linux-kernel - RE: [PATCH v4 08/11] x86/cpufeatures: Add feature bits for AMD heterogeneous processor

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Date: Wed, 19 Jun 2024 03:40:41 +0000
From: "Yuan, Perry" <Perry.Yuan@....com>
To: Borislav Petkov <bp@...en8.de>
CC: "rafael.j.wysocki@...el.com" <rafael.j.wysocki@...el.com>, "Limonciello,
 Mario" <Mario.Limonciello@....com>, "viresh.kumar@...aro.org"
	<viresh.kumar@...aro.org>, "Huang, Ray" <Ray.Huang@....com>, "Shenoy, Gautham
 Ranjal" <gautham.shenoy@....com>, "Deucher, Alexander"
	<Alexander.Deucher@....com>, "Huang, Shimmer" <Shimmer.Huang@....com>, "Du,
 Xiaojian" <Xiaojian.Du@....com>, "Meng, Li (Jassmine)" <Li.Meng@....com>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v4 08/11] x86/cpufeatures: Add feature bits for AMD
 heterogeneous processor

[AMD Official Use Only - AMD Internal Distribution Only]

> -----Original Message-----
> From: Borislav Petkov <bp@...en8.de>
> Sent: Monday, June 17, 2024 4:39 PM
> To: Yuan, Perry <Perry.Yuan@....com>
> Cc: rafael.j.wysocki@...el.com; Limonciello, Mario
> <Mario.Limonciello@....com>; viresh.kumar@...aro.org; Huang, Ray
> <Ray.Huang@....com>; Shenoy, Gautham Ranjal
> <gautham.shenoy@....com>; Deucher, Alexander
> <Alexander.Deucher@....com>; Huang, Shimmer
> <Shimmer.Huang@....com>; Du, Xiaojian <Xiaojian.Du@....com>; Meng,
> Li (Jassmine) <Li.Meng@....com>; linux-pm@...r.kernel.org; linux-
> kernel@...r.kernel.org
> Subject: Re: [PATCH v4 08/11] x86/cpufeatures: Add feature bits for AMD
> heterogeneous processor
>
> On Mon, Jun 17, 2024 at 02:59:10PM +0800, Perry Yuan wrote:
> > CPUID leaf 0x80000026 advertises core types with different efficiency
> > rankings
> >
> > Bit 30 indicates the heterogeneous core topology feature, if the bit
> > set, it means not all instances at the current hierarchical level have
> > the same core topology.
> >
> > For better utilization of feature words and help to identify core
> > type, X86_FEATURE_HETERO_CORE_TOPOLOGY is added as a few scattered
> feature bits.
> >
> > Reference:
> > See the page 119 of PPR for AMD Family 19h Model 61h B1, docID 56713
> >
> > Signed-off-by: Perry Yuan <perry.yuan@....com>
> > ---
> >  arch/x86/include/asm/cpufeatures.h | 1 +
> >  arch/x86/kernel/cpu/scattered.c    | 1 +
> >  2 files changed, 2 insertions(+)
> >
> > diff --git a/arch/x86/include/asm/cpufeatures.h
> > b/arch/x86/include/asm/cpufeatures.h
> > index 6c128d463a14..eceaa0df0137 100644
> > --- a/arch/x86/include/asm/cpufeatures.h
> > +++ b/arch/x86/include/asm/cpufeatures.h
> > @@ -471,6 +471,7 @@
> >  #define X86_FEATURE_CLEAR_BHB_HW   (21*32+ 3) /* "" BHI_DIS_S
> HW control enabled */
> >  #define X86_FEATURE_CLEAR_BHB_LOOP_ON_VMEXIT (21*32+ 4) /* ""
> Clear branch history at vmexit using SW loop */
> >  #define X86_FEATURE_FAST_CPPC              (21*32 + 5) /* "" AMD Fast
> CPPC */
> > +#define X86_FEATURE_HETERO_CORE_TOPOLOGY       (21*32+ 6) /* ""
> Heterogeneous Core Topology */
> >
> >  /*
> >   * BUG word(s)
> > diff --git a/arch/x86/kernel/cpu/scattered.c
> > b/arch/x86/kernel/cpu/scattered.c index c84c30188fdf..6b3477503dd0
> > 100644
> > --- a/arch/x86/kernel/cpu/scattered.c
> > +++ b/arch/x86/kernel/cpu/scattered.c
> > @@ -52,6 +52,7 @@ static const struct cpuid_bit cpuid_bits[] = {
> >     { X86_FEATURE_PERFMON_V2,       CPUID_EAX,  0, 0x80000022, 0 },
> >     { X86_FEATURE_AMD_LBR_V2,       CPUID_EAX,  1, 0x80000022, 0 },
> >     { X86_FEATURE_AMD_LBR_PMC_FREEZE,       CPUID_EAX,  2,
> 0x80000022, 0 },
> > +   { X86_FEATURE_HETERO_CORE_TOPOLOGY,     CPUID_EAX,  30,
> 0x80000026, 0 },
> >     { 0, 0, 0, 0, 0 }
> >  };
> >
> > --
>
> Nacked-by: Borislav Petkov (AMD) <bp@...en8.de>
>
> Until all review comments have been addressed:
>
> https://lore.kernel.org/r/20240611105216.GAZmgsYC-
> J_yLfdupF@..._crate.local
>
> --
> Regards/Gruss,
>     Boris.
>
> https://people.kernel.org/tglx/notes-about-netiquette

Boris,
I Just accidentally missed the other comments,  will address it in v5.
Thanks for your review  ~