctrl.trace_buf, list)
>>>> +		if (cur->index == index)
>>>> +			break;
>>>> +
>>>> +	memcpy(buf->base + buf->pos, cur->addr, cur->size);
>>>> +	memset(cur->addr, 0, cur->size);
>>>> +	buf->pos += cur->size;
>>>> +
>>>> +	if (stop) {
>>>> +		perf_aux_output_end(handle, buf->pos);
>>>> +	} else if (buf->length - buf->pos < cur->size) {
>>>> +		perf_aux_output_skip(handle, buf->length - buf->pos);
>>>> +		perf_aux_output_end(handle, buf->pos);
>>>> +
>>>> +		buf = perf_aux_output_begin(handle, event);
>>>> +		if (!buf)
>>>> +			return -EINVAL;
>>>> +
>>>> +		buf->pos = handle->head % buf->length;
>>>> +		if (buf->length - buf->pos < cur->size) {
>>>> +			perf_aux_output_end(handle, 0);
>>>> +			return -EINVAL;
>>>> +		}
>>>> +	}
>>>> +
>>>> +	return 0;
>>>> +}
>>>> +
>>>> +static irqreturn_t hisi_ptt_isr(int irq, void *context)
>>>> +{
>>>> +	struct hisi_ptt *hisi_ptt = context;
>>>> +	u32 status, buf_idx;
>>>> +
>>>> +	status = readl(hisi_ptt->iobase + HISI_PTT_TRACE_INT_STAT);
>>>> +	buf_idx = ffs(status) - 1;
>>>> +
>>>> +	/* Clear the interrupt status of buflet @buf_idx */
>>>> +	writel(status, hisi_ptt->iobase + HISI_PTT_TRACE_INT_STAT);
>>>> +
>>>> +	/*
>>>> +	 * Update the AUX buffer and cache the current buflet index,
>>>> +	 * as we need to know this and save the data when the trace
>>>> +	 * is ended out of the interrupt handler. End the trace
>>>> +	 * if the updating fails.
>>>> +	 */
>>>> +	if (hisi_ptt_update_aux(hisi_ptt, buf_idx, false))
>>>> +		hisi_ptt_trace_end(hisi_ptt);
>>>> +	else
>>>> +		hisi_ptt->trace_ctrl.buf_index = (buf_idx + 1) % HISI_PTT_TRACE_BUFLETS_CNT;
>>>> +
>>>> +	return IRQ_HANDLED;
>>>> +}
>>>> +
>>>> +static irqreturn_t hisi_ptt_irq(int irq, void *context)
>>>> +{
>>>> +	struct hisi_ptt *hisi_ptt = context;
>>>> +	u32 status;
>>>> +
>>>> +	status = readl(hisi_ptt->iobase + HISI_PTT_TRACE_INT_STAT);
>>>> +	if (!(status & HISI_PTT_TRACE_INT_STAT_MASK))
>>>> +		return IRQ_NONE;
>>>> +
>>>> +	return IRQ_WAKE_THREAD;
>>>> +}
>>>> +
>>>> +static void hisi_ptt_irq_free_vectors(void *pdev)
>>>> +{
>>>> +	pci_free_irq_vectors(pdev);
>>>> +}
>>>> +
>>>> +static int hisi_ptt_register_irq(struct hisi_ptt *hisi_ptt)
>>>> +{
>>>> +	struct pci_dev *pdev = hisi_ptt->pdev;
>>>> +	int ret;
>>>> +
>>>> +	ret = pci_alloc_irq_vectors(pdev, 1, 1, PCI_IRQ_MSI);
>>>> +	if (ret < 0) {
>>>> +		pci_err(pdev, "failed to allocate irq vector, ret = %d.\n", ret);
>>>> +		return ret;
>>>> +	}
>>>> +
>>>> +	ret = devm_add_action_or_reset(&pdev->dev, hisi_ptt_irq_free_vectors, pdev);
>>>> +	if (ret < 0)
>>>> +		return ret;
>>>> +
>>>> +	ret = devm_request_threaded_irq(&pdev->dev,
>>>> +					pci_irq_vector(pdev, HISI_PTT_TRACE_DMA_IRQ),
>>>> +					hisi_ptt_irq, hisi_ptt_isr, 0,
>>>> +					"hisi-ptt", hisi_ptt);
>>>> +	if (ret) {
>>>> +		pci_err(pdev, "failed to request irq %d, ret = %d.\n",
>>>> +			pci_irq_vector(pdev, HISI_PTT_TRACE_DMA_IRQ), ret);
>>>> +		return ret;
>>>> +	}
>>>> +
>>>> +	return 0;
>>>> +}
>>>> +
>>>> +static void hisi_ptt_update_filters(struct work_struct *work)
>>>> +{
>>>> +	struct delayed_work *delayed_work = to_delayed_work(work);
>>>> +	struct hisi_ptt_filter_update_info info;
>>>> +	struct hisi_ptt_filter_desc *filter;
>>>> +	struct list_head *target_list;
>>>> +	struct hisi_ptt *hisi_ptt;
>>>> +
>>>> +	hisi_ptt = container_of(delayed_work, struct hisi_ptt, work);
>>>> +
>>>> +	if (!mutex_trylock(&hisi_ptt->mutex)) {
>>>> +		schedule_delayed_work(&hisi_ptt->work, HISI_PTT_WORK_DELAY_MS);
>>>> +		return;
>>>> +	}
>>>> +
>>>> +	while (kfifo_get(&hisi_ptt->filter_update_kfifo, &info)) {
>>>> +		target_list = info.is_port ? &hisi_ptt->port_filters :
>>>> +			      &hisi_ptt->req_filters;
>>>> +
>>>> +		if (info.is_add) {
>>>> +			filter = kzalloc(sizeof(*filter), GFP_KERNEL);
>>>> +			if (!filter)
>>>> +				continue;
>>>> +
>>>> +			filter->pdev = info.pdev;
>>>> +			filter->val = info.val;
>>>> +
>>>> +			list_add_tail(&filter->list, target_list);
>>>> +		} else {
>>>> +			list_for_each_entry(filter, target_list, list)
>>>> +				if (filter->val == info.val) {
>>>> +					list_del(&filter->list);
>>>> +					kfree(filter);
>>>> +					break;
>>>> +				}
>>>> +		}
>>>> +
>>>> +		/* Update the available port mask */
>>>> +		if (!info.is_port)
>>>> +			continue;
>>>> +
>>>> +		if (info.is_add)
>>>> +			hisi_ptt->port_mask |= info.val;
>>>> +		else
>>>> +			hisi_ptt->port_mask &= ~info.val;
>>>> +	}
>>>> +
>>>> +	mutex_unlock(&hisi_ptt->mutex);
>>>> +}
>>>> +
>>>> +static void hisi_ptt_update_fifo_in(struct hisi_ptt *hisi_ptt,
>>>> +				    struct hisi_ptt_filter_update_info *info)
>>>> +{
>>>> +	struct pci_dev *root_port = pcie_find_root_port(info->pdev);
>>>> +
>>>> +	if (!root_port)
>>>> +		return;
>>>> +
>>>> +	info->port_devid = PCI_DEVID(root_port->bus->number, root_port->devfn);
>>>> +	if (info->port_devid < hisi_ptt->lower ||
>>>> +	    info->port_devid > hisi_ptt->upper)
>>>> +		return;
>>>> +
>>>> +	info->is_port = pci_pcie_type(info->pdev) == PCI_EXP_TYPE_ROOT_PORT;
>>>> +	info->val = hisi_ptt_get_filter_val(info->pdev);
>>>> +
>>>> +	if (kfifo_in_spinlocked(&hisi_ptt->filter_update_kfifo, info, 1,
>>>> +				&hisi_ptt->filter_update_lock))
>>>> +		schedule_delayed_work(&hisi_ptt->work, 0);
>>>> +	else
>>>> +		pci_warn(hisi_ptt->pdev,
>>>> +			 "filter update fifo overflow for target %s\n",
>>>> +			 pci_name(info->pdev));
>>>> +}
>>>> +
>>>> +/*
>>>> + * A PCI bus notifier is used here for dynamically updating the filter
>>>> + * list.
>>>> + */
>>>> +static int hisi_ptt_notifier_call(struct notifier_block *nb, unsigned long action,
>>>> +				  void *data)
>>>> +{
>>>> +	struct hisi_ptt *hisi_ptt = container_of(nb, struct hisi_ptt, hisi_ptt_nb);
>>>> +	struct hisi_ptt_filter_update_info info;
>>>> +	struct device *dev = data;
>>>> +	struct pci_dev *pdev = to_pci_dev(dev);
>>>> +
>>>> +	info.pdev = pdev;
>>>> +
>>>> +	switch (action) {
>>>> +	case BUS_NOTIFY_ADD_DEVICE:
>>>> +		info.is_add = true;
>>>> +		break;
>>>> +	case BUS_NOTIFY_DEL_DEVICE:
>>>> +		info.is_add = false;
>>>> +		break;
>>>> +	default:
>>>> +		return 0;
>>>> +	}
>>>> +
>>>> +	hisi_ptt_update_fifo_in(hisi_ptt, &info);
>>>> +
>>>> +	return 0;
>>>> +}
>>>> +
>>>> +static int hisi_ptt_init_filters(struct pci_dev *pdev, void *data)
>>>> +{
>>>> +	struct hisi_ptt_filter_update_info info = {
>>>> +		.pdev = pdev,
>>>> +		.is_add = true,
>>>> +	};
>>>> +	struct hisi_ptt *hisi_ptt = data;
>>>> +
>>>> +	hisi_ptt_update_fifo_in(hisi_ptt, &info);
>>>> +
>>>> +	return 0;
>>>> +}
>>>> +
>>>> +static void hisi_ptt_release_filters(struct hisi_ptt *hisi_ptt)
>>>> +{
>>>> +	struct hisi_ptt_filter_desc *filter, *tfilter;
>>>> +
>>>> +	list_for_each_entry_safe(filter, tfilter, &hisi_ptt->req_filters, list) {
>>>> +		list_del(&filter->list);
>>>> +		kfree(filter);
>>>> +	}
>>>> +
>>>> +	list_for_each_entry_safe(filter, tfilter, &hisi_ptt->port_filters, list) {
>>>> +		list_del(&filter->list);
>>>> +		kfree(filter);
>>>> +	}
>>>> +}
>>>> +
>>>> +static void hisi_ptt_init_ctrls(struct hisi_ptt *hisi_ptt)
>>>> +{
>>>> +	struct pci_dev *pdev = hisi_ptt->pdev;
>>>> +	struct pci_bus *bus;
>>>> +	u32 reg;
>>>> +
>>>> +	INIT_DELAYED_WORK(&hisi_ptt->work, hisi_ptt_update_filters);
>>>> +	spin_lock_init(&hisi_ptt->filter_update_lock);
>>>> +	INIT_KFIFO(hisi_ptt->filter_update_kfifo);
>>>> +	INIT_LIST_HEAD(&hisi_ptt->port_filters);
>>>> +	INIT_LIST_HEAD(&hisi_ptt->req_filters);
>>>> +
>>>> +	/*
>>>> +	 * The device range register provides the information about the
>>>> +	 * root ports which the RCiEP can control and trace. The RCiEP
>>>> +	 * and the root ports it support are on the same PCIe core, with
>>>> +	 * same domain number but maybe different bus number. The device
>>>> +	 * range register will tell us which root ports we can support,
>>>> +	 * Bit[31:16] indicates the upper BDF numbers of the root port,
>>>> +	 * while Bit[15:0] indicates the lower.
>>>> +	 */
>>>> +	reg = readl(hisi_ptt->iobase + HISI_PTT_DEVICE_RANGE);
>>>> +	hisi_ptt->upper = reg >> 16;
>>>> +	hisi_ptt->lower = reg & 0xffff;
>>>> +	hisi_ptt->busnr = PCI_BUS_NUM(hisi_ptt->upper);
>>>> +
>>>> +	reg = readl(hisi_ptt->iobase + HISI_PTT_LOCATION);
>>>> +	hisi_ptt->core_id = FIELD_GET(HISI_PTT_CORE_ID, reg);
>>>> +	hisi_ptt->sicl_id = FIELD_GET(HISI_PTT_SICL_ID, reg);
>>>> +
>>>> +	bus = pci_find_bus(pci_domain_nr(pdev->bus), hisi_ptt->busnr);
>>>> +	if (bus)
>>>> +		pci_walk_bus(bus, hisi_ptt_init_filters, hisi_ptt);
>>>
>>> What happens if bus is NULL?  Should this be reported to the caller and cause
>>> hisi_ptt_probe() to fail?  Please add a comment that describes the scenario.
