sparc64: Increase max_phys_bits to 51 and VA bits to 53 for M8.

On M8 chips, use a max_phys_bits value of 51.

Also, M8 supports VA bits up to 54 bits. However, for now
restrict VA bits to 53 due to 4-level pagetable limitation.
Signed-off-by: NVijay Kumar <vijay.ac.kumar@oracle.com>
Reviewed-by: NBob Picco <bob.picco@oracle.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

arch/sparc/mm/init_64.c

@@ -1944,12 +1944,22 @@ static void __init setup_page_offset(void)
 			break;
 		case SUN4V_CHIP_SPARC_M7:
 		case SUN4V_CHIP_SPARC_SN:
-		default:
 			/* M7 and later support 52-bit virtual addresses.  */
 			sparc64_va_hole_top =    0xfff8000000000000UL;
 			sparc64_va_hole_bottom = 0x0008000000000000UL;
 			max_phys_bits = 49;
 			break;
+		case SUN4V_CHIP_SPARC_M8:
+		default:
+			/* M8 and later support 54-bit virtual addresses.
+			 * However, restricting M8 and above VA bits to 53
+			 * as 4-level page table cannot support more than
+			 * 53 VA bits.
+			 */
+			sparc64_va_hole_top =    0xfff0000000000000UL;
+			sparc64_va_hole_bottom = 0x0010000000000000UL;
+			max_phys_bits = 51;
+			break;
 		}
 	}