linux-kernel - Re: [PATCH v4 08/15] x86/sev: Provide SVSM discovery support

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Message-ID: <20240531124829.GDZlnHHZnj-oByMTIK@fat_crate.local>
Date: Fri, 31 May 2024 14:48:29 +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 08/15] x86/sev: Provide SVSM discovery support

On Tue, May 28, 2024 at 03:57:10PM -0500, Tom Lendacky wrote:
> The alternative method is really meant for things like UEFI runtime services
> (which uses the kernels #VC handler), not the kernel directly.
> 
> Some of those checks have to be made very early, I'll see if it is feasible
> to rely on the CPUID check / cpu_feature_enabled() support.

Put that in the commit message.

> We can separate out SVSM vs VMPL, but if the kernel isn't running at VMPL0
> then it requires that an SVSM be present.

Ok, I guess the two things are identical.

> I'll incorporate this, but probably won't change the way exit_info_1 is
> assigned.

Oh, but we love our '!!' construct:

git grep -E '\s!![^!]' *.[ch] | wc -l
7776

At least so many, my pattern is not precise.

-- 
Regards/Gruss,
    Boris.

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