Re: [Xen-devel] [PATCH v6 1/5] x86/hvm: Setup TSC scaling ratio

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

On 02/29/2016 08:41 AM, Jan Beulich wrote:
> > > > On 28.02.16 at 13:54, <haozhong.zhang@xxxxxxxxx> wrote:
> > This patch adds a field tsc_scaling_ratio in struct hvm_domain to record
> > the per-domain TSC scaling ratio, and sets it in tsc_set_info().
> >
> > Before setting the per-domain TSC scaling ratio, we check its validity
> > in tsc_set_info(). If an invalid ratio is given, we will leave the
> > default value in tsc_scaling_ratio (i.e. ratio = 1) and setup guest TSC
> > as if no TSC scaling is used:
> > * For TSC_MODE_FAULT,
s/TSC_MODE_FAULT/TSC_MODE_DEFAULT/

-boris

> >    - if a user-specified TSC frequency is given, we will set the guest
> >      TSC frequency to it; otherwise, we set it to the host TSC frequency.
> >    - if guest TSC frequency does not equal to host TSC frequency, we will
> >      emulate guest TSC (i.e. d->arch.vtsc is set to 1). In both cases,
> >      guest TSC runs in the guest TSC frequency.
> > * For TSC_MODE_PVRDTSCP,
> >    - we set the guest TSC frequency to the host TSC frequency.
> >    - guest rdtsc is executed natively in the host TSC frequency as
> >      before.
> >    - if rdtscp is not available to guest, it will be emulated; otherwise,
> >      it will be executed natively. In both cases, guest rdtscp gets TSC
> >      in the host TSC frequency as before.
> >
> > Signed-off-by: Haozhong Zhang <haozhong.zhang@xxxxxxxxx>
> Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>

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