[PATCH] drm/amdgpu: fix broken debug sdma vram access function

[Christian König]

Am 19.01.22 um 16:47 schrieb Jonathan Kim:
> Debug VRAM access through SDMA has several broken parts resulting in
> silent MMIO fallback.
>
> BO kernel creation takes the location of the cpu addr pointer, not
> the pointer itself for address kmap.
>
> drm_dev_enter return true on success so change access check.
>
> The source BO is reserved but not pinned so find the address using the
> cursor offset relative to its memory domain start.
>
> Signed-off-by: Jonathan Kim <jonathan.kim at amd.com>

Reviewed-by: Christian König <christian.koenig at amd.com>

> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 15 ++++++++-------
>   1 file changed, 8 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> index b489cd8abe31..0a2e8e355eaa 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> @@ -1436,6 +1436,7 @@ static int amdgpu_ttm_access_memory_sdma(struct ttm_buffer_object *bo,
>   {
>   	struct amdgpu_bo *abo = ttm_to_amdgpu_bo(bo);
>   	struct amdgpu_device *adev = amdgpu_ttm_adev(abo->tbo.bdev);
> +	struct amdgpu_res_cursor src_mm;
>   	struct amdgpu_job *job;
>   	struct dma_fence *fence;
>   	uint64_t src_addr, dst_addr;
> @@ -1448,9 +1449,8 @@ static int amdgpu_ttm_access_memory_sdma(struct ttm_buffer_object *bo,
>   	if (!adev->mman.sdma_access_ptr)
>   		return -EACCES;
>   
> -	r = drm_dev_enter(adev_to_drm(adev), &idx);
> -	if (r)
> -		return r;
> +	if (!drm_dev_enter(adev_to_drm(adev), &idx))
> +		return -ENODEV;
>   
>   	if (write)
>   		memcpy(adev->mman.sdma_access_ptr, buf, len);
> @@ -1460,7 +1460,8 @@ static int amdgpu_ttm_access_memory_sdma(struct ttm_buffer_object *bo,
>   	if (r)
>   		goto out;
>   
> -	src_addr = amdgpu_bo_gpu_offset(abo);
> +	amdgpu_res_first(abo->tbo.resource, offset, len, &src_mm);
> +	src_addr = amdgpu_ttm_domain_start(adev, bo->resource->mem_type) + src_mm.start;
>   	dst_addr = amdgpu_bo_gpu_offset(adev->mman.sdma_access_bo);
>   	if (write)
>   		swap(src_addr, dst_addr);
> @@ -1858,7 +1859,7 @@ int amdgpu_ttm_init(struct amdgpu_device *adev)
>   	if (amdgpu_bo_create_kernel(adev, PAGE_SIZE, PAGE_SIZE,
>   				AMDGPU_GEM_DOMAIN_GTT,
>   				&adev->mman.sdma_access_bo, NULL,
> -				adev->mman.sdma_access_ptr))
> +				&adev->mman.sdma_access_ptr))
>   		DRM_WARN("Debug VRAM access will use slowpath MM access\n");
>   
>   	return 0;
> @@ -1882,6 +1883,8 @@ void amdgpu_ttm_fini(struct amdgpu_device *adev)
>   	if (adev->mman.stolen_reserved_size)
>   		amdgpu_bo_free_kernel(&adev->mman.stolen_reserved_memory,
>   				      NULL, NULL);
> +	amdgpu_bo_free_kernel(&adev->mman.sdma_access_bo, NULL,
> +					&adev->mman.sdma_access_ptr);
>   	amdgpu_ttm_fw_reserve_vram_fini(adev);
>   
>   	if (drm_dev_enter(adev_to_drm(adev), &idx)) {
> @@ -1901,8 +1904,6 @@ void amdgpu_ttm_fini(struct amdgpu_device *adev)
>   	ttm_range_man_fini(&adev->mman.bdev, AMDGPU_PL_OA);
>   	ttm_device_fini(&adev->mman.bdev);
>   	adev->mman.initialized = false;
> -	amdgpu_bo_free_kernel(&adev->mman.sdma_access_bo, NULL,
> -					&adev->mman.sdma_access_ptr);
>   	DRM_INFO("amdgpu: ttm finalized\n");
>   }
>