linux-kernel - Re: [PATCH v4 05/15] x86/sev: Use kernel provided SVSM Calling Areas

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Date: Fri, 17 May 2024 21:23:41 +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 05/15] x86/sev: Use kernel provided SVSM Calling Areas

On Wed, May 08, 2024 at 03:09:02PM -0500, Tom Lendacky wrote:
> If we're not running at VMPL0 (based on the RMPADJUST check) and if the SVSM
> doesn't advertise a non-zero VMPL value, we will self-terminate. So those
> values are only set if we are not running at VMPL0 and the SVSM has provided
> a non-zero value to us.
> 
> I'm going to turn the function into a bool function so that the call
> becomes:
> 
> 	if (!svsm_setup_caa(cc_info))
> 		return;

Sure, I guess I'm misled by the

	if (bla)
		sev_es_terminate()

which is a function call but I need to read its name to realize that
after that point we're either terminated or we have all the stuff
required to run on a SVSM.

> I do. I think you're missing the RMPADJUST check that causes the function to
> return early if we're running at VMPL0.

Yap.

-- 
Regards/Gruss,
    Boris.

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