[PATCH 6.18 168/752] drm/amdkfd: Fix GART PTE for non-4K pagesize in svm_migrate_gart_map()

Sasha Levin
2026-02-28T17:50:30Z

From: Donet Tom <donettom@linux.ibm.com>

[ Upstream commit 6c160001661b6c4e20f5c31909c722741e14c2d8 ]

In svm_migrate_gart_map(), while migrating GART mapping, the number of
bytes copied for the GART table only accounts for CPU pages. On non-4K
systems, each CPU page can contain multiple GPU pages, and the GART
requires one 8-byte PTE per GPU page. As a result, an incorrect size was
passed to the DMA, causing only a partial update of the GART table.

Fix this function to work correctly on non-4K page-size systems by
accounting for the number of GPU pages per CPU page when calculating the
number of bytes to be copied.

Acked-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Philip Yang <Philip.Yang@amd.com>
Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Signed-off-by: Donet Tom <donettom@linux.ibm.com>
Signed-off-by: Felix Kuehling <felix.kuehling@amd.com>
Reviewed-by: Felix Kuehling <felix.kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/gpu/drm/amd/amdkfd/kfd_migrate.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c b/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
index 59a5a3fea65df..ea8377071c390 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_migrate.c
@@ -62,7 +62,7 @@ svm_migrate_gart_map(struct amdgpu_ring *ring, u64 npages,
*gart_addr = adev->gmc.gart_start;

num_dw = ALIGN(adev->mman.buffer_funcs->copy_num_dw, 8);
- num_bytes = npages * 8;
+ num_bytes = npages * 8 * AMDGPU_GPU_PAGES_IN_CPU_PAGE;

r = amdgpu_job_alloc_with_ib(adev, &adev->mman.high_pr,
AMDGPU_FENCE_OWNER_UNDEFINED,
--
2.51.0