virtio: Use virtqueue_get_buffer() helpers

Length was being read without first invalidating. There are functions that
handle invalidating and reading from vq_ring members. Use those here.

Signed-off-by: Andrew Davis <[email protected]>

lib/virtio/virtqueue.c

@@ -177,13 +177,15 @@ void *virtqueue_get_buffer(struct virtqueue *vq, uint32_t *len, uint16_t *idx)
 
 uint32_t virtqueue_get_buffer_length(struct virtqueue *vq, uint16_t idx)
 {
+ /* Invalidate the desc entry written by driver before accessing it */
  VRING_INVALIDATE(&vq->vq_ring.desc[idx].len,
  sizeof(vq->vq_ring.desc[idx].len));
  return vq->vq_ring.desc[idx].len;
 }
 
 void *virtqueue_get_buffer_addr(struct virtqueue *vq, uint16_t idx)
 {
+ /* Invalidate the desc entry written by driver before accessing it */
  VRING_INVALIDATE(&vq->vq_ring.desc[idx].addr,
  sizeof(vq->vq_ring.desc[idx].addr));
  return virtqueue_phys_to_virt(vq, vq->vq_ring.desc[idx].addr);
@@ -225,11 +227,8 @@ void *virtqueue_get_available_buffer(struct virtqueue *vq, uint16_t *avail_idx,
  sizeof(vq->vq_ring.avail->ring[head_idx]));
  *avail_idx = vq->vq_ring.avail->ring[head_idx];
 
- /* Invalidate the desc entry written by driver before accessing it */
- VRING_INVALIDATE(&vq->vq_ring.desc[*avail_idx],
- sizeof(vq->vq_ring.desc[*avail_idx]));
- buffer = virtqueue_phys_to_virt(vq, vq->vq_ring.desc[*avail_idx].addr);
- *len = vq->vq_ring.desc[*avail_idx].len;
+ buffer = virtqueue_get_buffer_addr(vq, *avail_idx);
+ *len = virtqueue_get_buffer_length(vq, *avail_idx);
 
  VQUEUE_IDLE(vq);