please consider for stable: "s390/mm: use non-quiescing sske for KVM switch to keyed guest"

[Christian Borntraeger <borntraeger@xxxxxxxxxxxxx>]

stable team, please consider
commit 3ae11dbcfac906a8c3a480e98660a823130dc16a
It will noticeable reduce system overhead when this happens on multiple CPUs.

----snip----
commit 3ae11dbcfac906a8c3a480e98660a823130dc16a
    s390/mm: use non-quiescing sske for KVM switch to keyed guest
    
    The switch to a keyed guest does not require a classic sske as the other
    guest CPUs are not accessing the key before the switch is complete.
    By using the NQ SSKE things are faster especially with multiple guests.

    
Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxxxxx>
Suggested-by: Janis Schoetterl-Glausch <scgl@xxxxxxxxxxxxx>
Reviewed-by: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20220530092706.11637-3-borntraeger@xxxxxxxxxxxxx
Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxxxxx>
Signed-off-by: Heiko Carstens <hca@xxxxxxxxxxxxx>

diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
index 697df02362af..4909dcd762e8 100644
--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -748,7 +748,7 @@ void ptep_zap_key(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
 	pgste_val(pgste) |= PGSTE_GR_BIT | PGSTE_GC_BIT;
 	ptev = pte_val(*ptep);
 	if (!(ptev & _PAGE_INVALID) && (ptev & _PAGE_WRITE))
-		page_set_storage_key(ptev & PAGE_MASK, PAGE_DEFAULT_KEY, 1);
+		page_set_storage_key(ptev & PAGE_MASK, PAGE_DEFAULT_KEY, 0);
 	pgste_set_unlock(ptep, pgste);
 	preempt_enable();
 }