Re: [PATCH 5.15 00/78] 5.15.55-rc1 review

Linus Torvalds
2022-07-13T18:40:34Z

On Wed, Jul 13, 2022 at 11:33 AM Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> So I think that that is where the "xaddw_ax_dx+8" comes from: some
> code assumes that FASTOP_SIZE is 8, but that xaddw_ax_dx case was
> actually 9 bytes and thus got that "int3 + padding" in the next 8
> bytes.
>
> The whole kvm x86 emulation thing is quite complicated and has lots
> of instruction size #defines and magic.
>
> I'm not familiar enough with it to go "Ahh, it's obviously XYZ", but
> I'm sure PeterZ and Borislav know exactly what's going on.

And I see that Thadeau already figured it out:

https://lore.kernel.org/all/20220713171241.184026-1-cascardo@canonical.com/

So presumably we need that patch everywhere.

Linus