Re: [PATCH v14 08/25] x86/kvmclock: Avoid TSC recalibration

Pavel Tatashin
2018-07-18T13:33:36Z

Thank you Paolo for letting me know. I will remove this patch from the
series, or it can be removed by whomever adds the series.

Thank you,
Pavel
On Wed, Jul 18, 2018 at 7:14 AM Paolo Bonzini <pbonzini@redhat.com> wrote:
>
> On 18/07/2018 04:21, Pavel Tatashin wrote:
> > From: Peter Zijlstra <peterz@infradead.org>
> >
> > If the host gives us a TSC rate, assume it is good and don't try and
> > recalibrate things against virtual timer hardware.
> >
> > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> > Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>
> > ---
> > arch/x86/kernel/kvmclock.c | 11 ++++++++++-
> > 1 file changed, 10 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c
> > index ed170171fe49..da0ede8ac8f6 100644
> > --- a/arch/x86/kernel/kvmclock.c
> > +++ b/arch/x86/kernel/kvmclock.c
> > @@ -141,7 +141,16 @@ static inline void kvm_sched_clock_init(bool stable)
> > */
> > static unsigned long kvm_get_tsc_khz(void)
> > {
> > - return pvclock_tsc_khz(this_cpu_pvti());
> > + unsigned long tsc_khz = pvclock_tsc_khz(this_cpu_pvti());
> > +
> > + /*
> > + * TSC frequency is reported by the host; calibration against (virtual)
> > + * HPET/PM-timer in a guest is dodgy and pointless since the host
> > + * already did it for us where required.
> > + */
> > + setup_force_cpu_cap(X86_FEATURE_TSC_KNOWN_FREQ);
> > +
> > + return tsc_khz;
> > }
> >
> > static void kvm_get_preset_lpj(void)
> >
>
> This patch (really a similar one) has just been sent to Linus.
>
> Paolo