From mboxrd@z Thu Jan  1 00:00:00 1970
From: Haozhong Zhang <haozhong.zhang@intel.com>
Subject: Re: [PATCH v3 12/13] vmx: Add VMX RDTSC(P) scaling
	support
Date: Thu, 14 Jan 2016 12:52:47 +0800
Message-ID: <20160114045247.GA3528@hz-desktop.sh.intel.com>
References: <1451531020-29964-1-git-send-email-haozhong.zhang@intel.com>
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To: Jan Beulich <JBeulich@suse.com>
Cc: Kevin Tian <kevin.tian@intel.com>, Keir Fraser <keir@xen.org>, Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>, Andrew Cooper <andrew.cooper3@citrix.com>, xen-devel@lists.xen.org, Aravind Gopalakrishnan <Aravind.Gopalakrishnan@amd.com>, Jun Nakajima <jun.nakajima@intel.com>, Boris Ostrovsky <boris.ostrovsky@oracle.com>
List-Id: xen-devel@lists.xenproject.org

On 01/12/16 09:48, Jan Beulich wrote:
> >>> On 31.12.15 at 04:03, <haozhong.zhang@intel.com> 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
>