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

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Date: Wed, 21 Feb 2024 12:21:20 +0100
From: Ard Biesheuvel <ardb@...nel.org>
To: Borislav Petkov <bp@...en8.de>
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, 21 Feb 2024 at 12:13, Borislav Petkov <bp@...en8.de> wrote:
>
> 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.
>

That all gets ripped out in the last patch.


Btw v5 is good to go, in case you're ok switching to that:

https://git.kernel.org/pub/scm/linux/kernel/git/ardb/linux.git/log/?h=x86-pie-for-sev-v5