KVM: s390: handle missing storage-key facility
Without the storage-key facility, SIE won't interpret SSKE, ISKE and
RRBE for us. So let's add proper interception handlers that will be called
if lazy sske cannot be enabled.
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
index e791e8b..fa286d0 100644
--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -572,6 +572,43 @@
}
EXPORT_SYMBOL(cond_set_guest_storage_key);
+/**
+ * Reset a guest reference bit (rrbe), returning the reference and changed bit.
+ *
+ * Returns < 0 in case of error, otherwise the cc to be reported to the guest.
+ */
+int reset_guest_reference_bit(struct mm_struct *mm, unsigned long addr)
+{
+ spinlock_t *ptl;
+ pgste_t old, new;
+ pte_t *ptep;
+ int cc = 0;
+
+ ptep = get_locked_pte(mm, addr, &ptl);
+ if (unlikely(!ptep))
+ return -EFAULT;
+
+ new = old = pgste_get_lock(ptep);
+ /* Reset guest reference bit only */
+ pgste_val(new) &= ~PGSTE_GR_BIT;
+
+ if (!(pte_val(*ptep) & _PAGE_INVALID)) {
+ cc = page_reset_referenced(pte_val(*ptep) & PAGE_MASK);
+ /* Merge real referenced bit into host-set */
+ pgste_val(new) |= ((unsigned long) cc << 53) & PGSTE_HR_BIT;
+ }
+ /* Reflect guest's logical view, not physical */
+ cc |= (pgste_val(old) & (PGSTE_GR_BIT | PGSTE_GC_BIT)) >> 49;
+ /* Changing the guest storage key is considered a change of the page */
+ if ((pgste_val(new) ^ pgste_val(old)) & PGSTE_GR_BIT)
+ pgste_val(new) |= PGSTE_UC_BIT;
+
+ pgste_set_unlock(ptep, new);
+ pte_unmap_unlock(ptep, ptl);
+ return 0;
+}
+EXPORT_SYMBOL(reset_guest_reference_bit);
+
int get_guest_storage_key(struct mm_struct *mm, unsigned long addr,
unsigned char *key)
{