linux-kernel - Re: [PATCH 1/4 v3] x86: AMD: Replace numeric value for SME CPUID leaf with a #define

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Message-ID: <20200911212131.GB4110@zn.tnic>
Date:   Fri, 11 Sep 2020 23:21:31 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Krish Sadhukhan <krish.sadhukhan@...cle.com>
Cc:     kvm@...r.kernel.org, pbonzini@...hat.com, jmattson@...gle.com,
        tglx@...utronix.de, mingo@...hat.com, x86@...nel.org,
        sean.j.christopherson@...el.com, vkuznets@...hat.com,
        wanpengli@...cent.com, joro@...tes.org,
        dave.hansen@...ux.intel.com, luto@...nel.org, peterz@...radead.org,
        linux-kernel@...r.kernel.org, hpa@...or.com
Subject: Re: [PATCH 1/4 v3] x86: AMD: Replace numeric value for SME CPUID
 leaf with a #define

On Fri, Sep 11, 2020 at 07:25:58PM +0000, Krish Sadhukhan wrote:

<-- patches need commit message.

...

> diff --git a/arch/x86/kernel/cpu/scattered.c b/arch/x86/kernel/cpu/scattered.c
> index 62b137c3c97a..033c112e03fc 100644
> --- a/arch/x86/kernel/cpu/scattered.c
> +++ b/arch/x86/kernel/cpu/scattered.c
> @@ -39,8 +39,8 @@ static const struct cpuid_bit cpuid_bits[] = {
>  	{ X86_FEATURE_CPB,		CPUID_EDX,  9, 0x80000007, 0 },
>  	{ X86_FEATURE_PROC_FEEDBACK,    CPUID_EDX, 11, 0x80000007, 0 },
>  	{ X86_FEATURE_MBA,		CPUID_EBX,  6, 0x80000008, 0 },
> -	{ X86_FEATURE_SME,		CPUID_EAX,  0, 0x8000001f, 0 },
> -	{ X86_FEATURE_SEV,		CPUID_EAX,  1, 0x8000001f, 0 },
> +	{ X86_FEATURE_SME,		CPUID_EAX,  0, CPUID_AMD_SME, 0 },
> +	{ X86_FEATURE_SEV,		CPUID_EAX,  1, CPUID_AMD_SME, 0 },

So this one gets a name and all the others above don't?

This fact should've given you a hint that there's no need for naming
CPUID leafs - it is easier to grep CPU manuals by the values so you can
drop this patch.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette