Am 09.01.2012 um 21:00 schrieb Scott Wood <scottw...@freescale.com>:

> On 01/09/2012 08:15 AM, Alexander Graf wrote:
>> 
>> On 05.01.2012, at 10:07, Liu Yu wrote:
>> 
>>> diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
>>> index c33f6a7..1242ee1 100644
>>> --- a/arch/powerpc/kvm/powerpc.c
>>> +++ b/arch/powerpc/kvm/powerpc.c
>>> @@ -81,6 +81,10 @@ int kvmppc_kvm_pv(struct kvm_vcpu *vcpu)
>>> 
>>>        /* Second return value is in r4 */
>>>        break;
>>> +    case HC_VENDOR_EPAPR | HC_EV_IDLE:
>>> +        r = HC_EV_SUCCESS;
>>> +        kvm_vcpu_block(vcpu);
>> 
>> Hrm. This will return on signal. So if the guest sends an idle hcall,
>> then user space gets a random signal, we'll continue executing the
>> guest CPU, getting us out of idle even though the guest didn't expect
>> it, since the guest really wants to get an interrupt after the idle
>> hcall.
> 
> The ePAPR description of this hcall is a little vague (Stuart, put on
> list to fix in next ePAPR revision?), but this is expected.  It will
> also be the case if a guest directly uses the wait instruction.  Guests
> must be able to deal with spurious wakeups.

The wait instruction does get executed in an infinite loop though, while this 
hcall is only executed once.

Alex

> 
> -Scott
> 
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