Re: [PATCH v3 13/22] x86: coldplug cpus

[Igor Mammedov <imammedo@redhat.com>]

On Wed, 20 May 2020 15:19:54 +0200
Gerd Hoffmann <kraxel@redhat.com> wrote:

> microvm needs this, for correct madt creation
> (make sure enable bit is set).
> 
> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
> ---
>  hw/i386/x86.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/hw/i386/x86.c b/hw/i386/x86.c
> index 7a3bc7ab6639..ac7a0a958781 100644
> --- a/hw/i386/x86.c
> +++ b/hw/i386/x86.c
> @@ -118,6 +118,7 @@ uint32_t x86_cpu_apic_id_from_index(X86MachineState *x86ms,
>  
>  void x86_cpu_new(X86MachineState *x86ms, int64_t apic_id, Error **errp)
>  {
> +    MachineClass *mc = MACHINE_GET_CLASS(x86ms);
>      Object *cpu = NULL;
>      Error *local_err = NULL;
>  
> @@ -126,6 +127,16 @@ void x86_cpu_new(X86MachineState *x86ms, int64_t apic_id, Error **errp)
>      object_property_set_uint(cpu, apic_id, "apic-id", &local_err);
>      object_property_set_bool(cpu, true, "realized", &local_err);
>  
> +    if (!mc->has_hotpluggable_cpus) {
> +        /* coldplug cpu */
> +        MachineState *ms = MACHINE(x86ms);
> +        int i = 0;
> +        while (ms->possible_cpus->cpus[i].arch_id != apic_id) {
> +            i++;
> +        }
> +        ms->possible_cpus->cpus[i].cpu = cpu;
> +    }

I'm thinking about removing x86_cpu_new alogether (in favor of device_add),
so I'd preffer avoid adding direct access to possible_cpus here.

that's the job of pc_cpu_plug (and possibly pc_cpu_pre_plug) in combination with
static const TypeInfo pc_machine_info = {
    .name = TYPE_PC_MACHINE,
...
    .interfaces = (InterfaceInfo[]) {
         { TYPE_HOTPLUG_HANDLER },
         { }
    },
};

I'd reuse common code if possible in microvm or make microvm specific simplified version of it
if it makes job easier.

>      object_unref(cpu);
>      error_propagate(errp, local_err);
>  }