[v6,3/4] drivers/perf: add DesignWare PCIe PMU driver

This commit adds the PCIe Performance Monitoring Unit (PMU) driver support
for T-Head Yitian SoC chip. Yitian is based on the Synopsys PCI Express
Core controller IP which provides statistics feature. The PMU is not a PCIe
Root Complex integrated End Point(RCiEP) device but only register counters
provided by each PCIe Root Port.

To facilitate collection of statistics the controller provides the
following two features for each Root Port:

- Time Based Analysis (RX/TX data throughput and time spent in each
  low-power LTSSM state)
- Event counters (Error and Non-Error for lanes)

Note, only one counter for each type and does not overflow interrupt.

This driver adds PMU devices for each PCIe Root Port. And the PMU device is
named based the BDF of Root Port. For example,

    30:03.0 PCI bridge: Device 1ded:8000 (rev 01)

the PMU device name for this Root Port is dwc_rootport_3018.

Example usage of counting PCIe RX TLP data payload (Units of 16 bytes)::

    $# perf stat -a -e dwc_rootport_3018/Rx_PCIe_TLP_Data_Payload/

average RX bandwidth can be calculated like this:

    PCIe TX Bandwidth = PCIE_TX_DATA * 16B / Measure_Time_Window

Signed-off-by: Shuai Xue <xueshuai@linux.alibaba.com>
Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/oe-kbuild-all/202305170639.XU3djFZX-lkp@intel.com/
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
---
 drivers/perf/Kconfig        |   7 +
 drivers/perf/Makefile       |   1 +
 drivers/perf/dwc_pcie_pmu.c | 706 ++++++++++++++++++++++++++++++++++++
 3 files changed, 714 insertions(+)
 create mode 100644 drivers/perf/dwc_pcie_pmu.c

On 2023/6/6 15:49, Shuai Xue wrote:
> This commit adds the PCIe Performance Monitoring Unit (PMU) driver support
> for T-Head Yitian SoC chip. Yitian is based on the Synopsys PCI Express
> Core controller IP which provides statistics feature. The PMU is not a PCIe
> Root Complex integrated End Point(RCiEP) device but only register counters
> provided by each PCIe Root Port.
> 
> To facilitate collection of statistics the controller provides the
> following two features for each Root Port:
> 
> - Time Based Analysis (RX/TX data throughput and time spent in each
>   low-power LTSSM state)
> - Event counters (Error and Non-Error for lanes)
> 
> Note, only one counter for each type and does not overflow interrupt.
> 
> This driver adds PMU devices for each PCIe Root Port. And the PMU device is
> named based the BDF of Root Port. For example,
> 
>     30:03.0 PCI bridge: Device 1ded:8000 (rev 01)
> 
> the PMU device name for this Root Port is dwc_rootport_3018.
> 
> Example usage of counting PCIe RX TLP data payload (Units of 16 bytes)::
> 
>     $# perf stat -a -e dwc_rootport_3018/Rx_PCIe_TLP_Data_Payload/
> 
> average RX bandwidth can be calculated like this:
> 
>     PCIe TX Bandwidth = PCIE_TX_DATA * 16B / Measure_Time_Window
> 
> Signed-off-by: Shuai Xue <xueshuai@linux.alibaba.com>
> Reported-by: kernel test robot <lkp@intel.com>
> Link: https://lore.kernel.org/oe-kbuild-all/202305170639.XU3djFZX-lkp@intel.com/
> Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
> ---
>  drivers/perf/Kconfig        |   7 +
>  drivers/perf/Makefile       |   1 +
>  drivers/perf/dwc_pcie_pmu.c | 706 ++++++++++++++++++++++++++++++++++++
>  3 files changed, 714 insertions(+)
>  create mode 100644 drivers/perf/dwc_pcie_pmu.c
> 
> diff --git a/drivers/perf/Kconfig b/drivers/perf/Kconfig
> index 711f82400086..6ff3921d7a62 100644
> --- a/drivers/perf/Kconfig
> +++ b/drivers/perf/Kconfig
> @@ -209,6 +209,13 @@ config MARVELL_CN10K_DDR_PMU
>  	  Enable perf support for Marvell DDR Performance monitoring
>  	  event on CN10K platform.
>  
> +config DWC_PCIE_PMU
> +	tristate "Enable Synopsys DesignWare PCIe PMU Support"
> +	depends on (ARM64 && PCI)
> +	help
> +	  Enable perf support for Synopsys DesignWare PCIe PMU Performance
> +	  monitoring event on Yitian 710 platform.
> +
>  source "drivers/perf/arm_cspmu/Kconfig"
>  
>  source "drivers/perf/amlogic/Kconfig"
> diff --git a/drivers/perf/Makefile b/drivers/perf/Makefile
> index dabc859540ce..13a6d1b286da 100644
> --- a/drivers/perf/Makefile
> +++ b/drivers/perf/Makefile
> @@ -22,5 +22,6 @@ obj-$(CONFIG_MARVELL_CN10K_TAD_PMU) += marvell_cn10k_tad_pmu.o
>  obj-$(CONFIG_MARVELL_CN10K_DDR_PMU) += marvell_cn10k_ddr_pmu.o
>  obj-$(CONFIG_APPLE_M1_CPU_PMU) += apple_m1_cpu_pmu.o
>  obj-$(CONFIG_ALIBABA_UNCORE_DRW_PMU) += alibaba_uncore_drw_pmu.o
> +obj-$(CONFIG_DWC_PCIE_PMU) += dwc_pcie_pmu.o
>  obj-$(CONFIG_ARM_CORESIGHT_PMU_ARCH_SYSTEM_PMU) += arm_cspmu/
>  obj-$(CONFIG_MESON_DDR_PMU) += amlogic/
> diff --git a/drivers/perf/dwc_pcie_pmu.c b/drivers/perf/dwc_pcie_pmu.c
> new file mode 100644
> index 000000000000..8bfcf6e0662d
> --- /dev/null
> +++ b/drivers/perf/dwc_pcie_pmu.c
> @@ -0,0 +1,706 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Synopsys DesignWare PCIe PMU driver
> + *
> + * Copyright (C) 2021-2023 Alibaba Inc.
> + */
> +
> +#include <linux/bitfield.h>
> +#include <linux/bitops.h>
> +#include <linux/cpuhotplug.h>
> +#include <linux/cpumask.h>
> +#include <linux/device.h>
> +#include <linux/errno.h>
> +#include <linux/kernel.h>
> +#include <linux/list.h>
> +#include <linux/perf_event.h>
> +#include <linux/pci.h>
> +#include <linux/platform_device.h>
> +#include <linux/smp.h>
> +#include <linux/sysfs.h>
> +#include <linux/types.h>
> +
> +#define DWC_PCIE_VSEC_RAS_DES_ID		0x02
> +
> +#define DWC_PCIE_EVENT_CNT_CTL			0x8
> +
> +/*
> + * Event Counter Data Select includes two parts:
> + * - 27-24: Group number(4-bit: 0..0x7)
> + * - 23-16: Event number(8-bit: 0..0x13) within the Group
> + *
> + * Put them togother as TRM used.
> + */
> +#define DWC_PCIE_CNT_EVENT_SEL			GENMASK(27, 16)
> +#define DWC_PCIE_CNT_LANE_SEL			GENMASK(11, 8)
> +#define DWC_PCIE_CNT_STATUS			BIT(7)
> +#define DWC_PCIE_CNT_ENABLE			GENMASK(4, 2)
> +#define DWC_PCIE_PER_EVENT_OFF			0x1
> +#define DWC_PCIE_PER_EVENT_ON			0x3
> +#define DWC_PCIE_EVENT_CLEAR			GENMASK(1, 0)
> +#define DWC_PCIE_EVENT_PER_CLEAR		0x1
> +
> +#define DWC_PCIE_EVENT_CNT_DATA			0xC
> +
> +#define DWC_PCIE_TIME_BASED_ANAL_CTL		0x10
> +#define DWC_PCIE_TIME_BASED_REPORT_SEL		GENMASK(31, 24)
> +#define DWC_PCIE_TIME_BASED_DURATION_SEL	GENMASK(15, 8)
> +#define DWC_PCIE_DURATION_MANUAL_CTL		0x0
> +#define DWC_PCIE_DURATION_1MS			0x1
> +#define DWC_PCIE_DURATION_10MS			0x2
> +#define DWC_PCIE_DURATION_100MS			0x3
> +#define DWC_PCIE_DURATION_1S			0x4
> +#define DWC_PCIE_DURATION_2S			0x5
> +#define DWC_PCIE_DURATION_4S			0x6
> +#define DWC_PCIE_DURATION_4US			0xFF
> +#define DWC_PCIE_TIME_BASED_TIMER_START		BIT(0)
> +#define DWC_PCIE_TIME_BASED_CNT_ENABLE		0x1
> +
> +#define DWC_PCIE_TIME_BASED_ANAL_DATA_REG_LOW	0x14
> +#define DWC_PCIE_TIME_BASED_ANAL_DATA_REG_HIGH	0x18
> +
> +/* Event attributes */
> +#define DWC_PCIE_CONFIG_EVENTID			GENMASK(15, 0)
> +#define DWC_PCIE_CONFIG_TYPE			GENMASK(19, 16)
> +#define DWC_PCIE_CONFIG_LANE			GENMASK(27, 20)
> +
> +#define DWC_PCIE_EVENT_ID(event)	FIELD_GET(DWC_PCIE_CONFIG_EVENTID, (event)->attr.config)
> +#define DWC_PCIE_EVENT_TYPE(event)	FIELD_GET(DWC_PCIE_CONFIG_TYPE, (event)->attr.config)
> +#define DWC_PCIE_EVENT_LANE(event)	FIELD_GET(DWC_PCIE_CONFIG_LANE, (event)->attr.config)
> +
> +enum dwc_pcie_event_type {
> +	DWC_PCIE_TYPE_INVALID,
> +	DWC_PCIE_TIME_BASE_EVENT,
> +	DWC_PCIE_LANE_EVENT,
> +};
> +
> +#define DWC_PCIE_LANE_EVENT_MAX_PERIOD		GENMASK_ULL(31, 0)
> +#define DWC_PCIE_TIME_BASED_EVENT_MAX_PERIOD	GENMASK_ULL(63, 0)
> +
> +
> +struct dwc_pcie_pmu {
> +	struct pci_dev		*pdev;		/* Root Port device */

If the root port removed after the probe of this PCIe PMU driver, we'll access the NULL
pointer. I didn't see you hold the root port to avoid the removal.

> +	u16			ras_des;	/* RAS DES capability offset */
> +	u32			nr_lanes;
> +
> +	struct list_head	pmu_node;
> +	struct hlist_node	cpuhp_node;
> +	struct pmu		pmu;
> +	struct perf_event	*event;
> +	int			oncpu;
> +};
> +
> +struct dwc_pcie_pmu_priv {
> +	struct device *dev;
> +	struct list_head pmu_nodes;
> +};
> +
> +#define to_dwc_pcie_pmu(p) (container_of(p, struct dwc_pcie_pmu, pmu))
> +

somebody told me to put @pmu as the first member then this macro will have no calculation. :)

> +static struct platform_device *dwc_pcie_pmu_dev;
> +static int dwc_pcie_pmu_hp_state;
> +
> +static ssize_t cpumask_show(struct device *dev,
> +					 struct device_attribute *attr,
> +					 char *buf)
> +{
> +	struct dwc_pcie_pmu *pcie_pmu = to_dwc_pcie_pmu(dev_get_drvdata(dev));
> +
> +	return cpumap_print_to_pagebuf(true, buf, cpumask_of(pcie_pmu->oncpu));
> +}
> +static DEVICE_ATTR_RO(cpumask);
> +
> +static struct attribute *dwc_pcie_pmu_cpumask_attrs[] = {
> +	&dev_attr_cpumask.attr,
> +	NULL
> +};
> +
> +static struct attribute_group dwc_pcie_cpumask_attr_group = {
> +	.attrs = dwc_pcie_pmu_cpumask_attrs,
> +};
> +
> +struct dwc_pcie_format_attr {
> +	struct device_attribute attr;
> +	u64 field;
> +	int config;
> +};
> +
> +static ssize_t dwc_pcie_pmu_format_show(struct device *dev,
> +					struct device_attribute *attr,
> +					char *buf)
> +{
> +	struct dwc_pcie_format_attr *fmt = container_of(attr, typeof(*fmt), attr);
> +	int lo = __ffs(fmt->field), hi = __fls(fmt->field);
> +
> +	return sysfs_emit(buf, "config:%d-%d\n", lo, hi);
> +}
> +
> +#define _dwc_pcie_format_attr(_name, _cfg, _fld)				\
> +	(&((struct dwc_pcie_format_attr[]) {{					\
> +		.attr = __ATTR(_name, 0444, dwc_pcie_pmu_format_show, NULL),	\
> +		.config = _cfg,							\
> +		.field = _fld,							\
> +	}})[0].attr.attr)
> +
> +#define dwc_pcie_format_attr(_name, _fld)	_dwc_pcie_format_attr(_name, 0, _fld)
> +
> +static struct attribute *dwc_pcie_format_attrs[] = {
> +	dwc_pcie_format_attr(type, DWC_PCIE_CONFIG_TYPE),
> +	dwc_pcie_format_attr(eventid, DWC_PCIE_CONFIG_EVENTID),
> +	dwc_pcie_format_attr(lane, DWC_PCIE_CONFIG_LANE),
> +	NULL,
> +};
> +
> +static struct attribute_group dwc_pcie_format_attrs_group = {
> +	.name = "format",
> +	.attrs = dwc_pcie_format_attrs,
> +};
> +
> +struct dwc_pcie_event_attr {
> +	struct device_attribute attr;
> +	enum dwc_pcie_event_type type;
> +	u16 eventid;
> +	u8 lane;
> +};
> +
> +static ssize_t dwc_pcie_event_show(struct device *dev,
> +				struct device_attribute *attr, char *buf)
> +{
> +	struct dwc_pcie_event_attr *eattr;
> +
> +	eattr = container_of(attr, typeof(*eattr), attr);
> +
> +	if (eattr->type == DWC_PCIE_LANE_EVENT)
> +		return sysfs_emit(buf, "eventid=0x%x,type=0x%x,lane=?\n",
> +				  eattr->eventid, eattr->type);
> +
> +	return sysfs_emit(buf, "eventid=0x%x,type=0x%x\n", eattr->eventid,
> +		       eattr->type);
> +}
> +
> +#define DWC_PCIE_EVENT_ATTR(_name, _type, _eventid, _lane)		\
> +	(&((struct dwc_pcie_event_attr[]) {{				\
> +		.attr = __ATTR(_name, 0444, dwc_pcie_event_show, NULL),	\
> +		.type = _type,						\
> +		.eventid = _eventid,					\
> +		.lane = _lane,						\
> +	}})[0].attr.attr)
> +
> +#define DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(_name, _eventid)		\
> +	DWC_PCIE_EVENT_ATTR(_name, DWC_PCIE_TIME_BASE_EVENT, _eventid, 0)
> +#define DWC_PCIE_PMU_LANE_EVENT_ATTR(_name, _eventid)			\
> +	DWC_PCIE_EVENT_ATTR(_name, DWC_PCIE_LANE_EVENT, _eventid, 0)
> +
> +static struct attribute *dwc_pcie_pmu_time_event_attrs[] = {
> +	/* Group #0 */
> +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(one_cycle, 0x00),
> +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(TX_L0S, 0x01),
> +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(RX_L0S, 0x02),
> +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(L0, 0x03),
> +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(L1, 0x04),
> +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(L1_1, 0x05),
> +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(L1_2, 0x06),
> +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(CFG_RCVRY, 0x07),
> +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(TX_RX_L0S, 0x08),
> +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(L1_AUX, 0x09),
> +
> +	/* Group #1 */
> +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(Tx_PCIe_TLP_Data_Payload, 0x20),
> +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(Rx_PCIe_TLP_Data_Payload, 0x21),
> +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(Tx_CCIX_TLP_Data_Payload, 0x22),
> +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(Rx_CCIX_TLP_Data_Payload, 0x23),
> +
> +	/*
> +	 * Leave it to the user to specify the lane ID to avoid generating
> +	 * a list of hundreds of events.
> +	 */
> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_ack_dllp, 0x600),
> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_update_fc_dllp, 0x601),
> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_ack_dllp, 0x602),
> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_update_fc_dllp, 0x603),
> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_nulified_tlp, 0x604),
> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_nulified_tlp, 0x605),
> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_duplicate_tl, 0x606),
> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_memory_write, 0x700),
> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_memory_read, 0x701),
> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_configuration_write, 0x702),
> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_configuration_read, 0x703),
> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_io_write, 0x704),
> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_io_read, 0x705),
> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_completion_without_data, 0x706),
> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_completion_with_data, 0x707),
> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_message_tlp, 0x708),
> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_atomic, 0x709),
> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_tlp_with_prefix, 0x70A),
> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_memory_write, 0x70B),
> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_memory_read, 0x70C),
> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_io_write, 0x70F),
> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_io_read, 0x710),
> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_completion_without_data, 0x711),
> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_completion_with_data, 0x712),
> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_message_tlp, 0x713),
> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_atomic, 0x714),
> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_tlp_with_prefix, 0x715),
> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_ccix_tlp, 0x716),
> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_ccix_tlp, 0x717),
> +

Intended blank line?

