[PATCH 2/2] drm/amdgpu: fix debug sdma vram access checks

[Jonathan Kim]

drm_dev_enter returns true when accessiable so correct the error check.

Source VRAM buffer is reserved by TTM but not pinned so the gpu offset
fetch throws a warning.  Get the gpu offset without a check and then
double check to make sure the source buffer hasn't fallen into a hole.
Otherwise use MMIO access to deal with non-contiguous VRAM cases as
usual.

Signed-off-by: Jonathan Kim <jonathan.kim at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
index 6178ae7ba624..0acfd872bfef 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
@@ -1440,6 +1440,7 @@ static int amdgpu_ttm_access_memory_sdma(struct ttm_buffer_object *bo,
 	struct dma_fence *fence;
 	uint64_t src_addr, dst_addr;
 	unsigned int num_dw;
+	bool vram_is_contiguous;
 	int r, idx;
 
 	if (len != PAGE_SIZE)
@@ -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 +1460,18 @@ static int amdgpu_ttm_access_memory_sdma(struct ttm_buffer_object *bo,
 	if (r)
 		goto out;
 
-	src_addr = amdgpu_bo_gpu_offset(abo);
+	src_addr = amdgpu_bo_gpu_offset_no_check(abo);
+	vram_is_contiguous = (adev->gmc.real_vram_size - 1 ==
+				adev->gmc.vram_end - adev->gmc.vram_start) &&
+				src_addr >= adev->gmc.vram_start &&
+				src_addr + len <= adev->gmc.vram_end;
+
+	if (!vram_is_contiguous) {
+		amdgpu_job_free(job);
+		r = -EACCES;
+		goto out;
+	}
+
 	dst_addr = amdgpu_bo_gpu_offset(adev->mman.sdma_access_bo);
 	if (write)
 		swap(src_addr, dst_addr);
-- 
2.25.1