Re: [Qemu-devel] [for-2.7 PATCH v3 13/15] QMP: Add query-hotpluggable-cpus

[Igor Mammedov <imammedo@redhat.com>]

On Mon, 6 Jun 2016 15:28:09 +1000
David Gibson <david@gibson.dropbear.id.au> wrote:

> On Thu, May 12, 2016 at 09:18:23AM +0530, Bharata B Rao wrote:
> > From: Igor Mammedov <imammedo@redhat.com>
> > 
> > It will allow mgmt to query present and hotpluggable CPU objects,
> > it is required from a target platform that wishes to support command
> > to implement and set MachineClass.query_hotpluggable_cpus callback,
> > which will return a list of possible CPU objects with options that
> > would be needed for hotplugging possible CPU objects.
> > 
> > There are:
> > 'type': 'str' - QOM CPU object type for usage with device_add
> > 'vcpus-count': 'int' - number of logical VCPU threads per
> >                         CPU object (mgmt needs to know)
> > 
> > and a set of optional fields that are to used for hotplugging a CPU
> > objects and would allows mgmt tools to know what/where it could be
> > hotplugged;
> > [node],[socket],[core],[thread]
> > 
> > For present CPUs there is a 'qom-path' field which would allow mgmt to
> > inspect whatever object/abstraction the target platform considers
> > as CPU object.
> > 
> > Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> > Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>  
> 
> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
> 
> Igor, if you're ready for this to go ahead, I'll take it through my tree.
yep, it will allow me drop the same patch(es) from my ACPI CPU hotplug refactoring,
please take it through your tree.

> 
> > ---
> >  include/hw/boards.h |  5 +++++
> >  monitor.c           | 13 +++++++++++++
> >  qapi-schema.json    | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++++
> >  qmp-commands.hx     | 23 ++++++++++++++++++++++
> >  4 files changed, 96 insertions(+)
> > 
> > diff --git a/include/hw/boards.h b/include/hw/boards.h
> > index 8d4fe56..0db0c1e 100644
> > --- a/include/hw/boards.h
> > +++ b/include/hw/boards.h
> > @@ -81,6 +81,10 @@ typedef struct {
> >   *    Returns an array of @CPUArchId architecture-dependent CPU IDs
> >   *    which includes CPU IDs for present and possible to hotplug CPUs.
> >   *    Caller is responsible for freeing returned list.
> > + * @query_hotpluggable_cpus:
> > + *    Returns a @HotpluggableCPUList, which describes CPUs objects which
> > + *    could be added with -device/device_add.
> > + *    Caller is responsible for freeing returned list.
> >   */
> >  struct MachineClass {
> >      /*< private >*/
> > @@ -124,6 +128,7 @@ struct MachineClass {
> >                                             DeviceState *dev);
> >      unsigned (*cpu_index_to_socket_id)(unsigned cpu_index);
> >      CPUArchIdList *(*possible_cpu_arch_ids)(MachineState *machine);
> > +    HotpluggableCPUList *(*query_hotpluggable_cpus)(MachineState *machine);
> >  };
> >  
> >  /**
> > diff --git a/monitor.c b/monitor.c
> > index d1c1930..b469225 100644
> > --- a/monitor.c
> > +++ b/monitor.c
> > @@ -4267,3 +4267,16 @@ GICCapabilityList *qmp_query_gic_capabilities(Error **errp)
> >      return NULL;
> >  }
> >  #endif
> > +
> > +HotpluggableCPUList *qmp_query_hotpluggable_cpus(Error **errp)
> > +{
> > +    MachineState *ms = MACHINE(qdev_get_machine());
> > +    MachineClass *mc = MACHINE_GET_CLASS(ms);
> > +
> > +    if (!mc->query_hotpluggable_cpus) {
> > +        error_setg(errp, QERR_FEATURE_DISABLED, "query-hotpluggable-cpus");
> > +        return NULL;
> > +    }
> > +
> > +    return mc->query_hotpluggable_cpus(ms);
> > +}
> > diff --git a/qapi-schema.json b/qapi-schema.json
> > index 54634c4..137e532 100644
> > --- a/qapi-schema.json
> > +++ b/qapi-schema.json
> > @@ -4178,3 +4178,58 @@
> >  # Since: 2.6
> >  ##
> >  { 'command': 'query-gic-capabilities', 'returns': ['GICCapability'] }
> > +
> > +##
> > +# CpuInstanceProperties
> > +#
> > +# List of properties to be used for hotplugging a CPU instance,
> > +# it should be passed by management with device_add command when
> > +# a CPU is being hotplugged.
> > +#
> > +# Note: currently there are 4 properties that could be present
> > +# but management should be prepared to pass through other
> > +# properties with device_add command to allow for future
> > +# interface extension.
> > +#
> > +# @node: #optional NUMA node ID the CPU belongs to
> > +# @socket: #optional socket number within node/board the CPU belongs to
> > +# @core: #optional core number within socket the CPU belongs to
> > +# @thread: #optional thread number within core the CPU belongs to
> > +#
> > +# Since: 2.7
> > +##
> > +{ 'struct': 'CpuInstanceProperties',
> > +  'data': { '*node': 'int',
> > +            '*socket': 'int',
> > +            '*core': 'int',
> > +            '*thread': 'int'
> > +  }
> > +}
> > +
> > +##
> > +# @HotpluggableCPU
> > +#
> > +# @type: CPU object type for usage with device_add command
> > +# @props: list of properties to be used for hotplugging CPU
> > +# @vcpus-count: number of logical VCPU threads @HotpluggableCPU provides
> > +# @qom-path: #optional link to existing CPU object if CPU is present or
> > +#            omitted if CPU is not present.
> > +#
> > +# Since: 2.7
> > +##
> > +{ 'struct': 'HotpluggableCPU',
> > +  'data': { 'type': 'str',
> > +            'vcpus-count': 'int',
> > +            'props': 'CpuInstanceProperties',
> > +            '*qom-path': 'str'
> > +          }
> > +}
> > +
> > +##
> > +# @query-hotpluggable-cpus
> > +#
> > +# Returns: a list of HotpluggableCPU objects.
> > +#
> > +# Since: 2.7
> > +##
> > +{ 'command': 'query-hotpluggable-cpus', 'returns': ['HotpluggableCPU'] }
> > diff --git a/qmp-commands.hx b/qmp-commands.hx
> > index de896a5..5640147 100644
> > --- a/qmp-commands.hx
> > +++ b/qmp-commands.hx
> > @@ -4880,3 +4880,26 @@ Example:
> >                  { "version": 3, "emulated": false, "kernel": true } ] }
> >  
> >  EQMP
> > +
> > +    {
> > +        .name       = "query-hotpluggable-cpus",
> > +        .args_type  = "",
> > +        .mhandler.cmd_new = qmp_marshal_query_hotpluggable_cpus,
> > +    },
> > +
> > +SQMP
> > +Show existing/possible CPUs
> > +---------------------------
> > +
> > +Arguments: None.
> > +
> > +Example for pseries machine type started with
> > +-smp 2,cores=2,maxcpus=4 -cpu POWER8:
> > +
> > +-> { "execute": "query-hotpluggable-cpus" }
> > +<- {"return": [
> > +     { "props": { "core": 8 }, "type": "POWER8-spapr-cpu-core",
> > +       "vcpus-count": 1 },
> > +     { "props": { "core": 0 }, "type": "POWER8-spapr-cpu-core",
> > +       "vcpus-count": 1, "qom-path": "/machine/unattached/device[0]"}
> > +   ]}'  
>