[PATCH 5.15 1/9] s390/mm: use non-quiescing sske for KVM switch to keyed guest

Greg Kroah-Hartman
2022-06-23T17:51:07Z

From: Christian Borntraeger <borntraeger@linux.ibm.com>

commit 3ae11dbcfac906a8c3a480e98660a823130dc16a upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/s390/mm/pgtable.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -748,7 +748,7 @@ void ptep_zap_key(struct mm_struct *mm,
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();
}