linux-kernel - Re: [PATCH] x86/sev: Make SEV

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Message-ID: <20250305113155.GCZ8g2K1XEdgynTA9D@fat_crate.local>
Date: Wed, 5 Mar 2025 12:31:55 +0100
From: Borislav Petkov <bp@...en8.de>
To: Ingo Molnar <mingo@...nel.org>
Cc: Joerg Roedel <joro@...tes.org>, x86@...nel.org, hpa@...or.com,
	Tom Lendacky <thomas.lendacky@....com>,
	Nikunj A Dadhania <nikunj@....com>, linux-kernel@...r.kernel.org,
	Larry.Dewey@....com, Joerg Roedel <jroedel@...e.de>
Subject: Re: [PATCH] x86/sev: Make SEV_STATUS available via SYSFS

On Wed, Mar 05, 2025 at 12:26:13PM +0100, Ingo Molnar wrote:
> It's *far* better to expose this via a targeted sysfs entry than 
> polluting /proc/cpuinfo with it that everyone and their dog is parsing 
> all the time ...

Pasting what we're talking on IRC:

- we don't want to expose a naked MSR u64 to userspace. Might as well use
  msr-tools

- the backstory is, there are a bunch of tools which wanna know this so we
  need to agree on how to supply it to them

- I think /proc/cpuinfo is the best option right now

- and then TDX can use the same thing too

- we have a general need to expose what a confidential guest supports

- a .../sev sysfs file clearly doesn't cut it because TDX doesn't have "sev"
  - it is the Intel version of a confidential guest

- and I don't want to have "0xdeadbeef" in some sys file but "SEV SEV-ES TDX
  SecureTSC" and so on user-readable strings

-- 
Regards/Gruss,
    Boris.

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