linux-kernel - Re: [PATCH v14 03/13] x86/mm: add INVLPGB support code

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Message-ID: <20250228184640.GEZ8IEkBFDZhOpyK4e@fat_crate.local>
Date: Fri, 28 Feb 2025 19:46:40 +0100
From: Borislav Petkov <bp@...en8.de>
To: Rik van Riel <riel@...riel.com>
Cc: x86@...nel.org, linux-kernel@...r.kernel.org, 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, jackmanb@...gle.com,
	jannh@...gle.com, mhklinux@...look.com, andrew.cooper3@...rix.com,
	Manali.Shukla@....com, mingo@...nel.org,
	Dave Hansen <dave.hansen@...el.com>
Subject: Re: [PATCH v14 03/13] x86/mm: add INVLPGB support code

On Tue, Feb 25, 2025 at 10:00:38PM -0500, Rik van Riel wrote:
> Add helper functions and definitions needed to use broadcast TLB
> invalidation on AMD EPYC 3 and newer CPUs.
> 
> All the functions defined in invlpgb.h are used later in the series.

Uff, that's tlb.h now. As already said. :-\

Btw, this is why there's no point to write *what* the patch does - that is
visible from the diff itself. This sentence is simply not needed.

> Compile time disabling X86_FEATURE_INVLPGB when the config
> option is not set allows the compiler to omit unnecessary code.
> 
> Signed-off-by: Rik van Riel <riel@...riel.com>
> Tested-by: Manali Shukla <Manali.Shukla@....com>
> Tested-by: Brendan Jackman <jackmanb@...gle.com>
> Tested-by: Michael Kelley <mhklinux@...look.com>
> Acked-by: Dave Hansen <dave.hansen@...el.com>

And I asked you already but still crickets:

What do those Tested-by tags mean if you keep changing the patches?!

https://lore.kernel.org/r/20250224123142.GFZ7xmruuyrc2Wy0r7@fat_crate.local

...

IOW, you need to drop those tags.

> +/* Flush all mappings for all PCIDs except globals. */

This comment should state that addr=0 means both rax[1] (valid PCID) and
rax[2] (valid ASID) are clear and this means: flush *any* PCID and ASID. So
that it is clear.

> +static inline void invlpgb_flush_all_nonglobals(void)
> +{
> +	__invlpgb(0, 0, 0, 1, 0, 0);
> +	__tlbsync();
> +}
> +
>  #endif /* _ASM_X86_TLB_H */
> -- 

-- 
Regards/Gruss,
    Boris.

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