linux-kernel - Re: [PATCH v12 04/16] x86/mm: get INVLPGB count max from CPUID

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Message-ID: <20250221015801.GHZ7fdqaGFEvsG6qW1@fat_crate.local>
Date: Fri, 21 Feb 2025 02:58:01 +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, Dave Hansen <dave.hansen@...el.com>
Subject: Re: [PATCH v12 04/16] x86/mm: get INVLPGB count max from CPUID

On Thu, Feb 20, 2025 at 07:53:03PM -0500, Rik van Riel wrote:
> diff --git a/arch/x86/Kconfig.cpu b/arch/x86/Kconfig.cpu
> index 2a7279d80460..bb6943c21b7f 100644
> --- a/arch/x86/Kconfig.cpu
> +++ b/arch/x86/Kconfig.cpu
> @@ -401,6 +401,10 @@ menuconfig PROCESSOR_SELECT
>  	  This lets you choose what x86 vendor support code your kernel
>  	  will include.
>  
> +config X86_BROADCAST_TLB_FLUSH
> +	def_bool y
> +	depends on CPU_SUP_AMD && 64BIT
> +
>  config CPU_SUP_INTEL
>  	default y
>  	bool "Support Intel processors" if PROCESSOR_SELECT
> @@ -431,6 +435,7 @@ config CPU_SUP_CYRIX_32
>  config CPU_SUP_AMD
>  	default y
>  	bool "Support AMD processors" if PROCESSOR_SELECT
> +	select X86_BROADCAST_TLB_FLUSH
>  	help
>  	  This enables detection, tunings and quirks for AMD processors

You missed my comment again. How about you read review feedback more carefully
please?

CPU_SUP_AMD selects X86_BROADCAST_TLB_FLUSH which depends on CPU_SUP_AMD which
selects X86_BROADCAST_TLB_FLUSH which depends on CPU_SUP_AMD...

You need to make up your mind in which way the dependency should be. Certainly
not circular.

-- 
Regards/Gruss,
    Boris.

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