[PATCH v2 2/4] powerpc/spinlock: support vcpu preempted check

Wanpeng Li
Wed, 06 Jul 2016 08:32:07 -0000

2016-07-06 15:58 GMT+08:00 Peter Zijlstra <peterz at
infradead.org>:
> On Wed, Jul 06, 2016 at 02:46:34PM +0800, Wanpeng Li wrote:
>> > SO it's easy for ppc to implement such interface. Note that
yield_count is
>> > set by powerVM/KVM.
>> > and only pSeries can run a guest for now. :)
>> >
>> > I also review x86 related code, looks like we need add one
hyer-call to get
>> > such vcpu preemption info?
>>
>> There is no such stuff to record lock holder in x86 kvm, maybe we
>> don't need to depend on PLE handler algorithm to guess it if we can
>> know lock holder vCPU directly.
>
> x86/kvm has vcpu->preempted to indicate if a vcpu is currently preempted
> or not. I'm just not sure if that is visible to the guest or how to
make
> it so.

Yeah, I miss it. I can be the volunteer to do it if there is any idea,
ping Paolo. :)

Regards,
Wanpeng Li