Commit 97ca7bfc authored Jul 06, 2017 by Christian Borntraeger Committed by Martin Schwidefsky Jul 13, 2017

s390/mm: set change and reference bit on lazy key enablement

When we enable storage keys for a guest lazily, we reset the ACC and F
values. That is correct assuming that these are 0 on a clear reset and
the guest obviously has not used any key setting instruction.

We also zero out the change and reference bit. This is not correct as
the architecture prefers over-indication instead of under-indication
for the keyless->keyed transition.

This patch fixes the behaviour and always sets guest change and guest
reference for all guest storage keys on the keyless -> keyed switch.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

parent 2daace78

arch/s390/mm/pgtable.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -591,11 +591,11 @@ void ptep_zap_key(struct mm_struct mm, unsigned long addr, pte_t ptep)
		unsigned long ptev;
		pgste_t pgste;

		/* Clear storage key */
		/* Clear storage key ACC and F, but set R/C */
		preempt_disable();
		pgste = pgste_get_lock(ptep);
		pgste_val(pgste) &= ~(PGSTE_ACC_BITS \| PGSTE_FP_BIT \|
		PGSTE_GR_BIT \| PGSTE_GC_BIT);
		pgste_val(pgste) &= ~(PGSTE_ACC_BITS \| PGSTE_FP_BIT);
		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);

Admin message