qom/cpu: Add MemoryRegion property

Add a MemoryRegion property, which if set is used to construct
the CPU's initial (default) AddressSpace.

Signed-off-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
[PMM: code is moved from qom/cpu.c to exec.c to avoid having to
 make qom/cpu.o be a non-common object file; code to use the
 MemoryRegion and to default it to system_memory added.]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Acked-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>

cpus.c

@@ -1375,8 +1375,10 @@ void qemu_init_vcpu(CPUState *cpu)
         /* If the target cpu hasn't set up any address spaces itself,
          * give it the default one.
          */
+        AddressSpace *as = address_space_init_shareable(cpu->memory,
+                                                        "cpu-memory");
         cpu->num_ases = 1;
-        cpu_address_space_init(cpu, &address_space_memory, 0);
+        cpu_address_space_init(cpu, as, 0);
     }
 
     if (kvm_enabled()) {

exec.c

@@ -628,6 +628,20 @@ void cpu_exec_init(CPUState *cpu, Error **errp)
 
 #ifndef CONFIG_USER_ONLY
     cpu->thread_id = qemu_get_thread_id();
+
+    /* This is a softmmu CPU object, so create a property for it
+     * so users can wire up its memory. (This can't go in qom/cpu.c
+     * because that file is compiled only once for both user-mode
+     * and system builds.) The default if no link is set up is to use
+     * the system address space.
+     */
+    object_property_add_link(OBJECT(cpu), "memory", TYPE_MEMORY_REGION,
+                             (Object **)&cpu->memory,
+                             qdev_prop_allow_set_link_before_realize,
+                             OBJ_PROP_LINK_UNREF_ON_RELEASE,
+                             &error_abort);
+    cpu->memory = system_memory;
+    object_ref(OBJECT(cpu->memory));
 #endif
 
 #if defined(CONFIG_USER_ONLY)

include/qom/cpu.h

@@ -297,6 +297,7 @@ struct CPUState {
     CPUAddressSpace *cpu_ases;
     int num_ases;
     AddressSpace *as;
+    MemoryRegion *memory;
 
     void *env_ptr; /* CPUArchState */
     struct TranslationBlock *current_tb;