> +	NULL
> +};
> +
> +static const struct attribute_group dwc_pcie_event_attrs_group = {
> +	.name = "events",
> +	.attrs = dwc_pcie_pmu_time_event_attrs,
> +};
> +
> +static const struct attribute_group *dwc_pcie_attr_groups[] = {
> +	&dwc_pcie_event_attrs_group,
> +	&dwc_pcie_format_attrs_group,
> +	&dwc_pcie_cpumask_attr_group,
> +	NULL
> +};
> +
> +static void dwc_pcie_pmu_lane_event_enable(struct dwc_pcie_pmu *pcie_pmu,
> +					   bool enable)
> +{
> +	struct pci_dev *pdev = pcie_pmu->pdev;
> +	u16 ras_des = pcie_pmu->ras_des;
> +	u32 val;
> +
> +	pci_read_config_dword(pdev, ras_des + DWC_PCIE_EVENT_CNT_CTL, &val);
> +
> +	/* Clear DWC_PCIE_CNT_ENABLE field first */
> +	val &= ~DWC_PCIE_CNT_ENABLE;
> +	if (enable)
> +		val |= FIELD_PREP(DWC_PCIE_CNT_ENABLE, DWC_PCIE_PER_EVENT_ON);
> +	else
> +		val |= FIELD_PREP(DWC_PCIE_CNT_ENABLE, DWC_PCIE_PER_EVENT_OFF);
> +
> +	pci_write_config_dword(pdev, ras_des + DWC_PCIE_EVENT_CNT_CTL, val);
> +}
> +
> +static void dwc_pcie_pmu_time_based_event_enable(struct dwc_pcie_pmu *pcie_pmu,
> +					  bool enable)
> +{
> +	struct pci_dev *pdev = pcie_pmu->pdev;
> +	u16 ras_des = pcie_pmu->ras_des;
> +	u32 val;
> +
> +	pci_read_config_dword(pdev, ras_des + DWC_PCIE_TIME_BASED_ANAL_CTL,
> +			      &val);
> +
> +	if (enable)
> +		val |= DWC_PCIE_TIME_BASED_CNT_ENABLE;
> +	else
> +		val &= ~DWC_PCIE_TIME_BASED_CNT_ENABLE;
> +
> +	pci_write_config_dword(pdev, ras_des + DWC_PCIE_TIME_BASED_ANAL_CTL,
> +			       val);
> +}
> +
> +static u64 dwc_pcie_pmu_read_lane_event_counter(struct dwc_pcie_pmu *pcie_pmu)
> +{
> +	struct pci_dev *pdev = pcie_pmu->pdev;
> +	u16 ras_des = pcie_pmu->ras_des;
> +	u32 val;
> +
> +	pci_read_config_dword(pdev, ras_des + DWC_PCIE_EVENT_CNT_DATA, &val);
> +
> +	return val;
> +}
> +
> +static u64 dwc_pcie_pmu_read_time_based_counter(struct dwc_pcie_pmu *pcie_pmu)
> +{
> +	struct pci_dev *pdev = pcie_pmu->pdev;
> +	u16 ras_des = pcie_pmu->ras_des;
> +	u64 count;
> +	u32 val;
> +
> +	pci_read_config_dword(
> +		pdev, ras_des + DWC_PCIE_TIME_BASED_ANAL_DATA_REG_HIGH, &val);
> +	count = val;
> +	count <<= 32;
> +
> +	pci_read_config_dword(
> +		pdev, ras_des + DWC_PCIE_TIME_BASED_ANAL_DATA_REG_LOW, &val);
> +
> +	count += val;
> +
> +	return count;
> +}
> +
> +static void dwc_pcie_pmu_event_update(struct perf_event *event)
> +{
> +	struct dwc_pcie_pmu *pcie_pmu = to_dwc_pcie_pmu(event->pmu);
> +	struct hw_perf_event *hwc = &event->hw;
> +	enum dwc_pcie_event_type type = DWC_PCIE_EVENT_TYPE(event);
> +	u64 delta, prev, now;
> +
> +	do {
> +		prev = local64_read(&hwc->prev_count);
> +
> +		if (type == DWC_PCIE_LANE_EVENT)
> +			now = dwc_pcie_pmu_read_lane_event_counter(pcie_pmu);
> +		else if (type == DWC_PCIE_TIME_BASE_EVENT)
> +			now = dwc_pcie_pmu_read_time_based_counter(pcie_pmu);
> +
> +	} while (local64_cmpxchg(&hwc->prev_count, prev, now) != prev);
> +
> +	if (type == DWC_PCIE_LANE_EVENT)
> +		delta = (now - prev) & DWC_PCIE_LANE_EVENT_MAX_PERIOD;
> +	else if (type == DWC_PCIE_TIME_BASE_EVENT)
> +		delta = (now - prev) & DWC_PCIE_TIME_BASED_EVENT_MAX_PERIOD;
> +
> +	local64_add(delta, &event->count);
> +}
> +
> +static int dwc_pcie_pmu_event_init(struct perf_event *event)
> +{
> +	struct dwc_pcie_pmu *pcie_pmu = to_dwc_pcie_pmu(event->pmu);
> +	enum dwc_pcie_event_type type = DWC_PCIE_EVENT_TYPE(event);
> +	struct perf_event *sibling;
> +	u32 lane;
> +
> +	if (event->attr.type != event->pmu->type)
> +		return -ENOENT;
> +
> +	/* We don't support sampling */
> +	if (is_sampling_event(event))
> +		return -EINVAL;
> +
> +	/* We cannot support task bound events */
> +	if (event->cpu < 0 || event->attach_state & PERF_ATTACH_TASK)
> +		return -EINVAL;
> +
> +	if (event->group_leader != event &&
> +	    !is_software_event(event->group_leader))
> +		return -EINVAL;
> +
> +	for_each_sibling_event(sibling, event->group_leader) {
> +		if (sibling->pmu != event->pmu && !is_software_event(sibling))
> +			return -EINVAL;
> +	}
> +
> +	if (type == DWC_PCIE_LANE_EVENT) {
> +		lane = DWC_PCIE_EVENT_LANE(event);
> +		if (lane < 0 || lane >= pcie_pmu->nr_lanes)
> +			return -EINVAL;
> +	}
> +
> +	event->cpu = pcie_pmu->oncpu;
> +
> +	return 0;
> +}
> +
> +static void dwc_pcie_pmu_set_period(struct hw_perf_event *hwc)
> +{
> +	local64_set(&hwc->prev_count, 0);
> +}
> +
> +static void dwc_pcie_pmu_event_start(struct perf_event *event, int flags)
> +{
> +	struct hw_perf_event *hwc = &event->hw;
> +	struct dwc_pcie_pmu *pcie_pmu = to_dwc_pcie_pmu(event->pmu);
> +	enum dwc_pcie_event_type type = DWC_PCIE_EVENT_TYPE(event);
> +
> +	hwc->state = 0;
> +	dwc_pcie_pmu_set_period(hwc);
> +
> +	if (type == DWC_PCIE_LANE_EVENT)
> +		dwc_pcie_pmu_lane_event_enable(pcie_pmu, true);
> +	else if (type == DWC_PCIE_TIME_BASE_EVENT)
> +		dwc_pcie_pmu_time_based_event_enable(pcie_pmu, true);
> +}
> +
> +static void dwc_pcie_pmu_event_stop(struct perf_event *event, int flags)
> +{
> +	struct dwc_pcie_pmu *pcie_pmu = to_dwc_pcie_pmu(event->pmu);
> +	enum dwc_pcie_event_type type = DWC_PCIE_EVENT_TYPE(event);
> +	struct hw_perf_event *hwc = &event->hw;
> +
> +	if (event->hw.state & PERF_HES_STOPPED)
> +		return;
> +
> +	if (type == DWC_PCIE_LANE_EVENT)
> +		dwc_pcie_pmu_lane_event_enable(pcie_pmu, false);
> +	else if (type == DWC_PCIE_TIME_BASE_EVENT)
> +		dwc_pcie_pmu_time_based_event_enable(pcie_pmu, false);
> +
> +	dwc_pcie_pmu_event_update(event);
> +	hwc->state |= PERF_HES_STOPPED | PERF_HES_UPTODATE;
> +}
> +
> +static int dwc_pcie_pmu_event_add(struct perf_event *event, int flags)
> +{
> +	struct dwc_pcie_pmu *pcie_pmu = to_dwc_pcie_pmu(event->pmu);
> +	struct pci_dev *pdev = pcie_pmu->pdev;
> +	struct hw_perf_event *hwc = &event->hw;
> +	enum dwc_pcie_event_type type = DWC_PCIE_EVENT_TYPE(event);
> +	int event_id = DWC_PCIE_EVENT_ID(event);
> +	int lane = DWC_PCIE_EVENT_LANE(event);
> +	u16 ras_des = pcie_pmu->ras_des;
> +	u32 ctrl;
> +
> +	/* Only one counter and it is in use */
> +	if (pcie_pmu->event)
> +		return -ENOSPC;
> +
> +	pcie_pmu->event = event;
> +	hwc->state = PERF_HES_STOPPED | PERF_HES_UPTODATE;
> +
> +	if (type == DWC_PCIE_LANE_EVENT) {
> +		/* EVENT_COUNTER_DATA_REG needs clear manually */
> +		ctrl = FIELD_PREP(DWC_PCIE_CNT_EVENT_SEL, event_id) |
> +			FIELD_PREP(DWC_PCIE_CNT_LANE_SEL, lane) |
> +			FIELD_PREP(DWC_PCIE_CNT_ENABLE, DWC_PCIE_PER_EVENT_OFF) |
> +			FIELD_PREP(DWC_PCIE_EVENT_CLEAR, DWC_PCIE_EVENT_PER_CLEAR);
> +		pci_write_config_dword(pdev, ras_des + DWC_PCIE_EVENT_CNT_CTL,
> +				       ctrl);
> +	} else if (type == DWC_PCIE_TIME_BASE_EVENT) {
> +		/*
> +		 * TIME_BASED_ANAL_DATA_REG is a 64 bit register, we can safely
> +		 * use it with any manually controlled duration. And it is
> +		 * cleared when next measurement starts.
> +		 */
> +		ctrl = FIELD_PREP(DWC_PCIE_TIME_BASED_REPORT_SEL, event_id) |
> +			FIELD_PREP(DWC_PCIE_TIME_BASED_DURATION_SEL,
> +				   DWC_PCIE_DURATION_MANUAL_CTL) |
> +			DWC_PCIE_TIME_BASED_CNT_ENABLE;
> +		pci_write_config_dword(
> +			pdev, ras_des + DWC_PCIE_TIME_BASED_ANAL_CTL, ctrl);
> +	}
> +
> +	if (flags & PERF_EF_START)
> +		dwc_pcie_pmu_event_start(event, PERF_EF_RELOAD);
> +
> +	perf_event_update_userpage(event);
> +
> +	return 0;
> +}
> +
> +static void dwc_pcie_pmu_event_del(struct perf_event *event, int flags)
> +{
> +	struct dwc_pcie_pmu *pcie_pmu = to_dwc_pcie_pmu(event->pmu);
> +
> +	dwc_pcie_pmu_event_stop(event, flags | PERF_EF_UPDATE);
> +	perf_event_update_userpage(event);
> +	pcie_pmu->event = NULL;
> +}
> +
> +static int __dwc_pcie_pmu_probe(struct dwc_pcie_pmu_priv *priv)
> +{
> +	struct pci_dev *pdev = NULL;
> +	struct dwc_pcie_pmu *pcie_pmu;
> +	char *name;
> +	u32 bdf;
> +	int ret;
> +
> +	INIT_LIST_HEAD(&priv->pmu_nodes);
> +
> +	/* Match the rootport with VSEC_RAS_DES_ID, and register a PMU for it */
> +	for_each_pci_dev(pdev) {
> +		u16 vsec;
> +		u32 val;
> +
> +		if (!(pci_is_pcie(pdev) &&
> +		      pci_pcie_type(pdev) == PCI_EXP_TYPE_ROOT_PORT))
> +			continue;
> +
> +		vsec = pci_find_vsec_capability(pdev, PCI_VENDOR_ID_ALIBABA,
> +						DWC_PCIE_VSEC_RAS_DES_ID);
> +		if (!vsec)
> +			continue;
> +
> +		pci_read_config_dword(pdev, vsec + PCI_VNDR_HEADER, &val);
> +		if (PCI_VNDR_HEADER_REV(val) != 0x04 ||
> +		    PCI_VNDR_HEADER_LEN(val) != 0x100)
> +			continue;
> +		pci_dbg(pdev,
> +			"Detected PCIe Vendor-Specific Extended Capability RAS DES\n");
> +
> +		bdf = PCI_DEVID(pdev->bus->number, pdev->devfn);
> +		name = devm_kasprintf(priv->dev, GFP_KERNEL, "dwc_rootport_%x",
> +				      bdf);
> +		if (!name)
> +			return -ENOMEM;
> +
> +		/* All checks passed, go go go */
> +		pcie_pmu = devm_kzalloc(&pdev->dev, sizeof(*pcie_pmu), GFP_KERNEL);
> +		if (!pcie_pmu) {
> +			pci_dev_put(pdev);

we need to call pci_dev_put on all the return branch below and above and after the for_each_pci_dev()
loop to keep the refcnt balance.

> +			return -ENOMEM;
> +		}
> +
> +		pcie_pmu->pdev = pdev;
> +		pcie_pmu->ras_des = vsec;
> +		pcie_pmu->nr_lanes = pcie_get_width_cap(pdev);
> +		pcie_pmu->pmu = (struct pmu){
> +			.module		= THIS_MODULE,
> +			.attr_groups	= dwc_pcie_attr_groups,
> +			.capabilities	= PERF_PMU_CAP_NO_EXCLUDE,
> +			.task_ctx_nr	= perf_invalid_context,
> +			.event_init	= dwc_pcie_pmu_event_init,
> +			.add		= dwc_pcie_pmu_event_add,
> +			.del		= dwc_pcie_pmu_event_del,
> +			.start		= dwc_pcie_pmu_event_start,
> +			.stop		= dwc_pcie_pmu_event_stop,
> +			.read		= dwc_pcie_pmu_event_update,
> +		};
> +
> +		/* Add this instance to the list used by the offline callback */
> +		ret = cpuhp_state_add_instance(dwc_pcie_pmu_hp_state,
> +					       &pcie_pmu->cpuhp_node);
> +		if (ret) {
> +			pci_err(pcie_pmu->pdev,
> +				"Error %d registering hotplug @%x\n", ret, bdf);
> +			return ret;
> +		}
> +		ret = perf_pmu_register(&pcie_pmu->pmu, name, -1);
> +		if (ret) {
> +			pci_err(pcie_pmu->pdev,
> +				"Error %d registering PMU @%x\n", ret, bdf);
> +			cpuhp_state_remove_instance_nocalls(
> +				dwc_pcie_pmu_hp_state, &pcie_pmu->cpuhp_node);
> +			return ret;
> +		}
> +
> +		/* Add registered PMUs and unregister them when this driver remove */
> +		list_add(&pcie_pmu->pmu_node, &priv->pmu_nodes);
> +	}
> +
> +	return 0;
> +}
> +
> +static int dwc_pcie_pmu_remove(struct platform_device *pdev)
> +{
> +	struct dwc_pcie_pmu_priv *priv = platform_get_drvdata(pdev);
> +	struct dwc_pcie_pmu *pcie_pmu;
> +
> +	list_for_each_entry(pcie_pmu, &priv->pmu_nodes, pmu_node) {
> +		cpuhp_state_remove_instance(dwc_pcie_pmu_hp_state,
> +					    &pcie_pmu->cpuhp_node);
> +		perf_pmu_unregister(&pcie_pmu->pmu);

should unregister the PMU first, keep the order reverse to __dwc_pcie_pmu_probe().

> +	}
> +
> +	return 0;
> +}
> +
> +static int dwc_pcie_pmu_probe(struct platform_device *pdev)
> +{
> +	struct dwc_pcie_pmu_priv *priv;
> +	int ret;
> +
> +	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	priv->dev = &pdev->dev;
> +	platform_set_drvdata(pdev, priv);
> +
> +	/* If one PMU registration fails, remove all. */
> +	ret = __dwc_pcie_pmu_probe(priv);
> +	if (ret) {
> +		dwc_pcie_pmu_remove(pdev);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static void dwc_pcie_pmu_migrate(struct dwc_pcie_pmu *pcie_pmu, unsigned int cpu)
> +{
> +	/* This PMU does NOT support interrupt, just migrate context. */
> +	perf_pmu_migrate_context(&pcie_pmu->pmu, pcie_pmu->oncpu, cpu);
> +	pcie_pmu->oncpu = cpu;
> +}
> +
> +static int dwc_pcie_pmu_online_cpu(unsigned int cpu, struct hlist_node *cpuhp_node)
> +{
> +	struct dwc_pcie_pmu *pcie_pmu;
> +	struct pci_dev *pdev;
> +	int node;
> +
> +	pcie_pmu = hlist_entry_safe(cpuhp_node, struct dwc_pcie_pmu, cpuhp_node);
> +	pdev = pcie_pmu->pdev;
> +	node = dev_to_node(&pdev->dev);
> +
> +	if (node != NUMA_NO_NODE && cpu_to_node(pcie_pmu->oncpu) != node &&
> +	    cpu_to_node(cpu) == node)
> +		dwc_pcie_pmu_migrate(pcie_pmu, cpu);
> +
> +	return 0;
> +}
> +
> +static int dwc_pcie_pmu_offline_cpu(unsigned int cpu, struct hlist_node *cpuhp_node)
> +{
> +	struct dwc_pcie_pmu *pcie_pmu;
> +	struct pci_dev *pdev;
> +	int node;
> +	cpumask_t mask;
> +	unsigned int target;
> +
> +	pcie_pmu = hlist_entry_safe(cpuhp_node, struct dwc_pcie_pmu, cpuhp_node);
> +	if (cpu != pcie_pmu->oncpu)
> +		return 0;
> +
> +	pdev = pcie_pmu->pdev;
> +	node = dev_to_node(&pdev->dev);
> +	if (cpumask_and(&mask, cpumask_of_node(node), cpu_online_mask) &&
> +	    cpumask_andnot(&mask, &mask, cpumask_of(cpu)))
> +		target = cpumask_any(&mask);

The cpumask_of_node() only contains the online CPUs so this branch is redundant. For arm64
using arch_numa.c the node cpumask is updated in numa_{add, remove}_cpu() and for other
arthitecture the behaviour should keep consistenct. Please correct my if I'm wrong.

> +	else
> +		target = cpumask_any_but(cpu_online_mask, cpu);
> +	if (target < nr_cpu_ids)
> +		dwc_pcie_pmu_migrate(pcie_pmu, target);
> +
> +	return 0;
> +}
> +
> +static struct platform_driver dwc_pcie_pmu_driver = {
> +	.probe = dwc_pcie_pmu_probe,
> +	.remove = dwc_pcie_pmu_remove,
> +	.driver = {.name = "dwc_pcie_pmu",},
> +};
> +
> +static int __init dwc_pcie_pmu_init(void)
> +{
> +	int ret;
> +
> +	ret = cpuhp_setup_state_multi(CPUHP_AP_ONLINE_DYN,
> +				      "perf/dwc_pcie_pmu:online",
> +				      dwc_pcie_pmu_online_cpu,
> +				      dwc_pcie_pmu_offline_cpu);
> +	if (ret < 0)
> +		return ret;
> +
> +	dwc_pcie_pmu_hp_state = ret;
> +
> +	ret = platform_driver_register(&dwc_pcie_pmu_driver);
> +	if (ret) {
> +		cpuhp_remove_multi_state(dwc_pcie_pmu_hp_state);
> +		return ret;
> +	}
> +
> +	dwc_pcie_pmu_dev = platform_device_register_simple(
> +				"dwc_pcie_pmu", PLATFORM_DEVID_NONE, NULL, 0);
> +	if (IS_ERR(dwc_pcie_pmu_dev)) {
> +		platform_driver_unregister(&dwc_pcie_pmu_driver);

On failure we also need to remove cpuhp state as well.

Thanks,
Yicong

> +		return PTR_ERR(dwc_pcie_pmu_dev);
> +	}
> +
> +	return 0;
> +}
> +
> +static void __exit dwc_pcie_pmu_exit(void)
> +{
> +	platform_device_unregister(dwc_pcie_pmu_dev);
> +	platform_driver_unregister(&dwc_pcie_pmu_driver);
> +	cpuhp_remove_multi_state(dwc_pcie_pmu_hp_state);
> +}
> +
> +module_init(dwc_pcie_pmu_init);
> +module_exit(dwc_pcie_pmu_exit);
> +
> +MODULE_DESCRIPTION("PMU driver for DesignWare Cores PCI Express Controller");
> +MODULE_AUTHOR("Shuai xue <xueshuai@linux.alibaba.com>");
> +MODULE_AUTHOR("Wen Cheng <yinxuan_cw@linux.alibaba.com>");
> +MODULE_LICENSE("GPL v2");
>

On Tue, 6 Jun 2023 23:14:07 +0800
Yicong Yang <yangyicong@huawei.com> wrote:

> On 2023/6/6 15:49, Shuai Xue wrote:
> > This commit adds the PCIe Performance Monitoring Unit (PMU) driver support
> > for T-Head Yitian SoC chip. Yitian is based on the Synopsys PCI Express
> > Core controller IP which provides statistics feature. The PMU is not a PCIe
> > Root Complex integrated End Point(RCiEP) device but only register counters
> > provided by each PCIe Root Port.
> > 
> > To facilitate collection of statistics the controller provides the
> > following two features for each Root Port:
> > 
> > - Time Based Analysis (RX/TX data throughput and time spent in each
> >   low-power LTSSM state)
> > - Event counters (Error and Non-Error for lanes)
> > 
> > Note, only one counter for each type and does not overflow interrupt.
> > 
> > This driver adds PMU devices for each PCIe Root Port. And the PMU device is
> > named based the BDF of Root Port. For example,
> > 
> >     30:03.0 PCI bridge: Device 1ded:8000 (rev 01)
> > 
> > the PMU device name for this Root Port is dwc_rootport_3018.
> > 
> > Example usage of counting PCIe RX TLP data payload (Units of 16 bytes)::
> > 
> >     $# perf stat -a -e dwc_rootport_3018/Rx_PCIe_TLP_Data_Payload/
> > 
> > average RX bandwidth can be calculated like this:
> > 
> >     PCIe TX Bandwidth = PCIE_TX_DATA * 16B / Measure_Time_Window
> > 
> > Signed-off-by: Shuai Xue <xueshuai@linux.alibaba.com>
> > Reported-by: kernel test robot <lkp@intel.com>
> > Link: https://lore.kernel.org/oe-kbuild-all/202305170639.XU3djFZX-lkp@intel.com/
> > Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>

I'll review on top to avoid any duplication with Yicong.

Note I've cropped the stuff neither of us commented on so it's
easier to spot the feedback.

Jonathan

> > ---
> >  drivers/perf/Kconfig        |   7 +
> >  drivers/perf/Makefile       |   1 +
> >  drivers/perf/dwc_pcie_pmu.c | 706 ++++++++++++++++++++++++++++++++++++
> >  3 files changed, 714 insertions(+)
> >  create mode 100644 drivers/perf/dwc_pcie_pmu.c
> > 
> > diff --git a/drivers/perf/Kconfig b/drivers/perf/Kconfig
> > index 711f82400086..6ff3921d7a62 100644
> > --- a/drivers/perf/Kconfig
> > +++ b/drivers/perf/Kconfig
> > @@ -209,6 +209,13 @@ config MARVELL_CN10K_DDR_PMU
> >  	  Enable perf support for Marvell DDR Performance monitoring
> >  	  event on CN10K platform.
> >  
> > +config DWC_PCIE_PMU
> > +	tristate "Enable Synopsys DesignWare PCIe PMU Support"
> > +	depends on (ARM64 && PCI)
> > +	help
> > +	  Enable perf support for Synopsys DesignWare PCIe PMU Performance
> > +	  monitoring event on Yitian 710 platform.

The documentation kind of implies this isn't platform specific.
If some parts are (such as which events exist) then you may want to push
that to userspace / perftool with appropriate matching against specific SoC.

If it is generic, then change this text to "event on platform including the Yitian 710."

> > +
> >  source "drivers/perf/arm_cspmu/Kconfig"
> >  
> >  source "drivers/perf/amlogic/Kconfig"

> > new file mode 100644
> > index 000000000000..8bfcf6e0662d
> > --- /dev/null
> > +++ b/drivers/perf/dwc_pcie_pmu.c
> > @@ -0,0 +1,706 @@

...

> > +
> > +struct dwc_pcie_pmu {
> > +	struct pci_dev		*pdev;		/* Root Port device */  
> 
> If the root port removed after the probe of this PCIe PMU driver, we'll access the NULL
> pointer. I didn't see you hold the root port to avoid the removal.
> 
> > +	u16			ras_des;	/* RAS DES capability offset */
> > +	u32			nr_lanes;
> > +
> > +	struct list_head	pmu_node;
> > +	struct hlist_node	cpuhp_node;
> > +	struct pmu		pmu;
> > +	struct perf_event	*event;
> > +	int			oncpu;
> > +};
> > +
> > +struct dwc_pcie_pmu_priv {
> > +	struct device *dev;
> > +	struct list_head pmu_nodes;
> > +};
> > +
> > +#define to_dwc_pcie_pmu(p) (container_of(p, struct dwc_pcie_pmu, pmu))
> > +  
> 
> somebody told me to put @pmu as the first member then this macro will have no calculation. :)
> 

...

> > +static ssize_t dwc_pcie_event_show(struct device *dev,
> > +				struct device_attribute *attr, char *buf)
> > +{
> > +	struct dwc_pcie_event_attr *eattr;
> > +
> > +	eattr = container_of(attr, typeof(*eattr), attr);
> > +
> > +	if (eattr->type == DWC_PCIE_LANE_EVENT)
> > +		return sysfs_emit(buf, "eventid=0x%x,type=0x%x,lane=?\n",
> > +				  eattr->eventid, eattr->type);
> > +

Elsewhere you always check for DWC_PCIE_TIME_BASE_EVENT.
Should probably do so here as well for consistency.

> > +	return sysfs_emit(buf, "eventid=0x%x,type=0x%x\n", eattr->eventid,
> > +		       eattr->type);
> > +}

> > +static struct attribute *dwc_pcie_pmu_time_event_attrs[] = {
> > +	/* Group #0 */
> > +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(one_cycle, 0x00),
> > +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(TX_L0S, 0x01),
> > +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(RX_L0S, 0x02),
> > +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(L0, 0x03),
> > +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(L1, 0x04),
> > +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(L1_1, 0x05),
> > +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(L1_2, 0x06),
> > +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(CFG_RCVRY, 0x07),
> > +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(TX_RX_L0S, 0x08),
> > +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(L1_AUX, 0x09),
> > +
> > +	/* Group #1 */
> > +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(Tx_PCIe_TLP_Data_Payload, 0x20),
> > +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(Rx_PCIe_TLP_Data_Payload, 0x21),
> > +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(Tx_CCIX_TLP_Data_Payload, 0x22),
> > +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(Rx_CCIX_TLP_Data_Payload, 0x23),
> > +
> > +	/*
> > +	 * Leave it to the user to specify the lane ID to avoid generating
> > +	 * a list of hundreds of events.
> > +	 */
> > +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_ack_dllp, 0x600),
> > +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_update_fc_dllp, 0x601),
> > +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_ack_dllp, 0x602),
> > +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_update_fc_dllp, 0x603),
> > +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_nulified_tlp, 0x604),
> > +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_nulified_tlp, 0x605),
> > +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_duplicate_tl, 0x606),
> > +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_memory_write, 0x700),
> > +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_memory_read, 0x701),
> > +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_configuration_write, 0x702),
> > +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_configuration_read, 0x703),
> > +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_io_write, 0x704),
> > +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_io_read, 0x705),
> > +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_completion_without_data, 0x706),
> > +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_completion_with_data, 0x707),
> > +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_message_tlp, 0x708),
> > +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_atomic, 0x709),
> > +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_tlp_with_prefix, 0x70A),
> > +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_memory_write, 0x70B),
> > +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_memory_read, 0x70C),
> > +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_io_write, 0x70F),
> > +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_io_read, 0x710),
> > +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_completion_without_data, 0x711),
> > +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_completion_with_data, 0x712),
> > +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_message_tlp, 0x713),
> > +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_atomic, 0x714),
> > +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_tlp_with_prefix, 0x715),
> > +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_ccix_tlp, 0x716),
> > +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_ccix_tlp, 0x717),
> > +  
> 
> Intended blank line?
> 
> > +	NULL
> > +};


...

