RE: [PATCH 1/2] x86/hyperv: Allow guests to enable InvariantTSC

[Michael Kelley]

From: Andrea Parri <parri.andrea@xxxxxxxxx> Sent: Thursday, October 3, 2019 8:52 AM
> 
> If the hardware supports TSC scaling, Hyper-V will set bit 15 of the
> HV_PARTITION_PRIVILEGE_MASK in guest VMs with a compatible Hyper-V
> configuration version.  Bit 15 corresponds to the
> AccessTscInvariantControls privilege.  If this privilege bit is set,
> guests can access the HvSyntheticInvariantTscControl MSR: guests can
> set bit 0 of this synthetic MSR to enable the InvariantTSC feature.
> After setting the synthetic MSR, CPUID will enumerate support for
> InvariantTSC.
> 
> Signed-off-by: Andrea Parri <parri.andrea@xxxxxxxxx>
> ---
>  arch/x86/include/asm/hyperv-tlfs.h | 5 +++++
>  arch/x86/kernel/cpu/mshyperv.c     | 7 ++++++-
>  2 files changed, 11 insertions(+), 1 deletion(-)
> 

As noted in a separate email, this patch is standalone, not 1 of 2 as
indicated in the subject line.  Modulo that,

Reviewed-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>