Re: [PATCH v5 16/20] microvm: wire up hotplug

[Igor Mammedov]

On Tue,  7 Jul 2020 14:53:52 +0200
Gerd Hoffmann <kraxel@redhat.com> wrote:

> The cpu hotplug code handles the initialization of coldplugged cpus
> too, so it is needed even in case cpu hotplug is not supported.
> 
> Wire cpu hotplug up for microvm.
> Without this we get a broken MADT table.
> 
> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

Blame is on me for calling it hotplug, HotplugHandlerClass is basically
a set of hooks to wire things up regardless if it's hotplug or coldplug.
In hindsight it was obvious at the time it was introduced.

Reviewed-by: Igor Mammedov <imammedo@redhat.com>

> ---
>  hw/i386/microvm.c | 42 ++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 42 insertions(+)
> 
> diff --git a/hw/i386/microvm.c b/hw/i386/microvm.c
> index 3d8a66cfc3ac..a5b16b728f9f 100644
> --- a/hw/i386/microvm.c
> +++ b/hw/i386/microvm.c
> @@ -320,6 +320,39 @@ static void microvm_fix_kernel_cmdline(MachineState 
> *machine)
>      g_free(cmdline);
>  }
>  
> +static void microvm_device_pre_plug_cb(HotplugHandler *hotplug_dev,
> +                                       DeviceState *dev, Error **errp)
> +{
> +    x86_cpu_pre_plug(hotplug_dev, dev, errp);
> +}
> +
> +static void microvm_device_plug_cb(HotplugHandler *hotplug_dev,
> +                                   DeviceState *dev, Error **errp)
> +{
> +    x86_cpu_plug(hotplug_dev, dev, errp);
> +}
> +
> +static void microvm_device_unplug_request_cb(HotplugHandler *hotplug_dev,
> +                                             DeviceState *dev, Error **errp)
> +{
> +    error_setg(errp, "unplug not supported by microvm");
> +}
> +
> +static void microvm_device_unplug_cb(HotplugHandler *hotplug_dev,
> +                                     DeviceState *dev, Error **errp)
> +{
> +    error_setg(errp, "unplug not supported by microvm");
> +}
> +
> +static HotplugHandler *microvm_get_hotplug_handler(MachineState *machine,
> +                                                   DeviceState *dev)
> +{
> +    if (object_dynamic_cast(OBJECT(dev), TYPE_CPU)) {
> +        return HOTPLUG_HANDLER(machine);
> +    }
> +    return NULL;
> +}
> +
>  static void microvm_machine_state_init(MachineState *machine)
>  {
>      MicrovmMachineState *mms = MICROVM_MACHINE(machine);
> @@ -503,6 +536,7 @@ static void microvm_machine_initfn(Object *obj)
>  static void microvm_class_init(ObjectClass *oc, void *data)
>  {
>      MachineClass *mc = MACHINE_CLASS(oc);
> +    HotplugHandlerClass *hc = HOTPLUG_HANDLER_CLASS(oc);
>  
>      mc->init = microvm_machine_state_init;
>  
> @@ -523,6 +557,13 @@ static void microvm_class_init(ObjectClass *oc, void 
> *data)
>      /* Machine class handlers */
>      mc->reset = microvm_machine_reset;
>  
> +    /* hotplug (for cpu coldplug) */
> +    mc->get_hotplug_handler = microvm_get_hotplug_handler;
> +    hc->pre_plug = microvm_device_pre_plug_cb;
> +    hc->plug = microvm_device_plug_cb;
> +    hc->unplug_request = microvm_device_unplug_request_cb;
> +    hc->unplug = microvm_device_unplug_cb;
> +
>      object_class_property_add(oc, MICROVM_MACHINE_PIC, "OnOffAuto",
>                                microvm_machine_get_pic,
>                                microvm_machine_set_pic,
> @@ -572,6 +613,7 @@ static const TypeInfo microvm_machine_info = {
>      .class_size    = sizeof(MicrovmMachineClass),
>      .class_init    = microvm_class_init,
>      .interfaces = (InterfaceInfo[]) {
> +         { TYPE_HOTPLUG_HANDLER },
>           { }
>      },
>  };