Re: [PART1 RFC v2 06/10] svm: Add interrupt injection via AVIC

[Suravee Suthikulpanit]

Hi

On 03/09/2016 11:00 PM, Radim KrÄmÃÅ wrote:
> 2016-03-09 12:10+0100, Paolo Bonzini:
> > On 08/03/2016 22:54, Radim KrÄmÃÅ wrote:
> > > 2016-03-07 16:36+0100, Paolo Bonzini:
> > > > On 04/03/2016 21:46, Suravee Suthikulpanit wrote:
> > > > > +static void svm_deliver_avic_intr(struct kvm_vcpu *vcpu, int vec)
> > > > > +{
> > > > > +	struct vcpu_svm *svm = to_svm(vcpu);
> > > > > +
> > > > > +	kvm_lapic_set_vector(vec, avic_get_bk_page_entry(svm, APIC_IRR));
> > >
> > > (I think that smp_mb here would make sense, even though we're fine now
> > >   thanks to re-checking vcpu->mode in kvm_vcpu_kick.
> >
> > Right, though only a smp_mb__after_atomic() is required (which is a
> > compiler barrier).  It is similarly required in vmx.
>
> True, kvm_lapic_set_vector uses a lock prefix.
>
> (I thought it behaves like atomic_set, which would require MFENCE for
>   correct ordering here ... I don't like smp_mb__after_atomic much
>   because of the discrepancy on some atomic operations.)

So, should i just use smb_mb() in this case?

Suravee.