Re: [PATCH] x86/pvqspinlock: Use LOCK_PREFIX in __pv_queued_spin_unlock assembly code

[Waiman Long]

On 07/18/2018 04:19 AM, Peter Zijlstra wrote:
> On Tue, Jul 17, 2018 at 04:16:00PM -0400, Waiman Long wrote:
>> The LOCK_PREFIX macro should be used in the assembly
>> __raw_callee_save___pv_queued_spin_unlock code so that the lock prefix
>> can be patched out on UP systems.
> True; but does paravirt locking realy make sense on UP guests?
>
Yes, it doesn't make sense. That is why I have another kvm patch that
turns off pvqspinlock for UP guest. However, I am not that familiar with
the Xen code. So I don't have a corresponding one for Xen.

Cheers,
Longman