linux-kernel - Re: [PATCH v4 11/22] x86/mce: Define BSP-only init

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Message-ID: <20250625112617.GBaFvc2SdsGhEFPiYR@fat_crate.local>
Date: Wed, 25 Jun 2025 13:26:17 +0200
From: Borislav Petkov <bp@...en8.de>
To: Nikolay Borisov <nik.borisov@...e.com>
Cc: Yazen Ghannam <yazen.ghannam@....com>, x86@...nel.org,
	Tony Luck <tony.luck@...el.com>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	Len Brown <lenb@...nel.org>, linux-kernel@...r.kernel.org,
	linux-edac@...r.kernel.org, Smita.KoralahalliChannabasappa@....com,
	Qiuxu Zhuo <qiuxu.zhuo@...el.com>, linux-acpi@...r.kernel.org
Subject: Re: [PATCH v4 11/22] x86/mce: Define BSP-only init

On Wed, Jun 25, 2025 at 02:04:24PM +0300, Nikolay Borisov wrote:
> nit: Why use cpu_feature_enabled VS say boot_cpu_has since none of the 3
> features are defined in cpufeaturemasks.h, meaning that cpu_feature_enabled
> is essentially static_cpu_has, given that this is not a fast path?
> 
> It's not wrong per-se but I think the cpu_feature_enabled api is somewhat of
> a trainwreck i.e we ought to have a version that uses boot_cpu_has for
> "ordinary uses" and probably cpu_feature_enabled_fast for fastpaths.

Look at the resulting asm of *cpu_has().

And, we need exactly one interface that everyone should use and everyone
should not care about what it does underneath. Not 10 interfaces as it is now.

-- 
Regards/Gruss,
    Boris.

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