On Mon, Nov 03, 2014 at 04:57:18PM -0800, Owen Hofmann wrote: > kvm updates the version number for the guest paravirt clock structure by > incrementing the version of its private copy. It does not read the guest > version, so will write version = 2 in the first update for every new VM, > including after restoring a saved state. If guest state is saved during > reading the clock, it could read and accept struct fields and guest TSC > from two different updates. This changes the code to increment the guest > version and write it back. > > Signed-off-by: Owen Hofmann <osh@xxxxxxxxxx> > --- > arch/x86/kvm/x86.c | 10 +++++----- > 1 file changed, 5 insertions(+), 5 deletions(-) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 0033df3..c25c9d8 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -1637,16 +1637,16 @@ static int kvm_guest_time_update(struct kvm_vcpu *v) > vcpu->hv_clock.system_time = kernel_ns + v->kvm->arch.kvmclock_offset; > vcpu->last_guest_tsc = tsc_timestamp; > > + if (unlikely(kvm_read_guest_cached(v->kvm, &vcpu->pv_time, > + &guest_hv_clock, sizeof(guest_hv_clock)))) > + return 0; > + > /* > * The interface expects us to write an even number signaling that the > * update is finished. Since the guest won't see the intermediate > * state, we just increase by 2 at the end. > */ > - vcpu->hv_clock.version += 2; > - > - if (unlikely(kvm_read_guest_cached(v->kvm, &vcpu->pv_time, > - &guest_hv_clock, sizeof(guest_hv_clock)))) > - return 0; > + vcpu->hv_clock.version = guest_hv_clock.version + 2; > > /* retain PVCLOCK_GUEST_STOPPED if set in guest copy */ > pvclock_flags = (guest_hv_clock.flags & PVCLOCK_GUEST_STOPPED); > -- > 2.1.0.rc2.206.gedb03e5 Reviewed-by: Marcelo Tosatti <mtosatti@xxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
