Re: [PATCH v4 5/5] x86, kvm: support vcpu preempted check

[Pan Xinhui]

å 2016/10/24 23:18, Paolo Bonzini åé:
> On 24/10/2016 17:14, Radim KrÄmÃÅ wrote:
> > 2016-10-24 16:39+0200, Paolo Bonzini:
> > > On 19/10/2016 19:24, Radim KrÄmÃÅ wrote:
> > > > > > +	if (vcpu->arch.st.msr_val & KVM_MSR_ENABLED)
> > > > > > +		if (kvm_read_guest_cached(vcpu->kvm, &vcpu->arch.st.stime,
> > > > > > +					&vcpu->arch.st.steal,
> > > > > > +					sizeof(struct kvm_steal_time)) == 0) {
> > > > > > +			vcpu->arch.st.steal.preempted = 1;
> > > > > > +			kvm_write_guest_cached(vcpu->kvm, &vcpu->arch.st.stime,
> > > > > > +					&vcpu->arch.st.steal,
> > > > > > +					sizeof(struct kvm_steal_time));
> > > > > > +		}
> > > > Please name this block of code.  Something like
> > > >   kvm_steal_time_set_preempted(vcpu);
> > >
> > > While at it:
> > >
> > > 1) the kvm_read_guest_cached is not necessary.  You can rig the call to
> > > kvm_write_guest_cached so that it only writes vcpu->arch.st.steal.preempted.
> >
> > I agree.  kvm_write_guest_cached() always writes from offset 0, so we'd
> > want a new function that allows to specify a starting offset.
>
> Yeah, let's leave it for a follow-up then!
I think I can make a having-offset version. :)

> Thanks,
>
> Paolo
>
> > Using cached vcpu->arch.st.steal to avoid the read wouldn't be as good.