drm/ttm: move SG flag check into ttm_bo_vm_reserve

Just check earlier if a BO can be page faulted in the first place.
Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Dave Airlie <airlied@redhat.com>
Link: https://patchwork.freedesktop.org/patch/392321/

drivers/gpu/drm/ttm/ttm_bo_vm.c

@@ -157,6 +157,15 @@ vm_fault_t ttm_bo_vm_reserve(struct ttm_buffer_object *bo,
 			return VM_FAULT_NOPAGE;
 	}
 
+	/*
+	 * Refuse to fault imported pages. This should be handled
+	 * (if at all) by redirecting mmap to the exporter.
+	 */
+	if (bo->ttm && (bo->ttm->page_flags & TTM_PAGE_FLAG_SG)) {
+		dma_resv_unlock(bo->base.resv);
+		return VM_FAULT_SIGBUS;
+	}
+
 	return 0;
 }
 EXPORT_SYMBOL(ttm_bo_vm_reserve);
@@ -281,13 +290,6 @@ vm_fault_t ttm_bo_vm_fault_reserved(struct vm_fault *vmf,
 	vm_fault_t ret = VM_FAULT_NOPAGE;
 	unsigned long address = vmf->address;
 
-	/*
-	 * Refuse to fault imported pages. This should be handled
-	 * (if at all) by redirecting mmap to the exporter.
-	 */
-	if (bo->ttm && (bo->ttm->page_flags & TTM_PAGE_FLAG_SG))
-		return VM_FAULT_SIGBUS;
-
 	if (bdev->driver->fault_reserve_notify) {
 		struct dma_fence *moving = dma_fence_get(bo->moving);