diff mbox series

[v2,2/5] iommu: Implement of_iommu_get_resv_regions()

Message ID 20210423163234.3651547-3-thierry.reding@gmail.com
State Not Applicable, archived
Headers show
Series iommu: Support identity mappings of reserved-memory regions | expand

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Commit Message

Thierry Reding April 23, 2021, 4:32 p.m. UTC 
From: Thierry Reding <treding@nvidia.com>

This is an implementation that IOMMU drivers can use to obtain reserved
memory regions from a device tree node. It uses the reserved-memory DT
bindings to find the regions associated with a given device. If these
regions are marked accordingly, identity mappings will be created for
them in the IOMMU domain that the devices will be attached to.

Cc: Frank Rowand <frowand.list@gmail.com>
Cc: devicetree@vger.kernel.org
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>
---
Changes in v3:
- change "active" property to identity mapping flag that is part of the
  memory region specifier (as defined by #memory-region-cells) to allow
  per-reference flags to be used

Changes in v2:
- use "active" property to determine whether direct mappings are needed
---
 drivers/iommu/of_iommu.c | 54 ++++++++++++++++++++++++++++++++++++++++
 include/linux/of_iommu.h |  8 ++++++
 2 files changed, 62 insertions(+)

Comments

Dmitry Osipenko July 2, 2021, 2:05 p.m. UTC | #1 
23.04.2021 19:32, Thierry Reding пишет:
> +void of_iommu_get_resv_regions(struct device *dev, struct list_head *list)
> +{
> +	struct of_phandle_iterator it;
> +	int err;
> +
> +	of_for_each_phandle(&it, err, dev->of_node, "memory-region", "#memory-region-cells", 0) {
> +		struct iommu_resv_region *region;
> +		struct of_phandle_args args;
> +		struct resource res;
> +
> +		args.args_count = of_phandle_iterator_args(&it, args.args, MAX_PHANDLE_ARGS);
> +
> +		err = of_address_to_resource(it.node, 0, &res);
> +		if (err < 0) {
> +			dev_err(dev, "failed to parse memory region %pOF: %d\n",
> +				it.node, err);
> +			continue;
> +		}
> +
> +		if (args.args_count > 0) {
> +			/*
> +			 * Active memory regions are expected to be accessed by hardware during
> +			 * boot and must therefore have an identity mapping created prior to the
> +			 * driver taking control of the hardware. This ensures that non-quiescent
> +			 * hardware doesn't cause IOMMU faults during boot.
> +			 */
> +			if (args.args[0] & MEMORY_REGION_IDENTITY_MAPPING) {
> +				region = iommu_alloc_resv_region(res.start, resource_size(&res),
> +								 IOMMU_READ | IOMMU_WRITE,
> +								 IOMMU_RESV_DIRECT_RELAXABLE);
> +				if (!region)
> +					continue;
> +
> +				list_add_tail(&region->list, list);
> +			}
> +		}
> +	}
> +}
> +EXPORT_SYMBOL(of_iommu_get_resv_regions);

Any reason why this is not EXPORT_SYMBOL_GPL? I'm curious what is the
logic behind the OF symbols in general since it looks like half of them
are GPL.
Rob Herring July 16, 2021, 2:41 p.m. UTC | #2 
On Fri, Jul 2, 2021 at 8:05 AM Dmitry Osipenko <digetx@gmail.com> wrote:
>
> 23.04.2021 19:32, Thierry Reding пишет:
> > +void of_iommu_get_resv_regions(struct device *dev, struct list_head *list)
> > +{
> > +     struct of_phandle_iterator it;
> > +     int err;
> > +
> > +     of_for_each_phandle(&it, err, dev->of_node, "memory-region", "#memory-region-cells", 0) {
> > +             struct iommu_resv_region *region;
> > +             struct of_phandle_args args;
> > +             struct resource res;
> > +
> > +             args.args_count = of_phandle_iterator_args(&it, args.args, MAX_PHANDLE_ARGS);
> > +
> > +             err = of_address_to_resource(it.node, 0, &res);
> > +             if (err < 0) {
> > +                     dev_err(dev, "failed to parse memory region %pOF: %d\n",
> > +                             it.node, err);
> > +                     continue;
> > +             }
> > +
> > +             if (args.args_count > 0) {
> > +                     /*
> > +                      * Active memory regions are expected to be accessed by hardware during
> > +                      * boot and must therefore have an identity mapping created prior to the
> > +                      * driver taking control of the hardware. This ensures that non-quiescent
> > +                      * hardware doesn't cause IOMMU faults during boot.
> > +                      */
> > +                     if (args.args[0] & MEMORY_REGION_IDENTITY_MAPPING) {
> > +                             region = iommu_alloc_resv_region(res.start, resource_size(&res),
> > +                                                              IOMMU_READ | IOMMU_WRITE,
> > +                                                              IOMMU_RESV_DIRECT_RELAXABLE);
> > +                             if (!region)
> > +                                     continue;
> > +
> > +                             list_add_tail(&region->list, list);
> > +                     }
> > +             }
> > +     }
> > +}
> > +EXPORT_SYMBOL(of_iommu_get_resv_regions);
>
> Any reason why this is not EXPORT_SYMBOL_GPL? I'm curious what is the
> logic behind the OF symbols in general since it looks like half of them
> are GPL.

