Re: [libvirt] [PATCH] Allow suspend during live migration

Currently no command can be sent to a qemu process while another job is active. This patch adds support for signaling long-running jobs (such as migration) so that other threads may request predefined operations to be done during such jobs. Two signals are defined so far: - QEMU_JOB_SIGNAL_CANCEL - QEMU_JOB_SIGNAL_SUSPEND The first one is used by qemuDomainAbortJob. The second one is used by qemudDomainSuspend for suspending a domain during migration, which allows for changing live migration into offline migration. However, there is a small issue in the way qemudDomainSuspend is currently implemented for migrating domains. The API calls returns immediately after signaling migration job which means it is asynchronous in this specific case.

@@ -3560,6 +3572,7 @@ static int qemudDomainSuspend(virDomainPtr dom) { virDomainObjPtr vm; int ret = -1; virDomainEventPtr event = NULL; + qemuDomainObjPrivatePtr priv; qemuDriverLock(driver); vm = virDomainFindByUUID(&driver->domains, dom->uuid); @@ -3571,30 +3584,48 @@ static int qemudDomainSuspend(virDomainPtr dom) { _("no domain with matching uuid '%s'"), uuidstr); goto cleanup; } - if (qemuDomainObjBeginJobWithDriver(driver, vm) < 0) - goto cleanup; - if (!virDomainObjIsActive(vm)) { qemuReportError(VIR_ERR_OPERATION_INVALID, "%s", _("domain is not running")); - goto endjob; + goto cleanup; } - if (vm->state != VIR_DOMAIN_PAUSED) { - qemuDomainObjPrivatePtr priv = vm->privateData; - qemuDomainObjEnterMonitorWithDriver(driver, vm); - if (qemuMonitorStopCPUs(priv->mon) < 0) { - qemuDomainObjExitMonitorWithDriver(driver, vm); + + priv = vm->privateData; + + if (priv->jobActive == QEMU_JOB_MIGRATION) { + if (vm->state != VIR_DOMAIN_PAUSED) { + VIR_DEBUG("Requesting domain pause on %s", + vm->def->name); + priv->jobSignals |= QEMU_JOB_SIGNAL_SUSPEND;

+ } + ret = 0; + goto cleanup; + } else { + if (qemuDomainObjBeginJobWithDriver(driver, vm) < 0) + goto cleanup; + + if (!virDomainObjIsActive(vm)) { + qemuReportError(VIR_ERR_OPERATION_INVALID, + "%s", _("domain is not running")); goto endjob; } - qemuDomainObjExitMonitorWithDriver(driver, vm); - vm->state = VIR_DOMAIN_PAUSED; - event = virDomainEventNewFromObj(vm, - VIR_DOMAIN_EVENT_SUSPENDED, - VIR_DOMAIN_EVENT_SUSPENDED_PAUSED); + if (vm->state != VIR_DOMAIN_PAUSED) { + int rc; + + qemuDomainObjEnterMonitorWithDriver(driver, vm); + rc = qemuMonitorStopCPUs(priv->mon); + qemuDomainObjExitMonitorWithDriver(driver, vm); + if (rc < 0) + goto endjob; + vm->state = VIR_DOMAIN_PAUSED; + event = virDomainEventNewFromObj(vm, + VIR_DOMAIN_EVENT_SUSPENDED, + VIR_DOMAIN_EVENT_SUSPENDED_PAUSED); + } + if (virDomainSaveStatus(driver->caps, driver->stateDir, vm) < 0) + goto endjob; + ret = 0; } - if (virDomainSaveStatus(driver->caps, driver->stateDir, vm) < 0) - goto endjob; - ret = 0; endjob: if (qemuDomainObjEndJob(vm) == 0)