> > +static u64 dwc_pcie_pmu_read_time_based_counter(struct dwc_pcie_pmu *pcie_pmu)
> > +{
> > +	struct pci_dev *pdev = pcie_pmu->pdev;
> > +	u16 ras_des = pcie_pmu->ras_des;
> > +	u64 count;
> > +	u32 val;
> > +
> > +	pci_read_config_dword(
> > +		pdev, ras_des + DWC_PCIE_TIME_BASED_ANAL_DATA_REG_HIGH, &val);
> > +	count = val;
> > +	count <<= 32;
> > +
> > +	pci_read_config_dword(
> > +		pdev, ras_des + DWC_PCIE_TIME_BASED_ANAL_DATA_REG_LOW, &val);

This looks like tearing can occur.  you probably need to protect against that
(usual trick is re read the _HIGH part and if it changed, try again)

The hardware might prevent tearing (it would freeze the low register when you
read the high one, then only let it change after a read of the low registers is
done).  If that's the case - add a comment to say so.

> > +
> > +	count += val;
> > +
> > +	return count;
> > +}
> > +


...
> > +static int dwc_pcie_pmu_event_add(struct perf_event *event, int flags)
> > +{
> > +	struct dwc_pcie_pmu *pcie_pmu = to_dwc_pcie_pmu(event->pmu);
> > +	struct pci_dev *pdev = pcie_pmu->pdev;
> > +	struct hw_perf_event *hwc = &event->hw;
> > +	enum dwc_pcie_event_type type = DWC_PCIE_EVENT_TYPE(event);
> > +	int event_id = DWC_PCIE_EVENT_ID(event);
> > +	int lane = DWC_PCIE_EVENT_LANE(event);
> > +	u16 ras_des = pcie_pmu->ras_des;
> > +	u32 ctrl;
> > +
> > +	/* Only one counter and it is in use */

Yikes. That's quite a restriction.  Probably good to mention in the docs.
I'm a little confused about the architecture though - there seem to be separate
registers for the Lane and time based events.  Can't count those at same time?

> > +	if (pcie_pmu->event)
> > +		return -ENOSPC;
> > +
> > +	pcie_pmu->event = event;
> > +	hwc->state = PERF_HES_STOPPED | PERF_HES_UPTODATE;
> > +
> > +	if (type == DWC_PCIE_LANE_EVENT) {
> > +		/* EVENT_COUNTER_DATA_REG needs clear manually */
> > +		ctrl = FIELD_PREP(DWC_PCIE_CNT_EVENT_SEL, event_id) |
> > +			FIELD_PREP(DWC_PCIE_CNT_LANE_SEL, lane) |
> > +			FIELD_PREP(DWC_PCIE_CNT_ENABLE, DWC_PCIE_PER_EVENT_OFF) |
> > +			FIELD_PREP(DWC_PCIE_EVENT_CLEAR, DWC_PCIE_EVENT_PER_CLEAR);
> > +		pci_write_config_dword(pdev, ras_des + DWC_PCIE_EVENT_CNT_CTL,
> > +				       ctrl);
> > +	} else if (type == DWC_PCIE_TIME_BASE_EVENT) {
> > +		/*
> > +		 * TIME_BASED_ANAL_DATA_REG is a 64 bit register, we can safely
> > +		 * use it with any manually controlled duration. And it is
> > +		 * cleared when next measurement starts.
> > +		 */
> > +		ctrl = FIELD_PREP(DWC_PCIE_TIME_BASED_REPORT_SEL, event_id) |
> > +			FIELD_PREP(DWC_PCIE_TIME_BASED_DURATION_SEL,
> > +				   DWC_PCIE_DURATION_MANUAL_CTL) |
> > +			DWC_PCIE_TIME_BASED_CNT_ENABLE;
> > +		pci_write_config_dword(
> > +			pdev, ras_des + DWC_PCIE_TIME_BASED_ANAL_CTL, ctrl);
> > +	}
> > +
> > +	if (flags & PERF_EF_START)
> > +		dwc_pcie_pmu_event_start(event, PERF_EF_RELOAD);
> > +
> > +	perf_event_update_userpage(event);
> > +
> > +	return 0;
> > +}
...

> > +static int __dwc_pcie_pmu_probe(struct dwc_pcie_pmu_priv *priv)
> > +{
> > +	struct pci_dev *pdev = NULL;
> > +	struct dwc_pcie_pmu *pcie_pmu;
> > +	char *name;
> > +	u32 bdf;
> > +	int ret;
> > +
> > +	INIT_LIST_HEAD(&priv->pmu_nodes);
> > +
> > +	/* Match the rootport with VSEC_RAS_DES_ID, and register a PMU for it */
> > +	for_each_pci_dev(pdev) {
> > +		u16 vsec;
> > +		u32 val;
> > +
> > +		if (!(pci_is_pcie(pdev) &&
> > +		      pci_pcie_type(pdev) == PCI_EXP_TYPE_ROOT_PORT))
> > +			continue;
> > +
> > +		vsec = pci_find_vsec_capability(pdev, PCI_VENDOR_ID_ALIBABA,
> > +						DWC_PCIE_VSEC_RAS_DES_ID);
> > +		if (!vsec)
> > +			continue;
> > +
> > +		pci_read_config_dword(pdev, vsec + PCI_VNDR_HEADER, &val);
> > +		if (PCI_VNDR_HEADER_REV(val) != 0x04 ||
> > +		    PCI_VNDR_HEADER_LEN(val) != 0x100)
> > +			continue;
> > +		pci_dbg(pdev,
> > +			"Detected PCIe Vendor-Specific Extended Capability RAS DES\n");
> > +
> > +		bdf = PCI_DEVID(pdev->bus->number, pdev->devfn);
> > +		name = devm_kasprintf(priv->dev, GFP_KERNEL, "dwc_rootport_%x",
> > +				      bdf);
> > +		if (!name)
> > +			return -ENOMEM;
> > +
> > +		/* All checks passed, go go go */
> > +		pcie_pmu = devm_kzalloc(&pdev->dev, sizeof(*pcie_pmu), GFP_KERNEL);
> > +		if (!pcie_pmu) {
> > +			pci_dev_put(pdev);  
> 
> we need to call pci_dev_put on all the return branch below and above and after the for_each_pci_dev()
> loop to keep the refcnt balance.

Good spot. I'd use a goto for this given there are lots of places.

> 
> > +			return -ENOMEM;
> > +		}
> > +
> > +		pcie_pmu->pdev = pdev;
> > +		pcie_pmu->ras_des = vsec;
> > +		pcie_pmu->nr_lanes = pcie_get_width_cap(pdev);
> > +		pcie_pmu->pmu = (struct pmu){
> > +			.module		= THIS_MODULE,
> > +			.attr_groups	= dwc_pcie_attr_groups,
> > +			.capabilities	= PERF_PMU_CAP_NO_EXCLUDE,
> > +			.task_ctx_nr	= perf_invalid_context,
> > +			.event_init	= dwc_pcie_pmu_event_init,
> > +			.add		= dwc_pcie_pmu_event_add,
> > +			.del		= dwc_pcie_pmu_event_del,
> > +			.start		= dwc_pcie_pmu_event_start,
> > +			.stop		= dwc_pcie_pmu_event_stop,
> > +			.read		= dwc_pcie_pmu_event_update,
> > +		};
> > +
> > +		/* Add this instance to the list used by the offline callback */
> > +		ret = cpuhp_state_add_instance(dwc_pcie_pmu_hp_state,
> > +					       &pcie_pmu->cpuhp_node);
> > +		if (ret) {
> > +			pci_err(pcie_pmu->pdev,
> > +				"Error %d registering hotplug @%x\n", ret, bdf);
> > +			return ret;
> > +		}

Here you mix non devm_ handling in mid way through a series of devm_ calls.
Whilst I 'think' what you have here is fine, I prefer to minimize thinking
whilst reviewing and using devm_add_action_or_reset() with callbacks
in appropriate places would ensure automatic unwinding in the error
path deals with everything in the reverse order of setup.

You just need two instances - one to unwind the cpuhp_state_add_instance() and
one to unwind the perf_pmu_register()
 
> > +		ret = perf_pmu_register(&pcie_pmu->pmu, name, -1);
> > +		if (ret) {
> > +			pci_err(pcie_pmu->pdev,
> > +				"Error %d registering PMU @%x\n", ret, bdf);
> > +			cpuhp_state_remove_instance_nocalls(
> > +				dwc_pcie_pmu_hp_state, &pcie_pmu->cpuhp_node);
> > +			return ret;
> > +		}
> > +
> > +		/* Add registered PMUs and unregister them when this driver remove */
> > +		list_add(&pcie_pmu->pmu_node, &priv->pmu_nodes);

This handling would be replaced by the tracking devm is doing for us. So I think
there will be no need for the list.


> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +static int dwc_pcie_pmu_remove(struct platform_device *pdev)
> > +{
> > +	struct dwc_pcie_pmu_priv *priv = platform_get_drvdata(pdev);
> > +	struct dwc_pcie_pmu *pcie_pmu;
> > +
> > +	list_for_each_entry(pcie_pmu, &priv->pmu_nodes, pmu_node) {
> > +		cpuhp_state_remove_instance(dwc_pcie_pmu_hp_state,
> > +					    &pcie_pmu->cpuhp_node);
> > +		perf_pmu_unregister(&pcie_pmu->pmu);  
> 
> should unregister the PMU first, keep the order reverse to __dwc_pcie_pmu_probe().
These two could have been handled via appropriate devm_add_action_or_reset()
above and let that infrastructure unwind for us in the error path.

If anyone fixes the whole pmu drivers aren't removable mess, then we will
also end up with remove handling for free :)

> 
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +static int dwc_pcie_pmu_probe(struct platform_device *pdev)
> > +{
> > +	struct dwc_pcie_pmu_priv *priv;
> > +	int ret;
> > +
> > +	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
> > +	if (!priv)
> > +		return -ENOMEM;
> > +
> > +	priv->dev = &pdev->dev;
> > +	platform_set_drvdata(pdev, priv);
> > +
> > +	/* If one PMU registration fails, remove all. */
> > +	ret = __dwc_pcie_pmu_probe(priv);
> > +	if (ret) {
> > +		dwc_pcie_pmu_remove(pdev);

There is a bit of mixing of devm and not here which makes things somewhat
hard to reason about.  Perhaps take the whole unwind flow over to devm managed.
See above.

> > +		return ret;
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +static void dwc_pcie_pmu_migrate(struct dwc_pcie_pmu *pcie_pmu, unsigned int cpu)
> > +{
> > +	/* This PMU does NOT support interrupt, just migrate context. */
> > +	perf_pmu_migrate_context(&pcie_pmu->pmu, pcie_pmu->oncpu, cpu);
> > +	pcie_pmu->oncpu = cpu;
> > +}
> > +
> > +static int dwc_pcie_pmu_online_cpu(unsigned int cpu, struct hlist_node *cpuhp_node)
> > +{
> > +	struct dwc_pcie_pmu *pcie_pmu;
> > +	struct pci_dev *pdev;
> > +	int node;
> > +
> > +	pcie_pmu = hlist_entry_safe(cpuhp_node, struct dwc_pcie_pmu, cpuhp_node);
> > +	pdev = pcie_pmu->pdev;
> > +	node = dev_to_node(&pdev->dev);
> > +
> > +	if (node != NUMA_NO_NODE && cpu_to_node(pcie_pmu->oncpu) != node &&

Perhaps worth a comment on when you might see node == NUMA_NO_NODE?
Beyond NUMA being entirely disabled, I'd hope that never happens and for that you
might be able to use a compile time check.

I wonder if this can be simplified by a flag that says if we are already in the
right node? Might be easier to follow than having similar dance in online and offline
to figure that out.


> > +	    cpu_to_node(cpu) == node)
> > +		dwc_pcie_pmu_migrate(pcie_pmu, cpu);
> > +
> > +	return 0;
> > +}
> > +
> > +static int dwc_pcie_pmu_offline_cpu(unsigned int cpu, struct hlist_node *cpuhp_node)
> > +{
> > +	struct dwc_pcie_pmu *pcie_pmu;
> > +	struct pci_dev *pdev;
> > +	int node;
> > +	cpumask_t mask;
> > +	unsigned int target;
> > +
> > +	pcie_pmu = hlist_entry_safe(cpuhp_node, struct dwc_pcie_pmu, cpuhp_node);
> > +	if (cpu != pcie_pmu->oncpu)
> > +		return 0;
> > +
> > +	pdev = pcie_pmu->pdev;
> > +	node = dev_to_node(&pdev->dev);
> > +	if (cpumask_and(&mask, cpumask_of_node(node), cpu_online_mask) &&
> > +	    cpumask_andnot(&mask, &mask, cpumask_of(cpu)))
> > +		target = cpumask_any(&mask);  
> 
> The cpumask_of_node() only contains the online CPUs so this branch is redundant. For arm64
> using arch_numa.c the node cpumask is updated in numa_{add, remove}_cpu() and for other
> arthitecture the behaviour should keep consistenct. Please correct my if I'm wrong.
> 
> > +	else
> > +		target = cpumask_any_but(cpu_online_mask, cpu);

If following above suggestion, would set flag to say in wrong node here - and wherever
you end up in a node to start with...


> > +	if (target < nr_cpu_ids)
> > +		dwc_pcie_pmu_migrate(pcie_pmu, target);
> > +
> > +	return 0;
> > +}
> > +
> > +static struct platform_driver dwc_pcie_pmu_driver = {
> > +	.probe = dwc_pcie_pmu_probe,
> > +	.remove = dwc_pcie_pmu_remove,
> > +	.driver = {.name = "dwc_pcie_pmu",},
> > +};
> > +
> > +static int __init dwc_pcie_pmu_init(void)
> > +{
> > +	int ret;
> > +
> > +	ret = cpuhp_setup_state_multi(CPUHP_AP_ONLINE_DYN,
> > +				      "perf/dwc_pcie_pmu:online",
> > +				      dwc_pcie_pmu_online_cpu,
> > +				      dwc_pcie_pmu_offline_cpu);
> > +	if (ret < 0)
> > +		return ret;
> > +
> > +	dwc_pcie_pmu_hp_state = ret;
> > +
> > +	ret = platform_driver_register(&dwc_pcie_pmu_driver);
> > +	if (ret) {
> > +		cpuhp_remove_multi_state(dwc_pcie_pmu_hp_state);
> > +		return ret;
> > +	}
> > +
> > +	dwc_pcie_pmu_dev = platform_device_register_simple(
> > +				"dwc_pcie_pmu", PLATFORM_DEVID_NONE, NULL, 0);
> > +	if (IS_ERR(dwc_pcie_pmu_dev)) {
> > +		platform_driver_unregister(&dwc_pcie_pmu_driver);  
> 
> On failure we also need to remove cpuhp state as well.

I'd suggest using gotos and a single error handling block. That
makes it both harder to forget things like this and easier to
compare that block with what happens in exit() - so slightly 
easier to review!

> 
> Thanks,
> Yicong
> 
> > +		return PTR_ERR(dwc_pcie_pmu_dev);
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +static void __exit dwc_pcie_pmu_exit(void)
> > +{
> > +	platform_device_unregister(dwc_pcie_pmu_dev);
> > +	platform_driver_unregister(&dwc_pcie_pmu_driver);
> > +	cpuhp_remove_multi_state(dwc_pcie_pmu_hp_state);
> > +}
> > +
> > +module_init(dwc_pcie_pmu_init);
> > +module_exit(dwc_pcie_pmu_exit);
> > +
> > +MODULE_DESCRIPTION("PMU driver for DesignWare Cores PCI Express Controller");
> > +MODULE_AUTHOR("Shuai xue <xueshuai@linux.alibaba.com>");
> > +MODULE_AUTHOR("Wen Cheng <yinxuan_cw@linux.alibaba.com>");
> > +MODULE_LICENSE("GPL v2");
> >

On 2023/6/6 23:14, Yicong Yang wrote:

Hi, Yicong,

Thank you for your valuable comments, and I apologize for missing your previous
message. It appears that Thunderbird had mistakenly placed your email in the
junk folder, causing me to overlook it.

Jonathan's reply served as a reminder, prompting me to realize that I had missed
some emails. Since Jonathan's reply is on top of yours, I will give my feedback
on both of your messages in his thread.

Thank you.

