Re: [PATCH v2 0/4] i386/kvm: advertise Hyper-V frequency MSRs

[Marcelo Tosatti <mtosatti@redhat.com>]

On Mon, Aug 07, 2017 at 10:56:59AM +0200, Ladi Prosek wrote:
> This is the QEMU part of the changes required for nested Hyper-V to read
> timestamps with RDTSC + TSC page. Without exposing the frequency MSRs,
> Windows with the Hyper-V role enabled use the much slower
> HV_X64_MSR_TIME_REF_COUNT (0x40000020) RDMSR to read timestamps.
> 
> The new registers are exposed only if the TSC frequency is stable across
> migration and known, as suggested by Paolo.
> 
> v1->v2:
> * deleted an extra empty line in patch 1
> * added patch 3 introducing a helper function for the "TSC is stable and
>   known" check (David)
> 
> Ladi Prosek (4):
>   i386/kvm: use a switch statement for MSR detection
>   i386/kvm: set tsc_khz before configuring Hyper-V CPUID
>   i386/kvm: introduce tsc_is_stable_and_known()
>   i386/kvm: advertise Hyper-V frequency MSRs
> 
>  target/i386/kvm.c | 138 ++++++++++++++++++++++++++++--------------------------
>  1 file changed, 71 insertions(+), 67 deletions(-)
> 
> -- 
> 2.9.3


Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>