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

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

On 02/23/2016 09:10 AM, Jan Beulich wrote:
> > > > On 23.02.16 at 15:00, <boris.ostrovsky@xxxxxxxxxx> wrote:
> > On 02/22/2016 09:04 PM, Haozhong Zhang wrote:
> >
> > >    
> > > +    if ( cpu_has_tsc_ratio )
> > > +        svm_function_table.tsc_scaling.ratio_frac_bits = 32;
> > > +
> > >    
> > > +#define hvm_tsc_scaling_supported \
> > > +    (!!hvm_funcs.tsc_scaling.ratio_frac_bits)
> > > +
> > What is the difference (in usage) between cpu_has_tsc_ratio and
> > hvm_tsc_scaling_supported? Isn't the first imply the second (and if yes
> > then what's the reason for having the latter)?
> Iiuc cpu_has_tsc_ratio is AMD/SVM specific, while
> hvm_tsc_scaling_supported is meant to be vendor independent.
Ah, OK. Can we then

#define hvm_tsc_scaling_supported (cpu_has_vmx_tsc_scaling || 
cpu_has_tsc_ratio)
-boris

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