From 2d70fdd9b5c9a10c5a4b15179b425ff554b60c6d Mon Sep 17 00:00:00 2001 From: Kaustabh Chakraborty Date: Sat, 12 Jul 2025 17:19:30 +0530 Subject: [PATCH] iommu/exynos: add support for reserved regions 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 Link: https://lore.kernel.org/r/20250712-exynos-sysmmu-resv-regions-v1-1-e79681fcab1a@disroot.org Signed-off-by: Will Deacon --- drivers/iommu/exynos-iommu.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/iommu/exynos-iommu.c b/drivers/iommu/exynos-iommu.c index fcb6a0f7c0827..f499861da1b16 100644 --- a/drivers/iommu/exynos-iommu.c +++ b/drivers/iommu/exynos-iommu.c @@ -22,6 +22,7 @@ #include #include +#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, -- 2.47.2