Re: [PATCHv6 01/16] x86/cpu: Enumerate the LASS feature bits

Borislav Petkov
2025-06-23T10:22:16Z

On Mon, Jun 23, 2025 at 11:17:02AM +0300, Kirill A. Shutemov wrote:
> What about this:
>
> LASS provides protection against a class of speculative attacks, such as
> SLAM[1]. Add the "lass" flag to /proc/cpuinfo to indicate that the feature
> is supported by hardware and enabled by the kernel. This allows userspace
> to determine if the setup is secure against such attacks.

Yeah, thanks.

I'm still not fully on board with userspace determining whether they're
mitigated or not but that's a general problem with our mitigations.

Also, I haven't looked at the patchset yet but I think it should be also
adding code to bugs.c to make all those vulns which it addresses, report that
they're mitigated by LASS now in

grep -r . /sys/devices/system/cpu/vulnerabilities/

output.

Which makes your cpuinfo flag not really needed as we already have a special
method for the mitigations reporting.

But ok, it has gotten kernel enablement so stating so in cpuinfo is ok.

Thx.

--
Regards/Gruss,
Boris.