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



(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 redhat com>
> Acked-by: Luiz Capitulino <lcapitulino redhat com>
> Reviewed-by: Eric Blake <eblake 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?


> ---
> 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 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
> 

-- 
Eduardo


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