Re: [Qemu-devel] [RFC PATCH 1/2] qapi: Add vcpu id to query-hotpluggable-cpus output

[David Gibson <dgibson@redhat.com>]

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On Thu,  7 Jul 2016 17:17:13 +0200
Peter Krempa <pkrempa@redhat.com> wrote:

> Add 'vcpu index' to the output of query hotpluggable cpus. This output
> is identical to the linear cpu index taken by the 'cpus' attribute
> passed to -numa.


The problem is, the vcpu index of what?  Each entry in the hotpluggable
cpus table could represent more than one vcpu.

> This will allow to reliably map the cpu number to a given topology
> element without making mgmt apps to reimplement the mapping.
> 
> Signed-off-by: Peter Krempa <pkrempa@redhat.com>
> ---
>  hmp.c            | 1 +
>  hw/i386/pc.c     | 1 +
>  hw/ppc/spapr.c   | 1 +
>  qapi-schema.json | 2 ++
>  4 files changed, 5 insertions(+)
> 
> diff --git a/hmp.c b/hmp.c
> index 0cf5baa..613601e 100644
> --- a/hmp.c
> +++ b/hmp.c
> @@ -2450,6 +2450,7 @@ void hmp_hotpluggable_cpus(Monitor *mon, const QDict *qdict)
>          monitor_printf(mon, "  type: \"%s\"\n", l->value->type);
>          monitor_printf(mon, "  vcpus_count: \"%" PRIu64 "\"\n",
>                         l->value->vcpus_count);
> +        monitor_printf(mon, "  vcpu_id: \"%" PRIu64 "\"\n", l->value->vcpu_id);
>          if (l->value->has_qom_path) {
>              monitor_printf(mon, "  qom_path: \"%s\"\n", l->value->qom_path);
>          }
> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> index f293a0c..4ba02c4 100644
> --- a/hw/i386/pc.c
> +++ b/hw/i386/pc.c
> @@ -2131,6 +2131,7 @@ static HotpluggableCPUList *pc_query_hotpluggable_cpus(MachineState *machine)
> 
>          cpu_item->type = g_strdup(cpu_type);
>          cpu_item->vcpus_count = 1;
> +        cpu_item->vcpu_id = i;
>          cpu_props->has_socket_id = true;
>          cpu_props->socket_id = topo.pkg_id;
>          cpu_props->has_core_id = true;
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index 7f33a1b..d1f5195 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -2378,6 +2378,7 @@ static HotpluggableCPUList *spapr_query_hotpluggable_cpus(MachineState *machine)
> 
>          cpu_item->type = spapr_get_cpu_core_type(machine->cpu_model);
>          cpu_item->vcpus_count = smp_threads;
> +        cpu_item->vcpu_id = i;

This is wrong.  This is the index of the core.  The individual vcpus
within the core will have ids starting at core_id and working up.

>          cpu_props->has_core_id = true;
>          cpu_props->core_id = i * smt;
>          /* TODO: add 'has_node/node' here to describe
> diff --git a/qapi-schema.json b/qapi-schema.json
> index ba3bf14..6db9294 100644
> --- a/qapi-schema.json
> +++ b/qapi-schema.json
> @@ -4292,6 +4292,7 @@
>  # @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
> +# @vcpu-id: linear index of the vcpu
>  # @qom-path: #optional link to existing CPU object if CPU is present or
>  #            omitted if CPU is not present.
>  #
> @@ -4300,6 +4301,7 @@
>  { 'struct': 'HotpluggableCPU',
>    'data': { 'type': 'str',
>              'vcpus-count': 'int',
> +            'vcpu-id': 'int',
>              'props': 'CpuInstanceProperties',
>              '*qom-path': 'str'
>            }
> -- 
> 2.9.0
> 


-- 
David Gibson <dgibson@redhat.com>
Senior Software Engineer, Virtualization, Red Hat

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