[libvirt] [PATCH] Explicitly pin hotplugged vcpu to all cpus

QEMU does not join vcpu threads after vcpu hotunplug. The thread might stay pinned when we hotplug the cpu again. We were already pinning the hotplugged vcpus when a per-domain pinning was specified. Explicitly pin the hotplugged vcpu to all cpus if there is no cpuset specified in domain XML, to make sure the vcpupin stays accurate. https://bugzilla.redhat.com/show_bug.cgi?id=1099836 --- src/qemu/qemu_driver.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c index 6fda50d..a4fa488 100644 --- a/src/qemu/qemu_driver.c +++ b/src/qemu/qemu_driver.c @@ -3994,6 +3994,7 @@ static int qemuDomainHotplugVcpus(virQEMUDriverPtr driver, pid_t *cpupids = NULL; int ncpupids; virCgroupPtr cgroup_vcpu = NULL; + virBitmapPtr cpumask = NULL; qemuDomainObjEnterMonitor(driver, vm); @@ -4117,6 +4118,24 @@ static int qemuDomainHotplugVcpus(virQEMUDriverPtr driver, goto cleanup; } } + } else { + /* QEMU doesn't destroy vcpu threads on vcpu unplug. + * Pin the vcpu to all CPUs just to be sure */ + cpumask = qemuPrepareCpumap(driver, NULL); + virBitmapSetAll(cpumask); + if (cgroup_vcpu) { + if (qemuSetupCgroupEmulatorPin(cgroup_vcpu, cpumask) < 0) + goto cleanup; + } else { + if (virProcessSetAffinity(cpupids[i], cpumask) < 0) { + virReportError(VIR_ERR_SYSTEM_ERROR, + _("failed to set cpu affinity for vcpu %zu"), + i); + ret = -1; + goto cleanup; + } + } + VIR_FREE(cpumask); } virCgroupFree(&cgroup_vcpu); @@ -4145,6 +4164,7 @@ static int qemuDomainHotplugVcpus(virQEMUDriverPtr driver, cleanup: qemuDomainObjExitMonitor(driver, vm); vm->def->vcpus = vcpus; + VIR_FREE(cpumask); VIR_FREE(cpupids); virDomainAuditVcpu(vm, oldvcpus, nvcpus, "update", rc == 1); if (cgroup_vcpu) -- 1.8.3.2