Commit e6c2e6c2 authored by Philip Yang's avatar Philip Yang Committed by Alex Deucher
Browse files

drm/amdgpu: zero-initialize GART table on allocation 



GART TLB is flushed after unmapping but not after mapping. Since
amdgpu_bo_create_kernel() does not zero-initialize the buffer, when a
single PTE is written the TLB may speculatively load other uninitialized
entries from the same cacheline. Those garbage entries can appear valid,
and a subsequent write to another PTE in the same cacheline may cause the
GPU to use a stale garbage PTE from the TLB.

Fix this by calling memset_io() to zero-initialize the GART table with
gart_pte_flags immediately after allocation.

Using AMDGPU_GEM_CREATE_VRAM_CLEARED, SDMA-based clear will not work
since SDMA needs GART to be initialized to work.

Suggested-by: default avatarFelix Kuehling <felix.kuehling@amd.com>
Signed-off-by: default avatarPhilip Yang <Philip.Yang@amd.com>
Reviewed-by: default avatarChristian König <christian.koenig@amd.com>
Signed-off-by: default avatarAlex Deucher <alexander.deucher@amd.com>
(cherry picked from commit d9af8263b82b6eaa60c5718e0c6631c5037e4b24)
Cc: stable@vger.kernel.org
parent 78d2e624

drivers/gpu/drm/amd/amdgpu/amdgpu_gart.c

+10 −3
Original line number Diff line number Diff line
@@ -262,12 +262,19 @@ void amdgpu_gart_table_ram_free(struct amdgpu_device *adev) 
 */

int amdgpu_gart_table_vram_alloc(struct amdgpu_device *adev)

{

	int r;



	if (adev->gart.bo != NULL)

		return 0;



	return amdgpu_bo_create_kernel(adev,  adev->gart.table_size, PAGE_SIZE,

	r = amdgpu_bo_create_kernel(adev,  adev->gart.table_size, PAGE_SIZE,

				    AMDGPU_GEM_DOMAIN_VRAM, &adev->gart.bo,

				    NULL, (void *)&adev->gart.ptr);

	if (r)

		return r;



	memset_io(adev->gart.ptr, adev->gart.gart_pte_flags, adev->gart.table_size);

	return 0;

}



/**