Re: [libvirt] [PATCH 7/7] qemu: Allow making vcpus hotpluggable with virDomainSetVcpusFlags

On Thu, Sep 29, 2016 at 16:29:13 +0530, Shivaprasad G Bhat wrote: > On 09/21/2016 05:19 PM, Peter Krempa wrote: >> Implement support for VIR_DOMAIN_VCPU_HOTPLUGGABLE so that users can >> choose to make vcpus added by the API removable. >> --- >> src/qemu/qemu_driver.c | 22 ++++++++++++++++------ >> 1 file changed, 16 insertions(+), 6 deletions(-) >> >> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c >> index 357be4e..8453628 100644 >> --- a/src/qemu/qemu_driver.c >> +++ b/src/qemu/qemu_driver.c >> @@ -4912,7 +4912,8 @@ qemuDomainSetVcpusLive(virQEMUDriverPtr driver, >> */ >> static void >> qemuDomainSetVcpusConfig(virDomainDefPtr def, >> - unsigned int nvcpus) >> + unsigned int nvcpus, >> + bool hotpluggable) >> { >> virDomainVcpuDefPtr vcpu; > Here if (curvcpus == nvcpus) > > return > we still need to allow if someone wants to switch from hotpluggable > = yes to no/ vice versa. No. As no new vcpus were added there's nothing to turn to hotpluggable. The flag turns only the newly added vcpus as hotpluggable.

> >> size_t curvcpus = virDomainDefGetVcpus(def); >> @@ -4933,7 +4934,12 @@ qemuDomainSetVcpusConfig(virDomainDefPtr def, >> continue; >> >> vcpu->online = true; >> - vcpu->hotpluggable = VIR_TRISTATE_BOOL_NO; >> + if (hotpluggable) { >> + vcpu->hotpluggable = VIR_TRISTATE_BOOL_YES; >> + def->individualvcpus = true; >> + } else { >> + vcpu->hotpluggable = VIR_TRISTATE_BOOL_NO; >> + } >> >> if (++curvcpus == nvcpus) >> break; > Can we add checks here to see on PPC, the config is valid with a check > when topology is given in xml to see (curvcpus%threads_per_core == 0) No. For PPC and all the weird archs that don't have thread level hotplug we can't really know what to use and what is a legitimate configuration until we start the VM and query qemu. > Otherwise with virsh setvcpus rhel71 13 --config --hotpluggable > for a guest with topology <topology sockets='8' cores='2' threads='4'/> > we would see, > 2016-09-29 10:12:05.929+0000: 1137: error : > qemuProcessValidateHotpluggableVcpus:4829 : unsupported configuration: > vcpus '12' and '13' are in the same hotplug group but differ in > configuration Yes, you can configure the same thing manually in the XML. > OR > > Even when setvcpus live to a number not leading to a complete core, we > have checks leading to sensible error (error: unsupported configuration: > target vm vcpu granularity does not allow the desired vcpu count ) . So, > in case of --config also may be we can add the check to bring the > consistency. As said above. Libvirt can't surely detect that the "weird" approach is needed. Peter