Re: [Xen-devel] [PATCH v5 1/6] x86/hvm: Collect information of TSC scaling ratio

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 23.02.16 at 03:04, <haozhong.zhang@xxxxxxxxx> wrote:
> Both VMX TSC scaling and SVM TSC ratio use the 64-bit TSC scaling ratio,
> but the number of fractional bits of the ratio is different between VMX
> and SVM. This patch adds the architecture code to collect the number of
> fractional bits and other related information into fields of struct
> hvm_function_table so that they can be used in the common code.
> 
> Signed-off-by: Haozhong Zhang <haozhong.zhang@xxxxxxxxx>

Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>

albeit I would have wished ...

> @@ -312,8 +311,8 @@ void hvm_set_guest_tsc_fixed(struct vcpu *v, u64 
> guest_tsc, u64 at_tsc)
>      else
>      {
>          tsc = at_tsc ?: rdtsc();
> -        if ( cpu_has_tsc_ratio )
> -            tsc = hvm_funcs.scale_tsc(v, tsc);
> +        if ( hvm_tsc_scaling_supported )
> +            tsc = hvm_funcs.tsc_scaling.scale_tsc(v, tsc);

... for these to get their redundancy reduced, .e.g

            tsc = hvm_funcs.tsc_scaling.scale(v, tsc);

The R-b may be retained if you elect to make that adjustment.

Jan


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