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iommu: Implement of_iommu_get_resv_regions()

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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>
Acked-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Link: https://lore.kernel.org/r/20230120174251.4004100-4-thierry.reding@gmail.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
This commit is contained in:
Thierry Reding 2023-01-20 18:42:50 +01:00 committed by Joerg Roedel
parent af0d81357c
commit a5bf3cfce8
2 changed files with 102 additions and 0 deletions
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94
drivers/iommu/of_iommu.c
View File

@ -10,6 +10,7 @@
#include <linux/limits.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_iommu.h>
#include <linux/of_pci.h>
#include <linux/pci.h>
@ -171,3 +172,96 @@ const struct iommu_ops *of_iommu_configure(struct device *dev,
return ops;
}
static enum iommu_resv_type iommu_resv_region_get_type(struct device *dev, struct resource *phys,
phys_addr_t start, size_t length)
{
phys_addr_t end = start + length - 1;
/*
* IOMMU regions without an associated physical region cannot be
* mapped and are simply reservations.
*/
if (phys->start >= phys->end)
return IOMMU_RESV_RESERVED;
/* may be IOMMU_RESV_DIRECT_RELAXABLE for certain cases */
if (start == phys->start && end == phys->end)
return IOMMU_RESV_DIRECT;
dev_warn(dev, "treating non-direct mapping [%pr] -> [%pap-%pap] as reservation\n", &phys,
&start, &end);
return IOMMU_RESV_RESERVED;
}
/**
* 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)
{
#if IS_ENABLED(CONFIG_OF_ADDRESS)
struct of_phandle_iterator it;
int err;
of_for_each_phandle(&it, err, dev->of_node, "memory-region", NULL, 0) {
const __be32 *maps, *end;
struct resource phys;
int size;
memset(&phys, 0, sizeof(phys));
/*
* The "reg" property is optional and can be omitted by reserved-memory regions
* that represent reservations in the IOVA space, which are regions that should
* not be mapped.
*/
if (of_find_property(it.node, "reg", NULL)) {
err = of_address_to_resource(it.node, 0, &phys);
if (err < 0) {
dev_err(dev, "failed to parse memory region %pOF: %d\n",
it.node, err);
continue;
}
}
maps = of_get_property(it.node, "iommu-addresses", &size);
if (!maps)
continue;
end = maps + size / sizeof(__be32);
while (maps < end) {
struct device_node *np;
u32 phandle;
phandle = be32_to_cpup(maps++);
np = of_find_node_by_phandle(phandle);
if (np == dev->of_node) {
int prot = IOMMU_READ | IOMMU_WRITE;
struct iommu_resv_region *region;
enum iommu_resv_type type;
phys_addr_t iova;
size_t length;
maps = of_translate_dma_region(np, maps, &iova, &length);
type = iommu_resv_region_get_type(dev, &phys, iova, length);
region = iommu_alloc_resv_region(iova, length, prot, type,
GFP_KERNEL);
if (region)
list_add_tail(&region->list, list);
}
}
}
#endif
}
EXPORT_SYMBOL(of_iommu_get_resv_regions);

8
include/linux/of_iommu.h
View File

@ -12,6 +12,9 @@ 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 const struct iommu_ops *of_iommu_configure(struct device *dev,
@ -21,6 +24,11 @@ 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 */