qdev: Add Error parameter to hide_device() callbacks

hide_device() is used for virtio-net failover, where the standby virtio
device delays creation of the primary device. It only makes sense to
have a single primary device for each standby device. Adding a second
one should result in an error instead of hiding it and never using it
afterwards.

Prepare for this by adding an Error parameter to the hide_device()
callback where virtio-net is informed about adding a primary device.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20211008133442.141332-12-kwolf@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: Peter Krempa <pkrempa@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 6 insertions, 2 deletions

diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h
index 5a073fc368..74d8b614a7 100644
--- a/include/hw/qdev-core.h
+++ b/include/hw/qdev-core.h
@@ -201,8 +201,12 @@ struct DeviceListener {
      * informs qdev if a device should be visible or hidden.  We can
      * hide a failover device depending for example on the device
      * opts.
+     *
+     * On errors, it returns false and errp is set. Device creation
+     * should fail in this case.
      */
-    bool (*hide_device)(DeviceListener *listener, QemuOpts *device_opts);
+    bool (*hide_device)(DeviceListener *listener, QemuOpts *device_opts,
+                        Error **errp);
     QTAILQ_ENTRY(DeviceListener) link;
 };
 
@@ -837,7 +841,7 @@ void device_listener_unregister(DeviceListener *listener);
  * When a device is added via qdev_device_add() this will be called,
  * and return if the device should be added now or not.
  */
-bool qdev_should_hide_device(QemuOpts *opts);
+bool qdev_should_hide_device(QemuOpts *opts, Error **errp);
 
 typedef enum MachineInitPhase {
     /* current_machine is NULL.  */