linux-kernel - Re: [PATCH v9 04/12] x86/mm: get INVLPGB count max from CPUID

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Message-ID: <CA+i-1C3EwgvO_tgEvReDK8K5FMWYGeQRuvCu6Xy31oiS6WgcNQ@mail.gmail.com>
Date: Fri, 7 Feb 2025 18:34:11 +0100
From: Brendan Jackman <jackmanb@...gle.com>
To: Rik van Riel <riel@...riel.com>
Cc: x86@...nel.org, linux-kernel@...r.kernel.org, bp@...en8.de, 
	peterz@...radead.org, dave.hansen@...ux.intel.com, zhengqi.arch@...edance.com, 
	nadav.amit@...il.com, thomas.lendacky@....com, kernel-team@...a.com, 
	linux-mm@...ck.org, akpm@...ux-foundation.org, jannh@...gle.com, 
	mhklinux@...look.com, andrew.cooper3@...rix.com, 
	Manali Shukla <Manali.Shukla@....com>
Subject: Re: [PATCH v9 04/12] x86/mm: get INVLPGB count max from CPUID

Oh, sorry

On Fri, 7 Feb 2025 at 16:10, Brendan Jackman <jackmanb@...gle.com> wrote:
>
> On Thu, 6 Feb 2025 at 05:45, Rik van Riel <riel@...riel.com> wrote:
> > diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
> > index 17b6590748c0..f9b832e971c5 100644
> > --- a/arch/x86/include/asm/cpufeatures.h
> > +++ b/arch/x86/include/asm/cpufeatures.h
> > @@ -338,6 +338,7 @@
> >  #define X86_FEATURE_CLZERO             (13*32+ 0) /* "clzero" CLZERO instruction */
> >  #define X86_FEATURE_IRPERF             (13*32+ 1) /* "irperf" Instructions Retired Count */
> >  #define X86_FEATURE_XSAVEERPTR         (13*32+ 2) /* "xsaveerptr" Always save/restore FP error pointers */
> > +#define X86_FEATURE_INVLPGB            (13*32+ 3) /* INVLPGB and TLBSYNC instruction supported. */
>
> Why no "invlpgb" here? Seems like having this flag visible in cpuinfo
> would be worthwhile.
>
> If there's a reason to hide it maybe add a comment to explain the
> reason? Sorry if this is a stupid question - I also can't see an
> obvious rationale for why existing flags do or don't get a name at
> runtime.

Oh, found it:

https://lore.kernel.org/lkml/20250102120450.GNZ3aA4oVPnoJYRVUL@fat_crate.local/

Sorry for the noise, please ignore.