Re: [PATCH V1 2/4] hw/acpi: Update ACPI CPU Status `is_{present, enabled}` during vCPU hot(un)plug

[Igor Mammedov <imammedo@redhat.com>]

On Mon, 14 Oct 2024 20:22:03 +0100
Salil Mehta <salil.mehta@huawei.com> wrote:

> Update the `AcpiCpuStatus` for `is_enabled` and `is_present` accordingly when
> vCPUs are hot-plugged or hot-unplugged, taking into account the *persistence*
> of the vCPUs.
> 
> Signed-off-by: Salil Mehta <salil.mehta@huawei.com>
> ---
>  hw/acpi/cpu.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/hw/acpi/cpu.c b/hw/acpi/cpu.c
> index 083c4010c2..700aa855e9 100644
> --- a/hw/acpi/cpu.c
> +++ b/hw/acpi/cpu.c
> @@ -291,6 +291,8 @@ void acpi_cpu_plug_cb(HotplugHandler *hotplug_dev,
>      }
>  
>      cdev->cpu = CPU(dev);
> +    cdev->is_present = true;
> +    cdev->is_enabled = true;

hmm, if cpu is always present, then these fields are redundant
since
  (!cdev->cpu) == present
and
  then is_enabled could be fetched from cdev->cpu directly

>      if (dev->hotplugged) {
>          cdev->is_inserting = true;
>          acpi_send_event(DEVICE(hotplug_dev), ACPI_CPU_HOTPLUG_STATUS);
> @@ -322,6 +324,11 @@ void acpi_cpu_unplug_cb(CPUHotplugState *cpu_st,
>          return;
>      }
>  
> +    cdev->is_enabled = false;
> +    if (!acpi_persistent_cpu(CPU(dev))) {
> +        cdev->is_present = false;
> +    }

and other way around works as well.

then we don't have to carry around extra state and making sure that it's in sync/migrated.

> +
>      cdev->cpu = NULL;
>  }
>