>>>
>>
>> It's ok if the list is NULL in the probe process,
>> as the device maybe hotplugged after the PTT driver probe, in which case
>> we can detect the event and update the list as we register a bus notifier.
>>
> 
> Please add the above as a comment in the code.
> 

sure. will do.

> 
>>>> +
>>>> +	/* Initialize trace controls */
>>>> +	INIT_LIST_HEAD(&hisi_ptt->trace_ctrl.trace_buf);
>>>> +	hisi_ptt->trace_ctrl.buflet_size = HISI_PTT_TRACE_BUFLET_SIZE;
>>>> +	hisi_ptt->trace_ctrl.default_cpu = cpumask_first(cpumask_of_node(dev_to_node(&pdev->dev)));
>>>> +}
>>>> +
>>>> +#define HISI_PTT_PMU_FILTER_IS_PORT	BIT(19)
>>>> +#define HISI_PTT_PMU_FILTER_VAL_MASK	GENMASK(15, 0)
>>>> +#define HISI_PTT_PMU_DIRECTION_MASK	GENMASK(23, 20)
>>>> +#define HISI_PTT_PMU_TYPE_MASK		GENMASK(31, 24)
>>>> +#define HISI_PTT_PMU_FORMAT_MASK	GENMASK(35, 32)
>>>> +
>>>> +static ssize_t available_filters_show(struct device *dev,
>>>> +				      struct device_attribute *attr,
>>>> +				      char *buf)
>>>> +{
>>>> +	struct hisi_ptt *hisi_ptt = to_hisi_ptt(dev_get_drvdata(dev));
>>>> +	struct hisi_ptt_filter_desc *filter;
>>>> +	int pos = 0;
>>>> +
>>>> +	if (list_empty(&hisi_ptt->port_filters))
>>>> +		return sysfs_emit(buf, "#### No available filter ####\n");
>>>> +
>>>> +	mutex_lock(&hisi_ptt->mutex);
>>>> +	pos += sysfs_emit_at(buf, pos, "#### Root Ports ####\n");
>>>> +	list_for_each_entry(filter, &hisi_ptt->port_filters, list)
>>>> +		pos += sysfs_emit_at(buf, pos, "%s	0x%05lx\n",
>>>> +				     pci_name(filter->pdev),
>>>> +				     hisi_ptt_get_filter_val(filter->pdev) |
>>>> +				     HISI_PTT_PMU_FILTER_IS_PORT);
>>>> +
>>>> +	pos += sysfs_emit_at(buf, pos, "#### Requesters ####\n");
>>>> +	list_for_each_entry(filter, &hisi_ptt->req_filters, list)
>>>> +		pos += sysfs_emit_at(buf, pos, "%s	0x%05x\n",
>>>> +				     pci_name(filter->pdev),
>>>> +				     hisi_ptt_get_filter_val(filter->pdev));
>>>> +
>>>> +	mutex_unlock(&hisi_ptt->mutex);
>>>> +	return pos;
>>>> +}
>>>> +static DEVICE_ATTR_ADMIN_RO(available_filters);
>>>> +
>>>> +PMU_FORMAT_ATTR(filter,		"config:0-19");
>>>> +PMU_FORMAT_ATTR(direction,	"config:20-23");
>>>> +PMU_FORMAT_ATTR(type,		"config:24-31");
>>>> +PMU_FORMAT_ATTR(format,		"config:32-35");
>>>> +
>>>> +static struct attribute *hisi_ptt_pmu_format_attrs[] = {
>>>> +	&format_attr_filter.attr,
>>>> +	&format_attr_direction.attr,
>>>> +	&format_attr_type.attr,
>>>> +	&format_attr_format.attr,
>>>> +	NULL
>>>> +};
>>>> +
>>>> +static struct attribute_group hisi_ptt_pmu_format_group = {
>>>> +	.name = "format",
>>>> +	.attrs = hisi_ptt_pmu_format_attrs,
>>>> +};
>>>> +
>>>> +static struct attribute *hisi_ptt_pmu_filter_attrs[] = {
>>>> +	&dev_attr_available_filters.attr,
>>>> +	NULL
>>>> +};
>>>> +
>>>> +static struct attribute_group hisi_ptt_pmu_filter_group = {
>>>> +	.attrs = hisi_ptt_pmu_filter_attrs,
>>>> +};
>>>> +
>>>> +static const struct attribute_group *hisi_ptt_pmu_groups[] = {
>>>> +	&hisi_ptt_pmu_format_group,
>>>> +	&hisi_ptt_pmu_filter_group,
>>>> +	NULL
>>>> +};
>>>> +
>>>> +/*
>>>> + * The supported value of the direction parameter. See hisi_ptt.rst
>>>> + * documentation for more details.
>>>> + */
>>>> +static u32 hisi_ptt_trace_available_direction[] = {
>>>> +	0,
>>>> +	1,
>>>> +	2,
>>>> +	3,
>>>> +};
>>>> +
>>>> +/* Different types can be set simultaneously */
>>>> +static u32 hisi_ptt_trace_available_type[] = {
>>>> +	1,	/* posted_request */
>>>> +	2,	/* non-posted_request */
>>>> +	4,	/* completion */
>>>> +};
>>>> +
>>>> +static u32 hisi_ptt_trace_availble_format[] = {
>>>> +	0,	/* 4DW */
>>>> +	1,	/* 8DW */
>>>> +};
>>>> +
>>>> +/*
>>>> + * Check whether the config is valid or not. Some configs are multi-selectable
>>>> + * and can be set simultaneously, while some are single selectable (onehot).
>>>> + * Use this function to check the non-onehot configs while
>>>> + * hisi_ptt_trace_valid_config_onehot() for the onehot ones.
>>>> + */
>>>> +static int hisi_ptt_trace_valid_config(u32 val, u32 *available_list, u32 list_size)
>>>> +{
>>>> +	int i;
>>>> +
>>>> +	/*
>>>> +	 * The non-onehot configs cannot be 0. Walk the available
>>>> +	 * list and clear the valid bits of the config. If there
>>>> +	 * is any resident bit after the walk then the config is
>>>> +	 * invalid.
>>>> +	 */
>>>> +	for (i = 0; i < list_size; i++)
>>>> +		val &= ~available_list[i];
>>>> +
>>>> +	return val ? -EINVAL : 0;
>>>> +}
>>>> +
>>>> +static int hisi_ptt_trace_valid_config_onehot(u32 val, u32 *available_list, u32 list_size)
>>>> +{
>>>> +	int i, ret = -EINVAL;
>>>> +
>>>> +	for (i = 0; i < list_size; i++)
>>>> +		if (val == available_list[i]) {
>>>> +			ret = 0;
>>>> +			break;
>>>> +		}
>>>> +
>>>> +	return ret;
>>>> +}
>>>> +
>>>> +static int hisi_ptt_trace_init_filter(struct hisi_ptt *hisi_ptt, u64 config)
>>>> +{
>>>> +	unsigned long val, port_mask = hisi_ptt->port_mask;
>>>> +	struct hisi_ptt_filter_desc *filter;
>>>> +	int ret = -EINVAL;
>>>> +
>>>> +	hisi_ptt->trace_ctrl.is_port = FIELD_GET(HISI_PTT_PMU_FILTER_IS_PORT, config);
>>>> +	val = FIELD_GET(HISI_PTT_PMU_FILTER_VAL_MASK, config);
>>>> +
>>>> +	/*
>>>> +	 * Port filters are defined as bit mask. For port filters, check
>>>> +	 * the bits in the @val are within the range of hisi_ptt->port_mask
>>>> +	 * and whether it's empty or not, otherwise user has specified
>>>> +	 * some unsupported root ports.
>>>> +	 *
>>>> +	 * For Requester ID filters, walk the available filter list to see
>>>> +	 * whether we have one matched.
>>>> +	 */
>>>> +	if (hisi_ptt->trace_ctrl.is_port &&
>>>> +	    bitmap_subset(&val, &port_mask, BITS_PER_LONG)) {
>>>> +		ret = 0;
>>>> +	} else {
>>>> +		list_for_each_entry(filter, &hisi_ptt->req_filters, list)
>>>> +			if (filter->val == val) {
>>>> +				ret = 0;
>>>> +				break;
>>>> +			}
>>>> +	}
>>>> +
>>>> +	if (ret)
>>>> +		return ret;
>>>> +
>>>> +	hisi_ptt->trace_ctrl.filter = val;
>>>> +	return 0;
>>>> +}
>>>> +
>>>> +static int hisi_ptt_pmu_event_init(struct perf_event *event)
>>>> +{
>>>> +	struct hisi_ptt *hisi_ptt = to_hisi_ptt(event->pmu);
>>>> +	struct hisi_ptt_trace_ctrl *ctrl = &hisi_ptt->trace_ctrl;
>>>> +	int ret;
>>>> +	u32 val;
>>>> +
>>>> +	if (event->attr.type != hisi_ptt->hisi_ptt_pmu.type)
>>>> +		return -ENOENT;
>>>> +
>>>> +	mutex_lock(&hisi_ptt->mutex);
>>>> +
>>>> +	ret = hisi_ptt_trace_init_filter(hisi_ptt, event->attr.config);
>>>> +	if (ret < 0)
>>>> +		goto out;
>>>> +
>>>> +	val = FIELD_GET(HISI_PTT_PMU_DIRECTION_MASK, event->attr.config);
>>>> +	ret = hisi_ptt_trace_valid_config_onehot(val, hisi_ptt_trace_available_direction,
>>>> +						 ARRAY_SIZE(hisi_ptt_trace_available_direction));
>>>> +	if (ret < 0)
>>>> +		goto out;
>>>> +	ctrl->direction = val;
>>>> +
>>>> +	val = FIELD_GET(HISI_PTT_PMU_TYPE_MASK, event->attr.config);
>>>> +
>>>> +	ret = hisi_ptt_trace_valid_config(val, hisi_ptt_trace_available_type,
>>>> +					  ARRAY_SIZE(hisi_ptt_trace_available_type));
>>>> +	if (ret < 0)
>>>> +		goto out;
>>>> +	ctrl->type = val;
>>>> +
>>>> +	val = FIELD_GET(HISI_PTT_PMU_FORMAT_MASK, event->attr.config);
>>>> +	ret = hisi_ptt_trace_valid_config_onehot(val, hisi_ptt_trace_availble_format,
>>>> +						 ARRAY_SIZE(hisi_ptt_trace_availble_format));
>>>> +	if (ret < 0)
>>>> +		goto out;
>>>> +	ctrl->format = val;
>>>> +
>>>> +out:
>>>> +	mutex_unlock(&hisi_ptt->mutex);
>>>> +	return ret;
>>>> +}
>>>> +
>>>> +static void *hisi_ptt_pmu_setup_aux(struct perf_event *event, void **pages,
>>>> +				    int nr_pages, bool overwrite)
>>>> +{
>>>> +	struct hisi_ptt_pmu_buf *buf;
>>>> +	struct page **pagelist;
>>>> +	int i;
>>>> +
>>>> +	if (overwrite) {
>>>> +		dev_warn(event->pmu->dev, "Overwrite mode is not supported\n");
>>>> +		return NULL;
>>>> +	}
>>>> +
>>>> +	/* If the pages size less than buflets, we cannot start trace */
>>>> +	if (nr_pages < HISI_PTT_TRACE_BUFFER_SIZE / PAGE_SIZE)
>>>> +		return NULL;
>>>> +
>>>> +	buf = kzalloc(sizeof(*buf), GFP_KERNEL);
>>>> +	if (!buf)
>>>> +		return NULL;
>>>> +
>>>> +	pagelist = kcalloc(nr_pages, sizeof(*pagelist), GFP_KERNEL);
>>>> +	if (!pagelist) {
>>>> +		kfree(buf);
>>>> +		return NULL;
>>>> +	}
>>>> +
>>>> +	for (i = 0; i < nr_pages; i++)
>>>> +		pagelist[i] = virt_to_page(pages[i]);
>>>> +
>>>> +	buf->base = vmap(pagelist, nr_pages, VM_MAP, PAGE_KERNEL);
>>>> +	if (!buf->base) {
>>>> +		kfree(pagelist);
>>>> +		kfree(buf);
>>>> +		return NULL;
>>>> +	}
>>>> +
>>>> +	buf->nr_pages = nr_pages;
>>>> +	buf->length = nr_pages * PAGE_SIZE;
>>>> +	buf->pos = 0;
>>>> +
>>>> +	kfree(pagelist);
>>>> +	return buf;
>>>> +}
>>>> +
>>>> +static void hisi_ptt_pmu_free_aux(void *aux)
>>>> +{
>>>> +	struct hisi_ptt_pmu_buf *buf = aux;
>>>> +
>>>> +	vunmap(buf->base);
>>>> +	kfree(buf);
>>>> +}
>>>> +
>>>> +static void hisi_ptt_pmu_start(struct perf_event *event, int flags)
>>>> +{
>>>> +	struct hisi_ptt *hisi_ptt = to_hisi_ptt(event->pmu);
>>>> +	struct perf_output_handle *handle = &hisi_ptt->trace_ctrl.handle;
>>>> +	struct hw_perf_event *hwc = &event->hw;
>>>> +	struct hisi_ptt_pmu_buf *buf;
>>>> +	int cpu = event->cpu;
>>>> +	int ret;
>>>> +
>>>> +	hwc->state = 0;
>>>> +	mutex_lock(&hisi_ptt->mutex);
>>>> +	if (hisi_ptt->trace_ctrl.status == HISI_PTT_TRACE_STATUS_ON) {
>>>> +		pci_dbg(hisi_ptt->pdev, "trace has already started\n");
>>>> +		goto stop;
>>>> +	}
>>>> +
>>>> +	if (cpu == -1)
>>>> +		cpu = hisi_ptt->trace_ctrl.default_cpu;
>>>> +
>>>> +	/*
>>>> +	 * Handle the interrupt on the same cpu which starts the trace to avoid
>>>> +	 * context mismatch. Otherwise we'll trigger the WARN from the perf
>>>> +	 * core in event_function_local().
