[PATCH 1/2] drm/amdgpu: fix KFDMemoryTest.PtraceAccessInvisibleVram fail on SRIOV

[Samuel Zhang]

Ptrace access VRAM bo will first try sdma access in
amdgpu_ttm_access_memory_sdma(), if fails, it will fallback to mmio
access.

Since ptrace only access 8 bytes at a time and
amdgpu_ttm_access_memory_sdma() only allow PAGE_SIZE bytes access,
it returns fail.
On SRIOV, mmio access will also fail as MM_INDEX/MM_DATA register write
is blocked for security reasons.

The fix is just change len check in amdgpu_ttm_access_memory_sdma() so
that len in (0, PAGE_SIZE] are allowed. This will not only fix the ptrace
test case on SRIOV, but also improve the access performance when the
access length is < PAGE_SIZE.
len > PAGE_SIZE case support is not needed as larger size will be break
into chunks of PAGE_SIZE len max in mem_rw().

Signed-off-by: Samuel Zhang <guoqing.zhang at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
index 5daa05e23ddf..a6e90eada367 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
@@ -1486,7 +1486,7 @@ static int amdgpu_ttm_access_memory_sdma(struct ttm_buffer_object *bo,
 	unsigned int num_dw;
 	int r, idx;
 
-	if (len != PAGE_SIZE)
+	if (len > PAGE_SIZE)
 		return -EINVAL;
 
 	if (!adev->mman.sdma_access_ptr)
@@ -1514,7 +1514,7 @@ static int amdgpu_ttm_access_memory_sdma(struct ttm_buffer_object *bo,
 		swap(src_addr, dst_addr);
 
 	amdgpu_emit_copy_buffer(adev, &job->ibs[0], src_addr, dst_addr,
-				PAGE_SIZE, 0);
+				len, 0);
 
 	amdgpu_ring_pad_ib(adev->mman.buffer_funcs_ring, &job->ibs[0]);
 	WARN_ON(job->ibs[0].length_dw > num_dw);
-- 
2.25.1