Re: [Xen-devel] [PATCH v3 12/13] vmx: Add VMX RDTSC(P) scaling support

[Haozhong Zhang <haozhong.zhang@xxxxxxxxx>]

On 01/12/16 09:48, Jan Beulich wrote:
> >>> On 31.12.15 at 04:03, <haozhong.zhang@xxxxxxxxx> wrote:
> > @@ -2003,6 +2011,10 @@ static struct hvm_function_table __initdata 
> > vmx_function_table = {
> >      .altp2m_vcpu_update_vmfunc_ve = vmx_vcpu_update_vmfunc_ve,
> >      .altp2m_vcpu_emulate_ve = vmx_vcpu_emulate_ve,
> >      .altp2m_vcpu_emulate_vmfunc = vmx_vcpu_emulate_vmfunc,
> > +    .default_tsc_scaling_ratio   = VMX_TSC_MULTIPLIER_DEFAULT,
> > +    .max_tsc_scaling_ratio       = VMX_TSC_MULTIPLIER_MAX,
> > +    .tsc_scaling_ratio_frac_bits = 48,
> > +    .setup_tsc_scaling           = vmx_setup_tsc_scaling,
> >  };
> >  
> >  /* Handle VT-d posted-interrupt when VCPU is running. */
> > @@ -2107,6 +2119,9 @@ const struct hvm_function_table * __init 
> > start_vmx(void)
> >           && cpu_has_vmx_secondary_exec_control )
> >          vmx_function_table.pvh_supported = 1;
> >  
> > +    if ( cpu_has_vmx_tsc_scaling )
> > +        vmx_function_table.tsc_scaling_supported = 1;
> 
> Do you actually still need this separate flag field? I.e. can't you
> derive this from one of the other four fields?
>

Yes, unless other four fields are set conditionally instead of being
hardcoded in hvm_funcs.

Haozhong

> Jan
> 

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