virtio-ring: fix DMA metadata flags

The flags are currently overwritten, leading to the wrong direction
being passed to the DMA unmap functions.

Fixes: 72b5e8958738aaa4 ("virtio-ring: store DMA metadata in desc_extra for split virtqueue")
Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
Link: https://lore.kernel.org/r/20211026133100.17541-1-vincent.whitchurch@axis.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index dd95dfd..3035bb6 100644 (file)
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -576,7 +576,7 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
        /* Last one doesn't continue. */
        desc[prev].flags &= cpu_to_virtio16(_vq->vdev, ~VRING_DESC_F_NEXT);
        if (!indirect && vq->use_dma_api)
-               vq->split.desc_extra[prev & (vq->split.vring.num - 1)].flags =
+               vq->split.desc_extra[prev & (vq->split.vring.num - 1)].flags &=
                        ~VRING_DESC_F_NEXT;
 
        if (indirect) {