linux-kernel - RE: [PATCH v8 01/13] x86/cpufeatures: Add Slow Memory Bandwidth Allocation feature flag

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Date:   Wed, 23 Nov 2022 18:21:33 +0000
From:   "Yu, Fenghua" <fenghua.yu@...el.com>
To:     Babu Moger <babu.moger@....com>, "corbet@....net" <corbet@....net>,
        "Chatre, Reinette" <reinette.chatre@...el.com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "bp@...en8.de" <bp@...en8.de>
CC:     "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
        "x86@...nel.org" <x86@...nel.org>, "hpa@...or.com" <hpa@...or.com>,
        "paulmck@...nel.org" <paulmck@...nel.org>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "quic_neeraju@...cinc.com" <quic_neeraju@...cinc.com>,
        "rdunlap@...radead.org" <rdunlap@...radead.org>,
        "damien.lemoal@...nsource.wdc.com" <damien.lemoal@...nsource.wdc.com>,
        "songmuchun@...edance.com" <songmuchun@...edance.com>,
        "peterz@...radead.org" <peterz@...radead.org>,
        "jpoimboe@...nel.org" <jpoimboe@...nel.org>,
        "pbonzini@...hat.com" <pbonzini@...hat.com>,
        "Bae, Chang Seok" <chang.seok.bae@...el.com>,
        "pawan.kumar.gupta@...ux.intel.com" 
        <pawan.kumar.gupta@...ux.intel.com>,
        "jmattson@...gle.com" <jmattson@...gle.com>,
        "daniel.sneddon@...ux.intel.com" <daniel.sneddon@...ux.intel.com>,
        "sandipan.das@....com" <sandipan.das@....com>,
        "Luck, Tony" <tony.luck@...el.com>,
        "james.morse@....com" <james.morse@....com>,
        "linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "bagasdotme@...il.com" <bagasdotme@...il.com>,
        "Eranian, Stephane" <eranian@...gle.com>
Subject: RE: [PATCH v8 01/13] x86/cpufeatures: Add Slow Memory Bandwidth
 Allocation feature flag

Hi, Babu,

> diff --git a/arch/x86/include/asm/cpufeatures.h
> b/arch/x86/include/asm/cpufeatures.h
> index aefd0816a333..d68b4c9c181d 100644
> --- a/arch/x86/include/asm/cpufeatures.h
> +++ b/arch/x86/include/asm/cpufeatures.h
> @@ -305,6 +305,7 @@
>  #define X86_FEATURE_USE_IBPB_FW		(11*32+16) /* "" Use IBPB
> during runtime firmware calls */
>  #define X86_FEATURE_RSB_VMEXIT_LITE	(11*32+17) /* "" Fill RSB on VM
> exit when EIBRS is enabled */
>  #define X86_FEATURE_CALL_DEPTH		(11*32+18) /* "" Call depth
> tracking for RSB stuffing */
> +#define X86_FEATURE_SMBA		(11*32+19) /* Slow Memory
> Bandwidth Allocation */
> 
>  /* Intel-defined CPU features, CPUID level 0x00000007:1 (EAX), word 12 */
>  #define X86_FEATURE_AVX_VNNI		(12*32+ 4) /* AVX VNNI
> instructions */
> diff --git a/arch/x86/kernel/cpu/scattered.c b/arch/x86/kernel/cpu/scattered.c
> index fc01f81f6e2a..5a5f17ed69a2 100644
> --- a/arch/x86/kernel/cpu/scattered.c
> +++ b/arch/x86/kernel/cpu/scattered.c
> @@ -44,6 +44,7 @@ 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_SMBA,		CPUID_EBX,  2, 0x80000020, 0 },
>  	{ X86_FEATURE_PERFMON_V2,	CPUID_EAX,  0, 0x80000022, 0 },
>  	{ X86_FEATURE_AMD_LBR_V2,	CPUID_EAX,  1, 0x80000022, 0 },
>  	{ 0, 0, 0, 0, 0 }
> 

Shouldn't X86_FEATURE_SMBA depend on X86_FEATURE_MBA? Need to add the
dependency in cpuid-deps.c

Thanks.

-Fenghua