virtio: device_plugged() can fail

This patch passes error pointer to transport specific device_plugged()
callback. Through this way, device_plugged() can do some transport
specific check and fail. This will be uesd by following patches that
check the number of virtqueues against the transport limitation.

Cc: Cornelia Huck <cornelia.huck@de.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Alexander Graf <agraf@suse.de>
Signed-off-by: NJason Wang <jasowang@redhat.com>
Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>

hw/s390x/virtio-ccw.c

@@ -1378,7 +1378,7 @@ static int virtio_ccw_load_config(DeviceState *d, QEMUFile *f)
 }
 
 /* This is called by virtio-bus just after the device is plugged. */
-static void virtio_ccw_device_plugged(DeviceState *d)
+static void virtio_ccw_device_plugged(DeviceState *d, Error **errp)
 {
     VirtioCcwDevice *dev = VIRTIO_CCW_DEVICE(d);
     SubchDev *sch = dev->sch;

hw/virtio/virtio-bus.c

@@ -38,7 +38,7 @@ do { printf("virtio_bus: " fmt , ## __VA_ARGS__); } while (0)
 #endif
 
 /* A VirtIODevice is being plugged */
-int virtio_bus_device_plugged(VirtIODevice *vdev)
+void virtio_bus_device_plugged(VirtIODevice *vdev, Error **errp)
 {
     DeviceState *qdev = DEVICE(vdev);
     BusState *qbus = BUS(qdev_get_parent_bus(qdev));
@@ -49,13 +49,12 @@ int virtio_bus_device_plugged(VirtIODevice *vdev)
     DPRINTF("%s: plug device.\n", qbus->name);
 
     if (klass->device_plugged != NULL) {
-        klass->device_plugged(qbus->parent);
+        klass->device_plugged(qbus->parent, errp);
     }
 
     /* Get the features of the plugged device. */
     assert(vdc->get_features != NULL);
     vdev->host_features = vdc->get_features(vdev, vdev->host_features);
-    return 0;
 }
 
 /* Reset the virtio_bus */

hw/virtio/virtio-pci.c

@@ -912,7 +912,7 @@ static int virtio_pci_query_nvectors(DeviceState *d)
 }
 
 /* This is called by virtio-bus just after the device is plugged. */
-static void virtio_pci_device_plugged(DeviceState *d)
+static void virtio_pci_device_plugged(DeviceState *d, Error **errp)
 {
     VirtIOPCIProxy *proxy = VIRTIO_PCI(d);
     VirtioBusState *bus = &proxy->bus;

hw/virtio/virtio.c

@@ -1323,7 +1323,12 @@ static void virtio_device_realize(DeviceState *dev, Error **errp)
             return;
         }
     }
-    virtio_bus_device_plugged(vdev);
+
+    virtio_bus_device_plugged(vdev, &err);
+    if (err != NULL) {
+        error_propagate(errp, err);
+        return;
+    }
 }
 
 static void virtio_device_unrealize(DeviceState *dev, Error **errp)

include/hw/virtio/virtio-bus.h

@@ -55,7 +55,7 @@ typedef struct VirtioBusClass {
      * transport independent init function.
      * This is called by virtio-bus just after the device is plugged.
      */
-    void (*device_plugged)(DeviceState *d);
+    void (*device_plugged)(DeviceState *d, Error **errp);
     /*
      * transport independent exit function.
      * This is called by virtio-bus just before the device is unplugged.
@@ -74,7 +74,7 @@ struct VirtioBusState {
     BusState parent_obj;
 };
 
-int virtio_bus_device_plugged(VirtIODevice *vdev);
+void virtio_bus_device_plugged(VirtIODevice *vdev, Error **errp);
 void virtio_bus_reset(VirtioBusState *bus);
 void virtio_bus_device_unplugged(VirtIODevice *bus);
 /* Get the device id of the plugged device. */