Re: [Xen-devel] xen: PV on HVM: support PV spinlocks

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Fri, 13 Aug 2010, Jeremy Fitzhardinge wrote:
>  On 08/13/2010 12:06 PM, Stefano Stabellini wrote:
> > xen: PV on HVM: support PV spinlocks
> >
> > Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> >
> > diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
> > index 6f53453..5643c43 100644
> > --- a/arch/x86/xen/enlighten.c
> > +++ b/arch/x86/xen/enlighten.c
> > @@ -1290,6 +1290,8 @@ static int __cpuinit xen_hvm_cpu_notify(struct 
> > notifier_block *self,
> >     switch (action) {
> >     case CPU_UP_PREPARE:
> >             per_cpu(xen_vcpu, cpu) = 
> > &HYPERVISOR_shared_info->vcpu_info[cpu];
> > +           if (xen_have_vector_callback)
> > +                   xen_init_lock_cpu(cpu);
> 
> Why does this depend on vector_callback?  pv spinlocks never have events
> actually delivered.
> 

HVM guests cannot receive events on vcpus other than 0 without
vector_callback, this means they wouldn't receive even a vcpu_kick and
would get stuck.


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