x86: Add support for m5ops through a memory mapped interface

In order to support m5ops in virtualized environments, we need to use
a memory mapped interface. This changeset adds support for that by
reserving 0xFFFF0000-0xFFFFFFFF and mapping those to the generic IPR
interface for m5ops. The mapping is done in the
X86ISA::TLB::finalizePhysical() which means that it just works for all
of the CPU models, including virtualized ones.

util/m5/Makefile.x86

@@ -31,7 +31,7 @@ CC=gcc
 AS=as
 LD=ld
 
-CFLAGS=-O2 
+CFLAGS=-O2 -DM5OP_ADDR=0xFFFF0000
 OBJS=m5.o m5op_x86.o
 
 all: m5