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SubjectRe: [PATCH RFC V3 2/3] kvm: Note down when cpu relax intercepted or pause loop exited
On 07/13/2012 01:32 AM, Christian Borntraeger wrote:
> On 12/07/12 21:18, Raghavendra K T wrote:
>> +#ifdef CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT
> [...]
>> + struct {
>> + bool cpu_relax_intercepted;
>> + bool dy_eligible;
>> + } ple;
>> +#endif
> [...]
>> }
>> vcpu->run = page_address(page);
>> + vcpu->ple.cpu_relax_intercepted = false;
>> + vcpu->ple.dy_eligible = false;
>
> This struct is only defined if CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT is set, but here it
> is always accessed. Will break on !x86&& !s390.

Yes! I forgot about archs in init function.
How about having
#ifdef CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT
vcpu->ple.cpu_relax_intercepted = false;
vcpu->ple.dy_eligible = false;
#endif

This would solve all the problem.

>>
>> r = kvm_arch_vcpu_init(vcpu);
>> if (r< 0)
>> @@ -1577,6 +1579,7 @@ void kvm_vcpu_on_spin(struct kvm_vcpu *me)
>> int pass;
>> int i;
>>
>> + me->ple.cpu_relax_intercepted = true;
>
> dito

currently vcpu_on_spin is used only by x86 and s390. so if some other
arch in future uses vcpu_on_spin, I believe they also have to enable
CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT
what do you think?

otherwise we have to add hook everywhere
>> /*
>> * We boost the priority of a VCPU that is runnable but not
>> * currently running, because it got preempted by something
>> @@ -1602,6 +1605,7 @@ void kvm_vcpu_on_spin(struct kvm_vcpu *me)
>> }
>> }
>> }
>> + me->ple.cpu_relax_intercepted = false;
>
> again.
>
> maybe define static inline access functions in kvm_host.h that are no-ops
> if CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT is not set.
>



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