Re: [PATCH] x86/CPU/AMD: Fix AMD TLBI Erratum #1718

["Lorenzo Stoakes (ARM)" <ljs@kernel.org>]

+cc Rik FYI!

On Fri, Oct 02, 2026 at 02:16:17PM -0700, Borislav Petkov wrote:
> From: "Borislav Petkov (AMD)" <bp@alien8.de>
>
> The processor may fail to invalidate a TLB entry while executing an
> INVLPGB/TLBSYNC instruction pair.

Hi,

I've repro'd the issue on a threadripper - a Ryzen Threadripper 9980X
(family 0x1a model 0x08 stepping 1) on microcode 0x0b008121 (the latest I
believe).

It failed Matt's repro in seconds on 7.2.7 (round 3 on the first run, round
1 on the second, same stale-offset signature Rik described).

It doesn't seem there's a microcode fix for the threadripper yet.

I confirmed tlbi=ipi fixed it, 20 rounds with no failures.

And I built and ran a kernel with this patch applied (and tlbi=ipi removed
from the kernel command line) and this patch fixes it it too - 40 rounds
with no failures.

So:

Acked-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Tested-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>

Hopefully some useful datapoints also - + I hope there'll be a firmware fix
for the threadripper too :)

--
Cheers, Lorenzo