Re: [PATCH v2 2/2] s390/mm: re-enable the shared zeropage for !PV and !skeys KVM guests

[David Hildenbrand]

On 11.04.24 14:33, Alexander Gordeev wrote:
> On Wed, Mar 27, 2024 at 06:17:37PM +0100, David Hildenbrand wrote:
> > index 60950e7a25f5..1a71cb19c089 100644
> > --- a/arch/s390/include/asm/pgtable.h
> > +++ b/arch/s390/include/asm/pgtable.h
> > @@ -566,10 +566,19 @@ static inline pud_t set_pud_bit(pud_t pud, pgprot_t prot)
> >   }
> >   
> >   /*
> > - * In the case that a guest uses storage keys
> > - * faults should no longer be backed by zero pages
> > + * As soon as the guest uses storage keys or enables PV, we deduplicate all
> > + * mapped shared zeropages and prevent new shared zeropages from getting
> > + * mapped.
> >    */
> > -#define mm_forbids_zeropage mm_has_pgste
>
> Should it be the below insted?
>
> #define mm_forbids_zeropage mm_forbids_zeropage
>
> Once I add it, it fails to compile, due to the issue in patch #1.

I guess yes. So we tested the unsharing part (why I was seeing unsharing 
triggering), but would have allowed zeropages afterwards. Sight.

Let me retest and resend. Thanks!

--
Cheers,

David / dhildenb