>>>> +	 */
>>>> +	WARN_ON(irq_set_affinity(pci_irq_vector(hisi_ptt->pdev, HISI_PTT_TRACE_DMA_IRQ),
>>>> +				 cpumask_of(cpu)));
>>>> +
>>>> +	ret = hisi_ptt_alloc_trace_buf(hisi_ptt);
>>>> +	if (ret) {
>>>> +		pci_dbg(hisi_ptt->pdev, "alloc trace buf failed, ret = %d\n", ret);
>>>> +		goto stop;
>>>> +	}
>>>> +
>>>> +	buf = perf_aux_output_begin(handle, event);
>>>> +	if (!buf) {
>>>> +		pci_dbg(hisi_ptt->pdev, "aux output begin failed\n");
>>>> +		goto stop;
>>>> +	}
>>>> +
>>>> +	buf->pos = handle->head % buf->length;
>>>> +
>>>> +	ret = hisi_ptt_trace_start(hisi_ptt);
>>>> +	if (ret) {
>>>> +		pci_dbg(hisi_ptt->pdev, "trace start failed, ret = %d\n", ret);
>>>> +		perf_aux_output_end(handle, 0);
>>>> +		goto stop;
>>>> +	}
>>>> +
>>>> +	mutex_unlock(&hisi_ptt->mutex);
>>>> +	return;
>>>> +stop:
>>>> +	event->hw.state |= PERF_HES_STOPPED;
>>>> +	mutex_unlock(&hisi_ptt->mutex);
>>>> +}
>>>> +
>>>> +static void hisi_ptt_pmu_stop(struct perf_event *event, int flags)
>>>> +{
>>>> +	struct hisi_ptt *hisi_ptt = to_hisi_ptt(event->pmu);
>>>> +	struct hw_perf_event *hwc = &event->hw;
>>>> +
>>>> +	if (hwc->state & PERF_HES_STOPPED)
>>>> +		return;
>>>> +
>>>> +	mutex_lock(&hisi_ptt->mutex);
>>>> +	if (hisi_ptt->trace_ctrl.status == HISI_PTT_TRACE_STATUS_ON) {
>>>> +		hisi_ptt_trace_end(hisi_ptt);
>>>> +		WARN(hisi_ptt_wait_trace_hw_idle(hisi_ptt), "Device is still busy");
>>>> +		hisi_ptt_update_aux(hisi_ptt, hisi_ptt->trace_ctrl.buf_index, true);
>>>> +	}
>>>> +	mutex_unlock(&hisi_ptt->mutex);
>>>> +
>>>> +	hwc->state |= PERF_HES_STOPPED;
>>>> +	perf_event_update_userpage(event);
>>>> +	hwc->state |= PERF_HES_UPTODATE;
>>>> +}
>>>> +
>>>> +static int hisi_ptt_pmu_add(struct perf_event *event, int flags)
>>>> +{
>>>> +	struct hisi_ptt *hisi_ptt = to_hisi_ptt(event->pmu);
>>>> +	struct hw_perf_event *hwc = &event->hw;
>>>> +	int cpu = event->cpu;
>>>> +
>>>> +	if (cpu == -1 && smp_processor_id() != hisi_ptt->trace_ctrl.default_cpu)
>>>> +		return 0;
>>>> +
>>>> +	hwc->state = PERF_HES_STOPPED | PERF_HES_UPTODATE;
>>>> +
>>>> +	if (flags & PERF_EF_START) {
>>>> +		hisi_ptt_pmu_start(event, PERF_EF_RELOAD);
>>>> +		if (hwc->state & PERF_HES_STOPPED)
>>>> +			return -EINVAL;
>>>> +	}
>>>> +
>>>> +	return 0;
>>>> +}
>>>> +
>>>> +static void hisi_ptt_pmu_del(struct perf_event *event, int flags)
>>>> +{
>>>> +	hisi_ptt_pmu_stop(event, PERF_EF_UPDATE);
>>>> +}
>>>> +
>>>> +static void hisi_ptt_unregister_pmu(void *priv)
>>>> +{
>>>> +	perf_pmu_unregister(priv);
>>>> +}
>>>> +
>>>> +static int hisi_ptt_register_pmu(struct hisi_ptt *hisi_ptt)
>>>> +{
>>>> +	char *pmu_name;
>>>> +	int ret;
>>>> +
>>>> +	hisi_ptt->hisi_ptt_pmu = (struct pmu) {
>>>> +		.module		= THIS_MODULE,
>>>> +		.capabilities	= PERF_PMU_CAP_EXCLUSIVE | PERF_PMU_CAP_ITRACE,
>>>> +		.task_ctx_nr	= perf_sw_context,
>>>> +		.attr_groups	= hisi_ptt_pmu_groups,
>>>> +		.event_init	= hisi_ptt_pmu_event_init,
>>>> +		.setup_aux	= hisi_ptt_pmu_setup_aux,
>>>> +		.free_aux	= hisi_ptt_pmu_free_aux,
>>>> +		.start		= hisi_ptt_pmu_start,
>>>> +		.stop		= hisi_ptt_pmu_stop,
>>>> +		.add		= hisi_ptt_pmu_add,
>>>> +		.del		= hisi_ptt_pmu_del,
>>>> +	};
>>>> +
>>>> +	pmu_name = devm_kasprintf(&hisi_ptt->pdev->dev, GFP_KERNEL, "hisi_ptt%u_%u",
>>>> +				  hisi_ptt->sicl_id, hisi_ptt->core_id);
>>>> +	if (!pmu_name)
>>>> +		return -ENOMEM;
>>>> +
>>>> +	ret = perf_pmu_register(&hisi_ptt->hisi_ptt_pmu, pmu_name, -1);
>>>> +	if (ret)
>>>> +		return ret;
>>>> +
>>>> +	return devm_add_action_or_reset(&hisi_ptt->pdev->dev,
>>>> +					hisi_ptt_unregister_pmu,
>>>> +					&hisi_ptt->hisi_ptt_pmu);
>>>> +}
>>>> +
>>>> +/*
>>>> + * Get RMR address if provided by the firmware.
>>>> + * Return 0 if the IOMMU doesn't present or the policy of the
>>>> + * IOMMU domain is passthrough or we get a usable RMR region.
>>>> + * Otherwise a negative value is returned.
>>>> + */
>>>> +static int hisi_ptt_get_rmr(struct hisi_ptt *hisi_ptt)
>>>> +{
>>>> +	struct pci_dev *pdev = hisi_ptt->pdev;
>>>> +	struct iommu_domain *iommu_domain;
>>>> +	struct iommu_resv_region *region;
>>>> +	LIST_HEAD(list);
>>>> +
>>>> +	/*
>>>> +	 * Use direct DMA if IOMMU does not present or the policy of the
>>>> +	 * IOMMU domain is passthrough.
>>>> +	 */
>>>> +	iommu_domain = iommu_get_domain_for_dev(&pdev->dev);
>>>> +	if (!iommu_domain || iommu_domain->type == IOMMU_DOMAIN_IDENTITY)
>>>> +		return 0;
>>>> +
>>>> +	iommu_get_resv_regions(&pdev->dev, &list);
>>>> +	list_for_each_entry(region, &list, list)
>>>> +		if (region->type == IOMMU_RESV_DIRECT &&
>>>> +		    region->length >= HISI_PTT_TRACE_BUFFER_SIZE) {
>>>> +			hisi_ptt->trace_ctrl.has_rmr = true;
>>>> +			hisi_ptt->trace_ctrl.rmr_addr = region->start;
>>>> +			hisi_ptt->trace_ctrl.rmr_length = region->length;
>>>> +			break;
>>>> +		}
>>>> +
>>>> +	iommu_put_resv_regions(&pdev->dev, &list);
>>>> +	return hisi_ptt->trace_ctrl.has_rmr ? 0 : -ENOMEM;
>>>> +}
>>>> +
>>>> +static int hisi_ptt_probe(struct pci_dev *pdev,
>>>> +			  const struct pci_device_id *id)
>>>> +{
>>>> +	struct hisi_ptt *hisi_ptt;
>>>> +	int ret;
>>>> +
>>>> +	hisi_ptt = devm_kzalloc(&pdev->dev, sizeof(*hisi_ptt), GFP_KERNEL);
>>>> +	if (!hisi_ptt)
>>>> +		return -ENOMEM;
>>>> +
>>>> +	mutex_init(&hisi_ptt->mutex);
>>>> +	hisi_ptt->pdev = pdev;
>>>> +
>>>> +	/*
>>>> +	 * Lifetime of pci_dev is longer than hisi_ptt,
>>>> +	 * so directly reference to the pci name string.
>>>> +	 */
>>>> +	hisi_ptt->name = pci_name(hisi_ptt->pdev);
>>>> +	pci_set_drvdata(pdev, hisi_ptt);
>>>> +
>>>> +	ret = pcim_enable_device(pdev);
>>>> +	if (ret) {
>>>> +		pci_err(pdev, "failed to enable device, ret = %d.\n", ret);
>>>> +		return ret;
>>>> +	}
>>>> +
>>>> +	ret = pcim_iomap_regions(pdev, BIT(2), hisi_ptt->name);
>>>> +	if (ret) {
>>>> +		pci_err(pdev, "failed to remap io memory, ret = %d.\n", ret);
>>>> +		return ret;
>>>> +	}
>>>> +
>>>> +	hisi_ptt->iobase = pcim_iomap_table(pdev)[2];
>>>> +
>>>> +	ret = dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(64));
>>>> +	if (ret) {
>>>> +		pci_err(pdev, "failed to set 64 bit dma mask, ret = %d.\n", ret);
>>>> +		return ret;
>>>> +	}
>>>> +	pci_set_master(pdev);
>>>> +
>>>> +	ret = hisi_ptt_register_irq(hisi_ptt);
>>>> +	if (ret)
>>>> +		return ret;
>>>> +
>>>> +	hisi_ptt_init_ctrls(hisi_ptt);
>>>> +
>>>> +	ret = hisi_ptt_register_pmu(hisi_ptt);
>>>> +	if (ret) {
>>>> +		pci_err(pdev, "failed to register pmu device, ret = %d", ret);
>>>> +		return ret;
>>>> +	}
>>>
>>> If this fails the pci_free_irq_vectors() is not called.
>>>
>>
>> It'll be called as we've registered a devm callback when
>> allocating the irq vector. See hisi_ptt_register_irq().
> 
> Ah yes - thanks for pointing that out.
> 
>>
>>> I am out of time for today - I will continue tomorrow.
>>>
>>
>> Sure. Thanks!
