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

Brendan Jackman
2025-02-07T15:11:03Z

On Thu, 6 Feb 2025 at 05:45, Rik van Riel <riel@surriel.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.