Best Regards,
Shuai


> On 2023/6/6 15:49, Shuai Xue wrote:
>> This commit adds the PCIe Performance Monitoring Unit (PMU) driver support
>> for T-Head Yitian SoC chip. Yitian is based on the Synopsys PCI Express
>> Core controller IP which provides statistics feature. The PMU is not a PCIe
>> Root Complex integrated End Point(RCiEP) device but only register counters
>> provided by each PCIe Root Port.
>>
>> To facilitate collection of statistics the controller provides the
>> following two features for each Root Port:
>>
>> - Time Based Analysis (RX/TX data throughput and time spent in each
>>   low-power LTSSM state)
>> - Event counters (Error and Non-Error for lanes)
>>
>> Note, only one counter for each type and does not overflow interrupt.
>>
>> This driver adds PMU devices for each PCIe Root Port. And the PMU device is
>> named based the BDF of Root Port. For example,
>>
>>     30:03.0 PCI bridge: Device 1ded:8000 (rev 01)
>>
>> the PMU device name for this Root Port is dwc_rootport_3018.
>>
>> Example usage of counting PCIe RX TLP data payload (Units of 16 bytes)::
>>
>>     $# perf stat -a -e dwc_rootport_3018/Rx_PCIe_TLP_Data_Payload/
>>
>> average RX bandwidth can be calculated like this:
>>
>>     PCIe TX Bandwidth = PCIE_TX_DATA * 16B / Measure_Time_Window
>>
>> Signed-off-by: Shuai Xue <xueshuai@linux.alibaba.com>
>> Reported-by: kernel test robot <lkp@intel.com>
>> Link: https://lore.kernel.org/oe-kbuild-all/202305170639.XU3djFZX-lkp@intel.com/
>> Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
>> ---
>>  drivers/perf/Kconfig        |   7 +
>>  drivers/perf/Makefile       |   1 +
>>  drivers/perf/dwc_pcie_pmu.c | 706 ++++++++++++++++++++++++++++++++++++
>>  3 files changed, 714 insertions(+)
>>  create mode 100644 drivers/perf/dwc_pcie_pmu.c
>>
>> diff --git a/drivers/perf/Kconfig b/drivers/perf/Kconfig
>> index 711f82400086..6ff3921d7a62 100644
>> --- a/drivers/perf/Kconfig
>> +++ b/drivers/perf/Kconfig
>> @@ -209,6 +209,13 @@ config MARVELL_CN10K_DDR_PMU
>>  	  Enable perf support for Marvell DDR Performance monitoring
>>  	  event on CN10K platform.
>>  
>> +config DWC_PCIE_PMU
>> +	tristate "Enable Synopsys DesignWare PCIe PMU Support"
>> +	depends on (ARM64 && PCI)
>> +	help
>> +	  Enable perf support for Synopsys DesignWare PCIe PMU Performance
>> +	  monitoring event on Yitian 710 platform.
>> +
>>  source "drivers/perf/arm_cspmu/Kconfig"
>>  
>>  source "drivers/perf/amlogic/Kconfig"
>> diff --git a/drivers/perf/Makefile b/drivers/perf/Makefile
>> index dabc859540ce..13a6d1b286da 100644
>> --- a/drivers/perf/Makefile
>> +++ b/drivers/perf/Makefile
>> @@ -22,5 +22,6 @@ obj-$(CONFIG_MARVELL_CN10K_TAD_PMU) += marvell_cn10k_tad_pmu.o
>>  obj-$(CONFIG_MARVELL_CN10K_DDR_PMU) += marvell_cn10k_ddr_pmu.o
>>  obj-$(CONFIG_APPLE_M1_CPU_PMU) += apple_m1_cpu_pmu.o
>>  obj-$(CONFIG_ALIBABA_UNCORE_DRW_PMU) += alibaba_uncore_drw_pmu.o
>> +obj-$(CONFIG_DWC_PCIE_PMU) += dwc_pcie_pmu.o
>>  obj-$(CONFIG_ARM_CORESIGHT_PMU_ARCH_SYSTEM_PMU) += arm_cspmu/
>>  obj-$(CONFIG_MESON_DDR_PMU) += amlogic/
>> diff --git a/drivers/perf/dwc_pcie_pmu.c b/drivers/perf/dwc_pcie_pmu.c
>> new file mode 100644
>> index 000000000000..8bfcf6e0662d
>> --- /dev/null
>> +++ b/drivers/perf/dwc_pcie_pmu.c
>> @@ -0,0 +1,706 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Synopsys DesignWare PCIe PMU driver
>> + *
>> + * Copyright (C) 2021-2023 Alibaba Inc.
>> + */
>> +
>> +#include <linux/bitfield.h>
>> +#include <linux/bitops.h>
>> +#include <linux/cpuhotplug.h>
>> +#include <linux/cpumask.h>
>> +#include <linux/device.h>
>> +#include <linux/errno.h>
>> +#include <linux/kernel.h>
>> +#include <linux/list.h>
>> +#include <linux/perf_event.h>
>> +#include <linux/pci.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/smp.h>
>> +#include <linux/sysfs.h>
>> +#include <linux/types.h>
>> +
>> +#define DWC_PCIE_VSEC_RAS_DES_ID		0x02
>> +
>> +#define DWC_PCIE_EVENT_CNT_CTL			0x8
>> +
>> +/*
>> + * Event Counter Data Select includes two parts:
>> + * - 27-24: Group number(4-bit: 0..0x7)
>> + * - 23-16: Event number(8-bit: 0..0x13) within the Group
>> + *
>> + * Put them togother as TRM used.
>> + */
>> +#define DWC_PCIE_CNT_EVENT_SEL			GENMASK(27, 16)
>> +#define DWC_PCIE_CNT_LANE_SEL			GENMASK(11, 8)
>> +#define DWC_PCIE_CNT_STATUS			BIT(7)
>> +#define DWC_PCIE_CNT_ENABLE			GENMASK(4, 2)
>> +#define DWC_PCIE_PER_EVENT_OFF			0x1
>> +#define DWC_PCIE_PER_EVENT_ON			0x3
>> +#define DWC_PCIE_EVENT_CLEAR			GENMASK(1, 0)
>> +#define DWC_PCIE_EVENT_PER_CLEAR		0x1
>> +
>> +#define DWC_PCIE_EVENT_CNT_DATA			0xC
>> +
>> +#define DWC_PCIE_TIME_BASED_ANAL_CTL		0x10
>> +#define DWC_PCIE_TIME_BASED_REPORT_SEL		GENMASK(31, 24)
>> +#define DWC_PCIE_TIME_BASED_DURATION_SEL	GENMASK(15, 8)
>> +#define DWC_PCIE_DURATION_MANUAL_CTL		0x0
>> +#define DWC_PCIE_DURATION_1MS			0x1
>> +#define DWC_PCIE_DURATION_10MS			0x2
>> +#define DWC_PCIE_DURATION_100MS			0x3
>> +#define DWC_PCIE_DURATION_1S			0x4
>> +#define DWC_PCIE_DURATION_2S			0x5
>> +#define DWC_PCIE_DURATION_4S			0x6
>> +#define DWC_PCIE_DURATION_4US			0xFF
>> +#define DWC_PCIE_TIME_BASED_TIMER_START		BIT(0)
>> +#define DWC_PCIE_TIME_BASED_CNT_ENABLE		0x1
>> +
>> +#define DWC_PCIE_TIME_BASED_ANAL_DATA_REG_LOW	0x14
>> +#define DWC_PCIE_TIME_BASED_ANAL_DATA_REG_HIGH	0x18
>> +
>> +/* Event attributes */
>> +#define DWC_PCIE_CONFIG_EVENTID			GENMASK(15, 0)
>> +#define DWC_PCIE_CONFIG_TYPE			GENMASK(19, 16)
>> +#define DWC_PCIE_CONFIG_LANE			GENMASK(27, 20)
>> +
>> +#define DWC_PCIE_EVENT_ID(event)	FIELD_GET(DWC_PCIE_CONFIG_EVENTID, (event)->attr.config)
>> +#define DWC_PCIE_EVENT_TYPE(event)	FIELD_GET(DWC_PCIE_CONFIG_TYPE, (event)->attr.config)
>> +#define DWC_PCIE_EVENT_LANE(event)	FIELD_GET(DWC_PCIE_CONFIG_LANE, (event)->attr.config)
>> +
>> +enum dwc_pcie_event_type {
>> +	DWC_PCIE_TYPE_INVALID,
>> +	DWC_PCIE_TIME_BASE_EVENT,
>> +	DWC_PCIE_LANE_EVENT,
>> +};
>> +
>> +#define DWC_PCIE_LANE_EVENT_MAX_PERIOD		GENMASK_ULL(31, 0)
>> +#define DWC_PCIE_TIME_BASED_EVENT_MAX_PERIOD	GENMASK_ULL(63, 0)
>> +
>> +
>> +struct dwc_pcie_pmu {
>> +	struct pci_dev		*pdev;		/* Root Port device */
> 
> If the root port removed after the probe of this PCIe PMU driver, we'll access the NULL
> pointer. I didn't see you hold the root port to avoid the removal.
> 
>> +	u16			ras_des;	/* RAS DES capability offset */
>> +	u32			nr_lanes;
>> +
>> +	struct list_head	pmu_node;
>> +	struct hlist_node	cpuhp_node;
>> +	struct pmu		pmu;
>> +	struct perf_event	*event;
>> +	int			oncpu;
>> +};
>> +
>> +struct dwc_pcie_pmu_priv {
>> +	struct device *dev;
>> +	struct list_head pmu_nodes;
>> +};
>> +
>> +#define to_dwc_pcie_pmu(p) (container_of(p, struct dwc_pcie_pmu, pmu))
>> +
> 
> somebody told me to put @pmu as the first member then this macro will have no calculation. :)
> 
>> +static struct platform_device *dwc_pcie_pmu_dev;
>> +static int dwc_pcie_pmu_hp_state;
>> +
>> +static ssize_t cpumask_show(struct device *dev,
>> +					 struct device_attribute *attr,
>> +					 char *buf)
>> +{
>> +	struct dwc_pcie_pmu *pcie_pmu = to_dwc_pcie_pmu(dev_get_drvdata(dev));
>> +
>> +	return cpumap_print_to_pagebuf(true, buf, cpumask_of(pcie_pmu->oncpu));
>> +}
>> +static DEVICE_ATTR_RO(cpumask);
>> +
>> +static struct attribute *dwc_pcie_pmu_cpumask_attrs[] = {
>> +	&dev_attr_cpumask.attr,
>> +	NULL
>> +};
>> +
>> +static struct attribute_group dwc_pcie_cpumask_attr_group = {
>> +	.attrs = dwc_pcie_pmu_cpumask_attrs,
>> +};
>> +
>> +struct dwc_pcie_format_attr {
>> +	struct device_attribute attr;
>> +	u64 field;
>> +	int config;
>> +};
>> +
>> +static ssize_t dwc_pcie_pmu_format_show(struct device *dev,
>> +					struct device_attribute *attr,
>> +					char *buf)
>> +{
>> +	struct dwc_pcie_format_attr *fmt = container_of(attr, typeof(*fmt), attr);
>> +	int lo = __ffs(fmt->field), hi = __fls(fmt->field);
>> +
>> +	return sysfs_emit(buf, "config:%d-%d\n", lo, hi);
>> +}
>> +
>> +#define _dwc_pcie_format_attr(_name, _cfg, _fld)				\
>> +	(&((struct dwc_pcie_format_attr[]) {{					\
>> +		.attr = __ATTR(_name, 0444, dwc_pcie_pmu_format_show, NULL),	\
>> +		.config = _cfg,							\
>> +		.field = _fld,							\
>> +	}})[0].attr.attr)
>> +
>> +#define dwc_pcie_format_attr(_name, _fld)	_dwc_pcie_format_attr(_name, 0, _fld)
>> +
>> +static struct attribute *dwc_pcie_format_attrs[] = {
>> +	dwc_pcie_format_attr(type, DWC_PCIE_CONFIG_TYPE),
>> +	dwc_pcie_format_attr(eventid, DWC_PCIE_CONFIG_EVENTID),
>> +	dwc_pcie_format_attr(lane, DWC_PCIE_CONFIG_LANE),
>> +	NULL,
>> +};
>> +
>> +static struct attribute_group dwc_pcie_format_attrs_group = {
>> +	.name = "format",
>> +	.attrs = dwc_pcie_format_attrs,
>> +};
>> +
>> +struct dwc_pcie_event_attr {
>> +	struct device_attribute attr;
>> +	enum dwc_pcie_event_type type;
>> +	u16 eventid;
>> +	u8 lane;
>> +};
>> +
>> +static ssize_t dwc_pcie_event_show(struct device *dev,
>> +				struct device_attribute *attr, char *buf)
>> +{
>> +	struct dwc_pcie_event_attr *eattr;
>> +
>> +	eattr = container_of(attr, typeof(*eattr), attr);
>> +
>> +	if (eattr->type == DWC_PCIE_LANE_EVENT)
>> +		return sysfs_emit(buf, "eventid=0x%x,type=0x%x,lane=?\n",
>> +				  eattr->eventid, eattr->type);
>> +
>> +	return sysfs_emit(buf, "eventid=0x%x,type=0x%x\n", eattr->eventid,
>> +		       eattr->type);
>> +}
>> +
>> +#define DWC_PCIE_EVENT_ATTR(_name, _type, _eventid, _lane)		\
>> +	(&((struct dwc_pcie_event_attr[]) {{				\
>> +		.attr = __ATTR(_name, 0444, dwc_pcie_event_show, NULL),	\
>> +		.type = _type,						\
>> +		.eventid = _eventid,					\
>> +		.lane = _lane,						\
>> +	}})[0].attr.attr)
>> +
>> +#define DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(_name, _eventid)		\
>> +	DWC_PCIE_EVENT_ATTR(_name, DWC_PCIE_TIME_BASE_EVENT, _eventid, 0)
>> +#define DWC_PCIE_PMU_LANE_EVENT_ATTR(_name, _eventid)			\
>> +	DWC_PCIE_EVENT_ATTR(_name, DWC_PCIE_LANE_EVENT, _eventid, 0)
>> +
>> +static struct attribute *dwc_pcie_pmu_time_event_attrs[] = {
>> +	/* Group #0 */
>> +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(one_cycle, 0x00),
>> +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(TX_L0S, 0x01),
>> +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(RX_L0S, 0x02),
>> +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(L0, 0x03),
>> +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(L1, 0x04),
>> +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(L1_1, 0x05),
>> +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(L1_2, 0x06),
>> +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(CFG_RCVRY, 0x07),
>> +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(TX_RX_L0S, 0x08),
>> +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(L1_AUX, 0x09),
>> +
>> +	/* Group #1 */
>> +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(Tx_PCIe_TLP_Data_Payload, 0x20),
>> +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(Rx_PCIe_TLP_Data_Payload, 0x21),
>> +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(Tx_CCIX_TLP_Data_Payload, 0x22),
>> +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(Rx_CCIX_TLP_Data_Payload, 0x23),
>> +
>> +	/*
>> +	 * Leave it to the user to specify the lane ID to avoid generating
>> +	 * a list of hundreds of events.
>> +	 */
>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_ack_dllp, 0x600),
>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_update_fc_dllp, 0x601),
>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_ack_dllp, 0x602),
>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_update_fc_dllp, 0x603),
>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_nulified_tlp, 0x604),
>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_nulified_tlp, 0x605),
>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_duplicate_tl, 0x606),
>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_memory_write, 0x700),
>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_memory_read, 0x701),
>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_configuration_write, 0x702),
>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_configuration_read, 0x703),
>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_io_write, 0x704),
>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_io_read, 0x705),
>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_completion_without_data, 0x706),
>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_completion_with_data, 0x707),
>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_message_tlp, 0x708),
>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_atomic, 0x709),
>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_tlp_with_prefix, 0x70A),
>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_memory_write, 0x70B),
>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_memory_read, 0x70C),
>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_io_write, 0x70F),
>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_io_read, 0x710),
>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_completion_without_data, 0x711),
>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_completion_with_data, 0x712),
>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_message_tlp, 0x713),
>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_atomic, 0x714),
>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_tlp_with_prefix, 0x715),
>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_ccix_tlp, 0x716),
>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_ccix_tlp, 0x717),
>> +
> 
> Intended blank line?
> 
>> +	NULL
>> +};
>> +
>> +static const struct attribute_group dwc_pcie_event_attrs_group = {
>> +	.name = "events",
>> +	.attrs = dwc_pcie_pmu_time_event_attrs,
>> +};
>> +
>> +static const struct attribute_group *dwc_pcie_attr_groups[] = {
>> +	&dwc_pcie_event_attrs_group,
>> +	&dwc_pcie_format_attrs_group,
>> +	&dwc_pcie_cpumask_attr_group,
>> +	NULL
>> +};
>> +
>> +static void dwc_pcie_pmu_lane_event_enable(struct dwc_pcie_pmu *pcie_pmu,
>> +					   bool enable)
>> +{
>> +	struct pci_dev *pdev = pcie_pmu->pdev;
>> +	u16 ras_des = pcie_pmu->ras_des;
>> +	u32 val;
>> +
>> +	pci_read_config_dword(pdev, ras_des + DWC_PCIE_EVENT_CNT_CTL, &val);
>> +
>> +	/* Clear DWC_PCIE_CNT_ENABLE field first */
>> +	val &= ~DWC_PCIE_CNT_ENABLE;
>> +	if (enable)
>> +		val |= FIELD_PREP(DWC_PCIE_CNT_ENABLE, DWC_PCIE_PER_EVENT_ON);
>> +	else
>> +		val |= FIELD_PREP(DWC_PCIE_CNT_ENABLE, DWC_PCIE_PER_EVENT_OFF);
>> +
>> +	pci_write_config_dword(pdev, ras_des + DWC_PCIE_EVENT_CNT_CTL, val);
>> +}
>> +
>> +static void dwc_pcie_pmu_time_based_event_enable(struct dwc_pcie_pmu *pcie_pmu,
>> +					  bool enable)
>> +{
>> +	struct pci_dev *pdev = pcie_pmu->pdev;
>> +	u16 ras_des = pcie_pmu->ras_des;
>> +	u32 val;
>> +
>> +	pci_read_config_dword(pdev, ras_des + DWC_PCIE_TIME_BASED_ANAL_CTL,
>> +			      &val);
>> +
>> +	if (enable)
>> +		val |= DWC_PCIE_TIME_BASED_CNT_ENABLE;
>> +	else
>> +		val &= ~DWC_PCIE_TIME_BASED_CNT_ENABLE;
>> +
>> +	pci_write_config_dword(pdev, ras_des + DWC_PCIE_TIME_BASED_ANAL_CTL,
>> +			       val);
>> +}
>> +
>> +static u64 dwc_pcie_pmu_read_lane_event_counter(struct dwc_pcie_pmu *pcie_pmu)
>> +{
>> +	struct pci_dev *pdev = pcie_pmu->pdev;
>> +	u16 ras_des = pcie_pmu->ras_des;
>> +	u32 val;
>> +
>> +	pci_read_config_dword(pdev, ras_des + DWC_PCIE_EVENT_CNT_DATA, &val);
>> +
>> +	return val;
>> +}
>> +
>> +static u64 dwc_pcie_pmu_read_time_based_counter(struct dwc_pcie_pmu *pcie_pmu)
>> +{
>> +	struct pci_dev *pdev = pcie_pmu->pdev;
>> +	u16 ras_des = pcie_pmu->ras_des;
>> +	u64 count;
>> +	u32 val;
>> +
>> +	pci_read_config_dword(
>> +		pdev, ras_des + DWC_PCIE_TIME_BASED_ANAL_DATA_REG_HIGH, &val);
>> +	count = val;
>> +	count <<= 32;
>> +
>> +	pci_read_config_dword(
>> +		pdev, ras_des + DWC_PCIE_TIME_BASED_ANAL_DATA_REG_LOW, &val);
>> +
>> +	count += val;
>> +
>> +	return count;
>> +}
>> +
>> +static void dwc_pcie_pmu_event_update(struct perf_event *event)
>> +{
>> +	struct dwc_pcie_pmu *pcie_pmu = to_dwc_pcie_pmu(event->pmu);
>> +	struct hw_perf_event *hwc = &event->hw;
>> +	enum dwc_pcie_event_type type = DWC_PCIE_EVENT_TYPE(event);
>> +	u64 delta, prev, now;
>> +
>> +	do {
>> +		prev = local64_read(&hwc->prev_count);
>> +
>> +		if (type == DWC_PCIE_LANE_EVENT)
>> +			now = dwc_pcie_pmu_read_lane_event_counter(pcie_pmu);
>> +		else if (type == DWC_PCIE_TIME_BASE_EVENT)
>> +			now = dwc_pcie_pmu_read_time_based_counter(pcie_pmu);
>> +
>> +	} while (local64_cmpxchg(&hwc->prev_count, prev, now) != prev);
>> +
>> +	if (type == DWC_PCIE_LANE_EVENT)
>> +		delta = (now - prev) & DWC_PCIE_LANE_EVENT_MAX_PERIOD;
>> +	else if (type == DWC_PCIE_TIME_BASE_EVENT)
>> +		delta = (now - prev) & DWC_PCIE_TIME_BASED_EVENT_MAX_PERIOD;
>> +
>> +	local64_add(delta, &event->count);
>> +}
>> +
>> +static int dwc_pcie_pmu_event_init(struct perf_event *event)
>> +{
>> +	struct dwc_pcie_pmu *pcie_pmu = to_dwc_pcie_pmu(event->pmu);
>> +	enum dwc_pcie_event_type type = DWC_PCIE_EVENT_TYPE(event);
>> +	struct perf_event *sibling;
>> +	u32 lane;
>> +
>> +	if (event->attr.type != event->pmu->type)
>> +		return -ENOENT;
>> +
>> +	/* We don't support sampling */
>> +	if (is_sampling_event(event))
>> +		return -EINVAL;
>> +
>> +	/* We cannot support task bound events */
>> +	if (event->cpu < 0 || event->attach_state & PERF_ATTACH_TASK)
>> +		return -EINVAL;
>> +
>> +	if (event->group_leader != event &&
>> +	    !is_software_event(event->group_leader))
>> +		return -EINVAL;
>> +
>> +	for_each_sibling_event(sibling, event->group_leader) {
>> +		if (sibling->pmu != event->pmu && !is_software_event(sibling))
>> +			return -EINVAL;
>> +	}
>> +
>> +	if (type == DWC_PCIE_LANE_EVENT) {
>> +		lane = DWC_PCIE_EVENT_LANE(event);
>> +		if (lane < 0 || lane >= pcie_pmu->nr_lanes)
>> +			return -EINVAL;
>> +	}
>> +
>> +	event->cpu = pcie_pmu->oncpu;
>> +
>> +	return 0;
>> +}
>> +
>> +static void dwc_pcie_pmu_set_period(struct hw_perf_event *hwc)
>> +{
>> +	local64_set(&hwc->prev_count, 0);
>> +}
>> +
>> +static void dwc_pcie_pmu_event_start(struct perf_event *event, int flags)
>> +{
>> +	struct hw_perf_event *hwc = &event->hw;
>> +	struct dwc_pcie_pmu *pcie_pmu = to_dwc_pcie_pmu(event->pmu);
>> +	enum dwc_pcie_event_type type = DWC_PCIE_EVENT_TYPE(event);
>> +
>> +	hwc->state = 0;
>> +	dwc_pcie_pmu_set_period(hwc);
>> +
>> +	if (type == DWC_PCIE_LANE_EVENT)
>> +		dwc_pcie_pmu_lane_event_enable(pcie_pmu, true);
>> +	else if (type == DWC_PCIE_TIME_BASE_EVENT)
>> +		dwc_pcie_pmu_time_based_event_enable(pcie_pmu, true);
>> +}
>> +
>> +static void dwc_pcie_pmu_event_stop(struct perf_event *event, int flags)
>> +{
>> +	struct dwc_pcie_pmu *pcie_pmu = to_dwc_pcie_pmu(event->pmu);
>> +	enum dwc_pcie_event_type type = DWC_PCIE_EVENT_TYPE(event);
>> +	struct hw_perf_event *hwc = &event->hw;
>> +
>> +	if (event->hw.state & PERF_HES_STOPPED)
>> +		return;
>> +
>> +	if (type == DWC_PCIE_LANE_EVENT)
>> +		dwc_pcie_pmu_lane_event_enable(pcie_pmu, false);
>> +	else if (type == DWC_PCIE_TIME_BASE_EVENT)
>> +		dwc_pcie_pmu_time_based_event_enable(pcie_pmu, false);
>> +
>> +	dwc_pcie_pmu_event_update(event);
>> +	hwc->state |= PERF_HES_STOPPED | PERF_HES_UPTODATE;
>> +}
>> +
>> +static int dwc_pcie_pmu_event_add(struct perf_event *event, int flags)
>> +{
>> +	struct dwc_pcie_pmu *pcie_pmu = to_dwc_pcie_pmu(event->pmu);
>> +	struct pci_dev *pdev = pcie_pmu->pdev;
>> +	struct hw_perf_event *hwc = &event->hw;
>> +	enum dwc_pcie_event_type type = DWC_PCIE_EVENT_TYPE(event);
>> +	int event_id = DWC_PCIE_EVENT_ID(event);
>> +	int lane = DWC_PCIE_EVENT_LANE(event);
>> +	u16 ras_des = pcie_pmu->ras_des;
>> +	u32 ctrl;
>> +
>> +	/* Only one counter and it is in use */
>> +	if (pcie_pmu->event)
>> +		return -ENOSPC;
>> +
>> +	pcie_pmu->event = event;
>> +	hwc->state = PERF_HES_STOPPED | PERF_HES_UPTODATE;
>> +
>> +	if (type == DWC_PCIE_LANE_EVENT) {
>> +		/* EVENT_COUNTER_DATA_REG needs clear manually */
>> +		ctrl = FIELD_PREP(DWC_PCIE_CNT_EVENT_SEL, event_id) |
>> +			FIELD_PREP(DWC_PCIE_CNT_LANE_SEL, lane) |
>> +			FIELD_PREP(DWC_PCIE_CNT_ENABLE, DWC_PCIE_PER_EVENT_OFF) |
>> +			FIELD_PREP(DWC_PCIE_EVENT_CLEAR, DWC_PCIE_EVENT_PER_CLEAR);
>> +		pci_write_config_dword(pdev, ras_des + DWC_PCIE_EVENT_CNT_CTL,
>> +				       ctrl);
>> +	} else if (type == DWC_PCIE_TIME_BASE_EVENT) {
>> +		/*
>> +		 * TIME_BASED_ANAL_DATA_REG is a 64 bit register, we can safely
>> +		 * use it with any manually controlled duration. And it is
>> +		 * cleared when next measurement starts.
>> +		 */
>> +		ctrl = FIELD_PREP(DWC_PCIE_TIME_BASED_REPORT_SEL, event_id) |
>> +			FIELD_PREP(DWC_PCIE_TIME_BASED_DURATION_SEL,
>> +				   DWC_PCIE_DURATION_MANUAL_CTL) |
>> +			DWC_PCIE_TIME_BASED_CNT_ENABLE;
>> +		pci_write_config_dword(
>> +			pdev, ras_des + DWC_PCIE_TIME_BASED_ANAL_CTL, ctrl);
>> +	}
>> +
>> +	if (flags & PERF_EF_START)
>> +		dwc_pcie_pmu_event_start(event, PERF_EF_RELOAD);
>> +
>> +	perf_event_update_userpage(event);
>> +
>> +	return 0;
>> +}
>> +
>> +static void dwc_pcie_pmu_event_del(struct perf_event *event, int flags)
>> +{
>> +	struct dwc_pcie_pmu *pcie_pmu = to_dwc_pcie_pmu(event->pmu);
>> +
>> +	dwc_pcie_pmu_event_stop(event, flags | PERF_EF_UPDATE);
>> +	perf_event_update_userpage(event);
>> +	pcie_pmu->event = NULL;
>> +}
>> +
>> +static int __dwc_pcie_pmu_probe(struct dwc_pcie_pmu_priv *priv)
>> +{
>> +	struct pci_dev *pdev = NULL;
>> +	struct dwc_pcie_pmu *pcie_pmu;
>> +	char *name;
>> +	u32 bdf;
>> +	int ret;
>> +
>> +	INIT_LIST_HEAD(&priv->pmu_nodes);
>> +
>> +	/* Match the rootport with VSEC_RAS_DES_ID, and register a PMU for it */
>> +	for_each_pci_dev(pdev) {
>> +		u16 vsec;
>> +		u32 val;
>> +
>> +		if (!(pci_is_pcie(pdev) &&
>> +		      pci_pcie_type(pdev) == PCI_EXP_TYPE_ROOT_PORT))
>> +			continue;
>> +
>> +		vsec = pci_find_vsec_capability(pdev, PCI_VENDOR_ID_ALIBABA,
>> +						DWC_PCIE_VSEC_RAS_DES_ID);
>> +		if (!vsec)
>> +			continue;
>> +
>> +		pci_read_config_dword(pdev, vsec + PCI_VNDR_HEADER, &val);
>> +		if (PCI_VNDR_HEADER_REV(val) != 0x04 ||
>> +		    PCI_VNDR_HEADER_LEN(val) != 0x100)
>> +			continue;
>> +		pci_dbg(pdev,
>> +			"Detected PCIe Vendor-Specific Extended Capability RAS DES\n");
>> +
>> +		bdf = PCI_DEVID(pdev->bus->number, pdev->devfn);
>> +		name = devm_kasprintf(priv->dev, GFP_KERNEL, "dwc_rootport_%x",
>> +				      bdf);
>> +		if (!name)
>> +			return -ENOMEM;
>> +
>> +		/* All checks passed, go go go */
>> +		pcie_pmu = devm_kzalloc(&pdev->dev, sizeof(*pcie_pmu), GFP_KERNEL);
>> +		if (!pcie_pmu) {
>> +			pci_dev_put(pdev);
> 
> we need to call pci_dev_put on all the return branch below and above and after the for_each_pci_dev()
> loop to keep the refcnt balance.
> 
>> +			return -ENOMEM;
>> +		}
>> +
>> +		pcie_pmu->pdev = pdev;
>> +		pcie_pmu->ras_des = vsec;
>> +		pcie_pmu->nr_lanes = pcie_get_width_cap(pdev);
>> +		pcie_pmu->pmu = (struct pmu){
>> +			.module		= THIS_MODULE,
>> +			.attr_groups	= dwc_pcie_attr_groups,
>> +			.capabilities	= PERF_PMU_CAP_NO_EXCLUDE,
>> +			.task_ctx_nr	= perf_invalid_context,
>> +			.event_init	= dwc_pcie_pmu_event_init,
>> +			.add		= dwc_pcie_pmu_event_add,
>> +			.del		= dwc_pcie_pmu_event_del,
>> +			.start		= dwc_pcie_pmu_event_start,
>> +			.stop		= dwc_pcie_pmu_event_stop,
>> +			.read		= dwc_pcie_pmu_event_update,
>> +		};
>> +
>> +		/* Add this instance to the list used by the offline callback */
>> +		ret = cpuhp_state_add_instance(dwc_pcie_pmu_hp_state,
>> +					       &pcie_pmu->cpuhp_node);
>> +		if (ret) {
>> +			pci_err(pcie_pmu->pdev,
>> +				"Error %d registering hotplug @%x\n", ret, bdf);
>> +			return ret;
>> +		}
>> +		ret = perf_pmu_register(&pcie_pmu->pmu, name, -1);
>> +		if (ret) {
>> +			pci_err(pcie_pmu->pdev,
>> +				"Error %d registering PMU @%x\n", ret, bdf);
>> +			cpuhp_state_remove_instance_nocalls(
>> +				dwc_pcie_pmu_hp_state, &pcie_pmu->cpuhp_node);
>> +			return ret;
>> +		}
>> +
>> +		/* Add registered PMUs and unregister them when this driver remove */
>> +		list_add(&pcie_pmu->pmu_node, &priv->pmu_nodes);
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static int dwc_pcie_pmu_remove(struct platform_device *pdev)
>> +{
>> +	struct dwc_pcie_pmu_priv *priv = platform_get_drvdata(pdev);
>> +	struct dwc_pcie_pmu *pcie_pmu;
>> +
>> +	list_for_each_entry(pcie_pmu, &priv->pmu_nodes, pmu_node) {
>> +		cpuhp_state_remove_instance(dwc_pcie_pmu_hp_state,
>> +					    &pcie_pmu->cpuhp_node);
>> +		perf_pmu_unregister(&pcie_pmu->pmu);
> 
> should unregister the PMU first, keep the order reverse to __dwc_pcie_pmu_probe().
> 
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static int dwc_pcie_pmu_probe(struct platform_device *pdev)
>> +{
>> +	struct dwc_pcie_pmu_priv *priv;
>> +	int ret;
>> +
>> +	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
>> +	if (!priv)
>> +		return -ENOMEM;
>> +
>> +	priv->dev = &pdev->dev;
>> +	platform_set_drvdata(pdev, priv);
>> +
>> +	/* If one PMU registration fails, remove all. */
>> +	ret = __dwc_pcie_pmu_probe(priv);
>> +	if (ret) {
>> +		dwc_pcie_pmu_remove(pdev);
>> +		return ret;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static void dwc_pcie_pmu_migrate(struct dwc_pcie_pmu *pcie_pmu, unsigned int cpu)
>> +{
>> +	/* This PMU does NOT support interrupt, just migrate context. */
>> +	perf_pmu_migrate_context(&pcie_pmu->pmu, pcie_pmu->oncpu, cpu);
>> +	pcie_pmu->oncpu = cpu;
>> +}
>> +
>> +static int dwc_pcie_pmu_online_cpu(unsigned int cpu, struct hlist_node *cpuhp_node)
>> +{
>> +	struct dwc_pcie_pmu *pcie_pmu;
>> +	struct pci_dev *pdev;
>> +	int node;
>> +
>> +	pcie_pmu = hlist_entry_safe(cpuhp_node, struct dwc_pcie_pmu, cpuhp_node);
>> +	pdev = pcie_pmu->pdev;
>> +	node = dev_to_node(&pdev->dev);
>> +
>> +	if (node != NUMA_NO_NODE && cpu_to_node(pcie_pmu->oncpu) != node &&
>> +	    cpu_to_node(cpu) == node)
>> +		dwc_pcie_pmu_migrate(pcie_pmu, cpu);
>> +
>> +	return 0;
>> +}
>> +
>> +static int dwc_pcie_pmu_offline_cpu(unsigned int cpu, struct hlist_node *cpuhp_node)
>> +{
>> +	struct dwc_pcie_pmu *pcie_pmu;
>> +	struct pci_dev *pdev;
>> +	int node;
>> +	cpumask_t mask;
>> +	unsigned int target;
>> +
>> +	pcie_pmu = hlist_entry_safe(cpuhp_node, struct dwc_pcie_pmu, cpuhp_node);
>> +	if (cpu != pcie_pmu->oncpu)
>> +		return 0;
>> +
>> +	pdev = pcie_pmu->pdev;
>> +	node = dev_to_node(&pdev->dev);
>> +	if (cpumask_and(&mask, cpumask_of_node(node), cpu_online_mask) &&
>> +	    cpumask_andnot(&mask, &mask, cpumask_of(cpu)))
>> +		target = cpumask_any(&mask);
> 
> The cpumask_of_node() only contains the online CPUs so this branch is redundant. For arm64
> using arch_numa.c the node cpumask is updated in numa_{add, remove}_cpu() and for other
> arthitecture the behaviour should keep consistenct. Please correct my if I'm wrong.
> 
>> +	else
>> +		target = cpumask_any_but(cpu_online_mask, cpu);
>> +	if (target < nr_cpu_ids)
>> +		dwc_pcie_pmu_migrate(pcie_pmu, target);
>> +
>> +	return 0;
>> +}
>> +
>> +static struct platform_driver dwc_pcie_pmu_driver = {
>> +	.probe = dwc_pcie_pmu_probe,
>> +	.remove = dwc_pcie_pmu_remove,
>> +	.driver = {.name = "dwc_pcie_pmu",},
>> +};
>> +
>> +static int __init dwc_pcie_pmu_init(void)
>> +{
>> +	int ret;
>> +
>> +	ret = cpuhp_setup_state_multi(CPUHP_AP_ONLINE_DYN,
>> +				      "perf/dwc_pcie_pmu:online",
>> +				      dwc_pcie_pmu_online_cpu,
>> +				      dwc_pcie_pmu_offline_cpu);
>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	dwc_pcie_pmu_hp_state = ret;
>> +
>> +	ret = platform_driver_register(&dwc_pcie_pmu_driver);
>> +	if (ret) {
>> +		cpuhp_remove_multi_state(dwc_pcie_pmu_hp_state);
>> +		return ret;
>> +	}
>> +
>> +	dwc_pcie_pmu_dev = platform_device_register_simple(
>> +				"dwc_pcie_pmu", PLATFORM_DEVID_NONE, NULL, 0);
>> +	if (IS_ERR(dwc_pcie_pmu_dev)) {
>> +		platform_driver_unregister(&dwc_pcie_pmu_driver);
> 
> On failure we also need to remove cpuhp state as well.
> 
> Thanks,
> Yicong
> 
>> +		return PTR_ERR(dwc_pcie_pmu_dev);
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static void __exit dwc_pcie_pmu_exit(void)
>> +{
>> +	platform_device_unregister(dwc_pcie_pmu_dev);
>> +	platform_driver_unregister(&dwc_pcie_pmu_driver);
>> +	cpuhp_remove_multi_state(dwc_pcie_pmu_hp_state);
>> +}
>> +
>> +module_init(dwc_pcie_pmu_init);
>> +module_exit(dwc_pcie_pmu_exit);
>> +
>> +MODULE_DESCRIPTION("PMU driver for DesignWare Cores PCI Express Controller");
>> +MODULE_AUTHOR("Shuai xue <xueshuai@linux.alibaba.com>");
>> +MODULE_AUTHOR("Wen Cheng <yinxuan_cw@linux.alibaba.com>");
>> +MODULE_LICENSE("GPL v2");
>>

