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

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