Re: [PATCH for-4.21 1/2] x86/AMD: avoid REP MOVSB for Zen3/4

[Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>]

On 10/8/25 6:06 PM, Jan Beulich wrote:

> On 08.10.2025 13:20, Roger Pau Monné wrote:
> > On Mon, Sep 29, 2025 at 07:35:53PM -0400, Jason Andryuk wrote:
> > > On 2025-09-25 08:18, Teddy Astie wrote:
> > > > Le 25/09/2025 à 12:48, Jan Beulich a écrit :
> > > > > Along with Zen2 (which doesn't expose ERMS), both families reportedly
> > > > > suffer from sub-optimal aliasing detection when deciding whether REP MOVSB
> > > > > can actually be carried out the accelerated way. Therefore we want to
> > > > > avoid its use in the common case (memset(), copy_page_hot()).
> > > > >             
> > > > s/memset/memcpy (memset probably uses rep stosb which is not affected IIUC)
> > > >
> > > > > Reported-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> > > > > Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> > > > >             
> > > >           
> > > With Teddy's suggested change:
> > >
> > > Reviewed-by: Jason Andryuk <jason.andryuk@xxxxxxx>
> > >         
> > Acked-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> >       
> May I ask for a release-ack here, seeing that it alters behavior that went in
> close before the freeze?
>     
Release-Acked-by: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>

~ Oleksii