Re: [PATCH v4 0/3] qspinlock: Introducing a 4-byte queue spinlock

[Linus Torvalds]

On Fri, Feb 21, 2014 at 9:02 AM, Waiman Long <waiman.long@xxxxxx> wrote:
> On 02/20/2014 02:32 PM, Raghavendra K T wrote:
>>
>> On 02/20/2014 11:24 PM, Waiman Long wrote:
>>
>>> Now the key is how to detect if a kernel is really running in a PV
>>> environment. I need to ask some virtualization experts on that.
>>>
>>
>> For kvm you could just follow,
>> kvm_spinlock_init_jump() and KVM_FEATURE_* encoding in cpuid
>> part __do_cpuid_ent().
>>
>
> I saw that in the arch/x86/kernel/kvm.c file. So I think I can use the
> returned value of kvm_para_available() to decide if it is running in a KVM
> guest. However, I am not so sure of what to use in xen.

Just use that 'paravirt_ticketlocks_enabled' static key. Xen enables it too.

            Linus
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