Generally, new ones are _GPL. Old ones probably predate _GPL.

This one is up to the IOMMU maintainers.

Rob
Dmitry Osipenko July 17, 2021, 11:07 a.m. UTC | #3 
16.07.2021 17:41, Rob Herring пишет:
> On Fri, Jul 2, 2021 at 8:05 AM Dmitry Osipenko <digetx@gmail.com> wrote:
>>
>> 23.04.2021 19:32, Thierry Reding пишет:
>>> +void of_iommu_get_resv_regions(struct device *dev, struct list_head *list)
>>> +{
>>> +     struct of_phandle_iterator it;
>>> +     int err;
>>> +
>>> +     of_for_each_phandle(&it, err, dev->of_node, "memory-region", "#memory-region-cells", 0) {
>>> +             struct iommu_resv_region *region;
>>> +             struct of_phandle_args args;
>>> +             struct resource res;
>>> +
>>> +             args.args_count = of_phandle_iterator_args(&it, args.args, MAX_PHANDLE_ARGS);
>>> +
>>> +             err = of_address_to_resource(it.node, 0, &res);
>>> +             if (err < 0) {
>>> +                     dev_err(dev, "failed to parse memory region %pOF: %d\n",
>>> +                             it.node, err);
>>> +                     continue;
>>> +             }
>>> +
>>> +             if (args.args_count > 0) {
>>> +                     /*
>>> +                      * Active memory regions are expected to be accessed by hardware during
>>> +                      * boot and must therefore have an identity mapping created prior to the
>>> +                      * driver taking control of the hardware. This ensures that non-quiescent
>>> +                      * hardware doesn't cause IOMMU faults during boot.
>>> +                      */
>>> +                     if (args.args[0] & MEMORY_REGION_IDENTITY_MAPPING) {
>>> +                             region = iommu_alloc_resv_region(res.start, resource_size(&res),
>>> +                                                              IOMMU_READ | IOMMU_WRITE,
>>> +                                                              IOMMU_RESV_DIRECT_RELAXABLE);
>>> +                             if (!region)
>>> +                                     continue;
>>> +
>>> +                             list_add_tail(&region->list, list);
>>> +                     }
>>> +             }
>>> +     }
>>> +}
>>> +EXPORT_SYMBOL(of_iommu_get_resv_regions);
>>
>> Any reason why this is not EXPORT_SYMBOL_GPL? I'm curious what is the
>> logic behind the OF symbols in general since it looks like half of them
>> are GPL.
> 
> Generally, new ones are _GPL. Old ones probably predate _GPL.
> 
> This one is up to the IOMMU maintainers.

Thank you.
Will Deacon July 30, 2021, 12:18 p.m. UTC | #4 
On Sat, Jul 17, 2021 at 02:07:12PM +0300, Dmitry Osipenko wrote:
> 16.07.2021 17:41, Rob Herring пишет:
> > On Fri, Jul 2, 2021 at 8:05 AM Dmitry Osipenko <digetx@gmail.com> wrote:
> >>
> >> 23.04.2021 19:32, Thierry Reding пишет:
> >>> +void of_iommu_get_resv_regions(struct device *dev, struct list_head *list)
> >>> +{
> >>> +     struct of_phandle_iterator it;
> >>> +     int err;
> >>> +
> >>> +     of_for_each_phandle(&it, err, dev->of_node, "memory-region", "#memory-region-cells", 0) {
> >>> +             struct iommu_resv_region *region;
> >>> +             struct of_phandle_args args;
> >>> +             struct resource res;
> >>> +
> >>> +             args.args_count = of_phandle_iterator_args(&it, args.args, MAX_PHANDLE_ARGS);
> >>> +
> >>> +             err = of_address_to_resource(it.node, 0, &res);
> >>> +             if (err < 0) {
> >>> +                     dev_err(dev, "failed to parse memory region %pOF: %d\n",
> >>> +                             it.node, err);
> >>> +                     continue;
> >>> +             }
> >>> +
> >>> +             if (args.args_count > 0) {
> >>> +                     /*
> >>> +                      * Active memory regions are expected to be accessed by hardware during
> >>> +                      * boot and must therefore have an identity mapping created prior to the
> >>> +                      * driver taking control of the hardware. This ensures that non-quiescent
> >>> +                      * hardware doesn't cause IOMMU faults during boot.
> >>> +                      */
> >>> +                     if (args.args[0] & MEMORY_REGION_IDENTITY_MAPPING) {
> >>> +                             region = iommu_alloc_resv_region(res.start, resource_size(&res),
> >>> +                                                              IOMMU_READ | IOMMU_WRITE,
> >>> +                                                              IOMMU_RESV_DIRECT_RELAXABLE);
> >>> +                             if (!region)
> >>> +                                     continue;
> >>> +
> >>> +                             list_add_tail(&region->list, list);
> >>> +                     }
> >>> +             }
> >>> +     }
> >>> +}
> >>> +EXPORT_SYMBOL(of_iommu_get_resv_regions);
> >>
> >> Any reason why this is not EXPORT_SYMBOL_GPL? I'm curious what is the
> >> logic behind the OF symbols in general since it looks like half of them
> >> are GPL.
> > 
> > Generally, new ones are _GPL. Old ones probably predate _GPL.
> > 
> > This one is up to the IOMMU maintainers.
> 
> Thank you.

