[Kimchi-devel] [PATCH] [Kimchi 2/4] CPU Hot plug/unplug: model changes

[Aline Manera]

On 11/08/2016 11:33 AM, dhbarboza82 at gmail.com wrote:
> From: Daniel Henrique Barboza <danielhb at linux.vnet.ibm.com>
>
> This patch makes changes on model/vms.py to support
> the hotplug of new CPUs in a running VM.
>
> For CPU Hot unplug in Power hypervisors there is a need
> for guest software to be installed:
>
> * guest must have packages: powerpc-utils, ppc64-diag, librtas
> * guest must have service rtas_err.service running
>
> Signed-off-by: Daniel Henrique Barboza <danielhb at linux.vnet.ibm.com>
> ---
>   model/vms.py | 50 +++++++++++++++++++++++++++++++++++++++++++++++++-
>   1 file changed, 49 insertions(+), 1 deletion(-)
>
> diff --git a/model/vms.py b/model/vms.py
> index bff7ed2..cc9cd4c 100644
> --- a/model/vms.py
> +++ b/model/vms.py
> @@ -82,7 +82,8 @@ DOM_STATE_MAP = {0: 'nostate',
>                    7: 'pmsuspended'}
>
>   # update parameters which are updatable when the VM is online
> -VM_ONLINE_UPDATE_PARAMS = ['graphics', 'groups', 'memory', 'users']
> +VM_ONLINE_UPDATE_PARAMS = ['cpu_info', 'graphics', 'groups',
> +                           'memory', 'users']
>
>   # update parameters which are updatable when the VM is offline
>   VM_OFFLINE_UPDATE_PARAMS = ['cpu_info', 'graphics', 'groups', 'memory',
> @@ -1028,6 +1029,15 @@ class VMModel(object):
>                                                  unit='Kib'))
>           return ET.tostring(root, encoding="utf-8")
>
> +    def get_vm_cpu_cores(self, vm_xml):
> +        return xpath_get_text(vm_xml, XPATH_TOPOLOGY + '/@cores')[0]
> +
> +    def get_vm_cpu_sockets(self, vm_xml):
> +        return xpath_get_text(vm_xml, XPATH_TOPOLOGY + '/@sockets')[0]
> +
> +    def get_vm_cpu_threads(self, vm_xml):
> +        return xpath_get_text(vm_xml, XPATH_TOPOLOGY + '/@threads')[0]
> +
>       def _update_cpu_info(self, new_xml, dom, new_info):
>           topology = {}
>           if self.has_topology(dom):
> @@ -1064,6 +1074,44 @@ class VMModel(object):
>           if (('memory' in params) and ('current' in params['memory'])):
>               self._update_memory_live(dom, params)
>
> +        if 'vcpus' in params.get('cpu_info', {}):
> +            self.cpu_hotplug_precheck(dom, params)
> +            vcpus = params['cpu_info'].get('vcpus')
> +            self.update_cpu_live(dom, vcpus)
> +

> +    def cpu_hotplug_precheck(self, dom, params):
> +
> +        if (('maxvcpus' in params['cpu_info']) or
> +                ('topology' in params['cpu_info'])):
> +            raise InvalidParameter('KCHCPUHOTP0001E')
> +
> +        vcpus = params['cpu_info'].get('vcpus')
> +        if vcpus > dom.maxVcpus():
> +            raise InvalidParameter(
> +                'KCHCPUHOTP0002E',
> +                {'vm': dom.name(), 'cpus': dom.maxVcpus()}
> +            )
> +
> +        if self.has_topology(dom):
> +            sockets = int(self.get_vm_cpu_sockets(dom.XMLDesc(0)))
> +            cores = int(self.get_vm_cpu_cores(dom.XMLDesc(0)))
> +            threads = int(self.get_vm_cpu_threads(dom.XMLDesc(0)))
> +
> +            if vcpus % threads != 0:
> +                raise InvalidParameter(
> +                    'KCHCPUHOTP0003E',
> +                    {'sockets': str(sockets), 'cores': str(cores),
> +                     'threads': str(threads)}
> +                )
> +

Can't we use check_cpu_info() to do all the verification ? It would be 
better to have a single place where we can do the checks for CPU.

> +    def update_cpu_live(self, dom, vcpus):
> +        flags = libvirt.VIR_DOMAIN_AFFECT_LIVE | \
> +                libvirt.VIR_DOMAIN_AFFECT_CONFIG
> +        try:
> +            dom.setVcpusFlags(vcpus, flags)
> +        except libvirt.libvirtError as e:
> +            raise OperationFailed('KCHCPUHOTP0004E', {'err': e.message})
> +
>       def _get_mem_dev_total_size(self, xml):
>           root = ET.fromstring(xml)
>           totMemDevs = 0