vhost: Add Shadow VirtQueue kick forwarding capabilities

At this mode no buffer forwarding will be performed in SVQ mode: Qemu
will just forward the guest's kicks to the device.

Host memory notifiers regions are left out for simplicity, and they will
not be addressed in this series.

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>

1 files changed, 14 insertions, 0 deletions

diff --git a/hw/virtio/vhost-shadow-virtqueue.h b/hw/virtio/vhost-shadow-virtqueue.h
index f1519e3c7b..1cbc87d5d8 100644
--- a/hw/virtio/vhost-shadow-virtqueue.h
+++ b/hw/virtio/vhost-shadow-virtqueue.h
@@ -18,8 +18,22 @@ typedef struct VhostShadowVirtqueue {
     EventNotifier hdev_kick;
     /* Shadow call notifier, sent to vhost */
     EventNotifier hdev_call;
+
+    /*
+     * Borrowed virtqueue's guest to host notifier. To borrow it in this event
+     * notifier allows to recover the VhostShadowVirtqueue from the event loop
+     * easily. If we use the VirtQueue's one, we don't have an easy way to
+     * retrieve VhostShadowVirtqueue.
+     *
+     * So shadow virtqueue must not clean it, or we would lose VirtQueue one.
+     */
+    EventNotifier svq_kick;
 } VhostShadowVirtqueue;
 
+void vhost_svq_set_svq_kick_fd(VhostShadowVirtqueue *svq, int svq_kick_fd);
+
+void vhost_svq_stop(VhostShadowVirtqueue *svq);
+
 VhostShadowVirtqueue *vhost_svq_new(void);
 
 void vhost_svq_free(gpointer vq);