>> Yicong
>>
>>> Thanks,
>>> Mathieu
>>>
>>>> +
>>>> +	ret = hisi_ptt_get_rmr(hisi_ptt);
>>>> +	if (ret) {
>>>> +		pci_err(pdev, "failed to get RMR region, ret = %d", ret);
>>>> +		return ret;
>>>> +	}
>>>> +
>>>> +	/* Register the bus notifier for dynamically updating the filter list */
>>>> +	hisi_ptt->hisi_ptt_nb.notifier_call = hisi_ptt_notifier_call;
>>>> +	ret = bus_register_notifier(&pci_bus_type, &hisi_ptt->hisi_ptt_nb);
>>>> +	if (ret)
>>>> +		pci_warn(pdev, "failed to register filter update notifier, ret = %d", ret);
>>>> +
>>>> +	return 0;
>>>> +}
>>>> +
>>>> +void hisi_ptt_remove(struct pci_dev *pdev)
>>>> +{
>>>> +	struct hisi_ptt *hisi_ptt = pci_get_drvdata(pdev);
>>>> +
>>>> +	bus_unregister_notifier(&pci_bus_type, &hisi_ptt->hisi_ptt_nb);
>>>> +
>>>> +	/* Cancel any work that has been queued */
>>>> +	cancel_delayed_work_sync(&hisi_ptt->work);
>>>> +
>>>> +	if (hisi_ptt->trace_ctrl.status == HISI_PTT_TRACE_STATUS_ON)
>>>> +		hisi_ptt_trace_end(hisi_ptt);
>>>> +
>>>> +	hisi_ptt_free_trace_buf(hisi_ptt);
>>>> +	hisi_ptt_release_filters(hisi_ptt);
>>>> +}
>>>> +
>>>> +static const struct pci_device_id hisi_ptt_id_tbl[] = {
>>>> +	{ PCI_DEVICE(PCI_VENDOR_ID_HUAWEI, 0xa12e) },
>>>> +	{ }
>>>> +};
>>>> +MODULE_DEVICE_TABLE(pci, hisi_ptt_id_tbl);
>>>> +
>>>> +static struct pci_driver hisi_ptt_driver = {
>>>> +	.name = "hisi_ptt",
>>>> +	.id_table = hisi_ptt_id_tbl,
>>>> +	.probe = hisi_ptt_probe,
>>>> +	.remove = hisi_ptt_remove,
>>>> +};
>>>> +module_pci_driver(hisi_ptt_driver);
>>>> +
>>>> +MODULE_LICENSE("GPL v2");
>>>> +MODULE_AUTHOR("Yicong Yang <yangyicong@hisilicon.com>");
>>>> +MODULE_DESCRIPTION("Driver for HiSilicon PCIe tune and trace device");
>>>> -- 
>>>> 2.33.0
>>>>
>>> .
>>>
> .
>

On 2021/11/27 1:10, Mathieu Poirier wrote:
> 
> [...]
> 
>>
>>>>> +
>>>>> +#define HISI_PTT_TRACE_DMA_IRQ			0
>>>>> +#define HISI_PTT_TRACE_BUFLETS_CNT		4
>>>>> +#define HISI_PTT_TRACE_BUFLET_SIZE		SZ_4M
>>>>> +#define HISI_PTT_TRACE_BUFFER_SIZE		(HISI_PTT_TRACE_BUFLET_SIZE * \
>>>>> +						 HISI_PTT_TRACE_BUFLETS_CNT)
>>>>> +#define HISI_PTT_FILTER_UPDATE_FIFO_SIZE	16
>>>>> +
>>>>> +/* Delay time for filter updating work */
>>>>> +#define HISI_PTT_WORK_DELAY_MS		100UL
>>>>> +/* Wait time for DMA hardware to reset */
>>>>> +#define HISI_PTT_RESET_WAIT_MS		1000UL
>>>>> +/* Poll timeout and interval for waiting hardware work to finish */
>>>>> +#define HISI_PTT_WAIT_TIMEOUT_US	1000000UL
>>>>> +#define HISI_PTT_WAIT_POLL_INTERVAL_US	100UL
>>>>> +
>>>>> +#define HISI_PCIE_CORE_PORT_ID(devfn)	(PCI_FUNC(devfn) << 1)
>>>>> +
>>>>> +enum hisi_ptt_trace_status {
>>>>> +	HISI_PTT_TRACE_STATUS_OFF = 0,
>>>>> +	HISI_PTT_TRACE_STATUS_ON,
>>>>> +};
>>>>> +
>>>>> +struct hisi_ptt_dma_buflet {
>>>>
>>>> I'm not sure what a "buflet" is...  Probably best to just call this
>>>> hisi_ptt_dma_buffer" if it pertains to a buffer.  On that note it is hard to
>>>> know due to the lack of proper structure documentation.  Please have a look at
>>>> how "coresight_device" is documented.  The same applies to the rest of the
>>>> structures declared below.
>>>>
>>>
>>> It's mentioned in section 5 of hisi_ptt.rst as "Driver will allocate each DMA buffer
>>> (we call it buflet) of 4MiB ...".
>>
>> I just noticed the documentation in patch 5 - I will read it before continuing
>> with this set.
>>
> 
> As promised I read the documentation and it didn't do much to alliviate my
> concern about the terminology.  If a "buflet" is a DMA buffer than simply call
> it a DMA buffer, regardless of the size.  
> 

ok. If it's hard for the readers to understand, I'll use DMA buffer instead.

> The size of this patchset makes it hard enough to review as it is... On top
> of things reviewers have to remember that PTT means "PCIe tune and trace
> device", tune means "PCIe link's events" and trace means "TLP headers".
> 

ok. I used to make the complete function into one patch, will see how to split
it to make review easier.

Trace and tune denote the two function of the device. Trace denote the function
of tracing the TLP headers and tune denotes the function of read and modify
the PCIe link's events. It's unavoidable of knowing the acronyms for the user
of the device. :)

> But we also have to keep in mind that a buflet is really just a DMA buffer...
> 
> I will not continue reviewing this set.  Please fix the terminology and spin
> another revision.  Doing so I suggest you trim down the submission to the
> absolute minimum feature set this driver should provide - enhancements can be
> made later when a foundation has been laid out.
> 
> Robin has pointed out what seems to be serious problems with the
> implemenation.  That will also have to be sorted out for the next iteration.
> 
ok. Will discuss with robin with his concerns and with the comments fixed in
the next version.

Thanks,
Yicong

> Regards,
> Mathieu
> 
> 
>>>
>>> The total DMA buffer of PTT device is divided into 4 parts, and each part is called
>>> a 'buflet', which means a small buffer (there exists other words with similiar
>>> format: droplet, wavelet, ...).
>>>
>>> The device is designed like this to make sure we won't lose any data when we have to change
>>> the buffer address, the device can continue to write to the next buflet and don't
>>> neet to pause.
>>>
>>>>> +	struct list_head list;
>>>>> +	unsigned int size;
>>>>> +	dma_addr_t dma;
>>>>> +
>>>>> +	/*
>>>>> +	 * The address of the buflet holding the trace data.
>>>>> +	 * See Documentation/trace/hisi-ptt.rst for the details
>>>>
>>>> As of this writing, hisi-ptt.rst doesn't exist.
>>>>
>>>
>>> The comment intends to direct the user to the documentation if the user
>>> want to know details about the data format. The data format is decribed
>>> in the section 4 of the doc.
>>>
>>>>> +	 * of the data format.
>>>>> +	 */
>>>>> +	void *addr;
>>>>> +	int index;
>>>>> +};
>>>>> +
>>>>> +struct hisi_ptt_trace_ctrl {
>>>>> +	enum hisi_ptt_trace_status status;
>>>>> +	struct perf_output_handle handle;
>>>>> +	struct list_head trace_buf;
>>>>> +	/*
>>>>> +	 * The index of the buffer which trace data
>>>>> +	 * currently is writing to.
>>>>> +	 */
>>>>> +	u32 buf_index;
>>>>> +
>>>>> +	int default_cpu;
>>>>> +	u32 buflet_size;
>>>>> +	bool is_port;
>>>>> +	u32 format:1;		/* Format of the traced TLP headers */
>>>>> +	u32 type:4;		/* Type of the TLP headers to trace */
>>>>> +	u32 direction:2;	/* Direction of the TLP headers to trace */
>>>>> +	u32 filter:16;		/* Root port or Requester to filter the TLP headers */
>>>>> +
>>>>> +	phys_addr_t rmr_addr;
>>>>> +	size_t rmr_length;
>>>>> +	bool has_rmr;
>>>>> +};
>>>>> +
>>>>> +struct hisi_ptt_filter_desc {
>>>>> +	struct list_head list;
>>>>> +	struct pci_dev *pdev;
>>>>> +	u16 val;
>>>>> +};
>>>>> +
>>>>> +struct hisi_ptt_pmu_buf {
>>>>> +	size_t length;
>>>>> +	int nr_pages;
>>>>> +	void *base;
>>>>> +	long pos;
>>>>> +};
>>>>> +
>>>>> +/* Structure containing the information for filter updating */
>>>>> +struct hisi_ptt_filter_update_info {
>>>>> +	struct pci_dev *pdev;
>>>>> +	u32 port_devid;
>>>>> +	bool is_port;
>>>>> +	bool is_add;
>>>>> +	u16 val;
>>>>> +};
>>>>> +
>>>>> +struct hisi_ptt {
>>>>> +	struct hisi_ptt_trace_ctrl trace_ctrl;
>>>>> +	struct notifier_block hisi_ptt_nb;
>>>>> +	struct pmu hisi_ptt_pmu;
>>>>> +	void __iomem *iobase;
>>>>> +	struct pci_dev *pdev;
>>>>> +	/*
>>>>> +	 * Use the mutex to protect the filter list and
>>>>> +	 * serialize the perf process.
>>>>> +	 */
>>>>> +	struct mutex mutex;
>>>>> +	const char *name;
>>>>> +	u16 core_id;
>>>>> +	u16 sicl_id;
>>>>> +	/* PCI device range managed by the PTT device */
>>>>> +	u32 upper;
>>>>> +	u32 lower;
>>>>> +	u8 busnr;
>>>>> +
>>>>> +	/*
>>>>> +	 * The trace TLP headers can either be filtered by certain
>>>>> +	 * root port, or by the requester ID. Organize the filters
>>>>> +	 * by @port_filters and @req_filters here. The mask of all
>>>>> +	 * the valid ports is also cached for doing sanity check
>>>>> +	 * of user input.
>>>>> +	 */
>>>>> +	struct list_head port_filters;
>>>>> +	struct list_head req_filters;
>>>>> +	u16 port_mask;
>>>>> +
>>>>> +	/*
>>>>> +	 * We use a delayed work here to avoid indefinitely waiting for
>>>>> +	 * the hisi_ptt->mutex which protecting the filter list. The
>>>>> +	 * work will be delayed only if the mutex can not be held,
>>>>> +	 * otherwise no delay will be applied.
>>>>> +	 */
>>>>> +	struct delayed_work work;
>>>>> +	spinlock_t filter_update_lock;
>>>>> +	DECLARE_KFIFO(filter_update_kfifo, struct hisi_ptt_filter_update_info,
>>>>> +		      HISI_PTT_FILTER_UPDATE_FIFO_SIZE);
>>>>> +};
>>>>
>>>> It might be a good idea to spinoff a hisi_ptt.h for the above declarations.
>>>>
>>>
>>> I'm not sure whether it is common or permitted to provide a header which is only used by
>>> this driver with a single file.
>>
>> I've seen it done many times.
>>
>>>
>>>>> +
>>>>> +static inline struct hisi_ptt *to_hisi_ptt(struct pmu *pmu)
>>>>> +{
>>>>> +	return container_of(pmu, struct hisi_ptt, hisi_ptt_pmu);
>>>>> +}
>>>>
>>>> I'm not sure there is any value to this inline function.  I suggest to simply
>>>> call container_of() whenever it is needed.
>>>>
>>>
>>> ok.
