KVM: s390/mm: Properly reset no-dat

When the CMMA state needs to be reset, the no-dat bit also needs to be
reset. Failure to do so could cause issues in the guest, since the
guest expects the bit to be cleared after a reset.

Cc: <stable@vger.kernel.org>
Reviewed-by: Nico Boehr <nrb@linux.ibm.com>
Message-ID: <20231109123624.37314-1-imbrenda@linux.ibm.com>
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>

Author: Claudio Imbrenda

arch/s390/mm/pgtable.c

@@ -756,7 +756,7 @@ void ptep_zap_unused(struct mm_struct *mm, unsigned long addr,
 		pte_clear(mm, addr, ptep);
 	}
 	if (reset)
-		pgste_val(pgste) &= ~_PGSTE_GPS_USAGE_MASK;
+		pgste_val(pgste) &= ~(_PGSTE_GPS_USAGE_MASK | _PGSTE_GPS_NODAT);
 	pgste_set_unlock(ptep, pgste);
 	preempt_enable();
 }