[PATCH 2/2] powerpc: Free up _PAGE_COHERENCE for numa fault use later

[Aneesh Kumar K.V]

From: "Aneesh Kumar K.V" <aneesh.kumar at linux.vnet.ibm.com>

only hash 64 config we always set memory coherence, 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 at linux.vnet.ibm.com>
---
 arch/powerpc/include/asm/pte-hash64.h |  2 +-
 arch/powerpc/mm/hash_low_64.S         | 15 ++++++++++++---
 arch/powerpc/mm/hugepage-hash64.c     |  6 +++++-
 arch/powerpc/mm/hugetlbpage-hash64.c  |  4 ++++
 4 files changed, 22 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/include/asm/pte-hash64.h b/arch/powerpc/include/asm/pte-hash64.h
index 0419eeb..55aea0c 100644
--- a/arch/powerpc/include/asm/pte-hash64.h
+++ b/arch/powerpc/include/asm/pte-hash64.h
@@ -19,7 +19,7 @@
 #define _PAGE_FILE		0x0002 /* (!present only) software: pte holds file offset */
 #define _PAGE_EXEC		0x0004 /* No execute on POWER4 and newer (we invert) */
 #define _PAGE_GUARDED		0x0008
-#define _PAGE_COHERENT		0x0010 /* M: enforce memory coherence (SMP systems) */
+/* We can derive Memory coherence from _PAGE_NO_CACHE */
 #define _PAGE_NO_CACHE		0x0020 /* I: cache inhibit */
 #define _PAGE_WRITETHRU		0x0040 /* W: cache write-through */
 #define _PAGE_DIRTY		0x0080 /* C: page changed */
diff --git a/arch/powerpc/mm/hash_low_64.S b/arch/powerpc/mm/hash_low_64.S
index d3cbda6..1136d26 100644
--- a/arch/powerpc/mm/hash_low_64.S
+++ b/arch/powerpc/mm/hash_low_64.S
@@ -148,7 +148,10 @@ END_MMU_FTR_SECTION_IFSET(MMU_FTR_1T_SEGMENT)
 	and	r0,r0,r4		/* _PAGE_RW & _PAGE_DIRTY ->r0 bit 30*/
 	andc	r0,r30,r0		/* r0 = pte & ~r0 */
 	rlwimi	r3,r0,32-1,31,31	/* Insert result into PP lsb */
-	ori	r3,r3,HPTE_R_C		/* Always add "C" bit for perf. */
+	/*
+	 * Always add "C" bit for perf. Memory coherence is always enabled
+	 */
+	ori	r3,r3,HPTE_R_C | HPTE_R_M
 
 	/* We eventually do the icache sync here (maybe inline that
 	 * code rather than call a C function...) 
@@ -457,7 +460,10 @@ END_MMU_FTR_SECTION_IFSET(MMU_FTR_1T_SEGMENT)
 	and	r0,r0,r4		/* _PAGE_RW & _PAGE_DIRTY ->r0 bit 30*/
 	andc	r0,r3,r0		/* r0 = pte & ~r0 */
 	rlwimi	r3,r0,32-1,31,31	/* Insert result into PP lsb */
-	ori	r3,r3,HPTE_R_C		/* Always add "C" bit for perf. */
+	/*
+	 * Always add "C" bit for perf. Memory coherence is always enabled
+	 */
+	ori	r3,r3,HPTE_R_C | HPTE_R_M
 
 	/* We eventually do the icache sync here (maybe inline that
 	 * code rather than call a C function...)
@@ -795,7 +801,10 @@ END_MMU_FTR_SECTION_IFSET(MMU_FTR_1T_SEGMENT)
 	and	r0,r0,r4		/* _PAGE_RW & _PAGE_DIRTY ->r0 bit 30*/
 	andc	r0,r30,r0		/* r0 = pte & ~r0 */
 	rlwimi	r3,r0,32-1,31,31	/* Insert result into PP lsb */
-	ori	r3,r3,HPTE_R_C		/* Always add "C" bit for perf. */
+	/*
+	 * Always add "C" bit for perf. Memory coherence is always enabled
+	 */
+	ori	r3,r3,HPTE_R_C | HPTE_R_M
 
 	/* We eventually do the icache sync here (maybe inline that
 	 * code rather than call a C function...)
diff --git a/arch/powerpc/mm/hugepage-hash64.c b/arch/powerpc/mm/hugepage-hash64.c
index 34de9e0..b640595 100644
--- a/arch/powerpc/mm/hugepage-hash64.c
+++ b/arch/powerpc/mm/hugepage-hash64.c
@@ -127,7 +127,11 @@ repeat:
 
 		/* Add in WIMG bits */
 		rflags |= (new_pmd & (_PAGE_WRITETHRU | _PAGE_NO_CACHE |
-				      _PAGE_COHERENT | _PAGE_GUARDED));
+				      _PAGE_GUARDED));
+		/*
+		 * enable the memory coherence always
+		 */
+		rflgs |= HPTE_R_M;
 
 		/* Insert into the hash table, primary slot */
 		slot = ppc_md.hpte_insert(hpte_group, vpn, pa, rflags, 0,
diff --git a/arch/powerpc/mm/hugetlbpage-hash64.c b/arch/powerpc/mm/hugetlbpage-hash64.c
index 0b7fb67..a5bcf93 100644
--- a/arch/powerpc/mm/hugetlbpage-hash64.c
+++ b/arch/powerpc/mm/hugetlbpage-hash64.c
@@ -99,6 +99,10 @@ int __hash_page_huge(unsigned long ea, unsigned long access, unsigned long vsid,
 		/* Add in WIMG bits */
 		rflags |= (new_pte & (_PAGE_WRITETHRU | _PAGE_NO_CACHE |
 				      _PAGE_COHERENT | _PAGE_GUARDED));
+		/*
+		 * enable the memory coherence always
+		 */
+		rflags |= HPTE_R_M;
 
 		slot = hpte_insert_repeating(hash, vpn, pa, rflags, 0,
 					     mmu_psize, ssize);
-- 
1.8.1.2