s390/pgtable: fix mprotect for single-threaded KVM guests

For a single-threaded KVM guest ptep_modify_prot_start will not use
IPTE, the invalid bit will therefore not be set. If DEBUG_VM is set
pgste_set_key called by ptep_modify_prot_commit will complain about
the missing invalid bit. ptep_modify_prot_start should set the
invalid bit in all cases.

Cc: stable@vger.kernel.org # 3.10+
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h
index 125e37909998..1d144b6f3ba2 100644
--- a/arch/s390/include/asm/pgtable.h
+++ b/arch/s390/include/asm/pgtable.h
@@ -1093,6 +1093,7 @@ static inline pte_t ptep_modify_prot_start(struct mm_struct *mm,
 
         pte = *ptep;
         ptep_flush_lazy(mm, address, ptep);
+        pte_val(*ptep) |= _PAGE_INVALID;
 
         if (mm_has_pgste(mm)) {
                 pgste = pgste_update_all(&pte, pgste);