[RFC 01/10] virtio: Add virtqueue_set_handler

["Eugenio Pérez" <eperezma@redhat.com>]

This allows qemu to override vq handler.

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
---
 include/hw/virtio/virtio.h |  6 +++---
 hw/virtio/virtio.c         | 14 ++++++++++++++
 2 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
index b7ece7a6a8..9b5479e256 100644
--- a/include/hw/virtio/virtio.h
+++ b/include/hw/virtio/virtio.h
@@ -47,6 +47,8 @@ size_t virtio_feature_get_config_size(VirtIOFeature *features,
                                       uint64_t host_features);
 
 typedef struct VirtQueue VirtQueue;
+typedef void (*VirtIOHandleOutput)(VirtIODevice *, VirtQueue *);
+typedef bool (*VirtIOHandleAIOOutput)(VirtIODevice *, VirtQueue *);
 
 #define VIRTQUEUE_MAX_SIZE 1024
 
@@ -174,9 +176,6 @@ void virtio_error(VirtIODevice *vdev, const char *fmt, ...) GCC_FMT_ATTR(2, 3);
 /* Set the child bus name. */
 void virtio_device_set_child_bus_name(VirtIODevice *vdev, char *bus_name);
 
-typedef void (*VirtIOHandleOutput)(VirtIODevice *, VirtQueue *);
-typedef bool (*VirtIOHandleAIOOutput)(VirtIODevice *, VirtQueue *);
-
 VirtQueue *virtio_add_queue(VirtIODevice *vdev, int queue_size,
                             VirtIOHandleOutput handle_output);
 
@@ -184,6 +183,7 @@ void virtio_del_queue(VirtIODevice *vdev, int n);
 
 void virtio_delete_queue(VirtQueue *vq);
 
+void virtqueue_set_handler(VirtQueue *vq, VirtIOHandleOutput handler);
 void virtqueue_push(VirtQueue *vq, const VirtQueueElement *elem,
                     unsigned int len);
 void virtqueue_flush(VirtQueue *vq, unsigned int count);
diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index b308026596..ebb780fb42 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -1796,6 +1796,20 @@ unsigned int virtqueue_drop_all(VirtQueue *vq)
     }
 }
 
+/*
+ * virtqueue_set_handler:
+ * @vq The #VirtQueue
+ * @handler The handler to call on vq event
+ * Replaces vq handler.
+ *
+ * Note: It takes no protection, so make sure no other calls to the handler
+ * are happening.
+ */
+void virtqueue_set_handler(VirtQueue *vq, VirtIOHandleOutput handler)
+{
+    vq->handle_output = handler;
+}
+
 /* Reading and writing a structure directly to QEMUFile is *awful*, but
  * it is what QEMU has always done by mistake.  We can change it sooner
  * or later by bumping the version number of the affected vm states.
-- 
2.27.0