Re: [PATCH v14 08/25] x86/kvmclock: Avoid TSC recalibration
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 wrote:
>
> On 18/07/2018 04:21, Pavel Tatashin wrote:
> > From: Peter Zijlstra
> >
> > 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)
> > Signed-off-by: Pavel Tatashin
> > ---
> > 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
Re: [PATCH v14 08/25] x86/kvmclock: Avoid TSC recalibration
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 wrote:
>
> On 18/07/2018 04:21, Pavel Tatashin wrote:
> > From: Peter Zijlstra
> >
> > 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)
> > Signed-off-by: Pavel Tatashin
> > ---
> > 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
Re: [PATCH v14 08/25] x86/kvmclock: Avoid TSC recalibration
On 18/07/2018 04:21, Pavel Tatashin wrote:
> From: Peter Zijlstra
>
> 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)
> Signed-off-by: Pavel Tatashin
> ---
> 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
Re: [PATCH v14 08/25] x86/kvmclock: Avoid TSC recalibration
On 18/07/2018 04:21, Pavel Tatashin wrote:
> From: Peter Zijlstra
>
> 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)
> Signed-off-by: Pavel Tatashin
> ---
> 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
[PATCH v14 08/25] x86/kvmclock: Avoid TSC recalibration
From: Peter Zijlstra
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)
Signed-off-by: Pavel Tatashin
---
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)
--
2.18.0
[PATCH v14 08/25] x86/kvmclock: Avoid TSC recalibration
From: Peter Zijlstra
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)
Signed-off-by: Pavel Tatashin
---
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)
--
2.18.0
