linux-kernel - Re: [PATCH v4 10/15] virt: sev-guest: Choose the VMPCK key based on executing VMPL

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Message-ID: <20240531190348.GKZlofFDL4ESfpOQ6O@fat_crate.local>
Date: Fri, 31 May 2024 21:03:48 +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 10/15] virt: sev-guest: Choose the VMPCK key based on
 executing VMPL

On Fri, May 31, 2024 at 01:36:06PM -0500, Tom Lendacky wrote:
> The sev-guest driver needs to access it. Given it is a driver/module, I
> created the accessor rather than mark the variable EXPORT_SYMBOL_GPL(). Your
> call, I'm fine with either.

Yeah, if the variable doesn't change after init, then you don't really
need an accessor.

> Yes, the driver can and does figure it out. However, this module parameter
> was added in the off chance the default VMPCK gets wiped. Then you can
> reload the driver and use a different (less privileged) VMPCK.

Is that what the text over snp_disable_vmpck() is alluding to?

Or where are we documenting this intended use?

Thx.

-- 
Regards/Gruss,
    Boris.

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