linux-kernel - Re: [PATCH v4 04/11] x86/startup_64: Defer assignment of 5-level paging global variables

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Message-ID: <20240221111245.GDZdXarZsZd7eZw_BK@fat_crate.local>
Date: Wed, 21 Feb 2024 12:12:45 +0100
From: Borislav Petkov <bp@...en8.de>
To: Ard Biesheuvel <ardb@...nel.org>
Cc: linux-kernel@...r.kernel.org, Kevin Loughlin <kevinloughlin@...gle.com>,
	Tom Lendacky <thomas.lendacky@....com>,
	Dionna Glaze <dionnaglaze@...gle.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	Andy Lutomirski <luto@...nel.org>, Arnd Bergmann <arnd@...db.de>,
	Nathan Chancellor <nathan@...nel.org>,
	Nick Desaulniers <ndesaulniers@...gle.com>,
	Justin Stitt <justinstitt@...gle.com>,
	Kees Cook <keescook@...omium.org>, Brian Gerst <brgerst@...il.com>,
	linux-arch@...r.kernel.org, llvm@...ts.linux.dev
Subject: Re: [PATCH v4 04/11] x86/startup_64: Defer assignment of 5-level
 paging global variables

On Wed, Feb 21, 2024 at 11:20:13AM +0100, Ard Biesheuvel wrote:
> Just the below should be sufficient
> 
> --- a/arch/x86/include/asm/pgtable_64_types.h
> +++ b/arch/x86/include/asm/pgtable_64_types.h
> @@ -22,7 +22,7 @@ typedef struct { pteval_t pte; } pte_t;
>  typedef struct { pmdval_t pmd; } pmd_t;
> 
> -#ifdef CONFIG_X86_5LEVEL
>  extern unsigned int __pgtable_l5_enabled;
> 
> +#ifdef CONFIG_X86_5LEVEL
>  #ifdef USE_EARLY_PGTABLE_L5

Perhaps but the CONFIG_X86_5LEVEL ifdeffery is just ugly and getting
unnecessary.

-- 
Regards/Gruss,
    Boris.

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