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

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Message-ID: <Z8g01YhM_FtdB5n6@gmail.com>
Date: Wed, 5 Mar 2025 12:26:13 +0100
From: Ingo Molnar <mingo@...nel.org>
To: Borislav Petkov <bp@...en8.de>
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


* Borislav Petkov <bp@...en8.de> wrote:

> On Wed, Mar 05, 2025 at 11:52:34AM +0100, Joerg Roedel wrote:
> > From: Joerg Roedel <jroedel@...e.de>
> > 
> > Current user-space tooling which needs access to the SEV_STATUS MSR is
> > using the MSR module. The use of this module poses a security risk in
> > any trusted execution environment and is generally discouraged.
> > 
> > Instead, provide an file in SYSFS in the already existing
> > /sys/devices/system/cpu/sev/ directory to provide the value of the
> > SEV_STATUS MSR to user-space.
> 
> Right, to continue this discussion on the ML, like we said yesterday, I think
> that dumping a raw MSR value is not really user-friendly.
> 
> We could stick a
> 
> Coco:
> 
> line in /proc/cpuinfo and simply dump SEV_STATUS there and TDX can put the
> respective TDX-specific feature flags of what is enabled there and then we
> have a good tested and well-known interface to communicate such things to
> userspace through.
> 
> I'd say...

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 ...

Thanks,

	Ingo