Re: [PATCH] x86/mwait-idle: fix ubsan warning

[Tamas K Lengyel <tamas.k.lengyel@xxxxxxxxx>]

On Fri, Jan 5, 2024 at 2:34 AM Jan Beulich <jbeulich@xxxxxxxx> wrote:
>
> On 04.01.2024 18:13, Tamas K Lengyel wrote:
> > Fix warning:
> > (XEN) UBSAN: Undefined behaviour in arch/x86/cpu/mwait-idle.c:1300:44
> > (XEN) left shift of 15 by 28 places cannot be represented in type 'int'
> >
> > Signed-off-by: Tamas K Lengyel <tamas.lengyel@xxxxxxxxx>
> > Fixes: 5a211704e88 ("mwait-idle: prevent SKL-H boot failure when C8+C9+C10 
> > enabled")
>
> No matter that I appreciate the change, I think this wants fixing by a
> patch to the (Linux) original, which we'd then import (like we do for
> other changes, including the one referenced by the Fixes: tag).

Feel free to submit it to other projects if the same issue applies to
them. I only ran into this with Xen and can only test it with Xen.

Tamas