sparc64: Increase MAX_PHYS_ADDRESS_BITS to 53.

[ Upstream commit 7c0fa0f2 ]

Make sure, at compile time, that the kernel can properly support
whatever MAX_PHYS_ADDRESS_BITS is defined to.

On M7 chips, use a max_phys_bits value of 49.

Based upon a patch by Bob Picco.
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Bob Picco <bob.picco@oracle.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>

arch/sparc/include/asm/page_64.h

@@ -122,11 +122,11 @@ extern unsigned long PAGE_OFFSET;
 
 #endif /* !(__ASSEMBLY__) */
 
-/* The maximum number of physical memory address bits we support, this
- * is used to size various tables used to manage kernel TLB misses and
- * also the sparsemem code.
+/* The maximum number of physical memory address bits we support.  The
+ * largest value we can support is whatever "KPGD_SHIFT + KPTE_BITS"
+ * evaluates to.
  */
-#define MAX_PHYS_ADDRESS_BITS	47
+#define MAX_PHYS_ADDRESS_BITS	53
 
 #define ILOG2_4MB		22
 #define ILOG2_256MB		28

arch/sparc/include/asm/pgtable_64.h

@@ -67,6 +67,10 @@
 #define PGDIR_MASK	(~(PGDIR_SIZE-1))
 #define PGDIR_BITS	(PAGE_SHIFT - 3)
 
+#if (MAX_PHYS_ADDRESS_BITS > PGDIR_SHIFT + PGDIR_BITS)
+#error MAX_PHYS_ADDRESS_BITS exceeds what kernel page tables can support
+#endif
+
 #if (PGDIR_SHIFT + PGDIR_BITS) != 53
 #error Page table parameters do not cover virtual address space properly.
 #endif

arch/sparc/mm/init_64.c

@@ -1683,12 +1683,19 @@ static void __init setup_page_offset(void)
 		case SUN4V_CHIP_NIAGARA4:
 		case SUN4V_CHIP_NIAGARA5:
 		case SUN4V_CHIP_SPARC64X:
-		default:
+		case SUN4V_CHIP_SPARC_M6:
 			/* T4 and later support 52-bit virtual addresses.  */
 			sparc64_va_hole_top =    0xfff8000000000000UL;
 			sparc64_va_hole_bottom = 0x0008000000000000UL;
 			max_phys_bits = 47;
 			break;
+		case SUN4V_CHIP_SPARC_M7:
+		default:
+			/* M7 and later support 52-bit virtual addresses.  */
+			sparc64_va_hole_top =    0xfff8000000000000UL;
+			sparc64_va_hole_bottom = 0x0008000000000000UL;
+			max_phys_bits = 49;
+			break;
 		}
 	}