Re: [PATCH v4 4/8] KVM-HV: Add VCPU running/pre-empted state for guest

Marcelo Tosatti
2012-08-24T15:13:16Z

On Fri, Aug 24, 2012 at 10:49:26AM +0530, Nikunj A Dadhania wrote:
> On Thu, 23 Aug 2012 08:46:22 -0300, Marcelo Tosatti <mtosatti@redhat.com> wrote:
> > On Tue, Aug 21, 2012 at 04:56:43PM +0530, Nikunj A. Dadhania wrote:
> > > From: Nikunj A. Dadhania <nikunj@linux.vnet.ibm.com>
> > >
> > > Hypervisor code to indicate guest running/pre-empteded status through
> > > msr. The page is now pinned during MSR write time and use
> > > kmap_atomic/kunmap_atomic to access the shared area vcpu_state area.
> > >
> > > Suggested-by: Marcelo Tosatti <mtosatti@redhat.com>
> > > Signed-off-by: Nikunj A. Dadhania <nikunj@linux.vnet.ibm.com>
> > > ---
>
> [...]
>
> > > +
> > > +static void kvm_set_vcpu_state(struct kvm_vcpu *vcpu)
> > > +{
> > > + struct kvm_vcpu_state *vs;
> > > + char *kaddr;
> > > +
> > > + if (!((vcpu->arch.v_state.msr_val & KVM_MSR_ENABLED) &&
> > > + vcpu->arch.v_state.vs_page))
> > > + return;
> >
> > It was agreed it was necessary to have valid vs_page only if MSR was
> > enabled? Or was that a misunderstanding?
> >
> There is a case where MSR is enabled but vs_page is NULL, this is
> gaurding that case. The check is now:
>
> if (!(msr_enabled && vs_page))
> return;
>
> I had proposed that here:
> http://www.spinics.net/lists/kvm/msg77147.html

OK, its fine.