diff options
| author | Felix Kuehling <[email protected]> | 2021-07-15 15:05:37 -0400 |
|---|---|---|
| committer | Christian König <[email protected]> | 2021-07-16 09:22:57 +0200 |
| commit | fa5239f2af983ffdf08395a542a7d6356b6222c5 (patch) | |
| tree | 0f8338f92a816824522f6468a60217667a6a996d | |
| parent | 32a19de21ae40f0601f48575b610dde4f518ccc6 (diff) | |
drm/amdgpu: workaround failed COW checks for Thunk VMAs
KFD Thunk maps invisible VRAM BOs with PROT_NONE, MAP_PRIVATE.
is_cow_mapping returns true for these mappings, which causes mmap to fail
in ttm_bo_mmap_obj.
As a workaround, clear VM_MAYWRITE for PROT_NONE-COW mappings. This
should prevent the mapping from ever becoming writable and makes
is_cow_mapping(vm_flags) false.
Fixes: f91142c62161 ("drm/ttm: nuke VM_MIXEDMAP on BO mappings v3")
Suggested-by: Daniel Vetter <[email protected]>
Tested-by: Felix Kuehling <[email protected]>
Signed-off-by: Felix Kuehling <[email protected]>
Reviewed-by: Christian König <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
Signed-off-by: Christian König <[email protected]>
| -rw-r--r-- | drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c index b3404c43a911..9f952b7fc197 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c @@ -255,6 +255,15 @@ static int amdgpu_gem_object_mmap(struct drm_gem_object *obj, struct vm_area_str if (bo->flags & AMDGPU_GEM_CREATE_NO_CPU_ACCESS) return -EPERM; + /* Workaround for Thunk bug creating PROT_NONE,MAP_PRIVATE mappings + * for debugger access to invisible VRAM. Should have used MAP_SHARED + * instead. Clearing VM_MAYWRITE prevents the mapping from ever + * becoming writable and makes is_cow_mapping(vm_flags) false. + */ + if (is_cow_mapping(vma->vm_flags) && + !(vma->vm_flags & (VM_READ | VM_WRITE | VM_EXEC))) + vma->vm_flags &= ~VM_MAYWRITE; + return drm_gem_ttm_mmap(obj, vma); } |