>>>
>>>>> +
>>>>> +static u16 hisi_ptt_get_filter_val(struct pci_dev *pdev)
>>>>> +{
>>>>> +	if (pci_pcie_type(pdev) == PCI_EXP_TYPE_ROOT_PORT)
>>>>> +		return BIT(HISI_PCIE_CORE_PORT_ID(PCI_SLOT(pdev->devfn)));
>>>>> +
>>>>> +	return PCI_DEVID(pdev->bus->number, pdev->devfn);
>>>>> +}
>>>>> +
>>>>> +static int hisi_ptt_wait_trace_hw_idle(struct hisi_ptt *hisi_ptt)
>>>>> +{
>>>>> +	u32 val;
>>>>> +
>>>>> +	return readl_poll_timeout(hisi_ptt->iobase + HISI_PTT_TRACE_STS, val,
>>>>> +				  val & HISI_PTT_TRACE_IDLE,
>>>>> +				  HISI_PTT_WAIT_POLL_INTERVAL_US,
>>>>> +				  HISI_PTT_WAIT_TIMEOUT_US);
>>>>> +}
>>>>> +
>>>>> +static void hisi_ptt_free_trace_buf(struct hisi_ptt *hisi_ptt)
>>>>> +{
>>>>> +	struct hisi_ptt_trace_ctrl *ctrl = &hisi_ptt->trace_ctrl;
>>>>> +	struct device *dev = &hisi_ptt->pdev->dev;
>>>>> +	struct hisi_ptt_dma_buflet *buflet, *tbuflet;
>>>>> +
>>>>> +	list_for_each_entry_safe(buflet, tbuflet, &ctrl->trace_buf, list) {
>>>>> +		list_del(&buflet->list);
>>>>> +
>>>>> +		if (ctrl->has_rmr)
>>>>> +			memunmap(buflet->addr);
>>>>> +		else
>>>>> +			dma_free_coherent(dev, buflet->size, buflet->addr,
>>>>> +					  buflet->dma);
>>>>> +
>>>>> +		kfree(buflet);
>>>>> +	}
>>>>> +}
>>>>> +
>>>>> +static int hisi_ptt_alloc_trace_buf(struct hisi_ptt *hisi_ptt)
>>>>> +{
>>>>> +	struct hisi_ptt_trace_ctrl *ctrl = &hisi_ptt->trace_ctrl;
>>>>> +	struct device *dev = &hisi_ptt->pdev->dev;
>>>>> +	struct hisi_ptt_dma_buflet *buflet;
>>>>> +	int i, ret;
>>>>> +
>>>>> +	hisi_ptt->trace_ctrl.buf_index = 0;
>>>>> +
>>>>> +	/* Make sure the trace buffer is empty before allocating */
>>>>> +	if (!list_empty(&ctrl->trace_buf)) {
>>>>> +		list_for_each_entry(buflet, &ctrl->trace_buf, list)
>>>>> +			memset(buflet->addr, 0, buflet->size);
>>>>> +		return 0;
>>>>> +	}
>>>>> +
>>>>> +	for (i = 0; i < HISI_PTT_TRACE_BUFLETS_CNT; ++i) {
>>>>> +		buflet = kzalloc(sizeof(*buflet), GFP_KERNEL);
>>>>> +		if (!buflet) {
>>>>> +			ret = -ENOMEM;
>>>>> +			goto err;
>>>>> +		}
>>>>> +
>>>>> +		if (ctrl->has_rmr) {
>>>>> +			phys_addr_t base = ctrl->rmr_addr + i * ctrl->buflet_size;
>>>>> +
>>>>> +			buflet->dma = base;
>>>>> +			buflet->addr = memremap(base, ctrl->buflet_size, MEMREMAP_WB);
>>>>> +		} else {
>>>>> +			buflet->addr = dma_alloc_coherent(dev, ctrl->buflet_size,
>>>>> +							  &buflet->dma, GFP_KERNEL);
>>>>> +		}
>>>>> +
>>>>> +		if (!buflet->addr) {
>>>>> +			kfree(buflet);
>>>>> +			ret = -ENOMEM;
>>>>> +			goto err;
>>>>> +		}
>>>>> +
>>>>> +		memset(buflet->addr, 0, buflet->size);
>>>>> +
>>>>> +		buflet->index = i;
>>>>> +		buflet->size = ctrl->buflet_size;
>>>>> +		list_add_tail(&buflet->list, &ctrl->trace_buf);
>>>>> +	}
>>>>> +
>>>>> +	return 0;
>>>>> +err:
>>>>> +	hisi_ptt_free_trace_buf(hisi_ptt);
>>>>> +	return ret;
>>>>> +}
>>>>> +
>>>>> +static void hisi_ptt_trace_end(struct hisi_ptt *hisi_ptt)
>>>>> +{
>>>>> +	writel(0, hisi_ptt->iobase + HISI_PTT_TRACE_CTRL);
>>>>> +	hisi_ptt->trace_ctrl.status = HISI_PTT_TRACE_STATUS_OFF;
>>>>> +}
>>>>> +
>>>>> +static int hisi_ptt_trace_start(struct hisi_ptt *hisi_ptt)
>>>>> +{
>>>>> +	struct hisi_ptt_trace_ctrl *ctrl = &hisi_ptt->trace_ctrl;
>>>>> +	struct hisi_ptt_dma_buflet *cur;
>>>>> +	u32 val;
>>>>> +
>>>>> +	/* Check device idle before start trace */
>>>>> +	if (hisi_ptt_wait_trace_hw_idle(hisi_ptt)) {
>>>>> +		pci_err(hisi_ptt->pdev, "Failed to start trace, the device is still busy.\n");
>>>>> +		return -EBUSY;
>>>>> +	}
>>>>> +
>>>>> +	/* Reset the DMA before start tracing */
>>>>> +	val = readl(hisi_ptt->iobase + HISI_PTT_TRACE_CTRL);
>>>>> +	val |= HISI_PTT_TRACE_CTRL_RST;
>>>>> +	writel(val, hisi_ptt->iobase + HISI_PTT_TRACE_CTRL);
>>>>> +
>>>>> +	/*
>>>>> +	 * We'll be in the perf context where preemption is disabled,
>>>>> +	 * so use busy loop here.
>>>>> +	 */
>>>>> +	mdelay(HISI_PTT_RESET_WAIT_MS);
>>>>> +
>>>>> +	val = readl(hisi_ptt->iobase + HISI_PTT_TRACE_CTRL);
>>>>> +	val &= ~HISI_PTT_TRACE_CTRL_RST;
>>>>> +	writel(val, hisi_ptt->iobase + HISI_PTT_TRACE_CTRL);
>>>>> +
>>>>> +	/* clear the interrupt status */
>>>>> +	writel(HISI_PTT_TRACE_INT_STAT_MASK, hisi_ptt->iobase + HISI_PTT_TRACE_INT_STAT);
>>>>> +	writel(0, hisi_ptt->iobase + HISI_PTT_TRACE_INT_MASK);
>>>>> +
>>>>> +	list_for_each_entry(cur, &ctrl->trace_buf, list) {
>>>>> +		writel(lower_32_bits(cur->dma),
>>>>> +		       hisi_ptt->iobase + HISI_PTT_TRACE_ADDR_BASE_LO_0 +
>>>>> +		       cur->index * HISI_PTT_TRACE_ADDR_STRIDE);
>>>>> +		writel(upper_32_bits(cur->dma),
>>>>> +		       hisi_ptt->iobase + HISI_PTT_TRACE_ADDR_BASE_HI_0 +
>>>>> +		       cur->index * HISI_PTT_TRACE_ADDR_STRIDE);
>>>>> +	}
>>>>> +	writel(ctrl->buflet_size, hisi_ptt->iobase + HISI_PTT_TRACE_ADDR_SIZE);
>>>>> +
>>>>> +	/* set the trace control register */
>>>>> +	val = FIELD_PREP(HISI_PTT_TRACE_CTRL_TYPE_SEL, ctrl->type);
>>>>> +	val |= FIELD_PREP(HISI_PTT_TRACE_CTRL_RXTX_SEL, ctrl->direction);
>>>>> +	val |= FIELD_PREP(HISI_PTT_TRACE_CTRL_DATA_FORMAT, ctrl->format);
>>>>> +	val |= FIELD_PREP(HISI_PTT_TRACE_CTRL_TARGET_SEL, hisi_ptt->trace_ctrl.filter);
>>>>> +	if (!hisi_ptt->trace_ctrl.is_port)
>>>>> +		val |= HISI_PTT_TRACE_CTRL_FILTER_MODE;
>>>>> +
>>>>> +	val |= HISI_PTT_TRACE_CTRL_EN;
>>>>> +	writel(val, hisi_ptt->iobase + HISI_PTT_TRACE_CTRL);
>>>>> +
>>>>> +	ctrl->status = HISI_PTT_TRACE_STATUS_ON;
>>>>> +
>>>>> +	return 0;
>>>>> +}
>>>>> +
>>>>> +static int hisi_ptt_update_aux(struct hisi_ptt *hisi_ptt, int index, bool stop)
>>>>> +{
>>>>> +	struct perf_output_handle *handle = &hisi_ptt->trace_ctrl.handle;
>>>>> +	struct perf_event *event = handle->event;
>>>>> +	struct hisi_ptt_dma_buflet *cur;
>>>>> +	struct hisi_ptt_pmu_buf *buf;
>>>>> +
>>>>> +	buf = perf_get_aux(handle);
>>>>> +	if (!buf || !handle->size)
>>>>> +		return -EINVAL;
>>>>> +
>>>>> +	list_for_each_entry(cur, &hisi_ptt->trace_ctrl.trace_buf, list)
>>>>> +		if (cur->index == index)
>>>>> +			break;
>>>>> +
>>>>> +	memcpy(buf->base + buf->pos, cur->addr, cur->size);
>>>>> +	memset(cur->addr, 0, cur->size);
>>>>> +	buf->pos += cur->size;
>>>>> +
>>>>> +	if (stop) {
>>>>> +		perf_aux_output_end(handle, buf->pos);
>>>>> +	} else if (buf->length - buf->pos < cur->size) {
>>>>> +		perf_aux_output_skip(handle, buf->length - buf->pos);
>>>>> +		perf_aux_output_end(handle, buf->pos);
>>>>> +
>>>>> +		buf = perf_aux_output_begin(handle, event);
>>>>> +		if (!buf)
>>>>> +			return -EINVAL;
>>>>> +
>>>>> +		buf->pos = handle->head % buf->length;
>>>>> +		if (buf->length - buf->pos < cur->size) {
>>>>> +			perf_aux_output_end(handle, 0);
>>>>> +			return -EINVAL;
>>>>> +		}
>>>>> +	}
>>>>> +
>>>>> +	return 0;
>>>>> +}
>>>>> +
>>>>> +static irqreturn_t hisi_ptt_isr(int irq, void *context)
>>>>> +{
>>>>> +	struct hisi_ptt *hisi_ptt = context;
>>>>> +	u32 status, buf_idx;
>>>>> +
>>>>> +	status = readl(hisi_ptt->iobase + HISI_PTT_TRACE_INT_STAT);
>>>>> +	buf_idx = ffs(status) - 1;
>>>>> +
>>>>> +	/* Clear the interrupt status of buflet @buf_idx */
>>>>> +	writel(status, hisi_ptt->iobase + HISI_PTT_TRACE_INT_STAT);
>>>>> +
>>>>> +	/*
>>>>> +	 * Update the AUX buffer and cache the current buflet index,
>>>>> +	 * as we need to know this and save the data when the trace
>>>>> +	 * is ended out of the interrupt handler. End the trace
>>>>> +	 * if the updating fails.
