Re: [PATCH v6 2/6] hw/loongarch/virt: Fix error handling in cpu plug

[Igor Mammedov <imammedo@redhat.com>]

On Fri, 21 Mar 2025 11:12:55 +0800
Bibo Mao <maobibo@loongson.cn> wrote:

> In function virt_cpu_plug(), it will send cpu plug message to interrupt
> controller extioi and ipi irqchip. If there is problem in this function,
> system should continue to run and keep state the same before cpu is
> added.


_plug is not supposed to fail ever,
hence we are using error_abort.

so I'd drop those chunks 

> Object cpuslot::cpu is set at last only when there is no any error.
> If there is, send cpu unplug message to extioi and ipi irqchip, and then
> return immediately.

it doesn't matter when it's set since you are already in _plug() handler.
both way are correct.

(I'd set it as the last if calls to chained handlers do not depend on it)

> 
> Fixes: ab9935d2991e (hw/loongarch/virt: Implement cpu plug interface)
> Signed-off-by: Bibo Mao <maobibo@loongson.cn>
> ---
>  hw/loongarch/virt.c | 18 ++++++++++++++++--
>  1 file changed, 16 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/loongarch/virt.c b/hw/loongarch/virt.c
> index a5840ff968..8563967c8b 100644
> --- a/hw/loongarch/virt.c
> +++ b/hw/loongarch/virt.c
> @@ -981,8 +981,6 @@ static void virt_cpu_plug(HotplugHandler *hotplug_dev,
>      LoongArchVirtMachineState *lvms = LOONGARCH_VIRT_MACHINE(hotplug_dev);
>      Error *err = NULL;
>  
> -    cpu_slot = virt_find_cpu_slot(MACHINE(lvms), cpu->phy_id);
> -    cpu_slot->cpu = CPU(dev);
>      if (lvms->ipi) {
>          hotplug_handler_plug(HOTPLUG_HANDLER(lvms->ipi), dev, &err);
>          if (err) {
> @@ -995,6 +993,10 @@ static void virt_cpu_plug(HotplugHandler *hotplug_dev,
>          hotplug_handler_plug(HOTPLUG_HANDLER(lvms->extioi), dev, &err);
>          if (err) {
>              error_propagate(errp, err);
> +            if (lvms->ipi) {
> +                hotplug_handler_unplug(HOTPLUG_HANDLER(lvms->ipi), dev,
> +                                       &error_abort);
> +            }
>              return;
>          }
>      }
> @@ -1003,9 +1005,21 @@ static void virt_cpu_plug(HotplugHandler *hotplug_dev,
>          hotplug_handler_plug(HOTPLUG_HANDLER(lvms->acpi_ged), dev, &err);
>          if (err) {
>              error_propagate(errp, err);
> +            if (lvms->ipi) {
> +                hotplug_handler_unplug(HOTPLUG_HANDLER(lvms->ipi), dev,
> +                                       &error_abort);
> +            }
> +
> +            if (lvms->extioi) {
> +                hotplug_handler_unplug(HOTPLUG_HANDLER(lvms->extioi), dev,
> +                                       &error_abort);
> +            }
> +            return;
>          }
>      }
>  
> +    cpu_slot = virt_find_cpu_slot(MACHINE(lvms), cpu->phy_id);
> +    cpu_slot->cpu = CPU(dev);
>      return;
>  }
>