This allows SVQ to return all the inflight descriptors in order.

TODO: Rewind descriptors that can be fetched from avail ring again.

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
---
 hw/virtio/vhost-shadow-virtqueue.h |  2 ++
 hw/virtio/vhost-shadow-virtqueue.c | 20 ++++++++++++++++++++
 2 files changed, 22 insertions(+)

diff --git a/hw/virtio/vhost-shadow-virtqueue.h b/hw/virtio/vhost-shadow-virtqueue.h
index a01a7d4a18..e82da4b55c 100644
--- a/hw/virtio/vhost-shadow-virtqueue.h
+++ b/hw/virtio/vhost-shadow-virtqueue.h
@@ -133,6 +133,8 @@ size_t vhost_svq_device_area_size(const VhostShadowVirtqueue *svq);
 
 void vhost_svq_start(VhostShadowVirtqueue *svq, VirtIODevice *vdev,
                      VirtQueue *vq);
+VirtQueueElement **vhost_svq_save_inflight(VhostShadowVirtqueue *svq,
+                                           uint32_t *num);
 void vhost_svq_stop(VhostShadowVirtqueue *svq);
 
 VhostShadowVirtqueue *vhost_svq_new(VhostIOVATree *iova_tree,
diff --git a/hw/virtio/vhost-shadow-virtqueue.c b/hw/virtio/vhost-shadow-virtqueue.c
index e50bfba6dc..029ccee957 100644
--- a/hw/virtio/vhost-shadow-virtqueue.c
+++ b/hw/virtio/vhost-shadow-virtqueue.c
@@ -676,6 +676,26 @@ void vhost_svq_start(VhostShadowVirtqueue *svq, VirtIODevice *vdev,
     }
 }
 
+VirtQueueElement **vhost_svq_save_inflight(VhostShadowVirtqueue *svq,
+                                           uint32_t *num)
+{
+    GPtrArray *aret = g_ptr_array_new();
+    SVQDescState *s, *tmp;
+
+    QTAILQ_FOREACH_SAFE(s, &svq->desc_state_avail, entry, tmp) {
+        VirtQueueElement *elem = s->elem;
+
+        virtqueue_detach_element(svq->vq, elem, 0);
+        g_ptr_array_add(aret, elem);
+        QTAILQ_REMOVE(&svq->desc_state_avail, s, entry);
+    }
+
+    *num = aret->len;
+
+    /* TODO: return g_ptr_array_steal(aret) when min glib >= 2.64 */
+    return (void *)g_ptr_array_free(aret, false);
+}
+
 /**
  * Stop the shadow virtqueue operation.
  * @svq: Shadow Virtqueue
-- 
2.31.1