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iommu/exynos: add support for reserved regions

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The bootloader configures a reserved memory region for framebuffer,
which is protected by the IOMMU. The kernel-side driver is oblivious as
of which memory region is set up by the bootloader. In such case, the
IOMMU tries to reference the reserved region - which is not reserved in
the kernel anymore - and it results in an unrecoverable page fault. More
information about it is provided in [1].

Add support for reserved regions using iommu_dma_get_resv_regions().
For OF supported boards, this requires defining the region in the
iommu-addresses property of the IOMMU owner's node.

Link: https://lore.kernel.org/r/544ad69cba52a9b87447e3ac1c7fa8c3@disroot.org [1]
Signed-off-by: Kaustabh Chakraborty <kauschluss@disroot.org>
Link: https://lore.kernel.org/r/20250712-exynos-sysmmu-resv-regions-v1-1-e79681fcab1a@disroot.org
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Kaustabh Chakraborty 2025-07-12 17:19:30 +05:30 committed by Will Deacon
parent 86731a2a65
commit 2d70fdd9b5
1 changed files with 2 additions and 0 deletions
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2
drivers/iommu/exynos-iommu.c
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@ -22,6 +22,7 @@
#include <linux/pm_runtime.h>
#include <linux/slab.h>
#include "dma-iommu.h"
#include "iommu-pages.h"
typedef u32 sysmmu_iova_t;
@ -1478,6 +1479,7 @@ static const struct iommu_ops exynos_iommu_ops = {
.probe_device = exynos_iommu_probe_device,
.release_device = exynos_iommu_release_device,
.pgsize_bitmap = SECT_SIZE | LPAGE_SIZE | SPAGE_SIZE,
.get_resv_regions = iommu_dma_get_resv_regions,
.of_xlate = exynos_iommu_of_xlate,
.default_domain_ops = &(const struct iommu_domain_ops) {
.attach_dev = exynos_iommu_attach_device,