[libvirt] [Qemu-devel] [PATCH 2/4] QMP: add cpu-add command

[Igor Mammedov]

On Tue, 30 Apr 2013 10:46:20 -0300
Eduardo Habkost <ehabkost at redhat.com> wrote:

> (CCing libvir-list)
> 
> On Tue, Apr 30, 2013 at 08:34:01AM +0200, Igor Mammedov wrote:
> > Adds "cpu-add id=xxx" QMP command.
> > 
> > cpu-add's "id" argument is a CPU number in a range [0..max-cpus)
> > 
> > Example QMP command:
> >  -> { "execute": "cpu-add", "arguments": { "id": 2 } }
> >  <- { "return": {} }
> > 
> > Signed-off-by: Igor Mammedov <imammedo at redhat.com>
> > Acked-by: Luiz Capitulino <lcapitulino at redhat.com>
> > Reviewed-by: Eric Blake <eblake at redhat.com>
> 
> The only way to find out if CPU hotplug is really available on a given
> machine-type is by actually trying to run cpu-add, right? Is this
> sufficient for libvirt requirements?
yes, for now it is the only way.it was acked from their side.

> 
> 
> > ---
> > v7:
> >   * added "Since 1.5" to cpu-add qapi schema definition
> > v6:
> >   * added valid values description to qapi schema
> >   * split out cpu_hot_add hooks introduction into separate patch
> >   * split out implementation of cpu_hot_add for target-i386
> > v5:
> >   * accept id=[0..max_cpus) range in cpu-add command
> > v4:
> >   * merge "qmp: add cpu-add qmp command" & "target-i386: implement CPU hot-add" patches
> >   * move notifier call to CPUCLass.realize()
> >   * add hook cpu_hot_add to QEMUMachine
> >   * make QEMUMachineInitArgs global and keep default cpu_model there
> > 
> > v3:
> >   * it appears that 'online/offline' in cpu-set are confusing people
> >     with what command actually does and users might have to distinguish
> >     if 'offline' is not implemented by parsing error message. To simplify
> >     things replace cpu-set with cpu-add command to show more clear what
> >     command does and just add cpu-del when CPU remove is implemented.
> > 
> > v2:
> >   * s/cpu_set/cpu-set/
> >   * qmp doc style fix
> >   * use bool type instead of opencodding online/offline string
> >      suggested-by: Eric Blake <eblake at redhat.com>
> > ---
> >  qapi-schema.json | 13 +++++++++++++
> >  qmp-commands.hx  | 23 +++++++++++++++++++++++
> >  qmp.c            | 10 ++++++++++
> >  3 files changed, 46 insertions(+)
> > 
> > diff --git a/qapi-schema.json b/qapi-schema.json
> > index 5b0fb3b..6f58b0f 100644
> > --- a/qapi-schema.json
> > +++ b/qapi-schema.json
> > @@ -1387,6 +1387,19 @@
> >  { 'command': 'cpu', 'data': {'index': 'int'} }
> >  
> >  ##
> > +# @cpu-add
> > +#
> > +# Adds CPU with specified ID
> > +#
> > +# @id: ID of CPU to be created, valid values [0..max_cpus)
> > +#
> > +# Returns: Nothing on success
> > +#
> > +# Since 1.5
> > +##
> > +{ 'command': 'cpu-add', 'data': {'id': 'int'} }
> > +
> > +##
> >  # @memsave:
> >  #
> >  # Save a portion of guest memory to a file.
> > diff --git a/qmp-commands.hx b/qmp-commands.hx
> > index 0e89132..ed99eb8 100644
> > --- a/qmp-commands.hx
> > +++ b/qmp-commands.hx
> > @@ -385,6 +385,29 @@ Note: CPUs' indexes are obtained with the 'query-cpus' command.
> >  EQMP
> >  
> >      {
> > +        .name       = "cpu-add",
> > +        .args_type  = "id:i",
> > +        .mhandler.cmd_new = qmp_marshal_input_cpu_add,
> > +    },
> > +
> > +SQMP
> > +cpu-add
> > +-------
> > +
> > +Adds virtual cpu
> > +
> > +Arguments:
> > +
> > +- "id": cpu id (json-int)
> > +
> > +Example:
> > +
> > +-> { "execute": "cpu-add", "arguments": { "id": 2 } }
> > +<- { "return": {} }
> > +
> > +EQMP
> > +
> > +    {
> >          .name       = "memsave",
> >          .args_type  = "val:l,size:i,filename:s,cpu:i?",
> >          .mhandler.cmd_new = qmp_marshal_input_memsave,
> > diff --git a/qmp.c b/qmp.c
> > index ed6c7ef..dd34be6 100644
> > --- a/qmp.c
> > +++ b/qmp.c
> > @@ -24,6 +24,7 @@
> >  #include "hw/qdev.h"
> >  #include "sysemu/blockdev.h"
> >  #include "qom/qom-qobject.h"
> > +#include "hw/boards.h"
> >  
> >  NameInfo *qmp_query_name(Error **errp)
> >  {
> > @@ -108,6 +109,15 @@ void qmp_cpu(int64_t index, Error **errp)
> >      /* Just do nothing */
> >  }
> >  
> > +void qmp_cpu_add(int64_t id, Error **errp)
> > +{
> > +    if (current_machine->hot_add_cpu) {
> > +        current_machine->hot_add_cpu(id, errp);
> > +    } else {
> > +        error_setg(errp, "Not supported");
> > +    }
> > +}
> > +
> >  #ifndef CONFIG_VNC
> >  /* If VNC support is enabled, the "true" query-vnc command is
> >     defined in the VNC subsystem */
> > -- 
> > 1.8.2.1
> > 
>