Re: 32 bit qemu regression from v6.5 tip pull [6c480f222128 x86/alternative: Rewrite optimize_nops() some]

From: Richard Purdie
Date: Mon Oct 30 2023 - 06:55:39 EST


On Mon, 2023-10-30 at 09:26 +0100, Peter Zijlstra wrote:
> On Sun, Oct 29, 2023 at 02:41:46PM -0400, Paul Gortmaker wrote:
> > The TL;DR is that the Yocto folks encountered a regression in their
> > automated QA tests (after a move from v6.4 --> v6.5) where non-KVM
> > enabled boot tests on 32 bit x86 would (with ~2% frequency) splat with:
>
> You're sure you're not running into this here:
>
> https://lkml.kernel.org/r/20230706170537.95959-1-richard.henderson@xxxxxxxxxx
>
> ?

We're using qemu 8.1.0. Whilst I will get us updated to 8.1.2 and see
if that helps, I think those commits are in 8.1.0:

$ git show cb62bd15e14e304617d250158b77d0deb032f03
commit cb62bd15e14e304617d250158b77d0deb032f032
Author: Richard Henderson <richard.henderson@xxxxxxxxxx>
Date: Thu Jul 6 08:45:13 2023 +0100

accel/tcg: Split out cpu_exec_longjmp_cleanup
[...]
$ git tag --contains cb62bd15e14e304617d250158b77d0deb032f03
v8.1.0
v8.1.0-rc0
v8.1.0-rc1
v8.1.0-rc2
v8.1.0-rc3
v8.1.0-rc4
v8.1.1
v8.1.2

Similarly for:

commit deba78709ae8ce103e2248413857747f804cd1ef
Author: Richard Henderson <richard.henderson@xxxxxxxxxx>
Date: Thu Jul 6 17:55:48 2023 +0100

accel/tcg: Always lock pages before translation

and

commit ad17868eb162a5466d8ad43e5ccb428776403308
Author: Richard Henderson <richard.henderson@xxxxxxxxxx>
Date: Wed Jul 26 12:58:08 2023 -0700

accel/tcg: Clear tcg_ctx->gen_tb on buffer overflow
[...]
Fixes: deba78709ae8 ("accel/tcg: Always lock pages before translation")

Both of which are also in 8.1.0.

Is there any other patch related to those we might be missing?

Cheers,

Richard