On Thu, Nov 01, 2012 at 12:39:30PM +0200, Gleb Natapov wrote:
> On Wed, Oct 31, 2012 at 08:46:57PM -0200, Marcelo Tosatti wrote:
> > Otherwise its possible for an unrelated KVM_REQ_UPDATE_CLOCK (such as due to CPU
> > migration) to clear the bit.
> >
> > Noticed by Paolo Bonzini.
> >
> > Signed-off-by: Marcelo Tosatti <mtosatti@xxxxxxxxxx>
> >
> Reviewed-by: Gleb Natapov <gleb@xxxxxxxxxx>
>
> Small nitpick bellow.
>
> Also do we really need to call kvm_guest_time_update() on a guest pause?
> Wouldn't separate request bit, which only sets the flag, suffice?
Management of vcpu clock area better be isolated in a single place.
> > Index: vsyscall/arch/x86/kvm/x86.c
> > ===================================================================
> > --- vsyscall.orig/arch/x86/kvm/x86.c
> > +++ vsyscall/arch/x86/kvm/x86.c
> > @@ -1143,6 +1143,7 @@ static int kvm_guest_time_update(struct
> > unsigned long this_tsc_khz;
> > s64 kernel_ns, max_kernel_ns;
> > u64 tsc_timestamp;
> > + struct pvclock_vcpu_time_info *guest_hv_clock;
> > u8 pvclock_flags;
> >
> > /* Keep irq disabled to prevent changes to the clock */
> > @@ -1226,13 +1227,6 @@ static int kvm_guest_time_update(struct
> > vcpu->last_kernel_ns = kernel_ns;
> > vcpu->last_guest_tsc = tsc_timestamp;
> >
> > - pvclock_flags = 0;
> > - if (vcpu->pvclock_set_guest_stopped_request) {
> > - pvclock_flags |= PVCLOCK_GUEST_STOPPED;
> > - vcpu->pvclock_set_guest_stopped_request = false;
> > - }
> > -
> > - vcpu->hv_clock.flags = pvclock_flags;
> >
> > /*
> > * The interface expects us to write an even number signaling that the
> > @@ -1243,6 +1237,18 @@ static int kvm_guest_time_update(struct
> >
> > shared_kaddr = kmap_atomic(vcpu->time_page);
> >
> > + guest_hv_clock = shared_kaddr + vcpu->time_offset;
> > +
> > + /* retain PVCLOCK_GUEST_STOPPED if set in guest copy */
> > + pvclock_flags = (guest_hv_clock->flags & PVCLOCK_GUEST_STOPPED);
> > +
> > + if (vcpu->pvclock_set_guest_stopped_request) {
> > + pvclock_flags |= PVCLOCK_GUEST_STOPPED;
> > + vcpu->pvclock_set_guest_stopped_request = false;
> > + }
> > +
> > + vcpu->hv_clock.flags = pvclock_flags;
> > +
> > memcpy(shared_kaddr + vcpu->time_offset, &vcpu->hv_clock,
> We can use guest_hv_clock here now.
>
> > sizeof(vcpu->hv_clock));
> >
> >
>
> --
> Gleb.
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