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

diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
index 697df02362af179c209a170e7c07f997d3cb86e4..4909dcd762e8ce142de2eb8e2e1b0a7f9787a40a 100644 (file)
--- 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();
 }