Re: [Qemu-devel] [PATCH 1/5] acpi/cpu: add cpu hotplug callback function to match hotplug_handler API

[Gu Zheng]

Hi Igor,
On 09/11/2014 06:12 PM, Igor Mammedov wrote:

> On Thu, 11 Sep 2014 11:04:10 +0800
> Gu Zheng <address@hidden> wrote:
> 
>> Hi Igor,
>> On 09/10/2014 09:28 PM, Igor Mammedov wrote:
>>
>>> On Wed,  3 Sep 2014 17:06:13 +0800
>>> Gu Zheng <address@hidden> wrote:
>>>
>>>>
>>>> Signed-off-by: Gu Zheng <address@hidden>
>>>> ---
>>>>  hw/acpi/cpu_hotplug.c         |   17 +++++++++++++++++
>>>>  include/hw/acpi/cpu_hotplug.h |    3 +++
>>>>  2 files changed, 20 insertions(+), 0 deletions(-)
>>>>
>>>> diff --git a/hw/acpi/cpu_hotplug.c b/hw/acpi/cpu_hotplug.c
>>>> index 2ad83a0..92c189b 100644
>>>> --- a/hw/acpi/cpu_hotplug.c
>>>> +++ b/hw/acpi/cpu_hotplug.c
>>>> @@ -36,6 +36,23 @@ static const MemoryRegionOps AcpiCpuHotplug_ops = {
>>>>      },
>>>>  };
>>>>  
>>>> +void acpi_cpu_plug_cb(ACPIREGS *ar, qemu_irq irq,
>>>> +                          AcpiCpuHotplug *g, DeviceState *dev)
>>> wrong indentation ^^^
>>>
>>> it wouldn't hurt to add errp argument here ...
>>>
>>>> +{
>>>> +    CPUState *cpu = CPU(dev);
>>>> +    CPUClass *k = CPU_GET_CLASS(cpu);
>>>> +    int64_t cpu_id;
>>>> +
>>>> +    ar->gpe.sts[0] |= ACPI_CPU_HOTPLUG_STATUS;
>>>> +    cpu_id = k->get_arch_id(cpu);
>>>> +    g_assert((cpu_id / 8) < ACPI_GPE_PROC_LEN);
>>> ... and return error from here instead of aborting
>>
>> Got it.
>>
>>>
>>>> +    g->sts[cpu_id / 8] |= (1 << (cpu_id % 8));
>>>> +
>>>> +    acpi_update_sci(ar, irq);
>>>> +
>>>> +    cpu_resume(cpu);
>>> Why are you adding cpu_resume() here?
>>> check cpu_common_realizefn() which already does it.
>>
>> Because hot added callback is called after cpu_common_realizefn(), so I moved
>> cpu_resume(cpu) from cpu_common_realizefn() here to ensure the guest has 
>> already
>> hot added cpu before we resume it.
> cpu.realize() should create a fully working CPU and moving CPU internals to 
> ACPI
> is not correct. CPU hot-add shouyld not depend on whether guest OS supports 
> it or not.
> 
> More over there is no need to resume CPU when guest OS hot-added it,
> cpu.realize() creates secondary CPU in RESET state, so it does nothing and 
> waits
> for INIT/SIPI sequence (i.e. when guest OS decides to online CPU).

Seems I had a misreading on this, thanks for your explanation.

Best regards,
Gu

> 
>>
>>>
>>>> +}
>>>> +
>>>>  void AcpiCpuHotplug_add(ACPIGPE *gpe, AcpiCpuHotplug *g, CPUState *cpu)
>>>>  {
>>>>      CPUClass *k = CPU_GET_CLASS(cpu);
>>>> diff --git a/include/hw/acpi/cpu_hotplug.h b/include/hw/acpi/cpu_hotplug.h
>>>> index 9e5d30c..d025731 100644
>>>> --- a/include/hw/acpi/cpu_hotplug.h
>>>> +++ b/include/hw/acpi/cpu_hotplug.h
>>>> @@ -20,6 +20,9 @@ typedef struct AcpiCpuHotplug {
>>>>      uint8_t sts[ACPI_GPE_PROC_LEN];
>>>>  } AcpiCpuHotplug;
>>>>  
>>>> +void acpi_cpu_plug_cb(ACPIREGS *ar, qemu_irq irq,
>>>> +                          AcpiCpuHotplug *g, DeviceState *dev);
>>> wrong indentation ^^^
>>
>> OK, will fix this too.
>>
>> Thanks,
>> Gu
>>
>>>
>>>> +
>>>>  void AcpiCpuHotplug_add(ACPIGPE *gpe, AcpiCpuHotplug *g, CPUState *cpu);
>>>>  
>>>>  void AcpiCpuHotplug_init(MemoryRegion *parent, Object *owner,
>>>
>>>
>>> .
>>>
>>
>>
> 
> .
>