>>>>> +	 */
>>>>> +	if (hisi_ptt_update_aux(hisi_ptt, buf_idx, false))
>>>>> +		hisi_ptt_trace_end(hisi_ptt);
>>>>> +	else
>>>>> +		hisi_ptt->trace_ctrl.buf_index = (buf_idx + 1) % HISI_PTT_TRACE_BUFLETS_CNT;
>>>>> +
>>>>> +	return IRQ_HANDLED;
>>>>> +}
>>>>> +
>>>>> +static irqreturn_t hisi_ptt_irq(int irq, void *context)
>>>>> +{
>>>>> +	struct hisi_ptt *hisi_ptt = context;
>>>>> +	u32 status;
>>>>> +
>>>>> +	status = readl(hisi_ptt->iobase + HISI_PTT_TRACE_INT_STAT);
>>>>> +	if (!(status & HISI_PTT_TRACE_INT_STAT_MASK))
>>>>> +		return IRQ_NONE;
>>>>> +
>>>>> +	return IRQ_WAKE_THREAD;
>>>>> +}
>>>>> +
>>>>> +static void hisi_ptt_irq_free_vectors(void *pdev)
>>>>> +{
>>>>> +	pci_free_irq_vectors(pdev);
>>>>> +}
>>>>> +
>>>>> +static int hisi_ptt_register_irq(struct hisi_ptt *hisi_ptt)
>>>>> +{
>>>>> +	struct pci_dev *pdev = hisi_ptt->pdev;
>>>>> +	int ret;
>>>>> +
>>>>> +	ret = pci_alloc_irq_vectors(pdev, 1, 1, PCI_IRQ_MSI);
>>>>> +	if (ret < 0) {
>>>>> +		pci_err(pdev, "failed to allocate irq vector, ret = %d.\n", ret);
>>>>> +		return ret;
>>>>> +	}
>>>>> +
>>>>> +	ret = devm_add_action_or_reset(&pdev->dev, hisi_ptt_irq_free_vectors, pdev);
>>>>> +	if (ret < 0)
>>>>> +		return ret;
>>>>> +
>>>>> +	ret = devm_request_threaded_irq(&pdev->dev,
>>>>> +					pci_irq_vector(pdev, HISI_PTT_TRACE_DMA_IRQ),
>>>>> +					hisi_ptt_irq, hisi_ptt_isr, 0,
>>>>> +					"hisi-ptt", hisi_ptt);
>>>>> +	if (ret) {
>>>>> +		pci_err(pdev, "failed to request irq %d, ret = %d.\n",
>>>>> +			pci_irq_vector(pdev, HISI_PTT_TRACE_DMA_IRQ), ret);
>>>>> +		return ret;
>>>>> +	}
>>>>> +
>>>>> +	return 0;
>>>>> +}
>>>>> +
>>>>> +static void hisi_ptt_update_filters(struct work_struct *work)
>>>>> +{
>>>>> +	struct delayed_work *delayed_work = to_delayed_work(work);
>>>>> +	struct hisi_ptt_filter_update_info info;
>>>>> +	struct hisi_ptt_filter_desc *filter;
>>>>> +	struct list_head *target_list;
>>>>> +	struct hisi_ptt *hisi_ptt;
>>>>> +
>>>>> +	hisi_ptt = container_of(delayed_work, struct hisi_ptt, work);
>>>>> +
>>>>> +	if (!mutex_trylock(&hisi_ptt->mutex)) {
>>>>> +		schedule_delayed_work(&hisi_ptt->work, HISI_PTT_WORK_DELAY_MS);
>>>>> +		return;
>>>>> +	}
>>>>> +
>>>>> +	while (kfifo_get(&hisi_ptt->filter_update_kfifo, &info)) {
>>>>> +		target_list = info.is_port ? &hisi_ptt->port_filters :
>>>>> +			      &hisi_ptt->req_filters;
>>>>> +
>>>>> +		if (info.is_add) {
>>>>> +			filter = kzalloc(sizeof(*filter), GFP_KERNEL);
>>>>> +			if (!filter)
>>>>> +				continue;
>>>>> +
>>>>> +			filter->pdev = info.pdev;
>>>>> +			filter->val = info.val;
>>>>> +
>>>>> +			list_add_tail(&filter->list, target_list);
>>>>> +		} else {
>>>>> +			list_for_each_entry(filter, target_list, list)
>>>>> +				if (filter->val == info.val) {
>>>>> +					list_del(&filter->list);
>>>>> +					kfree(filter);
>>>>> +					break;
>>>>> +				}
>>>>> +		}
>>>>> +
>>>>> +		/* Update the available port mask */
>>>>> +		if (!info.is_port)
>>>>> +			continue;
>>>>> +
>>>>> +		if (info.is_add)
>>>>> +			hisi_ptt->port_mask |= info.val;
>>>>> +		else
>>>>> +			hisi_ptt->port_mask &= ~info.val;
>>>>> +	}
>>>>> +
>>>>> +	mutex_unlock(&hisi_ptt->mutex);
>>>>> +}
>>>>> +
>>>>> +static void hisi_ptt_update_fifo_in(struct hisi_ptt *hisi_ptt,
>>>>> +				    struct hisi_ptt_filter_update_info *info)
>>>>> +{
>>>>> +	struct pci_dev *root_port = pcie_find_root_port(info->pdev);
>>>>> +
>>>>> +	if (!root_port)
>>>>> +		return;
>>>>> +
>>>>> +	info->port_devid = PCI_DEVID(root_port->bus->number, root_port->devfn);
>>>>> +	if (info->port_devid < hisi_ptt->lower ||
>>>>> +	    info->port_devid > hisi_ptt->upper)
>>>>> +		return;
>>>>> +
>>>>> +	info->is_port = pci_pcie_type(info->pdev) == PCI_EXP_TYPE_ROOT_PORT;
>>>>> +	info->val = hisi_ptt_get_filter_val(info->pdev);
>>>>> +
>>>>> +	if (kfifo_in_spinlocked(&hisi_ptt->filter_update_kfifo, info, 1,
>>>>> +				&hisi_ptt->filter_update_lock))
>>>>> +		schedule_delayed_work(&hisi_ptt->work, 0);
>>>>> +	else
>>>>> +		pci_warn(hisi_ptt->pdev,
>>>>> +			 "filter update fifo overflow for target %s\n",
>>>>> +			 pci_name(info->pdev));
>>>>> +}
>>>>> +
>>>>> +/*
>>>>> + * A PCI bus notifier is used here for dynamically updating the filter
>>>>> + * list.
>>>>> + */
>>>>> +static int hisi_ptt_notifier_call(struct notifier_block *nb, unsigned long action,
>>>>> +				  void *data)
>>>>> +{
>>>>> +	struct hisi_ptt *hisi_ptt = container_of(nb, struct hisi_ptt, hisi_ptt_nb);
>>>>> +	struct hisi_ptt_filter_update_info info;
>>>>> +	struct device *dev = data;
>>>>> +	struct pci_dev *pdev = to_pci_dev(dev);
>>>>> +
>>>>> +	info.pdev = pdev;
>>>>> +
>>>>> +	switch (action) {
>>>>> +	case BUS_NOTIFY_ADD_DEVICE:
>>>>> +		info.is_add = true;
>>>>> +		break;
>>>>> +	case BUS_NOTIFY_DEL_DEVICE:
>>>>> +		info.is_add = false;
>>>>> +		break;
>>>>> +	default:
>>>>> +		return 0;
>>>>> +	}
>>>>> +
>>>>> +	hisi_ptt_update_fifo_in(hisi_ptt, &info);
>>>>> +
>>>>> +	return 0;
>>>>> +}
>>>>> +
>>>>> +static int hisi_ptt_init_filters(struct pci_dev *pdev, void *data)
>>>>> +{
>>>>> +	struct hisi_ptt_filter_update_info info = {
>>>>> +		.pdev = pdev,
>>>>> +		.is_add = true,
>>>>> +	};
>>>>> +	struct hisi_ptt *hisi_ptt = data;
>>>>> +
>>>>> +	hisi_ptt_update_fifo_in(hisi_ptt, &info);
>>>>> +
>>>>> +	return 0;
>>>>> +}
>>>>> +
>>>>> +static void hisi_ptt_release_filters(struct hisi_ptt *hisi_ptt)
>>>>> +{
>>>>> +	struct hisi_ptt_filter_desc *filter, *tfilter;
>>>>> +
>>>>> +	list_for_each_entry_safe(filter, tfilter, &hisi_ptt->req_filters, list) {
>>>>> +		list_del(&filter->list);
>>>>> +		kfree(filter);
>>>>> +	}
>>>>> +
>>>>> +	list_for_each_entry_safe(filter, tfilter, &hisi_ptt->port_filters, list) {
>>>>> +		list_del(&filter->list);
>>>>> +		kfree(filter);
>>>>> +	}
>>>>> +}
>>>>> +
>>>>> +static void hisi_ptt_init_ctrls(struct hisi_ptt *hisi_ptt)
>>>>> +{
>>>>> +	struct pci_dev *pdev = hisi_ptt->pdev;
>>>>> +	struct pci_bus *bus;
>>>>> +	u32 reg;
>>>>> +
>>>>> +	INIT_DELAYED_WORK(&hisi_ptt->work, hisi_ptt_update_filters);
>>>>> +	spin_lock_init(&hisi_ptt->filter_update_lock);
>>>>> +	INIT_KFIFO(hisi_ptt->filter_update_kfifo);
>>>>> +	INIT_LIST_HEAD(&hisi_ptt->port_filters);
>>>>> +	INIT_LIST_HEAD(&hisi_ptt->req_filters);
>>>>> +
>>>>> +	/*
>>>>> +	 * The device range register provides the information about the
>>>>> +	 * root ports which the RCiEP can control and trace. The RCiEP
>>>>> +	 * and the root ports it support are on the same PCIe core, with
>>>>> +	 * same domain number but maybe different bus number. The device
>>>>> +	 * range register will tell us which root ports we can support,
>>>>> +	 * Bit[31:16] indicates the upper BDF numbers of the root port,
>>>>> +	 * while Bit[15:0] indicates the lower.
>>>>> +	 */
>>>>> +	reg = readl(hisi_ptt->iobase + HISI_PTT_DEVICE_RANGE);
>>>>> +	hisi_ptt->upper = reg >> 16;
>>>>> +	hisi_ptt->lower = reg & 0xffff;
>>>>> +	hisi_ptt->busnr = PCI_BUS_NUM(hisi_ptt->upper);
>>>>> +
>>>>> +	reg = readl(hisi_ptt->iobase + HISI_PTT_LOCATION);
>>>>> +	hisi_ptt->core_id = FIELD_GET(HISI_PTT_CORE_ID, reg);
>>>>> +	hisi_ptt->sicl_id = FIELD_GET(HISI_PTT_SICL_ID, reg);
>>>>> +
>>>>> +	bus = pci_find_bus(pci_domain_nr(pdev->bus), hisi_ptt->busnr);
>>>>> +	if (bus)
>>>>> +		pci_walk_bus(bus, hisi_ptt_init_filters, hisi_ptt);
>>>>
>>>> What happens if bus is NULL?  Should this be reported to the caller and cause
>>>> hisi_ptt_probe() to fail?  Please add a comment that describes the scenario.
>>>>
>>>
>>> It's ok if the list is NULL in the probe process,
>>> as the device maybe hotplugged after the PTT driver probe, in which case
>>> we can detect the event and update the list as we register a bus notifier.
>>>
>>
>> Please add the above as a comment in the code.
>>
>>
>>>>> +
>>>>> +	/* Initialize trace controls */
>>>>> +	INIT_LIST_HEAD(&hisi_ptt->trace_ctrl.trace_buf);
>>>>> +	hisi_ptt->trace_ctrl.buflet_size = HISI_PTT_TRACE_BUFLET_SIZE;
>>>>> +	hisi_ptt->trace_ctrl.default_cpu = cpumask_first(cpumask_of_node(dev_to_node(&pdev->dev)));
>>>>> +}
>>>>> +
>>>>> +#define HISI_PTT_PMU_FILTER_IS_PORT	BIT(19)
>>>>> +#define HISI_PTT_PMU_FILTER_VAL_MASK	GENMASK(15, 0)
>>>>> +#define HISI_PTT_PMU_DIRECTION_MASK	GENMASK(23, 20)
>>>>> +#define HISI_PTT_PMU_TYPE_MASK		GENMASK(31, 24)
>>>>> +#define HISI_PTT_PMU_FORMAT_MASK	GENMASK(35, 32)
>>>>> +
>>>>> +static ssize_t available_filters_show(struct device *dev,
>>>>> +				      struct device_attribute *attr,
>>>>> +				      char *buf)
>>>>> +{
>>>>> +	struct hisi_ptt *hisi_ptt = to_hisi_ptt(dev_get_drvdata(dev));
>>>>> +	struct hisi_ptt_filter_desc *filter;
>>>>> +	int pos = 0;
>>>>> +
>>>>> +	if (list_empty(&hisi_ptt->port_filters))
>>>>> +		return sysfs_emit(buf, "#### No available filter ####\n");
>>>>> +
>>>>> +	mutex_lock(&hisi_ptt->mutex);
>>>>> +	pos += sysfs_emit_at(buf, pos, "#### Root Ports ####\n");
>>>>> +	list_for_each_entry(filter, &hisi_ptt->port_filters, list)
>>>>> +		pos += sysfs_emit_at(buf, pos, "%s	0x%05lx\n",
>>>>> +				     pci_name(filter->pdev),
>>>>> +				     hisi_ptt_get_filter_val(filter->pdev) |
>>>>> +				     HISI_PTT_PMU_FILTER_IS_PORT);
>>>>> +
>>>>> +	pos += sysfs_emit_at(buf, pos, "#### Requesters ####\n");
>>>>> +	list_for_each_entry(filter, &hisi_ptt->req_filters, list)
>>>>> +		pos += sysfs_emit_at(buf, pos, "%s	0x%05x\n",
>>>>> +				     pci_name(filter->pdev),
>>>>> +				     hisi_ptt_get_filter_val(filter->pdev));
>>>>> +
>>>>> +	mutex_unlock(&hisi_ptt->mutex);
>>>>> +	return pos;
>>>>> +}
>>>>> +static DEVICE_ATTR_ADMIN_RO(available_filters);
>>>>> +
>>>>> +PMU_FORMAT_ATTR(filter,		"config:0-19");
>>>>> +PMU_FORMAT_ATTR(direction,	"config:20-23");
>>>>> +PMU_FORMAT_ATTR(type,		"config:24-31");
>>>>> +PMU_FORMAT_ATTR(format,		"config:32-35");
>>>>> +
>>>>> +static struct attribute *hisi_ptt_pmu_format_attrs[] = {
>>>>> +	&format_attr_filter.attr,
>>>>> +	&format_attr_direction.attr,
>>>>> +	&format_attr_type.attr,
>>>>> +	&format_attr_format.attr,
>>>>> +	NULL
>>>>> +};
>>>>> +
>>>>> +static struct attribute_group hisi_ptt_pmu_format_group = {
>>>>> +	.name = "format",
>>>>> +	.attrs = hisi_ptt_pmu_format_attrs,
>>>>> +};
>>>>> +
>>>>> +static struct attribute *hisi_ptt_pmu_filter_attrs[] = {
>>>>> +	&dev_attr_available_filters.attr,
>>>>> +	NULL
>>>>> +};
>>>>> +
>>>>> +static struct attribute_group hisi_ptt_pmu_filter_group = {
>>>>> +	.attrs = hisi_ptt_pmu_filter_attrs,
>>>>> +};
>>>>> +
>>>>> +static const struct attribute_group *hisi_ptt_pmu_groups[] = {
>>>>> +	&hisi_ptt_pmu_format_group,
>>>>> +	&hisi_ptt_pmu_filter_group,
>>>>> +	NULL
>>>>> +};
>>>>> +
>>>>> +/*
>>>>> + * The supported value of the direction parameter. See hisi_ptt.rst
>>>>> + * documentation for more details.
