On Tue, Jun 11, 2024 at 07:51:48AM -0700, Roman Kisel wrote:
>
>
> On 6/5/2024 7:55 PM, mhkelley58@xxxxxxxxx wrote:
> > From: Michael Kelley <mhklinux@xxxxxxxxxxx>
> >
> > A Linux guest on Hyper-V gets the TSC frequency from a synthetic MSR, if
> > available. In this case, set X86_FEATURE_TSC_KNOWN_FREQ so that Linux
> > doesn't unnecessarily do refined TSC calibration when setting up the TSC
> > clocksource.
> >
> > With this change, a message such as this is no longer output during boot
> > when the TSC is used as the clocksource:
> >
> > [ 1.115141] tsc: Refined TSC clocksource calibration: 2918.408 MHz
> >
> > Furthermore, the guest and host will have exactly the same view of the
> > TSC frequency, which is important for features such as the TSC deadline
> > timer that are emulated by the Hyper-V host.
> >
> > Signed-off-by: Michael Kelley <mhklinux@xxxxxxxxxxx>
> > ---
> > arch/x86/kernel/cpu/mshyperv.c | 1 +
> > 1 file changed, 1 insertion(+)
> >
> > diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
> > index e0fd57a8ba84..c3e38eaf6d2f 100644
> > --- a/arch/x86/kernel/cpu/mshyperv.c
> > +++ b/arch/x86/kernel/cpu/mshyperv.c
> > @@ -424,6 +424,7 @@ static void __init ms_hyperv_init_platform(void)
> > ms_hyperv.misc_features & HV_FEATURE_FREQUENCY_MSRS_AVAILABLE) {
> > x86_platform.calibrate_tsc = hv_get_tsc_khz;
> > x86_platform.calibrate_cpu = hv_get_tsc_khz;
> > + setup_force_cpu_cap(X86_FEATURE_TSC_KNOWN_FREQ);
> > }
> > if (ms_hyperv.priv_high & HV_ISOLATION) {
>
> LGTM
>
> Reviewed-by: Roman Kisel <romank@xxxxxxxxxxxxxxxxxxx>
Applied to hyperv-fixes. Thanks!
