On Fri, Aug 12, 2022 at 12:04:23PM +0200, Michal Privoznik wrote: > As advertised in the previous commit, QEMU_SCHED_CORE_VCPUS case > is implemented for hotplug case. The implementation is very > similar to the cold boot case, except here we fork off for every > vCPU (because the implementation is done in > qemuProcessSetupVcpu() which is also the function that's called > from hotplug code). But that's okay because our hotplug APIs > allow hotplugging one device at the time. > > Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=2074559 > Signed-off-by: Michal Privoznik <mprivozn@xxxxxxxxxx> > --- > src/qemu/qemu_hotplug.c | 2 +- > src/qemu/qemu_process.c | 63 +++++++++++++++++++++++++++++++++++++++-- > src/qemu/qemu_process.h | 3 +- > 3 files changed, 64 insertions(+), 4 deletions(-) > > diff --git a/src/qemu/qemu_hotplug.c b/src/qemu/qemu_hotplug.c > index 30f146f2f4..ff7f87f362 100644 > --- a/src/qemu/qemu_hotplug.c > +++ b/src/qemu/qemu_hotplug.c > @@ -6240,7 +6240,7 @@ qemuDomainHotplugAddVcpu(virQEMUDriver *driver, > vcpuinfo->online = true; > > if (vcpupriv->tid > 0 && > - qemuProcessSetupVcpu(vm, i) < 0) > + qemuProcessSetupVcpu(vm, i, true) < 0) > return -1; > } > > diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c > index f9c4f72496..8892bf40e4 100644 > --- a/src/qemu/qemu_process.c > +++ b/src/qemu/qemu_process.c > @@ -5817,10 +5817,48 @@ qemuProcessNetworkPrepareDevices(virQEMUDriver *driver, > } > > > +struct qemuProcessSetupVcpuSchedCoreHelperData { > + pid_t vcpupid; > + pid_t dummypid; > +}; > + > +static int > +qemuProcessSetupVcpuSchedCoreHelper(pid_t ppid G_GNUC_UNUSED, > + void *opaque) > +{ > + struct qemuProcessSetupVcpuSchedCoreHelperData *data = opaque; > + > + if (data->dummypid != -1) { > + if (virProcessSchedCoreShareFrom(data->dummypid) < 0) { > + virReportSystemError(errno, > + _("unable to share scheduling cookie from %lld"), > + (long long) data->dummypid); > + return -1; > + } > + } else { > + if (virProcessSchedCoreCreate() < 0) { > + virReportSystemError(errno, "%s", > + _("unable to create new scheduling group")); > + return -1; > + } Surely this branch must be dead/unreachable code.... > + } > + > + if (virProcessSchedCoreShareTo(data->vcpupid) < 0) { > + virReportSystemError(errno, > + _("unable to share scheduling cookie to %lld"), > + (long long) data->vcpupid); > + return -1; > + } > + > + return 0; > +} > + > + > /** > * qemuProcessSetupVcpu: > * @vm: domain object > * @vcpuid: id of VCPU to set defaults > + * @schedCore: whether to set scheduling group > * > * This function sets resource properties (cgroups, affinity, scheduler) for a > * vCPU. This function expects that the vCPU is online and the vCPU pids were > @@ -5830,8 +5868,11 @@ qemuProcessNetworkPrepareDevices(virQEMUDriver *driver, > */ > int > qemuProcessSetupVcpu(virDomainObj *vm, > - unsigned int vcpuid) > + unsigned int vcpuid, > + bool schedCore) > { > + qemuDomainObjPrivate *priv = vm->privateData; > + g_autoptr(virQEMUDriverConfig) cfg = virQEMUDriverGetConfig(priv->driver); > pid_t vcpupid = qemuDomainGetVcpuPid(vm, vcpuid); > virDomainVcpuDef *vcpu = virDomainDefGetVcpu(vm->def, vcpuid); > virDomainResctrlMonDef *mon = NULL; > @@ -5844,6 +5885,24 @@ qemuProcessSetupVcpu(virDomainObj *vm, > &vcpu->sched) < 0) > return -1; > > + if (schedCore && > + cfg->schedCore == QEMU_SCHED_CORE_VCPUS) { > + struct qemuProcessSetupVcpuSchedCoreHelperData data = { .vcpupid = vcpupid, > + .dummypid = -1 }; > + > + for (i = 0; i < virDomainDefGetVcpusMax(vm->def); i++) { > + pid_t temptid = qemuDomainGetVcpuPid(vm, i); > + > + if (temptid > 0) { > + data.dummypid = temptid; > + break; > + } ....since when hotplugging a CPU there *must* always be at least 1 pre-existing vCPU - can't haave an existing running guest with 0 vCPUs. > + } So don't we just need to raise an error here if we see dummypid is still -1 ? > + > + if (virProcessRunInFork(qemuProcessSetupVcpuSchedCoreHelper, &data) < 0) > + return -1; > + } > + > for (i = 0; i < vm->def->nresctrls; i++) { > size_t j = 0; > virDomainResctrlDef *ct = vm->def->resctrls[i]; With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
