Adding a 2nd balloon device after unplugging the first one doesn't work. Also, the 'info balloon' command should indicate an error mentioning no balloon device is registered after unplug.
Reproduction steps given by Shaolong Hu: (qemu) info balloon Device 'balloon' has not been activated by the guest (qemu) device_add virtio-balloon-pci,id=balloon1 (qemu) info balloon balloon: actual=4096 (qemu) balloon 2048 (qemu) info balloon balloon: actual=2048 (qemu) device_del balloon1 (qemu) info balloon balloon: actual=4096 (qemu) balloon 2048 (qemu) info balloon balloon: actual=4096 (qemu) device_del balloon1 Device 'balloon1' not found (qemu) device_add virtio-balloon-pci,id=balloon1 Another balloon device already registered Device 'virtio-balloon-pci' could not be initialized (qemu) device_add virtio-balloon-pci,id=balloon2 Another balloon device already registered Device 'virtio-balloon-pci' could not be initialized Reported-by: Shaolong Hu <s...@redhat.com> Signed-off-by: Amit Shah <amit.s...@redhat.com> --- hw/virtio-balloon.c | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-) diff --git a/hw/virtio-balloon.c b/hw/virtio-balloon.c index 072a88a..5f8f4bd 100644 --- a/hw/virtio-balloon.c +++ b/hw/virtio-balloon.c @@ -303,6 +303,8 @@ VirtIODevice *virtio_balloon_init(DeviceState *dev) void virtio_balloon_exit(VirtIODevice *vdev) { VirtIOBalloon *s = DO_UPCAST(VirtIOBalloon, vdev, vdev); + + qemu_remove_balloon_handler(s); unregister_savevm(s->qdev, "virtio-balloon", s); virtio_cleanup(vdev); } -- 1.7.6