[PATCH 1/7] virtio: Allow to fill a whole virtqueue in order

["Eugenio Pérez" <eperezma@redhat.com>]

As the while steps < max_steps is already one less than the vq size, the
right maximum max_steps variable is queue length, not the maximum
possible remainder of % vq->vring.num.

Fixes: b44135daa37 ("virtio: virtqueue_ordered_fill - VIRTIO_F_IN_ORDER support")
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
---
Personally I'd just remove max_steps and let it be vq->vring.num, but
let's make the minimal changes for now.
---
 hw/virtio/virtio.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index e9d553295257..17f171551892 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -980,7 +980,7 @@ static void virtqueue_ordered_fill(VirtQueue *vq, const VirtQueueElement *elem,
      * We shouldn't need to increase 'i' by more than or equal to
      * the distance between used_idx and last_avail_idx (max_steps).
      */
-    max_steps = (vq->last_avail_idx - vq->used_idx) % vq->vring.num;
+    max_steps = MIN(vq->last_avail_idx - vq->used_idx, vq->vring.num);
 
     /* Search for element in vq->used_elems */
     while (steps < max_steps) {
-- 
2.53.0