[PATCH vhost v1] virtio: packed: fix unmap leak for indirect desc table

[Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>]

When use_dma_api and premapped are true, then the do_unmap is false.

Because the do_unmap is false, vring_unmap_extra_packed is not called by
detach_buf_packed.

  if (unlikely(vq->do_unmap)) {
                curr = id;
                for (i = 0; i < state->num; i++) {
                        vring_unmap_extra_packed(vq,
                                                 &vq->packed.desc_extra[curr]);
                        curr = vq->packed.desc_extra[curr].next;
                }
  }

So the indirect desc table is not unmapped. This causes the unmap leak.

So here, we check vq->use_dma_api instead. Synchronously, dma info is
updated based on use_dma_api judgment

This bug does not occur, because no driver use the premapped with
indirect.

Fixes: b319940f83c2 ("virtio_ring: skip unmap for premapped")
Signed-off-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
---

v1: check use_dma_api to update dma info and unmap

 drivers/virtio/virtio_ring.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 49299b1f9ec7..6f7e5010a673 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -1340,7 +1340,7 @@ static int virtqueue_add_indirect_packed(struct vring_virtqueue *vq,
 				sizeof(struct vring_packed_desc));
 	vq->packed.vring.desc[head].id = cpu_to_le16(id);

-	if (vq->do_unmap) {
+	if (vq->use_dma_api) {
 		vq->packed.desc_extra[id].addr = addr;
 		vq->packed.desc_extra[id].len = total_sg *
 				sizeof(struct vring_packed_desc);
@@ -1481,7 +1481,7 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq,
 			desc[i].len = cpu_to_le32(sg->length);
 			desc[i].id = cpu_to_le16(id);

-			if (unlikely(vq->do_unmap)) {
+			if (unlikely(vq->use_dma_api)) {
 				vq->packed.desc_extra[curr].addr = addr;
 				vq->packed.desc_extra[curr].len = sg->length;
 				vq->packed.desc_extra[curr].flags =
@@ -1615,7 +1615,7 @@ static void detach_buf_packed(struct vring_virtqueue *vq,
 	vq->free_head = id;
 	vq->vq.num_free += state->num;

-	if (unlikely(vq->do_unmap)) {
+	if (unlikely(vq->use_dma_api)) {
 		curr = id;
 		for (i = 0; i < state->num; i++) {
 			vring_unmap_extra_packed(vq,
--
2.32.0.3.g01195cf9f