Re: [libvirt] [PATCH] libvirt: qemu: Fix domain termination caused by query-hotpluggable-cpus not enabled

(Re-)Starting libvirt on a system with running qemu domains which earlier had been successfully started by libvirt results in the error internal error: unable to execute QEMU command 'query-hotpluggable-cpus': The feature 'query-hotpluggable-cpus' is not enabled if the qemu binary does not support the qmp command 'query-hotpluggable-cpus'. As libvirt tries to reconnect to the running qemu domains it reads in the capabilities but in qemuProcessReconnect misses to run virQEMUCapsCacheLookupCopy and not clearing the query-hotpluggable-cpus capability in virQEMUCapsFilterByMachineType which was introduced with commit 920bbe5c. Libvirt therefore issues the qmp command and qemu responds with the error 'The feature 'query-hotpluggable-cpus' is not enabled'. As a consequence libvirt terminates the running qemu process since it determines that it cannot reconnect to the domain. Signed-off-by: Boris Fiuczynski <fiuczy(a)linux.vnet.ibm.com&gt; Reviewed-by: Marc Hartmayer <mhartmay(a)linux.vnet.ibm.com&gt; --- Due to the severity of this issue I recommend to backport this fix into all maintenance releases up to v2.2.0. src/qemu/qemu_process.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c index f8f379a..675f5b5 100644 --- a/src/qemu/qemu_process.c +++ b/src/qemu/qemu_process.c @@ -3349,8 +3349,7 @@ qemuProcessReconnect(void *opaque) /* If upgrading from old libvirtd we won't have found any * caps in the domain status, so re-query them

*/ - if (!priv->qemuCaps && - !(priv->qemuCaps = virQEMUCapsCacheLookupCopy(caps, + if (!(priv->qemuCaps = virQEMUCapsCacheLookupCopy(caps, driver->qemuCapsCache, obj->def->emulator, obj->def->os.machine)))