[PATCH 2/2] virtio-balloon: correct used length

[Jason Wang]

Spec said:

"and len the total of bytes written into the buffer."

For inflateq, deflateq and statsq, we don't process in_sg so the used
length should be zero. For free_page_vq, since the pages could be
changed in the destination, we should make all pages used for safety.

Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 hw/virtio/virtio-balloon.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index 17de2558cb..fb4426ac0c 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -231,7 +231,7 @@ static void balloon_stats_poll_cb(void *opaque)
         return;
     }
 
-    virtqueue_push(s->svq, s->stats_vq_elem, s->stats_vq_offset);
+    virtqueue_push(s->svq, s->stats_vq_elem, 0);
     virtio_notify(vdev, s->svq);
     g_free(s->stats_vq_elem);
     s->stats_vq_elem = NULL;
@@ -438,7 +438,7 @@ static void virtio_balloon_handle_output(VirtIODevice 
*vdev, VirtQueue *vq)
             memory_region_unref(section.mr);
         }
 
-        virtqueue_push(vq, elem, offset);
+        virtqueue_push(vq, elem, 0);
         virtio_notify(vdev, vq);
         g_free(elem);
         virtio_balloon_pbp_free(&pbp);
@@ -510,6 +510,7 @@ static bool get_free_page_hints(VirtIOBalloon *dev)
     VirtIODevice *vdev = VIRTIO_DEVICE(dev);
     VirtQueue *vq = dev->free_page_vq;
     bool ret = true;
+    size_t used = 0;
     int i;
 
     while (dev->block_iothread) {
@@ -548,11 +549,12 @@ static bool get_free_page_hints(VirtIOBalloon *dev)
         for (i = 0; i < elem->in_num; i++) {
             qemu_guest_free_page_hint(elem->in_sg[i].iov_base,
                                       elem->in_sg[i].iov_len);
+            used += elem->in_sg[i].iov_len;
         }
     }
 
 out:
-    virtqueue_push(vq, elem, 1);
+    virtqueue_push(vq, elem, used);
     g_free(elem);
     return ret;
 }
-- 
2.25.1