linux-kernel - Re: [PATCH] x86/Centaur: show more HW features in /proc/cpuinfo

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Date:   Tue, 17 Apr 2018 12:19:29 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     David Wang <davidwang@...oxin.com>
cc:     mingo@...hat.com, hpa@...or.com, mingo@...nel.org,
        grehkg@...uxfoundation.org, x86@...nel.org,
        linux-kernel@...r.kernel.org, brucechang@...-alliance.com,
        cooperyan@...oxin.com, qiyuanwang@...oxin.com,
        benjaminpan@...tech.com, lukelin@...cpu.com, timguo@...oxin.com
Subject: Re: [PATCH] x86/Centaur: show more HW features in /proc/cpuinfo

On Sun, 8 Apr 2018, David Wang wrote:

> We add this patch to show correct HW features(arch_perfmon, tpr_shadow,
> vnmi, flexpriority, ept and vpid) when user execute "cat /proc/cpuinfo".

See the other mail vs. the changelog.

> 
> Signed-off-by: David Wang <davidwang@...oxin.com>
> ---
>  arch/x86/kernel/cpu/centaur.c | 49 +++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 49 insertions(+)
> 
> diff --git a/arch/x86/kernel/cpu/centaur.c b/arch/x86/kernel/cpu/centaur.c
> index e5ec0f1..969fb8f 100644
> --- a/arch/x86/kernel/cpu/centaur.c
> +++ b/arch/x86/kernel/cpu/centaur.c
> @@ -112,6 +112,44 @@ static void early_init_centaur(struct cpuinfo_x86 *c)
>  	}
>  }
>  
> +static void centaur_detect_vmx_virtcap(struct cpuinfo_x86 *c)
> +{
> +#define X86_VMX_FEATURE_PROC_CTLS_TPR_SHADOW	0x00200000
> +#define X86_VMX_FEATURE_PROC_CTLS_VNMI		0x00400000
> +#define X86_VMX_FEATURE_PROC_CTLS_2ND_CTLS	0x80000000
> +#define X86_VMX_FEATURE_PROC_CTLS2_VIRT_APIC	0x00000001
> +#define X86_VMX_FEATURE_PROC_CTLS2_EPT		0x00000002
> +#define X86_VMX_FEATURE_PROC_CTLS2_VPID		0x00000020

Please move the defines outside the function. This is horrible to read,

> +
> +	u32 vmx_msr_low, vmx_msr_high, msr_ctl, msr_ctl2;
> +
> +	clear_cpu_cap(c, X86_FEATURE_TPR_SHADOW);
> +	clear_cpu_cap(c, X86_FEATURE_VNMI);
> +	clear_cpu_cap(c, X86_FEATURE_FLEXPRIORITY);
> +	clear_cpu_cap(c, X86_FEATURE_EPT);
> +	clear_cpu_cap(c, X86_FEATURE_VPID);

Why are you clearing the capabilities? They are cleared at boot time.

> +	rdmsr(MSR_IA32_VMX_PROCBASED_CTLS, vmx_msr_low, vmx_msr_high);
> +	msr_ctl = vmx_msr_high | vmx_msr_low;
> +
> +	if (msr_ctl & X86_VMX_FEATURE_PROC_CTLS_TPR_SHADOW)
> +		set_cpu_cap(c, X86_FEATURE_TPR_SHADOW);
> +	if (msr_ctl & X86_VMX_FEATURE_PROC_CTLS_VNMI)
> +		set_cpu_cap(c, X86_FEATURE_VNMI);
> +	if (msr_ctl & X86_VMX_FEATURE_PROC_CTLS_2ND_CTLS) {
> +		rdmsr(MSR_IA32_VMX_PROCBASED_CTLS2,
> +		      vmx_msr_low, vmx_msr_high);
> +		msr_ctl2 = vmx_msr_high | vmx_msr_low;
> +		if ((msr_ctl2 & X86_VMX_FEATURE_PROC_CTLS2_VIRT_APIC) &&
> +		    (msr_ctl & X86_VMX_FEATURE_PROC_CTLS_TPR_SHADOW))
> +			set_cpu_cap(c, X86_FEATURE_FLEXPRIORITY);
> +		if (msr_ctl2 & X86_VMX_FEATURE_PROC_CTLS2_EPT)
> +			set_cpu_cap(c, X86_FEATURE_EPT);
> +		if (msr_ctl2 & X86_VMX_FEATURE_PROC_CTLS2_VPID)
> +			set_cpu_cap(c, X86_FEATURE_VPID);
> +	}
> +}
> +
>  static void init_centaur(struct cpuinfo_x86 *c)
>  {
>  #ifdef CONFIG_X86_32
> @@ -128,6 +166,14 @@ static void init_centaur(struct cpuinfo_x86 *c)
>  	clear_cpu_cap(c, 0*32+31);
>  #endif
>  	early_init_centaur(c);
> +
> +	if (c->cpuid_level > 9) {
> +		unsigned eax = cpuid_eax(10);

Missing newline between variable declaration and code. checkpatch.pl should
have told you that.

> +		/* Check for version and the number of counters */
> +		if ((eax & 0xff) && (((eax >> 8) & 0xff) > 1))

Magic constants and a comment which does not explain how the check works.

> +			set_cpu_cap(c, X86_FEATURE_ARCH_PERFMON);

Thanks,

	tglx