virtio: add AioContext-specific function for host notifiers

This is used to register ioeventfd with a dataplane thread.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Acked-by: NStefan Hajnoczi <stefanha@redhat.com>

hw/virtio/virtio.c

@@ -1786,6 +1786,22 @@ static void virtio_queue_host_notifier_read(EventNotifier *n)
     }
 }
 
+void virtio_queue_aio_set_host_notifier_handler(VirtQueue *vq, AioContext *ctx,
+                                                bool assign, bool set_handler)
+{
+    if (assign && set_handler) {
+        aio_set_event_notifier(ctx, &vq->host_notifier, true,
+                               virtio_queue_host_notifier_read);
+    } else {
+        aio_set_event_notifier(ctx, &vq->host_notifier, true, NULL);
+    }
+    if (!assign) {
+        /* Test and clear notifier before after disabling event,
+         * in case poll callback didn't have time to run. */
+        virtio_queue_host_notifier_read(&vq->host_notifier);
+    }
+}
+
 void virtio_queue_set_host_notifier_fd_handler(VirtQueue *vq, bool assign,
                                                bool set_handler)
 {

include/hw/virtio/virtio.h

@@ -249,6 +249,8 @@ void virtio_queue_set_guest_notifier_fd_handler(VirtQueue *vq, bool assign,
 EventNotifier *virtio_queue_get_host_notifier(VirtQueue *vq);
 void virtio_queue_set_host_notifier_fd_handler(VirtQueue *vq, bool assign,
                                                bool set_handler);
+void virtio_queue_aio_set_host_notifier_handler(VirtQueue *vq, AioContext *ctx,
+                                                bool assign, bool set_handler);
 void virtio_queue_notify_vq(VirtQueue *vq);
 void virtio_irq(VirtQueue *vq);
 VirtQueue *virtio_vector_first_queue(VirtIODevice *vdev, uint16_t vector);