On 2023/7/27 17:39, Jonathan Cameron wrote:
> On Tue, 6 Jun 2023 23:14:07 +0800
> Yicong Yang <yangyicong@huawei.com> wrote:
> 
>> On 2023/6/6 15:49, Shuai Xue wrote:
>>> This commit adds the PCIe Performance Monitoring Unit (PMU) driver support
>>> for T-Head Yitian SoC chip. Yitian is based on the Synopsys PCI Express
>>> Core controller IP which provides statistics feature. The PMU is not a PCIe
>>> Root Complex integrated End Point(RCiEP) device but only register counters
>>> provided by each PCIe Root Port.
>>>
>>> To facilitate collection of statistics the controller provides the
>>> following two features for each Root Port:
>>>
>>> - Time Based Analysis (RX/TX data throughput and time spent in each
>>>   low-power LTSSM state)
>>> - Event counters (Error and Non-Error for lanes)
>>>
>>> Note, only one counter for each type and does not overflow interrupt.
>>>
>>> This driver adds PMU devices for each PCIe Root Port. And the PMU device is
>>> named based the BDF of Root Port. For example,
>>>
>>>     30:03.0 PCI bridge: Device 1ded:8000 (rev 01)
>>>
>>> the PMU device name for this Root Port is dwc_rootport_3018.
>>>
>>> Example usage of counting PCIe RX TLP data payload (Units of 16 bytes)::
>>>
>>>     $# perf stat -a -e dwc_rootport_3018/Rx_PCIe_TLP_Data_Payload/
>>>
>>> average RX bandwidth can be calculated like this:
>>>
>>>     PCIe TX Bandwidth = PCIE_TX_DATA * 16B / Measure_Time_Window
>>>
>>> Signed-off-by: Shuai Xue <xueshuai@linux.alibaba.com>
>>> Reported-by: kernel test robot <lkp@intel.com>
>>> Link: https://lore.kernel.org/oe-kbuild-all/202305170639.XU3djFZX-lkp@intel.com/
>>> Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
> 
> I'll review on top to avoid any duplication with Yicong.

Thank you! It also served as a reminder that I missed Yicong's email. It appears
that Thunderbird mistakenly moved his email to the junk folder, resulting in me
overlooking it.

> 
> Note I've cropped the stuff neither of us commented on so it's
> easier to spot the feedback.

Thank you for noting that. My feedback is replied inline.

> 
> Jonathan
> 
>>> ---
>>>  drivers/perf/Kconfig        |   7 +
>>>  drivers/perf/Makefile       |   1 +
>>>  drivers/perf/dwc_pcie_pmu.c | 706 ++++++++++++++++++++++++++++++++++++
>>>  3 files changed, 714 insertions(+)
>>>  create mode 100644 drivers/perf/dwc_pcie_pmu.c
>>>
>>> diff --git a/drivers/perf/Kconfig b/drivers/perf/Kconfig
>>> index 711f82400086..6ff3921d7a62 100644
>>> --- a/drivers/perf/Kconfig
>>> +++ b/drivers/perf/Kconfig
>>> @@ -209,6 +209,13 @@ config MARVELL_CN10K_DDR_PMU
>>>  	  Enable perf support for Marvell DDR Performance monitoring
>>>  	  event on CN10K platform.
>>>  
>>> +config DWC_PCIE_PMU
>>> +	tristate "Enable Synopsys DesignWare PCIe PMU Support"
>>> +	depends on (ARM64 && PCI)
>>> +	help
>>> +	  Enable perf support for Synopsys DesignWare PCIe PMU Performance
>>> +	  monitoring event on Yitian 710 platform.
> 
> The documentation kind of implies this isn't platform specific.
> If some parts are (such as which events exist) then you may want to push
> that to userspace / perftool with appropriate matching against specific SoC.
> 
> If it is generic, then change this text to "event on platform including the Yitian 710."

It is generic without any platform specific, so I will change it as you expected.

> 
>>> +
>>>  source "drivers/perf/arm_cspmu/Kconfig"
>>>  
>>>  source "drivers/perf/amlogic/Kconfig"
> 
>>> new file mode 100644
>>> index 000000000000..8bfcf6e0662d
>>> --- /dev/null
>>> +++ b/drivers/perf/dwc_pcie_pmu.c
>>> @@ -0,0 +1,706 @@
> 
> ...
> 
>>> +
>>> +struct dwc_pcie_pmu {
>>> +	struct pci_dev		*pdev;		/* Root Port device */  
>>
>> If the root port removed after the probe of this PCIe PMU driver, we'll access the NULL
>> pointer. I didn't see you hold the root port to avoid the removal.

Do you mean that I should have a reference count of rootport by pci_dev_get() when allocating
pcie_pmu?

     pcie_pmu->pdev = pci_dev_get();

>>
>>> +	u16			ras_des;	/* RAS DES capability offset */
>>> +	u32			nr_lanes;
>>> +
>>> +	struct list_head	pmu_node;
>>> +	struct hlist_node	cpuhp_node;
>>> +	struct pmu		pmu;
>>> +	struct perf_event	*event;
>>> +	int			oncpu;
>>> +};
>>> +
>>> +struct dwc_pcie_pmu_priv {
>>> +	struct device *dev;
>>> +	struct list_head pmu_nodes;
>>> +};
>>> +
>>> +#define to_dwc_pcie_pmu(p) (container_of(p, struct dwc_pcie_pmu, pmu))
>>> +  
>>
>> somebody told me to put @pmu as the first member then this macro will have no calculation. :)
>>

Aha, you are right, I will move it as a first member.

> ...
> 
>>> +static ssize_t dwc_pcie_event_show(struct device *dev,
>>> +				struct device_attribute *attr, char *buf)
>>> +{
>>> +	struct dwc_pcie_event_attr *eattr;
>>> +
>>> +	eattr = container_of(attr, typeof(*eattr), attr);
>>> +
>>> +	if (eattr->type == DWC_PCIE_LANE_EVENT)
>>> +		return sysfs_emit(buf, "eventid=0x%x,type=0x%x,lane=?\n",
>>> +				  eattr->eventid, eattr->type);
>>> +
> 
> Elsewhere you always check for DWC_PCIE_TIME_BASE_EVENT.
> Should probably do so here as well for consistency.

Yes, I will also add the check here.

> 
>>> +	return sysfs_emit(buf, "eventid=0x%x,type=0x%x\n", eattr->eventid,
>>> +		       eattr->type);
>>> +}
> 
>>> +static struct attribute *dwc_pcie_pmu_time_event_attrs[] = {
>>> +	/* Group #0 */
>>> +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(one_cycle, 0x00),
>>> +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(TX_L0S, 0x01),
>>> +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(RX_L0S, 0x02),
>>> +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(L0, 0x03),
>>> +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(L1, 0x04),
>>> +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(L1_1, 0x05),
>>> +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(L1_2, 0x06),
>>> +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(CFG_RCVRY, 0x07),
>>> +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(TX_RX_L0S, 0x08),
>>> +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(L1_AUX, 0x09),
>>> +
>>> +	/* Group #1 */
>>> +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(Tx_PCIe_TLP_Data_Payload, 0x20),
>>> +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(Rx_PCIe_TLP_Data_Payload, 0x21),
>>> +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(Tx_CCIX_TLP_Data_Payload, 0x22),
>>> +	DWC_PCIE_PMU_TIME_BASE_EVENT_ATTR(Rx_CCIX_TLP_Data_Payload, 0x23),
>>> +
>>> +	/*
>>> +	 * Leave it to the user to specify the lane ID to avoid generating
>>> +	 * a list of hundreds of events.
>>> +	 */
>>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_ack_dllp, 0x600),
>>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_update_fc_dllp, 0x601),
>>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_ack_dllp, 0x602),
>>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_update_fc_dllp, 0x603),
>>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_nulified_tlp, 0x604),
>>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_nulified_tlp, 0x605),
>>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_duplicate_tl, 0x606),
>>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_memory_write, 0x700),
>>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_memory_read, 0x701),
>>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_configuration_write, 0x702),
>>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_configuration_read, 0x703),
>>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_io_write, 0x704),
>>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_io_read, 0x705),
>>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_completion_without_data, 0x706),
>>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_completion_with_data, 0x707),
>>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_message_tlp, 0x708),
>>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_atomic, 0x709),
>>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_tlp_with_prefix, 0x70A),
>>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_memory_write, 0x70B),
>>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_memory_read, 0x70C),
>>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_io_write, 0x70F),
>>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_io_read, 0x710),
>>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_completion_without_data, 0x711),
>>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_completion_with_data, 0x712),
>>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_message_tlp, 0x713),
>>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_atomic, 0x714),
>>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_tlp_with_prefix, 0x715),
>>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(tx_ccix_tlp, 0x716),
>>> +	DWC_PCIE_PMU_LANE_EVENT_ATTR(rx_ccix_tlp, 0x717),
>>> +  
>>
>> Intended blank line?

Nope, will delete it.

>>
>>> +	NULL
>>> +};
> 
> 
> ...
> 
>>> +static u64 dwc_pcie_pmu_read_time_based_counter(struct dwc_pcie_pmu *pcie_pmu)
>>> +{
>>> +	struct pci_dev *pdev = pcie_pmu->pdev;
>>> +	u16 ras_des = pcie_pmu->ras_des;
>>> +	u64 count;
>>> +	u32 val;
>>> +
>>> +	pci_read_config_dword(
>>> +		pdev, ras_des + DWC_PCIE_TIME_BASED_ANAL_DATA_REG_HIGH, &val);
>>> +	count = val;
>>> +	count <<= 32;
>>> +
>>> +	pci_read_config_dword(
>>> +		pdev, ras_des + DWC_PCIE_TIME_BASED_ANAL_DATA_REG_LOW, &val);
> 
> This looks like tearing can occur.  you probably need to protect against that
> (usual trick is re read the _HIGH part and if it changed, try again)
> 
> The hardware might prevent tearing (it would freeze the low register when you
> read the high one, then only let it change after a read of the low registers is
> done).  If that's the case - add a comment to say so.

Good catch, I will check with hardware designer and reply later.

> 
>>> +
>>> +	count += val;
>>> +
>>> +	return count;
>>> +}
>>> +
> 
> 
> ...
>>> +static int dwc_pcie_pmu_event_add(struct perf_event *event, int flags)
>>> +{
>>> +	struct dwc_pcie_pmu *pcie_pmu = to_dwc_pcie_pmu(event->pmu);
>>> +	struct pci_dev *pdev = pcie_pmu->pdev;
>>> +	struct hw_perf_event *hwc = &event->hw;
>>> +	enum dwc_pcie_event_type type = DWC_PCIE_EVENT_TYPE(event);
>>> +	int event_id = DWC_PCIE_EVENT_ID(event);
>>> +	int lane = DWC_PCIE_EVENT_LANE(event);
>>> +	u16 ras_des = pcie_pmu->ras_des;
>>> +	u32 ctrl;
>>> +
>>> +	/* Only one counter and it is in use */
> 
> Yikes. That's quite a restriction.  Probably good to mention in the docs.
> I'm a little confused about the architecture though - there seem to be separate
> registers for the Lane and time based events.  Can't count those at same time?
> 

I am not quite sure, I will double check it and reply later.

