powerpc: Decode the pte-lp-encoding bits correctly.

We look at both the segment base page size and actual page size and store
the pte-lp-encodings in an array per base page size.

We also update all relevant functions to take actual page size argument
so that we can use the correct PTE LP encoding in HPTE. This should also
get the basic Multiple Page Size per Segment (MPSS) support. This is needed
to enable THP on ppc64.

[Fixed PR KVM build --BenH]

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/include/asm/mmu-hash64.h b/arch/powerpc/include/asm/mmu-hash64.h
index de9e577..18171a8 100644
--- a/arch/powerpc/include/asm/mmu-hash64.h
+++ b/arch/powerpc/include/asm/mmu-hash64.h
@@ -155,7 +155,7 @@
 struct mmu_psize_def
 {
 	unsigned int	shift;	/* number of bits */
-	unsigned int	penc;	/* HPTE encoding */
+	int		penc[MMU_PAGE_COUNT];	/* HPTE encoding */
 	unsigned int	tlbiel;	/* tlbiel supported for that page size */
 	unsigned long	avpnm;	/* bits to mask out in AVPN in the HPTE */
 	unsigned long	sllp;	/* SLB L||LP (exact mask to use in slbmte) */
@@ -200,6 +200,13 @@
  */
 #define VPN_SHIFT	12
 
+/*
+ * HPTE Large Page (LP) details
+ */
+#define LP_SHIFT	12
+#define LP_BITS		8
+#define LP_MASK(i)	((0xFF >> (i)) << LP_SHIFT)
+
 #ifndef __ASSEMBLY__
 
 static inline int segment_shift(int ssize)
@@ -255,14 +262,14 @@
 
 /*
  * This function sets the AVPN and L fields of the HPTE  appropriately
- * for the page size
+ * using the base page size and actual page size.
  */
-static inline unsigned long hpte_encode_v(unsigned long vpn,
-					  int psize, int ssize)
+static inline unsigned long hpte_encode_v(unsigned long vpn, int base_psize,
+					  int actual_psize, int ssize)
 {
 	unsigned long v;
-	v = hpte_encode_avpn(vpn, psize, ssize);
-	if (psize != MMU_PAGE_4K)
+	v = hpte_encode_avpn(vpn, base_psize, ssize);
+	if (actual_psize != MMU_PAGE_4K)
 		v |= HPTE_V_LARGE;
 	return v;
 }
@@ -272,19 +279,17 @@
  * for the page size. We assume the pa is already "clean" that is properly
  * aligned for the requested page size
  */
-static inline unsigned long hpte_encode_r(unsigned long pa, int psize)
+static inline unsigned long hpte_encode_r(unsigned long pa, int base_psize,
+					  int actual_psize)
 {
-	unsigned long r;
-
 	/* A 4K page needs no special encoding */
-	if (psize == MMU_PAGE_4K)
+	if (actual_psize == MMU_PAGE_4K)
 		return pa & HPTE_R_RPN;
 	else {
-		unsigned int penc = mmu_psize_defs[psize].penc;
-		unsigned int shift = mmu_psize_defs[psize].shift;
-		return (pa & ~((1ul << shift) - 1)) | (penc << 12);
+		unsigned int penc = mmu_psize_defs[base_psize].penc[actual_psize];
+		unsigned int shift = mmu_psize_defs[actual_psize].shift;
+		return (pa & ~((1ul << shift) - 1)) | (penc << LP_SHIFT);
 	}
-	return r;
 }
 
 /*