linux-kernel - Re: [PATCH v4 04/15] x86/sev: Check for the presence of an SVSM in the SNP Secrets page

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Date: Wed, 22 May 2024 19:23:58 +0200
From: Borislav Petkov <bp@...en8.de>
To: Tom Lendacky <thomas.lendacky@....com>
Cc: linux-kernel@...r.kernel.org, x86@...nel.org,
	linux-coco@...ts.linux.dev, svsm-devel@...onut-svsm.dev,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	"H. Peter Anvin" <hpa@...or.com>, Andy Lutomirski <luto@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Dan Williams <dan.j.williams@...el.com>,
	Michael Roth <michael.roth@....com>,
	Ashish Kalra <ashish.kalra@....com>
Subject: Re: [PATCH v4 04/15] x86/sev: Check for the presence of an SVSM in
 the SNP Secrets page

On Wed, May 22, 2024 at 11:15:28AM -0500, Tom Lendacky wrote:
> Or what I originally proposed:
> 
> 	if (!IS_ALIGNED(caa, PAGE_SIZE))
> 
> Which also works without including mm.h.

It works because of the same nasty reason:

$ make arch/x86/boot/compressed/sev.i
  CALL    scripts/checksyscalls.sh
  DESCEND objtool
  INSTALL libsubcmd_headers
  CPP     arch/x86/boot/compressed/sev.i
$ grep align.h arch/x86/boot/compressed/sev.i
# 1 "./include/linux/align.h" 1

The include hell pulls in that linux/ namespace header into the
decompressor. Which it should not to.

So no, please use the open-coded thing. I probably should start
untangling the decompressor slowly and do small sets because otherwise
this'll never get split properly.

;-\

-- 
Regards/Gruss,
    Boris.

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