powerpc/mm: Free up _PAGE_COHERENCE for numa fault use later

Set  memory coherence always on hash64 config. If
a platform cannot have memory coherence always set they
can infer that from _PAGE_NO_CACHE and _PAGE_WRITETHRU
like in lpar. So we dont' really need a separate bit
for tracking _PAGE_COHERENCE.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
index 6176b3c..de68812 100644
--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c
@@ -169,9 +169,10 @@
 	if ((pteflags & _PAGE_USER) && !((pteflags & _PAGE_RW) &&
 					 (pteflags & _PAGE_DIRTY)))
 		rflags |= 1;
-
-	/* Always add C */
-	return rflags | HPTE_R_C;
+	/*
+	 * Always add "C" bit for perf. Memory coherence is always enabled
+	 */
+	return rflags | HPTE_R_C | HPTE_R_M;
 }
 
 int htab_bolt_mapping(unsigned long vstart, unsigned long vend,