[libvirt] [PATCHv3 6/6] qemu: refresh vcpu halted state only via query-cpus-fast

In order to not affect running VMs, refreshing the halted state is only performed if QEMU supports the query-cpus-fast QAPI. Signed-off-by: Viktor Mihajlovski <mihajlov(a)linux.vnet.ibm.com&gt; Reviewed-by: Boris Fiuczynski <fiuczy(a)linux.vnet.ibm.com&gt; Reviewed-by: Marc Hartmayer <mhartmay(a)linux.vnet.ibm.com&gt; --- src/qemu/qemu_domain.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c index 662937b..0331af7 100644 --- a/src/qemu/qemu_domain.c +++ b/src/qemu/qemu_domain.c @@ -9124,8 +9124,13 @@ qemuDomainRefreshVcpuHalted(virQEMUDriverPtr driver, return 0; /* The halted state is interresting only on s390(x). On other platforms - * the data would be stale at the time when it would be used. */ - if (!ARCH_IS_S390(vm->def->os.arch)) + * the data would be stale at the time when it would be used. + * Calling qemuMonitorGetCpuHalted() can adversely affect the running + * VM's performance unless QEMU supports query-cpus-fast. + */ + if (!ARCH_IS_S390(vm->def->os.arch) || + !virQEMUCapsGet(QEMU_DOMAIN_PRIVATE(vm)->qemuCaps, + QEMU_CAPS_QUERY_CPUS_FAST)) return 0; if (qemuDomainObjEnterMonitorAsync(driver, vm, asyncJob) < 0) -- 1.9.1