linux-kernel - Re: [PATCH] x86/asm: Use asm_inline() instead of asm() in amd_clear

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Message-ID: <CAFULd4YutpSGTQ2xkgZSBdp1eyJ1csaEoRk3RECp=TbL3xHUDA@mail.gmail.com>
Date: Fri, 14 Mar 2025 12:03:45 +0100
From: Uros Bizjak <ubizjak@...il.com>
To: Ingo Molnar <mingo@...nel.org>
Cc: Borislav Petkov <bp@...en8.de>, x86@...nel.org, linux-kernel@...r.kernel.org, 
	Thomas Gleixner <tglx@...utronix.de>, Dave Hansen <dave.hansen@...ux.intel.com>, 
	"H. Peter Anvin" <hpa@...or.com>, Linus Torvalds <torvalds@...ux-foundation.org>, 
	Peter Zijlstra <peterz@...radead.org>, Josh Poimboeuf <jpoimboe@...hat.com>
Subject: Re: [PATCH] x86/asm: Use asm_inline() instead of asm() in amd_clear_divider()

On Fri, Mar 14, 2025 at 11:15 AM Ingo Molnar <mingo@...nel.org> wrote:
>
>
> * Borislav Petkov <bp@...en8.de> wrote:
>
> > Sorry but this doesn't justify this churn. There's nothing
> > quantifyingly palpable here to warrant this.
>
> I disagree, asm() is a known-bad inlining interface for fundamentally
> single-instruction inlines like this one, ...

Please note the new patch [1] that uses alternative_input(), where "no
code changes" actually supports the change. alternative_input() uses
asm_inline internally.

[1] https://lore.kernel.org/lkml/20250314081453.565859-1-ubizjak@gmail.com/

Uros.