I prefer EXPORT_SYMBOL_GPL(). That's aligned with the symbols exported by
iommu.c, with the *single* exception of generic_iommu_put_resv_regions(),
which I think should be changed to _GPL() as well.

Will
diff mbox series

Patch

diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c
index a9d2df001149..321ebd5fdaba 100644
--- a/drivers/iommu/of_iommu.c
+++ b/drivers/iommu/of_iommu.c
@@ -11,12 +11,15 @@ 
 #include <linux/module.h>
 #include <linux/msi.h>
 #include <linux/of.h>
+#include <linux/of_address.h>
 #include <linux/of_iommu.h>
 #include <linux/of_pci.h>
 #include <linux/pci.h>
 #include <linux/slab.h>
 #include <linux/fsl/mc.h>
 
+#include <dt-bindings/reserved-memory.h>
+
 #define NO_IOMMU	1
 
 /**
@@ -240,3 +243,54 @@  const struct iommu_ops *of_iommu_configure(struct device *dev,
 
 	return ops;
 }
+
+/**
+ * of_iommu_get_resv_regions - reserved region driver helper for device tree
+ * @dev: device for which to get reserved regions
+ * @list: reserved region list
+ *
+ * IOMMU drivers can use this to implement their .get_resv_regions() callback
+ * for memory regions attached to a device tree node. See the reserved-memory
+ * device tree bindings on how to use these:
+ *
+ *   Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt
+ */
+void of_iommu_get_resv_regions(struct device *dev, struct list_head *list)
+{
+	struct of_phandle_iterator it;
+	int err;
+
+	of_for_each_phandle(&it, err, dev->of_node, "memory-region", "#memory-region-cells", 0) {
+		struct iommu_resv_region *region;
+		struct of_phandle_args args;
+		struct resource res;
+
+		args.args_count = of_phandle_iterator_args(&it, args.args, MAX_PHANDLE_ARGS);
+
+		err = of_address_to_resource(it.node, 0, &res);
+		if (err < 0) {
+			dev_err(dev, "failed to parse memory region %pOF: %d\n",
+				it.node, err);
+			continue;
+		}
+
+		if (args.args_count > 0) {
+			/*
+			 * Active memory regions are expected to be accessed by hardware during
+			 * boot and must therefore have an identity mapping created prior to the
+			 * driver taking control of the hardware. This ensures that non-quiescent
+			 * hardware doesn't cause IOMMU faults during boot.
+			 */
+			if (args.args[0] & MEMORY_REGION_IDENTITY_MAPPING) {
+				region = iommu_alloc_resv_region(res.start, resource_size(&res),
+								 IOMMU_READ | IOMMU_WRITE,
+								 IOMMU_RESV_DIRECT_RELAXABLE);
+				if (!region)
+					continue;
+
+				list_add_tail(&region->list, list);
+			}
+		}
+	}
+}
+EXPORT_SYMBOL(of_iommu_get_resv_regions);
diff --git a/include/linux/of_iommu.h b/include/linux/of_iommu.h
index 16f4b3e87f20..8412437acaac 100644
--- a/include/linux/of_iommu.h
+++ b/include/linux/of_iommu.h
@@ -16,6 +16,9 @@  extern const struct iommu_ops *of_iommu_configure(struct device *dev,
 					struct device_node *master_np,
 					const u32 *id);
 
+extern void of_iommu_get_resv_regions(struct device *dev,
+				      struct list_head *list);
+
 #else
 
 static inline int of_get_dma_window(struct device_node *dn, const char *prefix,
@@ -32,6 +35,11 @@  static inline const struct iommu_ops *of_iommu_configure(struct device *dev,
 	return NULL;
 }
 
+static inline void of_iommu_get_resv_regions(struct device *dev,
+					     struct list_head *list)
+{
+}
+
 #endif	/* CONFIG_OF_IOMMU */
 
 #endif /* __OF_IOMMU_H */