Re: [Qemu-devel] [RFC V2 05/10] i386: add cpu device_del support

[Igor Mammedov <imammedo@redhat.com>]

On Thu, 28 Aug 2014 11:36:37 +0800
Gu Zheng <guz.fnst@cn.fujitsu.com> wrote:

> In order to add cpu(i386) device_del support, introduce the cpu hot
> unplug hanlde(x86_cpu_unplug) which will trigger the unrealize routine,
> and just register it to the cpu class unplug handle.
> 
> Signed-off-by: Chen Fan <chen.fan.fnst@cn.fujitsu.com>
> Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
> ---
>  target-i386/cpu.c |   22 ++++++++++++++++++++++
>  1 files changed, 22 insertions(+), 0 deletions(-)
> 
> diff --git a/target-i386/cpu.c b/target-i386/cpu.c
> index 72a94a6..dc5153e 100644
> --- a/target-i386/cpu.c
> +++ b/target-i386/cpu.c
> @@ -2993,6 +2993,27 @@ static Property x86_cpu_properties[] = {
>      DEFINE_PROP_END_OF_LIST()
>  };
>  
> +static int x86_cpu_unplug(DeviceState *dev)
> +{
> +    CPUState *cpu = CPU(dev);
> +    X86CPUClass *xcc;
> +    Error *err = NULL;
> +
> +    if (cpu == first_cpu) {
> +        error_report("Can not remove the first cpu!\n");
> +        return -1;
> +    }
it might be too late error out at this time since, guest already got and
handled unplug request. This check should be done at unplug request time
instead of when CPU is destroyed.

We can try to prevent guest to eject first_cpu by not declaring
_EJ0 ACPI method for it.

> +
> +    xcc = X86_CPU_GET_CLASS(DEVICE(cpu));
> +    xcc->parent_unrealize(DEVICE(cpu), &err);
Why is it not just setting 'realize' property of device to 'false'?

> +    if (err != NULL) {
> +        error_report("%s", error_get_pretty(err));
> +        error_free(err);
> +        return -1;
> +    }
> +    return 0;
> +}
> +
>  static void x86_cpu_common_class_init(ObjectClass *oc, void *data)
>  {
>      X86CPUClass *xcc = X86_CPU_CLASS(oc);
> @@ -3005,6 +3026,7 @@ static void x86_cpu_common_class_init(ObjectClass *oc, void *data)
>      dc->unrealize = x86_cpu_unrealizefn;
>      dc->bus_type = TYPE_ICC_BUS;
>      dc->props = x86_cpu_properties;
> +    dc->unplug = x86_cpu_unplug;
>  
>      xcc->parent_reset = cc->reset;
>      cc->reset = x86_cpu_reset;