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

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> 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,
>   - 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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