Re: [PATCH] x86/sev: Make SEV_STATUS available via SYSFS

Ingo Molnar
2025-03-05T11:26:17Z

* Borislav Petkov <bp@alien8.de> wrote:

> On Wed, Mar 05, 2025 at 11:52:34AM +0100, Joerg Roedel wrote:
> > From: Joerg Roedel <jroedel@suse.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