On Tue, 17 Jul 2018 21:37:23 +0200
David Hildenbrand <david@xxxxxxxxxx> wrote:
> On 17.07.2018 14:44, Janosch Frank wrote:
> > Similarly to the pte skey handling, where we set the storage key to
> > the default key for each newly mapped pte, we have to also do that for
> > huge pmds.
> >
> > Signed-off-by: Janosch Frank <frankja@xxxxxxxxxxxxx>
> > ---
> > arch/s390/mm/pgtable.c | 22 ++++++++++++++++++++++
> > 1 file changed, 22 insertions(+)
> >
> > diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
> > index 09531f779271..60fff609ab61 100644
> > --- a/arch/s390/mm/pgtable.c
> > +++ b/arch/s390/mm/pgtable.c
> > @@ -410,12 +410,32 @@ static inline pmd_t pmdp_flush_lazy(struct mm_struct *mm,
> > return old;
> > }
> >
> > +static void pmdp_clear_skeys(struct mm_struct *mm, pmd_t *pmdp, pmd_t new)
> > +{
> > + unsigned long paddr = pmd_val(new) & HPAGE_MASK;
> > +
> > + /*
> > + * After a guest has used the first storage key instruction,
> > + * we must ensure, that each newly mapped huge pmd has all
> > + * skeys cleared before mapping it.
> > + */
> > + if (!mm_uses_skeys(mm) ||
>
> I would move this check to the callers. At least then it is clear why we
> don't call a skey function (as said, mm_has_pgste() is really misleading).
>
> > + !pmd_none(*pmdp) ||
> > + !pmd_large(new) ||
> > + (pmd_val(new) & _SEGMENT_ENTRY_INVALID))
> > + return;
> > +
> > + __storage_key_init_range(paddr, paddr + HPAGE_SIZE - 1);
> > +}
> > +
> > pmd_t pmdp_xchg_direct(struct mm_struct *mm, unsigned long addr,
> > pmd_t *pmdp, pmd_t new)
> > {
> > pmd_t old;
> >
> > preempt_disable();
> > + if (mm_has_pgste(mm))
> > + pmdp_clear_skeys(mm, pmdp, new);
> > old = pmdp_flush_direct(mm, addr, pmdp);
> > *pmdp = new;
> > preempt_enable();
> > @@ -429,6 +449,8 @@ pmd_t pmdp_xchg_lazy(struct mm_struct *mm, unsigned long addr,
> > pmd_t old;
> >
> > preempt_disable();
> > + if (mm_has_pgste(mm))
> > + pmdp_clear_skeys(mm, pmdp, new);
> > old = pmdp_flush_lazy(mm, addr, pmdp);
> > *pmdp = new;
> > preempt_enable();
> >
>
> Hoping Martin can have a look
>
> Acked-by: David Hildenbrand <david@xxxxxxxxxx>
Talked to Janosch about this, stay tuned for the next version.
--
blue skies,
Martin.
"Reality continues to ruin my life." - Calvin.
