Re: [PATCH] hw/virtio: Add a protection against duplicate vu_scmi_stop calls

[Milan Zamazal <mzamazal@redhat.com>]

Fabiano Rosas <farosas@suse.de> writes:

> Milan Zamazal <mzamazal@redhat.com> writes:
>
>> The QEMU CI fails in virtio-scmi test occasionally.  As reported by
>> Thomas Huth, this happens most likely when the system is loaded and it
>> fails with the following error:
>>
>>   qemu-system-aarch64: ../../devel/qemu/hw/pci/msix.c:659:
>>   msix_unset_vector_notifiers: Assertion
>> `dev->msix_vector_use_notifier && dev->msix_vector_release_notifier'
>> failed.
>>   ../../devel/qemu/tests/qtest/libqtest.c:200: kill_qemu() detected
>> QEMU death from signal 6 (Aborted) (core dumped)
>>
>> As discovered by Fabiano Rosas, the cause is a duplicate invocation of
>> msix_unset_vector_notifiers via duplicate vu_scmi_stop calls:
>>
>>   msix_unset_vector_notifiers
>>   virtio_pci_set_guest_notifiers
>>   vu_scmi_stop
>>   vu_scmi_disconnect
>>   ...
>>   qemu_chr_write_buffer
>>
>>   msix_unset_vector_notifiers
>>   virtio_pci_set_guest_notifiers
>>   vu_scmi_stop
>>   vu_scmi_set_status
>>   ...
>>   qemu_cleanup
>>
>> While vu_scmi_stop calls are protected by vhost_dev_is_started()
>> check, it's apparently not enough.  vhost-user-blk and vhost-user-gpio
>> use an extra protection, see f5b22d06fb (vhost: recheck dev state in
>> the vhost_migration_log routine) for the motivation.  Let's use the
>> same in vhost-user-scmi, which fixes the failure above.
>>
>> Fixes: a5dab090e142 ("hw/virtio: Add boilerplate for vhost-user-scmi device")
>> Signed-off-by: Milan Zamazal <mzamazal@redhat.com>
>
> Reviewed-by: Fabiano Rosas <farosas@suse.de>

Please note that this bug fix should IMO definitely go to 8.1, to not
have a bug in vhost-user-scmi and to not have broken tests.  Any chance
to get it merged?

Thanks,
Milan