1 files changed, 60 insertions, 4 deletions

diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 397c261c3c..9e10cbc058 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -744,6 +744,60 @@ int virtio_queue_empty(VirtQueue *vq)
     }
 }
 
+static bool virtio_queue_split_poll(VirtQueue *vq, unsigned shadow_idx)
+{
+    if (unlikely(!vq->vring.avail)) {
+        return false;
+    }
+
+    return (uint16_t)shadow_idx != vring_avail_idx(vq);
+}
+
+static bool virtio_queue_packed_poll(VirtQueue *vq, unsigned shadow_idx)
+{
+    VRingPackedDesc desc;
+    VRingMemoryRegionCaches *caches;
+
+    if (unlikely(!vq->vring.desc)) {
+        return false;
+    }
+
+    caches = vring_get_region_caches(vq);
+    if (!caches) {
+        return false;
+    }
+
+    vring_packed_desc_read(vq->vdev, &desc, &caches->desc,
+                           shadow_idx, true);
+
+    return is_desc_avail(desc.flags, vq->shadow_avail_wrap_counter);
+}
+
+static bool virtio_queue_poll(VirtQueue *vq, unsigned shadow_idx)
+{
+    if (virtio_device_disabled(vq->vdev)) {
+        return false;
+    }
+
+    if (virtio_vdev_has_feature(vq->vdev, VIRTIO_F_RING_PACKED)) {
+        return virtio_queue_packed_poll(vq, shadow_idx);
+    } else {
+        return virtio_queue_split_poll(vq, shadow_idx);
+    }
+}
+
+bool virtio_queue_enable_notification_and_check(VirtQueue *vq,
+                                                int opaque)
+{
+    virtio_queue_set_notification(vq, 1);
+
+    if (opaque >= 0) {
+        return virtio_queue_poll(vq, (unsigned)opaque);
+    } else {
+        return false;
+    }
+}
+
 static void virtqueue_unmap_sg(VirtQueue *vq, const VirtQueueElement *elem,
                                unsigned int len)
 {
@@ -1442,9 +1496,9 @@ err:
     goto done;
 }
 
-void virtqueue_get_avail_bytes(VirtQueue *vq, unsigned int *in_bytes,
-                               unsigned int *out_bytes,
-                               unsigned max_in_bytes, unsigned max_out_bytes)
+int virtqueue_get_avail_bytes(VirtQueue *vq, unsigned int *in_bytes,
+                              unsigned int *out_bytes, unsigned max_in_bytes,
+                              unsigned max_out_bytes)
 {
     uint16_t desc_size;
     VRingMemoryRegionCaches *caches;
@@ -1477,7 +1531,7 @@ void virtqueue_get_avail_bytes(VirtQueue *vq, unsigned int *in_bytes,
                                         caches);
     }
 
-    return;
+    return (int)vq->shadow_avail_idx;
 err:
     if (in_bytes) {
         *in_bytes = 0;
@@ -1485,6 +1539,8 @@ err:
     if (out_bytes) {
         *out_bytes = 0;
     }
+
+    return -1;
 }
 
 int virtqueue_avail_bytes(VirtQueue *vq, unsigned int in_bytes,