drm/nouveau/ttm: wait for bo fence to signal before unmapping vmas

TTM was changed a while back to allow for pipelining of buffer moves, and
part of this was the removal of waiting for a BO to idle before calling
move(), placing the responsibility on the driver to do this if required.

That's all well and good, except, we make use of move_notify() to handle
mapping/unmapping from the GPU VMM as move() isn't called on all paths.

This commit adds a wait before unmapping from a VMM in move_notify(), to
prevent GPU page faults where a buffer is still being accessed.

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Cc: stable@vger.kernel.org [v4.8+]

diff --git a/drivers/gpu/drm/nouveau/nouveau_bo.c b/drivers/gpu/drm/nouveau/nouveau_bo.c
index e0c0007..dd07ca1 100644 (file)
--- a/drivers/gpu/drm/nouveau/nouveau_bo.c
+++ b/drivers/gpu/drm/nouveau/nouveau_bo.c
@@ -1209,6 +1209,7 @@ nouveau_bo_move_ntfy(struct ttm_buffer_object *bo, struct ttm_mem_reg *new_mem)
                               nvbo->page_shift != vma->vm->mmu->lpg_shift)) {
                        nvkm_vm_map(vma, new_mem->mm_node);
                } else {
+                       WARN_ON(ttm_bo_wait(bo, false, false));
                        nvkm_vm_unmap(vma);
                }
        }