>>>>> + */
>>>>> +static u32 hisi_ptt_trace_available_direction[] = {
>>>>> +	0,
>>>>> +	1,
>>>>> +	2,
>>>>> +	3,
>>>>> +};
>>>>> +
>>>>> +/* Different types can be set simultaneously */
>>>>> +static u32 hisi_ptt_trace_available_type[] = {
>>>>> +	1,	/* posted_request */
>>>>> +	2,	/* non-posted_request */
>>>>> +	4,	/* completion */
>>>>> +};
>>>>> +
>>>>> +static u32 hisi_ptt_trace_availble_format[] = {
>>>>> +	0,	/* 4DW */
>>>>> +	1,	/* 8DW */
>>>>> +};
>>>>> +
>>>>> +/*
>>>>> + * Check whether the config is valid or not. Some configs are multi-selectable
>>>>> + * and can be set simultaneously, while some are single selectable (onehot).
>>>>> + * Use this function to check the non-onehot configs while
>>>>> + * hisi_ptt_trace_valid_config_onehot() for the onehot ones.
>>>>> + */
>>>>> +static int hisi_ptt_trace_valid_config(u32 val, u32 *available_list, u32 list_size)
>>>>> +{
>>>>> +	int i;
>>>>> +
>>>>> +	/*
>>>>> +	 * The non-onehot configs cannot be 0. Walk the available
>>>>> +	 * list and clear the valid bits of the config. If there
>>>>> +	 * is any resident bit after the walk then the config is
>>>>> +	 * invalid.
>>>>> +	 */
>>>>> +	for (i = 0; i < list_size; i++)
>>>>> +		val &= ~available_list[i];
>>>>> +
>>>>> +	return val ? -EINVAL : 0;
>>>>> +}
>>>>> +
>>>>> +static int hisi_ptt_trace_valid_config_onehot(u32 val, u32 *available_list, u32 list_size)
>>>>> +{
>>>>> +	int i, ret = -EINVAL;
>>>>> +
>>>>> +	for (i = 0; i < list_size; i++)
>>>>> +		if (val == available_list[i]) {
>>>>> +			ret = 0;
>>>>> +			break;
>>>>> +		}
>>>>> +
>>>>> +	return ret;
>>>>> +}
>>>>> +
>>>>> +static int hisi_ptt_trace_init_filter(struct hisi_ptt *hisi_ptt, u64 config)
>>>>> +{
>>>>> +	unsigned long val, port_mask = hisi_ptt->port_mask;
>>>>> +	struct hisi_ptt_filter_desc *filter;
>>>>> +	int ret = -EINVAL;
>>>>> +
>>>>> +	hisi_ptt->trace_ctrl.is_port = FIELD_GET(HISI_PTT_PMU_FILTER_IS_PORT, config);
>>>>> +	val = FIELD_GET(HISI_PTT_PMU_FILTER_VAL_MASK, config);
>>>>> +
>>>>> +	/*
>>>>> +	 * Port filters are defined as bit mask. For port filters, check
>>>>> +	 * the bits in the @val are within the range of hisi_ptt->port_mask
>>>>> +	 * and whether it's empty or not, otherwise user has specified
>>>>> +	 * some unsupported root ports.
>>>>> +	 *
>>>>> +	 * For Requester ID filters, walk the available filter list to see
>>>>> +	 * whether we have one matched.
>>>>> +	 */
>>>>> +	if (hisi_ptt->trace_ctrl.is_port &&
>>>>> +	    bitmap_subset(&val, &port_mask, BITS_PER_LONG)) {
>>>>> +		ret = 0;
>>>>> +	} else {
>>>>> +		list_for_each_entry(filter, &hisi_ptt->req_filters, list)
>>>>> +			if (filter->val == val) {
>>>>> +				ret = 0;
>>>>> +				break;
>>>>> +			}
>>>>> +	}
>>>>> +
>>>>> +	if (ret)
>>>>> +		return ret;
>>>>> +
>>>>> +	hisi_ptt->trace_ctrl.filter = val;
>>>>> +	return 0;
>>>>> +}
>>>>> +
>>>>> +static int hisi_ptt_pmu_event_init(struct perf_event *event)
>>>>> +{
>>>>> +	struct hisi_ptt *hisi_ptt = to_hisi_ptt(event->pmu);
>>>>> +	struct hisi_ptt_trace_ctrl *ctrl = &hisi_ptt->trace_ctrl;
>>>>> +	int ret;
>>>>> +	u32 val;
>>>>> +
>>>>> +	if (event->attr.type != hisi_ptt->hisi_ptt_pmu.type)
>>>>> +		return -ENOENT;
>>>>> +
>>>>> +	mutex_lock(&hisi_ptt->mutex);
>>>>> +
>>>>> +	ret = hisi_ptt_trace_init_filter(hisi_ptt, event->attr.config);
>>>>> +	if (ret < 0)
>>>>> +		goto out;
>>>>> +
>>>>> +	val = FIELD_GET(HISI_PTT_PMU_DIRECTION_MASK, event->attr.config);
>>>>> +	ret = hisi_ptt_trace_valid_config_onehot(val, hisi_ptt_trace_available_direction,
>>>>> +						 ARRAY_SIZE(hisi_ptt_trace_available_direction));
>>>>> +	if (ret < 0)
>>>>> +		goto out;
>>>>> +	ctrl->direction = val;
>>>>> +
>>>>> +	val = FIELD_GET(HISI_PTT_PMU_TYPE_MASK, event->attr.config);
>>>>> +
>>>>> +	ret = hisi_ptt_trace_valid_config(val, hisi_ptt_trace_available_type,
>>>>> +					  ARRAY_SIZE(hisi_ptt_trace_available_type));
>>>>> +	if (ret < 0)
>>>>> +		goto out;
>>>>> +	ctrl->type = val;
>>>>> +
>>>>> +	val = FIELD_GET(HISI_PTT_PMU_FORMAT_MASK, event->attr.config);
>>>>> +	ret = hisi_ptt_trace_valid_config_onehot(val, hisi_ptt_trace_availble_format,
>>>>> +						 ARRAY_SIZE(hisi_ptt_trace_availble_format));
>>>>> +	if (ret < 0)
>>>>> +		goto out;
>>>>> +	ctrl->format = val;
>>>>> +
>>>>> +out:
>>>>> +	mutex_unlock(&hisi_ptt->mutex);
>>>>> +	return ret;
>>>>> +}
>>>>> +
>>>>> +static void *hisi_ptt_pmu_setup_aux(struct perf_event *event, void **pages,
>>>>> +				    int nr_pages, bool overwrite)
>>>>> +{
>>>>> +	struct hisi_ptt_pmu_buf *buf;
>>>>> +	struct page **pagelist;
>>>>> +	int i;
>>>>> +
>>>>> +	if (overwrite) {
>>>>> +		dev_warn(event->pmu->dev, "Overwrite mode is not supported\n");
>>>>> +		return NULL;
>>>>> +	}
>>>>> +
>>>>> +	/* If the pages size less than buflets, we cannot start trace */
>>>>> +	if (nr_pages < HISI_PTT_TRACE_BUFFER_SIZE / PAGE_SIZE)
>>>>> +		return NULL;
>>>>> +
>>>>> +	buf = kzalloc(sizeof(*buf), GFP_KERNEL);
>>>>> +	if (!buf)
>>>>> +		return NULL;
>>>>> +
>>>>> +	pagelist = kcalloc(nr_pages, sizeof(*pagelist), GFP_KERNEL);
>>>>> +	if (!pagelist) {
>>>>> +		kfree(buf);
>>>>> +		return NULL;
>>>>> +	}
>>>>> +
>>>>> +	for (i = 0; i < nr_pages; i++)
>>>>> +		pagelist[i] = virt_to_page(pages[i]);
>>>>> +
>>>>> +	buf->base = vmap(pagelist, nr_pages, VM_MAP, PAGE_KERNEL);
>>>>> +	if (!buf->base) {
>>>>> +		kfree(pagelist);
>>>>> +		kfree(buf);
>>>>> +		return NULL;
>>>>> +	}
>>>>> +
>>>>> +	buf->nr_pages = nr_pages;
>>>>> +	buf->length = nr_pages * PAGE_SIZE;
>>>>> +	buf->pos = 0;
>>>>> +
>>>>> +	kfree(pagelist);
>>>>> +	return buf;
>>>>> +}
>>>>> +
>>>>> +static void hisi_ptt_pmu_free_aux(void *aux)
>>>>> +{
>>>>> +	struct hisi_ptt_pmu_buf *buf = aux;
>>>>> +
>>>>> +	vunmap(buf->base);
>>>>> +	kfree(buf);
>>>>> +}
>>>>> +
>>>>> +static void hisi_ptt_pmu_start(struct perf_event *event, int flags)
>>>>> +{
>>>>> +	struct hisi_ptt *hisi_ptt = to_hisi_ptt(event->pmu);
>>>>> +	struct perf_output_handle *handle = &hisi_ptt->trace_ctrl.handle;
>>>>> +	struct hw_perf_event *hwc = &event->hw;
>>>>> +	struct hisi_ptt_pmu_buf *buf;
>>>>> +	int cpu = event->cpu;
>>>>> +	int ret;
>>>>> +
>>>>> +	hwc->state = 0;
>>>>> +	mutex_lock(&hisi_ptt->mutex);
>>>>> +	if (hisi_ptt->trace_ctrl.status == HISI_PTT_TRACE_STATUS_ON) {
>>>>> +		pci_dbg(hisi_ptt->pdev, "trace has already started\n");
>>>>> +		goto stop;
>>>>> +	}
>>>>> +
>>>>> +	if (cpu == -1)
>>>>> +		cpu = hisi_ptt->trace_ctrl.default_cpu;
>>>>> +
>>>>> +	/*
>>>>> +	 * Handle the interrupt on the same cpu which starts the trace to avoid
>>>>> +	 * context mismatch. Otherwise we'll trigger the WARN from the perf
>>>>> +	 * core in event_function_local().
