Re: [Xen-devel] [PATCH v7 06/11] pvqspinlock, x86: Allow unfair queue spinlock in a KVM guest

[Waiman Long <waiman.long@xxxxxx>]

On 03/20/2014 06:01 PM, Paolo Bonzini wrote:
> Il 19/03/2014 21:14, Waiman Long ha scritto:
> > This patch adds a KVM init function to activate the unfair queue
> > spinlock in a KVM guest when the PARAVIRT_UNFAIR_LOCKS kernel config
> > option is selected.
> >
> > Signed-off-by: Waiman Long <Waiman.Long@xxxxxx>
> > ---
> >  arch/x86/kernel/kvm.c |   17 +++++++++++++++++
> >  1 files changed, 17 insertions(+), 0 deletions(-)
> >
> > diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
> > index 713f1b3..a489140 100644
> > --- a/arch/x86/kernel/kvm.c
> > +++ b/arch/x86/kernel/kvm.c
> > @@ -826,3 +826,20 @@ static __init int kvm_spinlock_init_jump(void)
> >  early_initcall(kvm_spinlock_init_jump);
> >
> >  #endif    /* CONFIG_PARAVIRT_SPINLOCKS */
> > +
> > +#ifdef CONFIG_PARAVIRT_UNFAIR_LOCKS
> > +/*
> > + * Enable unfair lock if running in a real para-virtualized environment
> > + */
> > +static __init int kvm_unfair_locks_init_jump(void)
> > +{
> > +    if (!kvm_para_available())
> > +        return 0;
> > +
> > +    static_key_slow_inc(&paravirt_unfairlocks_enabled);
> > +    printk(KERN_INFO "KVM setup unfair spinlock\n");
> > +
> > +    return 0;
> > +}
> > +early_initcall(kvm_unfair_locks_init_jump);
> > +#endif
> No!  Please do what I asked you to do.  You are not handling Hyper-V 
> or VMWare.  Just use X86_FEATURE_HYPERVISOR and it will cover all 
> hypervisors that actually follow Intel's guidelines.
> Paolo
OK, I can modify the patch to use X86_FEATURE_HYPERVISOR.

-Longman


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