memory: late initialization of ram_addr

For non-RAM memory regions, we cannot tell whether this is an I/O region
or an MMIO region.  Since the qemu backing registration is different for
the two, we have to defer initialization until we know which address
space we are in.

These shenanigans will be removed once the backing registration is unified
with the memory API.
Signed-off-by: NAvi Kivity <avi@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

memory.c

@@ -165,10 +165,14 @@ static void flatview_simplify(FlatView *view)
     }
 }
 
+static void memory_region_prepare_ram_addr(MemoryRegion *mr);
+
 static void as_memory_range_add(AddressSpace *as, FlatRange *fr)
 {
     ram_addr_t phys_offset, region_offset;
 
+    memory_region_prepare_ram_addr(fr->mr);
+
     phys_offset = fr->mr->ram_addr;
     region_offset = fr->offset_in_region;
     /* cpu_register_physical_memory_log() wants region_offset for
@@ -519,6 +523,19 @@ static CPUWriteMemoryFunc * const memory_region_write_thunk[] = {
     memory_region_write_thunk_l,
 };
 
+static void memory_region_prepare_ram_addr(MemoryRegion *mr)
+{
+    if (mr->backend_registered) {
+        return;
+    }
+
+    mr->ram_addr = cpu_register_io_memory(memory_region_read_thunk,
+                                          memory_region_write_thunk,
+                                          mr,
+                                          mr->ops->endianness);
+    mr->backend_registered = true;
+}
+
 void memory_region_init_io(MemoryRegion *mr,
                            const MemoryRegionOps *ops,
                            void *opaque,
@@ -529,10 +546,7 @@ void memory_region_init_io(MemoryRegion *mr,
     mr->ops = ops;
     mr->opaque = opaque;
     mr->terminates = true;
-    mr->ram_addr = cpu_register_io_memory(memory_region_read_thunk,
-                                          memory_region_write_thunk,
-                                          mr,
-                                          mr->ops->endianness);
+    mr->backend_registered = false;
 }
 
 void memory_region_init_ram(MemoryRegion *mr,
@@ -543,6 +557,7 @@ void memory_region_init_ram(MemoryRegion *mr,
     memory_region_init(mr, name, size);
     mr->terminates = true;
     mr->ram_addr = qemu_ram_alloc(dev, name, size);
+    mr->backend_registered = true;
 }
 
 void memory_region_init_ram_ptr(MemoryRegion *mr,
@@ -554,6 +569,7 @@ void memory_region_init_ram_ptr(MemoryRegion *mr,
     memory_region_init(mr, name, size);
     mr->terminates = true;
     mr->ram_addr = qemu_ram_alloc_from_ptr(dev, name, size, ptr);
+    mr->backend_registered = true;
 }
 
 void memory_region_init_alias(MemoryRegion *mr,

memory.h

@@ -89,6 +89,7 @@ struct MemoryRegion {
     uint64_t size;
     target_phys_addr_t addr;
     target_phys_addr_t offset;
+    bool backend_registered;
     ram_addr_t ram_addr;
     bool terminates;
     MemoryRegion *alias;