>>>>> +	 */
>>>>> +	WARN_ON(irq_set_affinity(pci_irq_vector(hisi_ptt->pdev, HISI_PTT_TRACE_DMA_IRQ),
>>>>> +				 cpumask_of(cpu)));
>>>>> +
>>>>> +	ret = hisi_ptt_alloc_trace_buf(hisi_ptt);
>>>>> +	if (ret) {
>>>>> +		pci_dbg(hisi_ptt->pdev, "alloc trace buf failed, ret = %d\n", ret);
>>>>> +		goto stop;
>>>>> +	}
>>>>> +
>>>>> +	buf = perf_aux_output_begin(handle, event);
>>>>> +	if (!buf) {
>>>>> +		pci_dbg(hisi_ptt->pdev, "aux output begin failed\n");
>>>>> +		goto stop;
>>>>> +	}
>>>>> +
>>>>> +	buf->pos = handle->head % buf->length;
>>>>> +
>>>>> +	ret = hisi_ptt_trace_start(hisi_ptt);
>>>>> +	if (ret) {
>>>>> +		pci_dbg(hisi_ptt->pdev, "trace start failed, ret = %d\n", ret);
>>>>> +		perf_aux_output_end(handle, 0);
>>>>> +		goto stop;
>>>>> +	}
>>>>> +
>>>>> +	mutex_unlock(&hisi_ptt->mutex);
>>>>> +	return;
>>>>> +stop:
>>>>> +	event->hw.state |= PERF_HES_STOPPED;
>>>>> +	mutex_unlock(&hisi_ptt->mutex);
>>>>> +}
>>>>> +
>>>>> +static void hisi_ptt_pmu_stop(struct perf_event *event, int flags)
>>>>> +{
>>>>> +	struct hisi_ptt *hisi_ptt = to_hisi_ptt(event->pmu);
>>>>> +	struct hw_perf_event *hwc = &event->hw;
>>>>> +
>>>>> +	if (hwc->state & PERF_HES_STOPPED)
>>>>> +		return;
>>>>> +
>>>>> +	mutex_lock(&hisi_ptt->mutex);
>>>>> +	if (hisi_ptt->trace_ctrl.status == HISI_PTT_TRACE_STATUS_ON) {
>>>>> +		hisi_ptt_trace_end(hisi_ptt);
>>>>> +		WARN(hisi_ptt_wait_trace_hw_idle(hisi_ptt), "Device is still busy");
>>>>> +		hisi_ptt_update_aux(hisi_ptt, hisi_ptt->trace_ctrl.buf_index, true);
>>>>> +	}
>>>>> +	mutex_unlock(&hisi_ptt->mutex);
>>>>> +
>>>>> +	hwc->state |= PERF_HES_STOPPED;
>>>>> +	perf_event_update_userpage(event);
>>>>> +	hwc->state |= PERF_HES_UPTODATE;
>>>>> +}
>>>>> +
>>>>> +static int hisi_ptt_pmu_add(struct perf_event *event, int flags)
>>>>> +{
>>>>> +	struct hisi_ptt *hisi_ptt = to_hisi_ptt(event->pmu);
>>>>> +	struct hw_perf_event *hwc = &event->hw;
>>>>> +	int cpu = event->cpu;
>>>>> +
>>>>> +	if (cpu == -1 && smp_processor_id() != hisi_ptt->trace_ctrl.default_cpu)
>>>>> +		return 0;
>>>>> +
>>>>> +	hwc->state = PERF_HES_STOPPED | PERF_HES_UPTODATE;
>>>>> +
>>>>> +	if (flags & PERF_EF_START) {
>>>>> +		hisi_ptt_pmu_start(event, PERF_EF_RELOAD);
>>>>> +		if (hwc->state & PERF_HES_STOPPED)
>>>>> +			return -EINVAL;
>>>>> +	}
>>>>> +
>>>>> +	return 0;
>>>>> +}
>>>>> +
>>>>> +static void hisi_ptt_pmu_del(struct perf_event *event, int flags)
>>>>> +{
>>>>> +	hisi_ptt_pmu_stop(event, PERF_EF_UPDATE);
>>>>> +}
>>>>> +
>>>>> +static void hisi_ptt_unregister_pmu(void *priv)
>>>>> +{
>>>>> +	perf_pmu_unregister(priv);
>>>>> +}
>>>>> +
>>>>> +static int hisi_ptt_register_pmu(struct hisi_ptt *hisi_ptt)
>>>>> +{
>>>>> +	char *pmu_name;
>>>>> +	int ret;
>>>>> +
>>>>> +	hisi_ptt->hisi_ptt_pmu = (struct pmu) {
>>>>> +		.module		= THIS_MODULE,
>>>>> +		.capabilities	= PERF_PMU_CAP_EXCLUSIVE | PERF_PMU_CAP_ITRACE,
>>>>> +		.task_ctx_nr	= perf_sw_context,
>>>>> +		.attr_groups	= hisi_ptt_pmu_groups,
>>>>> +		.event_init	= hisi_ptt_pmu_event_init,
>>>>> +		.setup_aux	= hisi_ptt_pmu_setup_aux,
>>>>> +		.free_aux	= hisi_ptt_pmu_free_aux,
>>>>> +		.start		= hisi_ptt_pmu_start,
>>>>> +		.stop		= hisi_ptt_pmu_stop,
>>>>> +		.add		= hisi_ptt_pmu_add,
>>>>> +		.del		= hisi_ptt_pmu_del,
>>>>> +	};
>>>>> +
>>>>> +	pmu_name = devm_kasprintf(&hisi_ptt->pdev->dev, GFP_KERNEL, "hisi_ptt%u_%u",
>>>>> +				  hisi_ptt->sicl_id, hisi_ptt->core_id);
>>>>> +	if (!pmu_name)
>>>>> +		return -ENOMEM;
>>>>> +
>>>>> +	ret = perf_pmu_register(&hisi_ptt->hisi_ptt_pmu, pmu_name, -1);
>>>>> +	if (ret)
>>>>> +		return ret;
>>>>> +
>>>>> +	return devm_add_action_or_reset(&hisi_ptt->pdev->dev,
>>>>> +					hisi_ptt_unregister_pmu,
>>>>> +					&hisi_ptt->hisi_ptt_pmu);
>>>>> +}
>>>>> +
>>>>> +/*
>>>>> + * Get RMR address if provided by the firmware.
>>>>> + * Return 0 if the IOMMU doesn't present or the policy of the
>>>>> + * IOMMU domain is passthrough or we get a usable RMR region.
>>>>> + * Otherwise a negative value is returned.
>>>>> + */
>>>>> +static int hisi_ptt_get_rmr(struct hisi_ptt *hisi_ptt)
>>>>> +{
>>>>> +	struct pci_dev *pdev = hisi_ptt->pdev;
>>>>> +	struct iommu_domain *iommu_domain;
>>>>> +	struct iommu_resv_region *region;
>>>>> +	LIST_HEAD(list);
>>>>> +
>>>>> +	/*
>>>>> +	 * Use direct DMA if IOMMU does not present or the policy of the
>>>>> +	 * IOMMU domain is passthrough.
>>>>> +	 */
>>>>> +	iommu_domain = iommu_get_domain_for_dev(&pdev->dev);
>>>>> +	if (!iommu_domain || iommu_domain->type == IOMMU_DOMAIN_IDENTITY)
>>>>> +		return 0;
>>>>> +
>>>>> +	iommu_get_resv_regions(&pdev->dev, &list);
>>>>> +	list_for_each_entry(region, &list, list)
>>>>> +		if (region->type == IOMMU_RESV_DIRECT &&
>>>>> +		    region->length >= HISI_PTT_TRACE_BUFFER_SIZE) {
>>>>> +			hisi_ptt->trace_ctrl.has_rmr = true;
>>>>> +			hisi_ptt->trace_ctrl.rmr_addr = region->start;
>>>>> +			hisi_ptt->trace_ctrl.rmr_length = region->length;
>>>>> +			break;
>>>>> +		}
>>>>> +
>>>>> +	iommu_put_resv_regions(&pdev->dev, &list);
>>>>> +	return hisi_ptt->trace_ctrl.has_rmr ? 0 : -ENOMEM;
>>>>> +}
>>>>> +
>>>>> +static int hisi_ptt_probe(struct pci_dev *pdev,
>>>>> +			  const struct pci_device_id *id)
>>>>> +{
>>>>> +	struct hisi_ptt *hisi_ptt;
>>>>> +	int ret;
>>>>> +
>>>>> +	hisi_ptt = devm_kzalloc(&pdev->dev, sizeof(*hisi_ptt), GFP_KERNEL);
>>>>> +	if (!hisi_ptt)
>>>>> +		return -ENOMEM;
>>>>> +
>>>>> +	mutex_init(&hisi_ptt->mutex);
>>>>> +	hisi_ptt->pdev = pdev;
>>>>> +
>>>>> +	/*
>>>>> +	 * Lifetime of pci_dev is longer than hisi_ptt,
>>>>> +	 * so directly reference to the pci name string.
>>>>> +	 */
>>>>> +	hisi_ptt->name = pci_name(hisi_ptt->pdev);
>>>>> +	pci_set_drvdata(pdev, hisi_ptt);
>>>>> +
>>>>> +	ret = pcim_enable_device(pdev);
>>>>> +	if (ret) {
>>>>> +		pci_err(pdev, "failed to enable device, ret = %d.\n", ret);
>>>>> +		return ret;
>>>>> +	}
>>>>> +
>>>>> +	ret = pcim_iomap_regions(pdev, BIT(2), hisi_ptt->name);
>>>>> +	if (ret) {
>>>>> +		pci_err(pdev, "failed to remap io memory, ret = %d.\n", ret);
>>>>> +		return ret;
>>>>> +	}
>>>>> +
>>>>> +	hisi_ptt->iobase = pcim_iomap_table(pdev)[2];
>>>>> +
>>>>> +	ret = dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(64));
>>>>> +	if (ret) {
>>>>> +		pci_err(pdev, "failed to set 64 bit dma mask, ret = %d.\n", ret);
>>>>> +		return ret;
>>>>> +	}
>>>>> +	pci_set_master(pdev);
>>>>> +
>>>>> +	ret = hisi_ptt_register_irq(hisi_ptt);
>>>>> +	if (ret)
>>>>> +		return ret;
>>>>> +
>>>>> +	hisi_ptt_init_ctrls(hisi_ptt);
>>>>> +
>>>>> +	ret = hisi_ptt_register_pmu(hisi_ptt);
>>>>> +	if (ret) {
>>>>> +		pci_err(pdev, "failed to register pmu device, ret = %d", ret);
>>>>> +		return ret;
>>>>> +	}
>>>>
>>>> If this fails the pci_free_irq_vectors() is not called.
>>>>
>>>
>>> It'll be called as we've registered a devm callback when
>>> allocating the irq vector. See hisi_ptt_register_irq().
>>
>> Ah yes - thanks for pointing that out.
>>
>>>
>>>> I am out of time for today - I will continue tomorrow.
>>>>
>>>
>>> Sure. Thanks!
>>> Yicong
>>>
>>>> Thanks,
>>>> Mathieu
>>>>
>>>>> +
>>>>> +	ret = hisi_ptt_get_rmr(hisi_ptt);
>>>>> +	if (ret) {
>>>>> +		pci_err(pdev, "failed to get RMR region, ret = %d", ret);
>>>>> +		return ret;
>>>>> +	}
>>>>> +
>>>>> +	/* Register the bus notifier for dynamically updating the filter list */
>>>>> +	hisi_ptt->hisi_ptt_nb.notifier_call = hisi_ptt_notifier_call;
>>>>> +	ret = bus_register_notifier(&pci_bus_type, &hisi_ptt->hisi_ptt_nb);
>>>>> +	if (ret)
>>>>> +		pci_warn(pdev, "failed to register filter update notifier, ret = %d", ret);
>>>>> +
>>>>> +	return 0;
>>>>> +}
>>>>> +
>>>>> +void hisi_ptt_remove(struct pci_dev *pdev)
>>>>> +{
>>>>> +	struct hisi_ptt *hisi_ptt = pci_get_drvdata(pdev);
>>>>> +
>>>>> +	bus_unregister_notifier(&pci_bus_type, &hisi_ptt->hisi_ptt_nb);
>>>>> +
>>>>> +	/* Cancel any work that has been queued */
>>>>> +	cancel_delayed_work_sync(&hisi_ptt->work);
>>>>> +
>>>>> +	if (hisi_ptt->trace_ctrl.status == HISI_PTT_TRACE_STATUS_ON)
>>>>> +		hisi_ptt_trace_end(hisi_ptt);
>>>>> +
>>>>> +	hisi_ptt_free_trace_buf(hisi_ptt);
>>>>> +	hisi_ptt_release_filters(hisi_ptt);
>>>>> +}
>>>>> +
>>>>> +static const struct pci_device_id hisi_ptt_id_tbl[] = {
>>>>> +	{ PCI_DEVICE(PCI_VENDOR_ID_HUAWEI, 0xa12e) },
>>>>> +	{ }
>>>>> +};
>>>>> +MODULE_DEVICE_TABLE(pci, hisi_ptt_id_tbl);
>>>>> +
>>>>> +static struct pci_driver hisi_ptt_driver = {
>>>>> +	.name = "hisi_ptt",
>>>>> +	.id_table = hisi_ptt_id_tbl,
>>>>> +	.probe = hisi_ptt_probe,
>>>>> +	.remove = hisi_ptt_remove,
>>>>> +};
>>>>> +module_pci_driver(hisi_ptt_driver);
>>>>> +
>>>>> +MODULE_LICENSE("GPL v2");
>>>>> +MODULE_AUTHOR("Yicong Yang <yangyicong@hisilicon.com>");
>>>>> +MODULE_DESCRIPTION("Driver for HiSilicon PCIe tune and trace device");
>>>>> -- 
>>>>> 2.33.0
>>>>>
>>>> .
>>>>
> .
>