>>> +	if (pcie_pmu->event)
>>> +		return -ENOSPC;
>>> +
>>> +	pcie_pmu->event = event;
>>> +	hwc->state = PERF_HES_STOPPED | PERF_HES_UPTODATE;
>>> +
>>> +	if (type == DWC_PCIE_LANE_EVENT) {
>>> +		/* EVENT_COUNTER_DATA_REG needs clear manually */
>>> +		ctrl = FIELD_PREP(DWC_PCIE_CNT_EVENT_SEL, event_id) |
>>> +			FIELD_PREP(DWC_PCIE_CNT_LANE_SEL, lane) |
>>> +			FIELD_PREP(DWC_PCIE_CNT_ENABLE, DWC_PCIE_PER_EVENT_OFF) |
>>> +			FIELD_PREP(DWC_PCIE_EVENT_CLEAR, DWC_PCIE_EVENT_PER_CLEAR);
>>> +		pci_write_config_dword(pdev, ras_des + DWC_PCIE_EVENT_CNT_CTL,
>>> +				       ctrl);
>>> +	} else if (type == DWC_PCIE_TIME_BASE_EVENT) {
>>> +		/*
>>> +		 * TIME_BASED_ANAL_DATA_REG is a 64 bit register, we can safely
>>> +		 * use it with any manually controlled duration. And it is
>>> +		 * cleared when next measurement starts.
>>> +		 */
>>> +		ctrl = FIELD_PREP(DWC_PCIE_TIME_BASED_REPORT_SEL, event_id) |
>>> +			FIELD_PREP(DWC_PCIE_TIME_BASED_DURATION_SEL,
>>> +				   DWC_PCIE_DURATION_MANUAL_CTL) |
>>> +			DWC_PCIE_TIME_BASED_CNT_ENABLE;
>>> +		pci_write_config_dword(
>>> +			pdev, ras_des + DWC_PCIE_TIME_BASED_ANAL_CTL, ctrl);
>>> +	}
>>> +
>>> +	if (flags & PERF_EF_START)
>>> +		dwc_pcie_pmu_event_start(event, PERF_EF_RELOAD);
>>> +
>>> +	perf_event_update_userpage(event);
>>> +
>>> +	return 0;
>>> +}
> ...
> 
>>> +static int __dwc_pcie_pmu_probe(struct dwc_pcie_pmu_priv *priv)
>>> +{
>>> +	struct pci_dev *pdev = NULL;
>>> +	struct dwc_pcie_pmu *pcie_pmu;
>>> +	char *name;
>>> +	u32 bdf;
>>> +	int ret;
>>> +
>>> +	INIT_LIST_HEAD(&priv->pmu_nodes);
>>> +
>>> +	/* Match the rootport with VSEC_RAS_DES_ID, and register a PMU for it */
>>> +	for_each_pci_dev(pdev) {
>>> +		u16 vsec;
>>> +		u32 val;
>>> +
>>> +		if (!(pci_is_pcie(pdev) &&
>>> +		      pci_pcie_type(pdev) == PCI_EXP_TYPE_ROOT_PORT))
>>> +			continue;
>>> +
>>> +		vsec = pci_find_vsec_capability(pdev, PCI_VENDOR_ID_ALIBABA,
>>> +						DWC_PCIE_VSEC_RAS_DES_ID);
>>> +		if (!vsec)
>>> +			continue;
>>> +
>>> +		pci_read_config_dword(pdev, vsec + PCI_VNDR_HEADER, &val);
>>> +		if (PCI_VNDR_HEADER_REV(val) != 0x04 ||
>>> +		    PCI_VNDR_HEADER_LEN(val) != 0x100)
>>> +			continue;
>>> +		pci_dbg(pdev,
>>> +			"Detected PCIe Vendor-Specific Extended Capability RAS DES\n");
>>> +
>>> +		bdf = PCI_DEVID(pdev->bus->number, pdev->devfn);
>>> +		name = devm_kasprintf(priv->dev, GFP_KERNEL, "dwc_rootport_%x",
>>> +				      bdf);
>>> +		if (!name)
>>> +			return -ENOMEM;
>>> +
>>> +		/* All checks passed, go go go */
>>> +		pcie_pmu = devm_kzalloc(&pdev->dev, sizeof(*pcie_pmu), GFP_KERNEL);
>>> +		if (!pcie_pmu) {
>>> +			pci_dev_put(pdev);  
>>
>> we need to call pci_dev_put on all the return branch below and above and after the for_each_pci_dev()
>> loop to keep the refcnt balance.
> 
> Good spot. I'd use a goto for this given there are lots of places.

Forgive me, it has been catched by other reviewers, I missed other return branches,
will fix it with goto.

> 
>>
>>> +			return -ENOMEM;
>>> +		}
>>> +
>>> +		pcie_pmu->pdev = pdev;
>>> +		pcie_pmu->ras_des = vsec;
>>> +		pcie_pmu->nr_lanes = pcie_get_width_cap(pdev);
>>> +		pcie_pmu->pmu = (struct pmu){
>>> +			.module		= THIS_MODULE,
>>> +			.attr_groups	= dwc_pcie_attr_groups,
>>> +			.capabilities	= PERF_PMU_CAP_NO_EXCLUDE,
>>> +			.task_ctx_nr	= perf_invalid_context,
>>> +			.event_init	= dwc_pcie_pmu_event_init,
>>> +			.add		= dwc_pcie_pmu_event_add,
>>> +			.del		= dwc_pcie_pmu_event_del,
>>> +			.start		= dwc_pcie_pmu_event_start,
>>> +			.stop		= dwc_pcie_pmu_event_stop,
>>> +			.read		= dwc_pcie_pmu_event_update,
>>> +		};
>>> +
>>> +		/* Add this instance to the list used by the offline callback */
>>> +		ret = cpuhp_state_add_instance(dwc_pcie_pmu_hp_state,
>>> +					       &pcie_pmu->cpuhp_node);
>>> +		if (ret) {
>>> +			pci_err(pcie_pmu->pdev,
>>> +				"Error %d registering hotplug @%x\n", ret, bdf);
>>> +			return ret;
>>> +		}
> 
> Here you mix non devm_ handling in mid way through a series of devm_ calls.
> Whilst I 'think' what you have here is fine, I prefer to minimize thinking
> whilst reviewing and using devm_add_action_or_reset() with callbacks
> in appropriate places would ensure automatic unwinding in the error
> path deals with everything in the reverse order of setup.
> 
> You just need two instances - one to unwind the cpuhp_state_add_instance() and
> one to unwind the perf_pmu_register()

Cool, devm_add_action_or_reset saves my life. I will use it.

>  
>>> +		ret = perf_pmu_register(&pcie_pmu->pmu, name, -1);
>>> +		if (ret) {
>>> +			pci_err(pcie_pmu->pdev,
>>> +				"Error %d registering PMU @%x\n", ret, bdf);
>>> +			cpuhp_state_remove_instance_nocalls(
>>> +				dwc_pcie_pmu_hp_state, &pcie_pmu->cpuhp_node);
>>> +			return ret;
>>> +		}
>>> +
>>> +		/* Add registered PMUs and unregister them when this driver remove */
>>> +		list_add(&pcie_pmu->pmu_node, &priv->pmu_nodes);
> 
> This handling would be replaced by the tracking devm is doing for us. So I think
> there will be no need for the list.

You are right, will remove it.

> 
>>> +	}
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +static int dwc_pcie_pmu_remove(struct platform_device *pdev)
>>> +{
>>> +	struct dwc_pcie_pmu_priv *priv = platform_get_drvdata(pdev);
>>> +	struct dwc_pcie_pmu *pcie_pmu;
>>> +
>>> +	list_for_each_entry(pcie_pmu, &priv->pmu_nodes, pmu_node) {
>>> +		cpuhp_state_remove_instance(dwc_pcie_pmu_hp_state,
>>> +					    &pcie_pmu->cpuhp_node);
>>> +		perf_pmu_unregister(&pcie_pmu->pmu);  
>>
>> should unregister the PMU first, keep the order reverse to __dwc_pcie_pmu_probe().
> These two could have been handled via appropriate devm_add_action_or_reset()
> above and let that infrastructure unwind for us in the error path.
> 
> If anyone fixes the whole pmu drivers aren't removable mess, then we will
> also end up with remove handling for free :)

As replied above, will use devm_add_action_or_reset.
> 
>>
>>> +	}
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +static int dwc_pcie_pmu_probe(struct platform_device *pdev)
>>> +{
>>> +	struct dwc_pcie_pmu_priv *priv;
>>> +	int ret;
>>> +
>>> +	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
>>> +	if (!priv)
>>> +		return -ENOMEM;
>>> +
>>> +	priv->dev = &pdev->dev;
>>> +	platform_set_drvdata(pdev, priv);
>>> +
>>> +	/* If one PMU registration fails, remove all. */
>>> +	ret = __dwc_pcie_pmu_probe(priv);
>>> +	if (ret) {
>>> +		dwc_pcie_pmu_remove(pdev);
> 
> There is a bit of mixing of devm and not here which makes things somewhat
> hard to reason about.  Perhaps take the whole unwind flow over to devm managed.
> See above.
> 

Got it, will do that.

>>> +		return ret;
>>> +	}
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +static void dwc_pcie_pmu_migrate(struct dwc_pcie_pmu *pcie_pmu, unsigned int cpu)
>>> +{
>>> +	/* This PMU does NOT support interrupt, just migrate context. */
>>> +	perf_pmu_migrate_context(&pcie_pmu->pmu, pcie_pmu->oncpu, cpu);
>>> +	pcie_pmu->oncpu = cpu;
>>> +}
>>> +
>>> +static int dwc_pcie_pmu_online_cpu(unsigned int cpu, struct hlist_node *cpuhp_node)
>>> +{
>>> +	struct dwc_pcie_pmu *pcie_pmu;
>>> +	struct pci_dev *pdev;
>>> +	int node;
>>> +
>>> +	pcie_pmu = hlist_entry_safe(cpuhp_node, struct dwc_pcie_pmu, cpuhp_node);
>>> +	pdev = pcie_pmu->pdev;
>>> +	node = dev_to_node(&pdev->dev);
>>> +
>>> +	if (node != NUMA_NO_NODE && cpu_to_node(pcie_pmu->oncpu) != node &&
> 
> Perhaps worth a comment on when you might see node == NUMA_NO_NODE?
> Beyond NUMA being entirely disabled, I'd hope that never happens and for that you
> might be able to use a compile time check.
> 
> I wonder if this can be simplified by a flag that says if we are already in the
> right node? Might be easier to follow than having similar dance in online and offline
> to figure that out.

Ok, I will add a comment for NUMA_NO_NODE. If no numa support, I think
any CPU is fine to bind.

pcie_pmu->on_cpu may be a good choise to be used as a flag, right? pcie_pmu->on_cpu
will be set as -1 when pcie_pmu is allocated and then check in
dwc_pcie_pmu_online_cpu() first.

Then, the code will be:

static int dwc_pcie_pmu_online_cpu(unsigned int cpu, struct hlist_node *cpuhp_node)
{
	struct dwc_pcie_pmu *pcie_pmu;
	struct pci_dev *pdev;
	int node;

	pcie_pmu = hlist_entry_safe(cpuhp_node, struct dwc_pcie_pmu, cpuhp_node);
	/* If another CPU is already managing this PMU, simply return. */
	if (pcie_pmu->on_cpu != -1)
		return 0;

	pdev = pcie_pmu->pdev;
	node = dev_to_node(&pdev->dev);

	/* Select the first CPU if no numa support. */
	if (node == NUMA_NO_NODE)
		pcie_pmu->on_cpu = cpu;
	else if (cpu_to_node(pcie_pmu->on_cpu) != node &&
		 cpu_to_node(cpu) == node)
		dwc_pcie_pmu_migrate(pcie_pmu, cpu);

	return 0;
}
> 
> 
>>> +	    cpu_to_node(cpu) == node)
>>> +		dwc_pcie_pmu_migrate(pcie_pmu, cpu);
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +static int dwc_pcie_pmu_offline_cpu(unsigned int cpu, struct hlist_node *cpuhp_node)
>>> +{
>>> +	struct dwc_pcie_pmu *pcie_pmu;
>>> +	struct pci_dev *pdev;
>>> +	int node;
>>> +	cpumask_t mask;
>>> +	unsigned int target;
>>> +
>>> +	pcie_pmu = hlist_entry_safe(cpuhp_node, struct dwc_pcie_pmu, cpuhp_node);
>>> +	if (cpu != pcie_pmu->oncpu)
>>> +		return 0;
>>> +
>>> +	pdev = pcie_pmu->pdev;
>>> +	node = dev_to_node(&pdev->dev);
>>> +	if (cpumask_and(&mask, cpumask_of_node(node), cpu_online_mask) &&
>>> +	    cpumask_andnot(&mask, &mask, cpumask_of(cpu)))
>>> +		target = cpumask_any(&mask);  
>>
>> The cpumask_of_node() only contains the online CPUs so this branch is redundant. For arm64
>> using arch_numa.c the node cpumask is updated in numa_{add, remove}_cpu() and for other
>> arthitecture the behaviour should keep consistenct. Please correct my if I'm wrong.

I am afraid that the behaviour is not consistenct among all arthitecture and cpumask_of_node()
may contains the offline CPUs.

cpu_online_mask  - has bit 'cpu' set iff cpu available to scheduler and it is updated by:

	set_cpu_online(cpu, true);
	set_cpu_online(cpu, false);


cpumask_of_node() is a interface for `node_to_cpumask_map` which is updated by

	numa_{add, remove}_cpu()


On arm64, when a CPU receives a IPI_CPU_STOP interrupt, local_cpu_stop will set current CPU offline,
but it will not be remove from cpumask_of_node.


For ARM64 and RISC-V arthitecture, numa_remove_cpu() and set_cpu_online(cpu, false)
are both executed in __cpu_disable() when a CPU is brought down. But for arm32, only
set_cpu_online(cpu, false) is called in __cpu_disable().


>>
>>> +	else
>>> +		target = cpumask_any_but(cpu_online_mask, cpu);
> 
> If following above suggestion, would set flag to say in wrong node here - and wherever
> you end up in a node to start with...

Based above, I will ignore this comment.

> 
> 
>>> +	if (target < nr_cpu_ids)
>>> +		dwc_pcie_pmu_migrate(pcie_pmu, target);
>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +static struct platform_driver dwc_pcie_pmu_driver = {
>>> +	.probe = dwc_pcie_pmu_probe,
>>> +	.remove = dwc_pcie_pmu_remove,
>>> +	.driver = {.name = "dwc_pcie_pmu",},
>>> +};
>>> +
>>> +static int __init dwc_pcie_pmu_init(void)
>>> +{
>>> +	int ret;
>>> +
>>> +	ret = cpuhp_setup_state_multi(CPUHP_AP_ONLINE_DYN,
>>> +				      "perf/dwc_pcie_pmu:online",
>>> +				      dwc_pcie_pmu_online_cpu,
>>> +				      dwc_pcie_pmu_offline_cpu);
>>> +	if (ret < 0)
>>> +		return ret;
>>> +
>>> +	dwc_pcie_pmu_hp_state = ret;
>>> +
>>> +	ret = platform_driver_register(&dwc_pcie_pmu_driver);
>>> +	if (ret) {
>>> +		cpuhp_remove_multi_state(dwc_pcie_pmu_hp_state);
>>> +		return ret;
>>> +	}
>>> +
>>> +	dwc_pcie_pmu_dev = platform_device_register_simple(
>>> +				"dwc_pcie_pmu", PLATFORM_DEVID_NONE, NULL, 0);
>>> +	if (IS_ERR(dwc_pcie_pmu_dev)) {
>>> +		platform_driver_unregister(&dwc_pcie_pmu_driver);  
>>
>> On failure we also need to remove cpuhp state as well.
> 
> I'd suggest using gotos and a single error handling block. That
> makes it both harder to forget things like this and easier to
> compare that block with what happens in exit() - so slightly 
> easier to review!

Given that we have a appropriate way to tear down the PMUs via devm_add_action_or_reset(),
I am going to remove the redundant probe/remove framework via platform_driver_{un}register().
for_each probe process in __dwc_pcie_pmu_probe() will be move into dwc_pcie_pmu_init().
Is it a better way?

Thank you very much for your valuable comments.

Best Regards,
Shuai

...


> >>> +
> >>> +static int dwc_pcie_pmu_online_cpu(unsigned int cpu, struct hlist_node *cpuhp_node)
> >>> +{
> >>> +	struct dwc_pcie_pmu *pcie_pmu;
> >>> +	struct pci_dev *pdev;
> >>> +	int node;
> >>> +
> >>> +	pcie_pmu = hlist_entry_safe(cpuhp_node, struct dwc_pcie_pmu, cpuhp_node);
> >>> +	pdev = pcie_pmu->pdev;
> >>> +	node = dev_to_node(&pdev->dev);
> >>> +
> >>> +	if (node != NUMA_NO_NODE && cpu_to_node(pcie_pmu->oncpu) != node &&  
> > 
> > Perhaps worth a comment on when you might see node == NUMA_NO_NODE?
> > Beyond NUMA being entirely disabled, I'd hope that never happens and for that you
> > might be able to use a compile time check.
> > 
> > I wonder if this can be simplified by a flag that says if we are already in the
> > right node? Might be easier to follow than having similar dance in online and offline
> > to figure that out.  
> 
> Ok, I will add a comment for NUMA_NO_NODE. If no numa support, I think
> any CPU is fine to bind.

Agreed. I would add a comment on that being the intent.

> 
> pcie_pmu->on_cpu may be a good choise to be used as a flag, right? pcie_pmu->on_cpu
> will be set as -1 when pcie_pmu is allocated and then check in
> dwc_pcie_pmu_online_cpu() first.

I think you still want to know whether it's in the right node - as maybe
there are no local CPUs available at startup.

> 
> Then, the code will be:
> 
> static int dwc_pcie_pmu_online_cpu(unsigned int cpu, struct hlist_node *cpuhp_node)
> {
> 	struct dwc_pcie_pmu *pcie_pmu;
> 	struct pci_dev *pdev;
> 	int node;
> 
> 	pcie_pmu = hlist_entry_safe(cpuhp_node, struct dwc_pcie_pmu, cpuhp_node);
> 	/* If another CPU is already managing this PMU, simply return. */
> 	if (pcie_pmu->on_cpu != -1)
> 		return 0;
> 
> 	pdev = pcie_pmu->pdev;
> 	node = dev_to_node(&pdev->dev);
> 
> 	/* Select the first CPU if no numa support. */
> 	if (node == NUMA_NO_NODE)
> 		pcie_pmu->on_cpu = cpu;
> 	else if (cpu_to_node(pcie_pmu->on_cpu) != node &&
> 		 cpu_to_node(cpu) == node)
> 		dwc_pcie_pmu_migrate(pcie_pmu, cpu);
> 
> 	return 0;
> }
> > 
> >>> +static int __init dwc_pcie_pmu_init(void)
> >>> +{
> >>> +	int ret;
> >>> +
> >>> +	ret = cpuhp_setup_state_multi(CPUHP_AP_ONLINE_DYN,
> >>> +				      "perf/dwc_pcie_pmu:online",
> >>> +				      dwc_pcie_pmu_online_cpu,
> >>> +				      dwc_pcie_pmu_offline_cpu);
> >>> +	if (ret < 0)
> >>> +		return ret;
> >>> +
> >>> +	dwc_pcie_pmu_hp_state = ret;
> >>> +
> >>> +	ret = platform_driver_register(&dwc_pcie_pmu_driver);
> >>> +	if (ret) {
> >>> +		cpuhp_remove_multi_state(dwc_pcie_pmu_hp_state);
> >>> +		return ret;
> >>> +	}
> >>> +
> >>> +	dwc_pcie_pmu_dev = platform_device_register_simple(
> >>> +				"dwc_pcie_pmu", PLATFORM_DEVID_NONE, NULL, 0);
> >>> +	if (IS_ERR(dwc_pcie_pmu_dev)) {
> >>> +		platform_driver_unregister(&dwc_pcie_pmu_driver);    
> >>
> >> On failure we also need to remove cpuhp state as well.  
> > 
> > I'd suggest using gotos and a single error handling block. That
> > makes it both harder to forget things like this and easier to
> > compare that block with what happens in exit() - so slightly 
> > easier to review!  
> 
> Given that we have a appropriate way to tear down the PMUs via devm_add_action_or_reset(),
> I am going to remove the redundant probe/remove framework via platform_driver_{un}register().
> for_each probe process in __dwc_pcie_pmu_probe() will be move into dwc_pcie_pmu_init().
> Is it a better way?

I think I'd prefer to see a standard driver creation / probe flow even if you could in theory
avoid it.

Jonathan

> 
> Thank you very much for your valuable comments.
> 
> Best Regards,
> Shuai
> 
>

On 2023/7/28 20:41, Shuai Xue wrote:
> 
> 
> On 2023/7/27 17:39, Jonathan Cameron wrote:
>> On Tue, 6 Jun 2023 23:14:07 +0800
>> Yicong Yang <yangyicong@huawei.com> wrote:
>>
>>> On 2023/6/6 15:49, Shuai Xue wrote:
>>>> This commit adds the PCIe Performance Monitoring Unit (PMU) driver support
>>>> for T-Head Yitian SoC chip. Yitian is based on the Synopsys PCI Express
>>>> Core controller IP which provides statistics feature. The PMU is not a PCIe
>>>> Root Complex integrated End Point(RCiEP) device but only register counters
>>>> provided by each PCIe Root Port.
>>>>
>>>> To facilitate collection of statistics the controller provides the
>>>> following two features for each Root Port:
>>>>
>>>> - Time Based Analysis (RX/TX data throughput and time spent in each
>>>>   low-power LTSSM state)
>>>> - Event counters (Error and Non-Error for lanes)
>>>>
>>>> Note, only one counter for each type and does not overflow interrupt.
>>>>
>>>> This driver adds PMU devices for each PCIe Root Port. And the PMU device is
>>>> named based the BDF of Root Port. For example,
>>>>
>>>>     30:03.0 PCI bridge: Device 1ded:8000 (rev 01)
>>>>
>>>> the PMU device name for this Root Port is dwc_rootport_3018.
>>>>
>>>> Example usage of counting PCIe RX TLP data payload (Units of 16 bytes)::
>>>>
>>>>     $# perf stat -a -e dwc_rootport_3018/Rx_PCIe_TLP_Data_Payload/
>>>>
>>>> average RX bandwidth can be calculated like this:
>>>>
>>>>     PCIe TX Bandwidth = PCIE_TX_DATA * 16B / Measure_Time_Window
>>>>
>>>> Signed-off-by: Shuai Xue <xueshuai@linux.alibaba.com>
>>>> Reported-by: kernel test robot <lkp@intel.com>
>>>> Link: https://lore.kernel.org/oe-kbuild-all/202305170639.XU3djFZX-lkp@intel.com/
>>>> Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
>>
>> I'll review on top to avoid any duplication with Yicong.
> 
> Thank you! It also served as a reminder that I missed Yicong's email. It appears
> that Thunderbird mistakenly moved his email to the junk folder, resulting in me
> overlooking it.
> 
>>
>> Note I've cropped the stuff neither of us commented on so it's
>> easier to spot the feedback.
> 
> Thank you for noting that. My feedback is replied inline.
> 
>>
>> Jonathan
>>
>>>> ---
>>>>  drivers/perf/Kconfig        |   7 +
>>>>  drivers/perf/Makefile       |   1 +
>>>>  drivers/perf/dwc_pcie_pmu.c | 706 ++++++++++++++++++++++++++++++++++++
>>>>  3 files changed, 714 insertions(+)
>>>>  create mode 100644 drivers/perf/dwc_pcie_pmu.c
>>>>
>>>> diff --git a/drivers/perf/Kconfig b/drivers/perf/Kconfig
>>>> index 711f82400086..6ff3921d7a62 100644
>>>> --- a/drivers/perf/Kconfig
>>>> +++ b/drivers/perf/Kconfig
>>>> @@ -209,6 +209,13 @@ config MARVELL_CN10K_DDR_PMU
>>>>  	  Enable perf support for Marvell DDR Performance monitoring
>>>>  	  event on CN10K platform.
>>>>  
>>>> +config DWC_PCIE_PMU
>>>> +	tristate "Enable Synopsys DesignWare PCIe PMU Support"
>>>> +	depends on (ARM64 && PCI)
>>>> +	help
>>>> +	  Enable perf support for Synopsys DesignWare PCIe PMU Performance
>>>> +	  monitoring event on Yitian 710 platform.
>>
>> The documentation kind of implies this isn't platform specific.
>> If some parts are (such as which events exist) then you may want to push
>> that to userspace / perftool with appropriate matching against specific SoC.
>>
>> If it is generic, then change this text to "event on platform including the Yitian 710."
> 
> It is generic without any platform specific, so I will change it as you expected.
> 
>>
>>>> +
>>>>  source "drivers/perf/arm_cspmu/Kconfig"
>>>>  
>>>>  source "drivers/perf/amlogic/Kconfig"
>>
>>>> new file mode 100644
>>>> index 000000000000..8bfcf6e0662d
>>>> --- /dev/null
>>>> +++ b/drivers/perf/dwc_pcie_pmu.c
>>>> @@ -0,0 +1,706 @@
>>
>> ...
>>
>>>> +
>>>> +struct dwc_pcie_pmu {
>>>> +	struct pci_dev		*pdev;		/* Root Port device */  
>>>
>>> If the root port removed after the probe of this PCIe PMU driver, we'll access the NULL
>>> pointer. I didn't see you hold the root port to avoid the removal.
> 
> Do you mean that I should have a reference count of rootport by pci_dev_get() when allocating
> pcie_pmu?
> 
>      pcie_pmu->pdev = pci_dev_get();

It could be one option, but will block the removal of device from userspace. Another option
is to register a PCI bus notifier then on removal/added the driver can get notified and handle
it, for example, remove the related PMU on the removal of the root ports.

