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authorChristian Borntraeger <borntraeger@de.ibm.com>2013-06-04 09:53:59 +0200
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2013-06-05 17:36:19 +0200
commit338679f7ba4a81906b3fdfa6507824fdf704be80 (patch)
tree794df0317cf02d6b32670887f081ffc8e7e73ebc /arch/s390
parent4d3797d7e1861ac1af150a6189315786c5e1c820 (diff)
s390/pgtable: Fix guest overindication for change bit
When doing the transition invalid->valid in the host page table for a guest, then the guest view of C/R is in the pgste. After validation the view is pgste OR real key. We must zero out the real key C/R to avoid guest over-indication for change (and reference). Touching the real key is ok also for the host: The change bit is tracked via write protection and the reference bit is also ok because set_pte_at was called and the page will be touched anyway soon. Furthermore architecture defines reference as "substantially accurate", over- and underindication are ok. Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390')
-rw-r--r--arch/s390/include/asm/pgtable.h16
1 files changed, 9 insertions, 7 deletions
diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h
index ac01463038f1..391e592356d0 100644
--- a/arch/s390/include/asm/pgtable.h
+++ b/arch/s390/include/asm/pgtable.h
@@ -704,17 +704,19 @@ static inline void pgste_set_key(pte_t *ptep, pgste_t pgste, pte_t entry)
{
#ifdef CONFIG_PGSTE
unsigned long address;
- unsigned long okey, nkey;
+ unsigned long nkey;
if (pte_val(entry) & _PAGE_INVALID)
return;
+ VM_BUG_ON(!(pte_val(*ptep) & _PAGE_INVALID));
address = pte_val(entry) & PAGE_MASK;
- okey = nkey = page_get_storage_key(address);
- nkey &= ~(_PAGE_ACC_BITS | _PAGE_FP_BIT);
- /* Set page access key and fetch protection bit from pgste */
- nkey |= (pgste_val(pgste) & (RCP_ACC_BITS | RCP_FP_BIT)) >> 56;
- if (okey != nkey)
- page_set_storage_key(address, nkey, 0);
+ /*
+ * Set page access key and fetch protection bit from pgste.
+ * The guest C/R information is still in the PGSTE, set real
+ * key C/R to 0.
+ */
+ nkey = (pgste_val(pgste) & (RCP_ACC_BITS | RCP_FP_BIT)) >> 56;
+ page_set_storage_key(address, nkey, 0);
#endif
}