drm/amdgpu: Fix amdgpu_bo_move() when old_mem and new_mem are both GTT

commit ee94a65 upstream.

The UVD code relies on GTT to GTT moves in order to ensure
that its BOs don't cross 256M segments.

Fixes: bfe5e58 ("drm/ttm: move last binding into the drivers.")
Signed-off-by: Timur Kristóf <timur.kristof@gmail.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 21fd45e)
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: Timur Kristóf

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

@@ -501,6 +501,15 @@ static int amdgpu_bo_move(struct ttm_buffer_object *bo, bool evict,
 
 	if (new_mem->mem_type == TTM_PL_TT ||
 	    new_mem->mem_type == AMDGPU_PL_PREEMPT) {
+		if (old_mem && (old_mem->mem_type == TTM_PL_TT ||
+				old_mem->mem_type == AMDGPU_PL_PREEMPT)) {
+			r = ttm_bo_wait_ctx(bo, ctx);
+			if (r)
+				return r;
+
+			amdgpu_ttm_backend_unbind(bo->bdev, bo->ttm);
+		}
+
 		r = amdgpu_ttm_backend_bind(bo->bdev, bo->ttm, new_mem);
 		if (r)
 			return r;
@@ -535,6 +544,15 @@ static int amdgpu_bo_move(struct ttm_buffer_object *bo, bool evict,
 		ttm_bo_assign_mem(bo, new_mem);
 		return 0;
 	}
+	if ((old_mem->mem_type == TTM_PL_TT ||
+	     old_mem->mem_type == AMDGPU_PL_PREEMPT) &&
+	    (new_mem->mem_type == TTM_PL_TT ||
+	     new_mem->mem_type == AMDGPU_PL_PREEMPT)) {
+		amdgpu_bo_move_notify(bo, evict, new_mem);
+		ttm_resource_free(bo, &bo->resource);
+		ttm_bo_assign_mem(bo, new_mem);
+		return 0;
+	}
 
 	if (old_mem->mem_type == AMDGPU_PL_GDS ||
 	    old_mem->mem_type == AMDGPU_PL_GWS ||