On 2023/8/1 19:46, Yicong Yang wrote:
> On 2023/7/28 20:41, Shuai Xue wrote:
>>
>>
>> On 2023/7/27 17:39, Jonathan Cameron wrote:
>>> On Tue, 6 Jun 2023 23:14:07 +0800
>>> Yicong Yang <yangyicong@huawei.com> wrote:
>>>
>>>> On 2023/6/6 15:49, Shuai Xue wrote:
>>>>> This commit adds the PCIe Performance Monitoring Unit (PMU) driver support
>>>>> for T-Head Yitian SoC chip. Yitian is based on the Synopsys PCI Express
>>>>> Core controller IP which provides statistics feature. The PMU is not a PCIe
>>>>> Root Complex integrated End Point(RCiEP) device but only register counters
>>>>> provided by each PCIe Root Port.
>>>>>
>>>>> To facilitate collection of statistics the controller provides the
>>>>> following two features for each Root Port:
>>>>>
>>>>> - Time Based Analysis (RX/TX data throughput and time spent in each
>>>>>   low-power LTSSM state)
>>>>> - Event counters (Error and Non-Error for lanes)
>>>>>
>>>>> Note, only one counter for each type and does not overflow interrupt.
>>>>>
>>>>> This driver adds PMU devices for each PCIe Root Port. And the PMU device is
>>>>> named based the BDF of Root Port. For example,
>>>>>
>>>>>     30:03.0 PCI bridge: Device 1ded:8000 (rev 01)
>>>>>
>>>>> the PMU device name for this Root Port is dwc_rootport_3018.
>>>>>
>>>>> Example usage of counting PCIe RX TLP data payload (Units of 16 bytes)::
>>>>>
>>>>>     $# perf stat -a -e dwc_rootport_3018/Rx_PCIe_TLP_Data_Payload/
>>>>>
>>>>> average RX bandwidth can be calculated like this:
>>>>>
>>>>>     PCIe TX Bandwidth = PCIE_TX_DATA * 16B / Measure_Time_Window
>>>>>
>>>>> Signed-off-by: Shuai Xue <xueshuai@linux.alibaba.com>
>>>>> Reported-by: kernel test robot <lkp@intel.com>
>>>>> Link: https://lore.kernel.org/oe-kbuild-all/202305170639.XU3djFZX-lkp@intel.com/
>>>>> Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
>>>
>>> I'll review on top to avoid any duplication with Yicong.
>>
>> Thank you! It also served as a reminder that I missed Yicong's email. It appears
>> that Thunderbird mistakenly moved his email to the junk folder, resulting in me
>> overlooking it.
>>
>>>
>>> Note I've cropped the stuff neither of us commented on so it's
>>> easier to spot the feedback.
>>
>> Thank you for noting that. My feedback is replied inline.
>>
>>>
>>> Jonathan
>>>
>>>>> ---
>>>>>  drivers/perf/Kconfig        |   7 +
>>>>>  drivers/perf/Makefile       |   1 +
>>>>>  drivers/perf/dwc_pcie_pmu.c | 706 ++++++++++++++++++++++++++++++++++++
>>>>>  3 files changed, 714 insertions(+)
>>>>>  create mode 100644 drivers/perf/dwc_pcie_pmu.c
>>>>>
>>>>> diff --git a/drivers/perf/Kconfig b/drivers/perf/Kconfig
>>>>> index 711f82400086..6ff3921d7a62 100644
>>>>> --- a/drivers/perf/Kconfig
>>>>> +++ b/drivers/perf/Kconfig
>>>>> @@ -209,6 +209,13 @@ config MARVELL_CN10K_DDR_PMU
>>>>>  	  Enable perf support for Marvell DDR Performance monitoring
>>>>>  	  event on CN10K platform.
>>>>>  
>>>>> +config DWC_PCIE_PMU
>>>>> +	tristate "Enable Synopsys DesignWare PCIe PMU Support"
>>>>> +	depends on (ARM64 && PCI)
>>>>> +	help
>>>>> +	  Enable perf support for Synopsys DesignWare PCIe PMU Performance
>>>>> +	  monitoring event on Yitian 710 platform.
>>>
>>> The documentation kind of implies this isn't platform specific.
>>> If some parts are (such as which events exist) then you may want to push
>>> that to userspace / perftool with appropriate matching against specific SoC.
>>>
>>> If it is generic, then change this text to "event on platform including the Yitian 710."
>>
>> It is generic without any platform specific, so I will change it as you expected.
>>
>>>
>>>>> +
>>>>>  source "drivers/perf/arm_cspmu/Kconfig"
>>>>>  
>>>>>  source "drivers/perf/amlogic/Kconfig"
>>>
>>>>> new file mode 100644
>>>>> index 000000000000..8bfcf6e0662d
>>>>> --- /dev/null
>>>>> +++ b/drivers/perf/dwc_pcie_pmu.c
>>>>> @@ -0,0 +1,706 @@
>>>
>>> ...
>>>
>>>>> +
>>>>> +struct dwc_pcie_pmu {
>>>>> +	struct pci_dev		*pdev;		/* Root Port device */  
>>>>
>>>> If the root port removed after the probe of this PCIe PMU driver, we'll access the NULL
>>>> pointer. I didn't see you hold the root port to avoid the removal.
>>
>> Do you mean that I should have a reference count of rootport by pci_dev_get() when allocating
>> pcie_pmu?
>>
>>      pcie_pmu->pdev = pci_dev_get();
> 
> It could be one option, but will block the removal of device from userspace. Another option
> is to register a PCI bus notifier then on removal/added the driver can get notified and handle
> it, for example, remove the related PMU on the removal of the root ports.

I see, but can root port be removed from userspace? I check the hotplug slot interface, no root
port is available to power off.

Thank you.

Best Regards,
Shuai

On 2023/8/4 9:39, Shuai Xue wrote:
> 
> 
> On 2023/8/1 19:46, Yicong Yang wrote:
>> On 2023/7/28 20:41, Shuai Xue wrote:
>>>
>>>
>>> On 2023/7/27 17:39, Jonathan Cameron wrote:
>>>> On Tue, 6 Jun 2023 23:14:07 +0800
>>>> Yicong Yang <yangyicong@huawei.com> wrote:
>>>>
>>>>> On 2023/6/6 15:49, Shuai Xue wrote:
>>>>>> This commit adds the PCIe Performance Monitoring Unit (PMU) driver support
>>>>>> for T-Head Yitian SoC chip. Yitian is based on the Synopsys PCI Express
>>>>>> Core controller IP which provides statistics feature. The PMU is not a PCIe
>>>>>> Root Complex integrated End Point(RCiEP) device but only register counters
>>>>>> provided by each PCIe Root Port.
>>>>>>
>>>>>> To facilitate collection of statistics the controller provides the
>>>>>> following two features for each Root Port:
>>>>>>
>>>>>> - Time Based Analysis (RX/TX data throughput and time spent in each
>>>>>>   low-power LTSSM state)
>>>>>> - Event counters (Error and Non-Error for lanes)
>>>>>>
>>>>>> Note, only one counter for each type and does not overflow interrupt.
>>>>>>
>>>>>> This driver adds PMU devices for each PCIe Root Port. And the PMU device is
>>>>>> named based the BDF of Root Port. For example,
>>>>>>
>>>>>>     30:03.0 PCI bridge: Device 1ded:8000 (rev 01)
>>>>>>
>>>>>> the PMU device name for this Root Port is dwc_rootport_3018.
>>>>>>
>>>>>> Example usage of counting PCIe RX TLP data payload (Units of 16 bytes)::
>>>>>>
>>>>>>     $# perf stat -a -e dwc_rootport_3018/Rx_PCIe_TLP_Data_Payload/
>>>>>>
>>>>>> average RX bandwidth can be calculated like this:
>>>>>>
>>>>>>     PCIe TX Bandwidth = PCIE_TX_DATA * 16B / Measure_Time_Window
>>>>>>
>>>>>> Signed-off-by: Shuai Xue <xueshuai@linux.alibaba.com>
>>>>>> Reported-by: kernel test robot <lkp@intel.com>
>>>>>> Link: https://lore.kernel.org/oe-kbuild-all/202305170639.XU3djFZX-lkp@intel.com/
>>>>>> Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
>>>>
>>>> I'll review on top to avoid any duplication with Yicong.
>>>
>>> Thank you! It also served as a reminder that I missed Yicong's email. It appears
>>> that Thunderbird mistakenly moved his email to the junk folder, resulting in me
>>> overlooking it.
>>>
>>>>
>>>> Note I've cropped the stuff neither of us commented on so it's
>>>> easier to spot the feedback.
>>>
>>> Thank you for noting that. My feedback is replied inline.
>>>
>>>>
>>>> Jonathan
>>>>
>>>>>> ---
>>>>>>  drivers/perf/Kconfig        |   7 +
>>>>>>  drivers/perf/Makefile       |   1 +
>>>>>>  drivers/perf/dwc_pcie_pmu.c | 706 ++++++++++++++++++++++++++++++++++++
>>>>>>  3 files changed, 714 insertions(+)
>>>>>>  create mode 100644 drivers/perf/dwc_pcie_pmu.c
>>>>>>
>>>>>> diff --git a/drivers/perf/Kconfig b/drivers/perf/Kconfig
>>>>>> index 711f82400086..6ff3921d7a62 100644
>>>>>> --- a/drivers/perf/Kconfig
>>>>>> +++ b/drivers/perf/Kconfig
>>>>>> @@ -209,6 +209,13 @@ config MARVELL_CN10K_DDR_PMU
>>>>>>  	  Enable perf support for Marvell DDR Performance monitoring
>>>>>>  	  event on CN10K platform.
>>>>>>  
>>>>>> +config DWC_PCIE_PMU
>>>>>> +	tristate "Enable Synopsys DesignWare PCIe PMU Support"
>>>>>> +	depends on (ARM64 && PCI)
>>>>>> +	help
>>>>>> +	  Enable perf support for Synopsys DesignWare PCIe PMU Performance
>>>>>> +	  monitoring event on Yitian 710 platform.
>>>>
>>>> The documentation kind of implies this isn't platform specific.
>>>> If some parts are (such as which events exist) then you may want to push
>>>> that to userspace / perftool with appropriate matching against specific SoC.
>>>>
>>>> If it is generic, then change this text to "event on platform including the Yitian 710."
>>>
>>> It is generic without any platform specific, so I will change it as you expected.
>>>
>>>>
>>>>>> +
>>>>>>  source "drivers/perf/arm_cspmu/Kconfig"
>>>>>>  
>>>>>>  source "drivers/perf/amlogic/Kconfig"
>>>>
>>>>>> new file mode 100644
>>>>>> index 000000000000..8bfcf6e0662d
>>>>>> --- /dev/null
>>>>>> +++ b/drivers/perf/dwc_pcie_pmu.c
>>>>>> @@ -0,0 +1,706 @@
>>>>
>>>> ...
>>>>
>>>>>> +
>>>>>> +struct dwc_pcie_pmu {
>>>>>> +	struct pci_dev		*pdev;		/* Root Port device */  
>>>>>
>>>>> If the root port removed after the probe of this PCIe PMU driver, we'll access the NULL
>>>>> pointer. I didn't see you hold the root port to avoid the removal.
>>>
>>> Do you mean that I should have a reference count of rootport by pci_dev_get() when allocating
>>> pcie_pmu?
>>>
>>>      pcie_pmu->pdev = pci_dev_get();
>>
>> It could be one option, but will block the removal of device from userspace. Another option
>> is to register a PCI bus notifier then on removal/added the driver can get notified and handle
>> it, for example, remove the related PMU on the removal of the root ports.
> 
> I see, but can root port be removed from userspace? I check the hotplug slot interface, no root
> port is available to power off.
> 

For hotplug maybe not, but user can remove certian device through sysfs:

echo 1 > /sys/bus/pci/devices/<root port>/remove

Thanks.

On 2023/8/4 10:28, Yicong Yang wrote:
> On 2023/8/4 9:39, Shuai Xue wrote:
>>
>>
>> On 2023/8/1 19:46, Yicong Yang wrote:
>>> On 2023/7/28 20:41, Shuai Xue wrote:
>>>>
>>>>
>>>> On 2023/7/27 17:39, Jonathan Cameron wrote:
>>>>> On Tue, 6 Jun 2023 23:14:07 +0800
>>>>> Yicong Yang <yangyicong@huawei.com> wrote:
>>>>>
>>>>>> On 2023/6/6 15:49, Shuai Xue wrote:
>>>>>>> This commit adds the PCIe Performance Monitoring Unit (PMU) driver support
>>>>>>> for T-Head Yitian SoC chip. Yitian is based on the Synopsys PCI Express
>>>>>>> Core controller IP which provides statistics feature. The PMU is not a PCIe
>>>>>>> Root Complex integrated End Point(RCiEP) device but only register counters
>>>>>>> provided by each PCIe Root Port.
>>>>>>>
>>>>>>> To facilitate collection of statistics the controller provides the
>>>>>>> following two features for each Root Port:
>>>>>>>
>>>>>>> - Time Based Analysis (RX/TX data throughput and time spent in each
>>>>>>>   low-power LTSSM state)
>>>>>>> - Event counters (Error and Non-Error for lanes)
>>>>>>>
>>>>>>> Note, only one counter for each type and does not overflow interrupt.
>>>>>>>
>>>>>>> This driver adds PMU devices for each PCIe Root Port. And the PMU device is
>>>>>>> named based the BDF of Root Port. For example,
>>>>>>>
>>>>>>>     30:03.0 PCI bridge: Device 1ded:8000 (rev 01)
>>>>>>>
>>>>>>> the PMU device name for this Root Port is dwc_rootport_3018.
>>>>>>>
>>>>>>> Example usage of counting PCIe RX TLP data payload (Units of 16 bytes)::
>>>>>>>
>>>>>>>     $# perf stat -a -e dwc_rootport_3018/Rx_PCIe_TLP_Data_Payload/
>>>>>>>
>>>>>>> average RX bandwidth can be calculated like this:
>>>>>>>
>>>>>>>     PCIe TX Bandwidth = PCIE_TX_DATA * 16B / Measure_Time_Window
>>>>>>>
>>>>>>> Signed-off-by: Shuai Xue <xueshuai@linux.alibaba.com>
>>>>>>> Reported-by: kernel test robot <lkp@intel.com>
>>>>>>> Link: https://lore.kernel.org/oe-kbuild-all/202305170639.XU3djFZX-lkp@intel.com/
>>>>>>> Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
>>>>>
>>>>> I'll review on top to avoid any duplication with Yicong.
>>>>
>>>> Thank you! It also served as a reminder that I missed Yicong's email. It appears
>>>> that Thunderbird mistakenly moved his email to the junk folder, resulting in me
>>>> overlooking it.
>>>>
>>>>>
>>>>> Note I've cropped the stuff neither of us commented on so it's
>>>>> easier to spot the feedback.
>>>>
>>>> Thank you for noting that. My feedback is replied inline.
>>>>
>>>>>
>>>>> Jonathan
>>>>>
>>>>>>> ---
>>>>>>>  drivers/perf/Kconfig        |   7 +
>>>>>>>  drivers/perf/Makefile       |   1 +
>>>>>>>  drivers/perf/dwc_pcie_pmu.c | 706 ++++++++++++++++++++++++++++++++++++
>>>>>>>  3 files changed, 714 insertions(+)
>>>>>>>  create mode 100644 drivers/perf/dwc_pcie_pmu.c
>>>>>>>
>>>>>>> diff --git a/drivers/perf/Kconfig b/drivers/perf/Kconfig
>>>>>>> index 711f82400086..6ff3921d7a62 100644
>>>>>>> --- a/drivers/perf/Kconfig
>>>>>>> +++ b/drivers/perf/Kconfig
>>>>>>> @@ -209,6 +209,13 @@ config MARVELL_CN10K_DDR_PMU
>>>>>>>  	  Enable perf support for Marvell DDR Performance monitoring
>>>>>>>  	  event on CN10K platform.
>>>>>>>  
>>>>>>> +config DWC_PCIE_PMU
>>>>>>> +	tristate "Enable Synopsys DesignWare PCIe PMU Support"
>>>>>>> +	depends on (ARM64 && PCI)
>>>>>>> +	help
>>>>>>> +	  Enable perf support for Synopsys DesignWare PCIe PMU Performance
>>>>>>> +	  monitoring event on Yitian 710 platform.
>>>>>
>>>>> The documentation kind of implies this isn't platform specific.
>>>>> If some parts are (such as which events exist) then you may want to push
>>>>> that to userspace / perftool with appropriate matching against specific SoC.
>>>>>
>>>>> If it is generic, then change this text to "event on platform including the Yitian 710."
>>>>
>>>> It is generic without any platform specific, so I will change it as you expected.
>>>>
>>>>>
>>>>>>> +
>>>>>>>  source "drivers/perf/arm_cspmu/Kconfig"
>>>>>>>  
>>>>>>>  source "drivers/perf/amlogic/Kconfig"
>>>>>
>>>>>>> new file mode 100644
>>>>>>> index 000000000000..8bfcf6e0662d
>>>>>>> --- /dev/null
>>>>>>> +++ b/drivers/perf/dwc_pcie_pmu.c
>>>>>>> @@ -0,0 +1,706 @@
>>>>>
>>>>> ...
>>>>>
>>>>>>> +
>>>>>>> +struct dwc_pcie_pmu {
>>>>>>> +	struct pci_dev		*pdev;		/* Root Port device */  
>>>>>>
>>>>>> If the root port removed after the probe of this PCIe PMU driver, we'll access the NULL
>>>>>> pointer. I didn't see you hold the root port to avoid the removal.
>>>>
>>>> Do you mean that I should have a reference count of rootport by pci_dev_get() when allocating
>>>> pcie_pmu?
>>>>
>>>>      pcie_pmu->pdev = pci_dev_get();
>>>
>>> It could be one option, but will block the removal of device from userspace. Another option
>>> is to register a PCI bus notifier then on removal/added the driver can get notified and handle
>>> it, for example, remove the related PMU on the removal of the root ports.
>>
>> I see, but can root port be removed from userspace? I check the hotplug slot interface, no root
>> port is available to power off.
>>
> 
> For hotplug maybe not, but user can remove certian device through sysfs:
> 
> echo 1 > /sys/bus/pci/devices/<root port>/remove
> 

Thank you, I will add a notifier for removal/added action.

Best Regards,
Shuai

On 2023/8/4 11:09, Shuai Xue wrote:
> 
> 
> On 2023/8/4 10:28, Yicong Yang wrote:
>> On 2023/8/4 9:39, Shuai Xue wrote:
>>>
>>>
>>> On 2023/8/1 19:46, Yicong Yang wrote:
>>>> On 2023/7/28 20:41, Shuai Xue wrote:
>>>>>
>>>>>
>>>>> On 2023/7/27 17:39, Jonathan Cameron wrote:
>>>>>> On Tue, 6 Jun 2023 23:14:07 +0800
>>>>>> Yicong Yang <yangyicong@huawei.com> wrote:
>>>>>>
>>>>>>> On 2023/6/6 15:49, Shuai Xue wrote:
>>>>>>>> This commit adds the PCIe Performance Monitoring Unit (PMU) driver support
>>>>>>>> for T-Head Yitian SoC chip. Yitian is based on the Synopsys PCI Express
>>>>>>>> Core controller IP which provides statistics feature. The PMU is not a PCIe
>>>>>>>> Root Complex integrated End Point(RCiEP) device but only register counters
>>>>>>>> provided by each PCIe Root Port.
>>>>>>>>
>>>>>>>> To facilitate collection of statistics the controller provides the
>>>>>>>> following two features for each Root Port:
>>>>>>>>
>>>>>>>> - Time Based Analysis (RX/TX data throughput and time spent in each
>>>>>>>>   low-power LTSSM state)
>>>>>>>> - Event counters (Error and Non-Error for lanes)
>>>>>>>>
>>>>>>>> Note, only one counter for each type and does not overflow interrupt.
>>>>>>>>
>>>>>>>> This driver adds PMU devices for each PCIe Root Port. And the PMU device is
>>>>>>>> named based the BDF of Root Port. For example,
>>>>>>>>
>>>>>>>>     30:03.0 PCI bridge: Device 1ded:8000 (rev 01)
>>>>>>>>
>>>>>>>> the PMU device name for this Root Port is dwc_rootport_3018.
>>>>>>>>
>>>>>>>> Example usage of counting PCIe RX TLP data payload (Units of 16 bytes)::
>>>>>>>>
>>>>>>>>     $# perf stat -a -e dwc_rootport_3018/Rx_PCIe_TLP_Data_Payload/
>>>>>>>>
>>>>>>>> average RX bandwidth can be calculated like this:
>>>>>>>>
>>>>>>>>     PCIe TX Bandwidth = PCIE_TX_DATA * 16B / Measure_Time_Window
>>>>>>>>
>>>>>>>> Signed-off-by: Shuai Xue <xueshuai@linux.alibaba.com>
>>>>>>>> Reported-by: kernel test robot <lkp@intel.com>
>>>>>>>> Link: https://lore.kernel.org/oe-kbuild-all/202305170639.XU3djFZX-lkp@intel.com/
>>>>>>>> Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
>>>>>>
>>>>>> I'll review on top to avoid any duplication with Yicong.
>>>>>
>>>>> Thank you! It also served as a reminder that I missed Yicong's email. It appears
>>>>> that Thunderbird mistakenly moved his email to the junk folder, resulting in me
>>>>> overlooking it.
>>>>>
>>>>>>
>>>>>> Note I've cropped the stuff neither of us commented on so it's
>>>>>> easier to spot the feedback.
>>>>>
>>>>> Thank you for noting that. My feedback is replied inline.
>>>>>
>>>>>>
>>>>>> Jonathan
>>>>>>
>>>>>>>> ---
>>>>>>>>  drivers/perf/Kconfig        |   7 +
>>>>>>>>  drivers/perf/Makefile       |   1 +
>>>>>>>>  drivers/perf/dwc_pcie_pmu.c | 706 ++++++++++++++++++++++++++++++++++++
>>>>>>>>  3 files changed, 714 insertions(+)
>>>>>>>>  create mode 100644 drivers/perf/dwc_pcie_pmu.c
>>>>>>>>
>>>>>>>> diff --git a/drivers/perf/Kconfig b/drivers/perf/Kconfig
>>>>>>>> index 711f82400086..6ff3921d7a62 100644
>>>>>>>> --- a/drivers/perf/Kconfig
>>>>>>>> +++ b/drivers/perf/Kconfig
>>>>>>>> @@ -209,6 +209,13 @@ config MARVELL_CN10K_DDR_PMU
>>>>>>>>  	  Enable perf support for Marvell DDR Performance monitoring
>>>>>>>>  	  event on CN10K platform.
>>>>>>>>  
>>>>>>>> +config DWC_PCIE_PMU
>>>>>>>> +	tristate "Enable Synopsys DesignWare PCIe PMU Support"
>>>>>>>> +	depends on (ARM64 && PCI)
>>>>>>>> +	help
>>>>>>>> +	  Enable perf support for Synopsys DesignWare PCIe PMU Performance
>>>>>>>> +	  monitoring event on Yitian 710 platform.
>>>>>>
>>>>>> The documentation kind of implies this isn't platform specific.
>>>>>> If some parts are (such as which events exist) then you may want to push
>>>>>> that to userspace / perftool with appropriate matching against specific SoC.
>>>>>>
>>>>>> If it is generic, then change this text to "event on platform including the Yitian 710."
>>>>>
>>>>> It is generic without any platform specific, so I will change it as you expected.
>>>>>
>>>>>>
>>>>>>>> +
>>>>>>>>  source "drivers/perf/arm_cspmu/Kconfig"
>>>>>>>>  
>>>>>>>>  source "drivers/perf/amlogic/Kconfig"
>>>>>>
>>>>>>>> new file mode 100644
>>>>>>>> index 000000000000..8bfcf6e0662d
>>>>>>>> --- /dev/null
>>>>>>>> +++ b/drivers/perf/dwc_pcie_pmu.c
>>>>>>>> @@ -0,0 +1,706 @@
>>>>>>
>>>>>> ...
>>>>>>
>>>>>>>> +
>>>>>>>> +struct dwc_pcie_pmu {
>>>>>>>> +	struct pci_dev		*pdev;		/* Root Port device */  
>>>>>>>
>>>>>>> If the root port removed after the probe of this PCIe PMU driver, we'll access the NULL
>>>>>>> pointer. I didn't see you hold the root port to avoid the removal.
>>>>>
>>>>> Do you mean that I should have a reference count of rootport by pci_dev_get() when allocating
>>>>> pcie_pmu?
>>>>>
>>>>>      pcie_pmu->pdev = pci_dev_get();
>>>>
>>>> It could be one option, but will block the removal of device from userspace. Another option
>>>> is to register a PCI bus notifier then on removal/added the driver can get notified and handle
>>>> it, for example, remove the related PMU on the removal of the root ports.
>>>
>>> I see, but can root port be removed from userspace? I check the hotplug slot interface, no root
>>> port is available to power off.
>>>
>>
>> For hotplug maybe not, but user can remove certian device through sysfs:
>>
>> echo 1 > /sys/bus/pci/devices/<root port>/remove
>>
> 
> Thank you, I will add a notifier for removal/added action.
> 
> Best Regards,
> Shuai

Hi, Yicong,

I am confused when adding a notifier by bus_register_notifier(). If I have added a action to
pdev->dev to unregister pmu:

		ret = perf_pmu_register(&pcie_pmu->pmu, name, -1);
		if (ret) {
			pci_err(pcie_pmu->pdev,
				"Error %d registering PMU @%x\n", ret, bdf);
			goto out;
		}
		ret = devm_add_action_or_reset(
			&pdev->dev, dwc_pcie_pmu_unregister_pmu, &pcie_pmu->pmu);

the pmu will be unregister when the port removes, so accessing the NULL pointer will never happen,
right? Do we still need the bus_register_notifier()?

Thank you.

Best Regards,
Shuai

On 2023/10/9 21:08, Shuai Xue wrote:
> 
> 
> On 2023/8/4 11:09, Shuai Xue wrote:
>>
>>
>> On 2023/8/4 10:28, Yicong Yang wrote:
>>> On 2023/8/4 9:39, Shuai Xue wrote:
>>>>
>>>>
>>>> On 2023/8/1 19:46, Yicong Yang wrote:
>>>>> On 2023/7/28 20:41, Shuai Xue wrote:
>>>>>>
>>>>>>
>>>>>> On 2023/7/27 17:39, Jonathan Cameron wrote:
>>>>>>> On Tue, 6 Jun 2023 23:14:07 +0800
>>>>>>> Yicong Yang <yangyicong@huawei.com> wrote:
>>>>>>>
>>>>>>>> On 2023/6/6 15:49, Shuai Xue wrote:
>>>>>>>>> This commit adds the PCIe Performance Monitoring Unit (PMU) driver support
>>>>>>>>> for T-Head Yitian SoC chip. Yitian is based on the Synopsys PCI Express
>>>>>>>>> Core controller IP which provides statistics feature. The PMU is not a PCIe
>>>>>>>>> Root Complex integrated End Point(RCiEP) device but only register counters
>>>>>>>>> provided by each PCIe Root Port.
>>>>>>>>>
>>>>>>>>> To facilitate collection of statistics the controller provides the
>>>>>>>>> following two features for each Root Port:
>>>>>>>>>
>>>>>>>>> - Time Based Analysis (RX/TX data throughput and time spent in each
>>>>>>>>>   low-power LTSSM state)
>>>>>>>>> - Event counters (Error and Non-Error for lanes)
>>>>>>>>>
>>>>>>>>> Note, only one counter for each type and does not overflow interrupt.
>>>>>>>>>
>>>>>>>>> This driver adds PMU devices for each PCIe Root Port. And the PMU device is
>>>>>>>>> named based the BDF of Root Port. For example,
>>>>>>>>>
>>>>>>>>>     30:03.0 PCI bridge: Device 1ded:8000 (rev 01)
>>>>>>>>>
>>>>>>>>> the PMU device name for this Root Port is dwc_rootport_3018.
>>>>>>>>>
>>>>>>>>> Example usage of counting PCIe RX TLP data payload (Units of 16 bytes)::
>>>>>>>>>
>>>>>>>>>     $# perf stat -a -e dwc_rootport_3018/Rx_PCIe_TLP_Data_Payload/
>>>>>>>>>
>>>>>>>>> average RX bandwidth can be calculated like this:
>>>>>>>>>
>>>>>>>>>     PCIe TX Bandwidth = PCIE_TX_DATA * 16B / Measure_Time_Window
>>>>>>>>>
>>>>>>>>> Signed-off-by: Shuai Xue <xueshuai@linux.alibaba.com>
>>>>>>>>> Reported-by: kernel test robot <lkp@intel.com>
>>>>>>>>> Link: https://lore.kernel.org/oe-kbuild-all/202305170639.XU3djFZX-lkp@intel.com/
>>>>>>>>> Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
>>>>>>>
>>>>>>> I'll review on top to avoid any duplication with Yicong.
>>>>>>
>>>>>> Thank you! It also served as a reminder that I missed Yicong's email. It appears
>>>>>> that Thunderbird mistakenly moved his email to the junk folder, resulting in me
>>>>>> overlooking it.
>>>>>>
>>>>>>>
>>>>>>> Note I've cropped the stuff neither of us commented on so it's
>>>>>>> easier to spot the feedback.
>>>>>>
>>>>>> Thank you for noting that. My feedback is replied inline.
>>>>>>
>>>>>>>
>>>>>>> Jonathan
>>>>>>>
>>>>>>>>> ---
>>>>>>>>>  drivers/perf/Kconfig        |   7 +
>>>>>>>>>  drivers/perf/Makefile       |   1 +
>>>>>>>>>  drivers/perf/dwc_pcie_pmu.c | 706 ++++++++++++++++++++++++++++++++++++
>>>>>>>>>  3 files changed, 714 insertions(+)
>>>>>>>>>  create mode 100644 drivers/perf/dwc_pcie_pmu.c
>>>>>>>>>
>>>>>>>>> diff --git a/drivers/perf/Kconfig b/drivers/perf/Kconfig
>>>>>>>>> index 711f82400086..6ff3921d7a62 100644
>>>>>>>>> --- a/drivers/perf/Kconfig
>>>>>>>>> +++ b/drivers/perf/Kconfig
>>>>>>>>> @@ -209,6 +209,13 @@ config MARVELL_CN10K_DDR_PMU
>>>>>>>>>  	  Enable perf support for Marvell DDR Performance monitoring
>>>>>>>>>  	  event on CN10K platform.
>>>>>>>>>  
>>>>>>>>> +config DWC_PCIE_PMU
>>>>>>>>> +	tristate "Enable Synopsys DesignWare PCIe PMU Support"
>>>>>>>>> +	depends on (ARM64 && PCI)
>>>>>>>>> +	help
>>>>>>>>> +	  Enable perf support for Synopsys DesignWare PCIe PMU Performance
>>>>>>>>> +	  monitoring event on Yitian 710 platform.
>>>>>>>
>>>>>>> The documentation kind of implies this isn't platform specific.
>>>>>>> If some parts are (such as which events exist) then you may want to push
>>>>>>> that to userspace / perftool with appropriate matching against specific SoC.
>>>>>>>
>>>>>>> If it is generic, then change this text to "event on platform including the Yitian 710."
>>>>>>
>>>>>> It is generic without any platform specific, so I will change it as you expected.
>>>>>>
>>>>>>>
>>>>>>>>> +
>>>>>>>>>  source "drivers/perf/arm_cspmu/Kconfig"
>>>>>>>>>  
>>>>>>>>>  source "drivers/perf/amlogic/Kconfig"
>>>>>>>
>>>>>>>>> new file mode 100644
>>>>>>>>> index 000000000000..8bfcf6e0662d
>>>>>>>>> --- /dev/null
>>>>>>>>> +++ b/drivers/perf/dwc_pcie_pmu.c
>>>>>>>>> @@ -0,0 +1,706 @@
>>>>>>>
>>>>>>> ...
>>>>>>>
>>>>>>>>> +
>>>>>>>>> +struct dwc_pcie_pmu {
>>>>>>>>> +	struct pci_dev		*pdev;		/* Root Port device */  
>>>>>>>>
>>>>>>>> If the root port removed after the probe of this PCIe PMU driver, we'll access the NULL
>>>>>>>> pointer. I didn't see you hold the root port to avoid the removal.
>>>>>>
>>>>>> Do you mean that I should have a reference count of rootport by pci_dev_get() when allocating
>>>>>> pcie_pmu?
>>>>>>
>>>>>>      pcie_pmu->pdev = pci_dev_get();
>>>>>
>>>>> It could be one option, but will block the removal of device from userspace. Another option
>>>>> is to register a PCI bus notifier then on removal/added the driver can get notified and handle
>>>>> it, for example, remove the related PMU on the removal of the root ports.
>>>>
>>>> I see, but can root port be removed from userspace? I check the hotplug slot interface, no root
>>>> port is available to power off.
>>>>
>>>
>>> For hotplug maybe not, but user can remove certian device through sysfs:
>>>
>>> echo 1 > /sys/bus/pci/devices/<root port>/remove
>>>
>>
>> Thank you, I will add a notifier for removal/added action.
>>
>> Best Regards,
>> Shuai
> 
> Hi, Yicong,
> 
> I am confused when adding a notifier by bus_register_notifier(). If I have added a action to
> pdev->dev to unregister pmu:
> 
> 		ret = perf_pmu_register(&pcie_pmu->pmu, name, -1);
> 		if (ret) {
> 			pci_err(pcie_pmu->pdev,
> 				"Error %d registering PMU @%x\n", ret, bdf);
> 			goto out;
> 		}
> 		ret = devm_add_action_or_reset(
> 			&pdev->dev, dwc_pcie_pmu_unregister_pmu, &pcie_pmu->pmu);
> 
> the pmu will be unregister when the port removes, so accessing the NULL pointer will never happen,
> right? Do we still need the bus_register_notifier()?
> 

Not necessary, a notifier is used to notice the device removal and avoid dereferencing the
NULL pointer. If you find another way like above to avoid the issue it will be ok. Since
your pmu is 1:1 related to the root port, add a devm action to unregister the PMU on root
port removal looks better.

Thanks.

On 2023/10/10 15:35, Yicong Yang wrote:
> On 2023/10/9 21:08, Shuai Xue wrote:
>>
>>
>> On 2023/8/4 11:09, Shuai Xue wrote:
>>>
>>>
>>> On 2023/8/4 10:28, Yicong Yang wrote:
>>>> On 2023/8/4 9:39, Shuai Xue wrote:
>>>>>
>>>>>
>>>>> On 2023/8/1 19:46, Yicong Yang wrote:
>>>>>> On 2023/7/28 20:41, Shuai Xue wrote:
>>>>>>>
>>>>>>>
>>>>>>> On 2023/7/27 17:39, Jonathan Cameron wrote:
>>>>>>>> On Tue, 6 Jun 2023 23:14:07 +0800
>>>>>>>> Yicong Yang <yangyicong@huawei.com> wrote:
>>>>>>>>
>>>>>>>>> On 2023/6/6 15:49, Shuai Xue wrote:
>>>>>>>>>> This commit adds the PCIe Performance Monitoring Unit (PMU) driver support
>>>>>>>>>> for T-Head Yitian SoC chip. Yitian is based on the Synopsys PCI Express
>>>>>>>>>> Core controller IP which provides statistics feature. The PMU is not a PCIe
>>>>>>>>>> Root Complex integrated End Point(RCiEP) device but only register counters
>>>>>>>>>> provided by each PCIe Root Port.
>>>>>>>>>>
>>>>>>>>>> To facilitate collection of statistics the controller provides the
>>>>>>>>>> following two features for each Root Port:
>>>>>>>>>>
>>>>>>>>>> - Time Based Analysis (RX/TX data throughput and time spent in each
>>>>>>>>>>   low-power LTSSM state)
>>>>>>>>>> - Event counters (Error and Non-Error for lanes)
>>>>>>>>>>
>>>>>>>>>> Note, only one counter for each type and does not overflow interrupt.
>>>>>>>>>>
>>>>>>>>>> This driver adds PMU devices for each PCIe Root Port. And the PMU device is
>>>>>>>>>> named based the BDF of Root Port. For example,
>>>>>>>>>>
>>>>>>>>>>     30:03.0 PCI bridge: Device 1ded:8000 (rev 01)
>>>>>>>>>>
>>>>>>>>>> the PMU device name for this Root Port is dwc_rootport_3018.
>>>>>>>>>>
>>>>>>>>>> Example usage of counting PCIe RX TLP data payload (Units of 16 bytes)::
>>>>>>>>>>
>>>>>>>>>>     $# perf stat -a -e dwc_rootport_3018/Rx_PCIe_TLP_Data_Payload/
>>>>>>>>>>
>>>>>>>>>> average RX bandwidth can be calculated like this:
>>>>>>>>>>
>>>>>>>>>>     PCIe TX Bandwidth = PCIE_TX_DATA * 16B / Measure_Time_Window
>>>>>>>>>>
>>>>>>>>>> Signed-off-by: Shuai Xue <xueshuai@linux.alibaba.com>
>>>>>>>>>> Reported-by: kernel test robot <lkp@intel.com>
>>>>>>>>>> Link: https://lore.kernel.org/oe-kbuild-all/202305170639.XU3djFZX-lkp@intel.com/
>>>>>>>>>> Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
>>>>>>>>
>>>>>>>> I'll review on top to avoid any duplication with Yicong.
>>>>>>>
>>>>>>> Thank you! It also served as a reminder that I missed Yicong's email. It appears
>>>>>>> that Thunderbird mistakenly moved his email to the junk folder, resulting in me
>>>>>>> overlooking it.
>>>>>>>
>>>>>>>>
>>>>>>>> Note I've cropped the stuff neither of us commented on so it's
>>>>>>>> easier to spot the feedback.
>>>>>>>
>>>>>>> Thank you for noting that. My feedback is replied inline.
>>>>>>>
>>>>>>>>
>>>>>>>> Jonathan
>>>>>>>>
>>>>>>>>>> ---
>>>>>>>>>>  drivers/perf/Kconfig        |   7 +
>>>>>>>>>>  drivers/perf/Makefile       |   1 +
>>>>>>>>>>  drivers/perf/dwc_pcie_pmu.c | 706 ++++++++++++++++++++++++++++++++++++
>>>>>>>>>>  3 files changed, 714 insertions(+)
>>>>>>>>>>  create mode 100644 drivers/perf/dwc_pcie_pmu.c
>>>>>>>>>>
>>>>>>>>>> diff --git a/drivers/perf/Kconfig b/drivers/perf/Kconfig
>>>>>>>>>> index 711f82400086..6ff3921d7a62 100644
>>>>>>>>>> --- a/drivers/perf/Kconfig
>>>>>>>>>> +++ b/drivers/perf/Kconfig
>>>>>>>>>> @@ -209,6 +209,13 @@ config MARVELL_CN10K_DDR_PMU
>>>>>>>>>>  	  Enable perf support for Marvell DDR Performance monitoring
>>>>>>>>>>  	  event on CN10K platform.
>>>>>>>>>>  
>>>>>>>>>> +config DWC_PCIE_PMU
>>>>>>>>>> +	tristate "Enable Synopsys DesignWare PCIe PMU Support"
>>>>>>>>>> +	depends on (ARM64 && PCI)
>>>>>>>>>> +	help
>>>>>>>>>> +	  Enable perf support for Synopsys DesignWare PCIe PMU Performance
>>>>>>>>>> +	  monitoring event on Yitian 710 platform.
>>>>>>>>
>>>>>>>> The documentation kind of implies this isn't platform specific.
>>>>>>>> If some parts are (such as which events exist) then you may want to push
>>>>>>>> that to userspace / perftool with appropriate matching against specific SoC.
>>>>>>>>
>>>>>>>> If it is generic, then change this text to "event on platform including the Yitian 710."
>>>>>>>
>>>>>>> It is generic without any platform specific, so I will change it as you expected.
>>>>>>>
>>>>>>>>
>>>>>>>>>> +
>>>>>>>>>>  source "drivers/perf/arm_cspmu/Kconfig"
>>>>>>>>>>  
>>>>>>>>>>  source "drivers/perf/amlogic/Kconfig"
>>>>>>>>
>>>>>>>>>> new file mode 100644
>>>>>>>>>> index 000000000000..8bfcf6e0662d
>>>>>>>>>> --- /dev/null
>>>>>>>>>> +++ b/drivers/perf/dwc_pcie_pmu.c
>>>>>>>>>> @@ -0,0 +1,706 @@
>>>>>>>>
>>>>>>>> ...
>>>>>>>>
>>>>>>>>>> +
>>>>>>>>>> +struct dwc_pcie_pmu {
>>>>>>>>>> +	struct pci_dev		*pdev;		/* Root Port device */  
>>>>>>>>>
>>>>>>>>> If the root port removed after the probe of this PCIe PMU driver, we'll access the NULL
>>>>>>>>> pointer. I didn't see you hold the root port to avoid the removal.
>>>>>>>
>>>>>>> Do you mean that I should have a reference count of rootport by pci_dev_get() when allocating
>>>>>>> pcie_pmu?
>>>>>>>
>>>>>>>      pcie_pmu->pdev = pci_dev_get();
>>>>>>
>>>>>> It could be one option, but will block the removal of device from userspace. Another option
>>>>>> is to register a PCI bus notifier then on removal/added the driver can get notified and handle
>>>>>> it, for example, remove the related PMU on the removal of the root ports.
>>>>>
>>>>> I see, but can root port be removed from userspace? I check the hotplug slot interface, no root
>>>>> port is available to power off.
>>>>>
>>>>
>>>> For hotplug maybe not, but user can remove certian device through sysfs:
>>>>
>>>> echo 1 > /sys/bus/pci/devices/<root port>/remove
>>>>
>>>
>>> Thank you, I will add a notifier for removal/added action.
>>>
>>> Best Regards,
>>> Shuai
>>
>> Hi, Yicong,
>>
>> I am confused when adding a notifier by bus_register_notifier(). If I have added a action to
>> pdev->dev to unregister pmu:
>>
>> 		ret = perf_pmu_register(&pcie_pmu->pmu, name, -1);
>> 		if (ret) {
>> 			pci_err(pcie_pmu->pdev,
>> 				"Error %d registering PMU @%x\n", ret, bdf);
>> 			goto out;
>> 		}
>> 		ret = devm_add_action_or_reset(
>> 			&pdev->dev, dwc_pcie_pmu_unregister_pmu, &pcie_pmu->pmu);
>>
>> the pmu will be unregister when the port removes, so accessing the NULL pointer will never happen,
>> right? Do we still need the bus_register_notifier()?
>>
> 
> Not necessary, a notifier is used to notice the device removal and avoid dereferencing the
> NULL pointer. If you find another way like above to avoid the issue it will be ok. Since
> your pmu is 1:1 related to the root port, add a devm action to unregister the PMU on root
> port removal looks better.
> 
> Thanks.

Hi, Yicong,

Got it. Thank you for your quick feedback:)

Best Regards.
Shuai