Store MemoryRegion in RAMBlock

As a step in moving live migration from RAMBlocks to MemoryRegions,
store the MemoryRegion in a RAMBlock.
Reviewed-by: NAnthony Liguori <aliguori@us.ibm.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

cpu-all.h

@@ -476,6 +476,7 @@ extern ram_addr_t ram_size;
 #define RAM_PREALLOC_MASK   (1 << 0)
 
 typedef struct RAMBlock {
+    struct MemoryRegion *mr;
     uint8_t *host;
     ram_addr_t offset;
     ram_addr_t length;

exec.c

@@ -2793,6 +2793,7 @@ ram_addr_t qemu_ram_alloc_from_ptr(ram_addr_t size, void *host,
     size = TARGET_PAGE_ALIGN(size);
     new_block = g_malloc0(sizeof(*new_block));
 
+    new_block->mr = mr;
     new_block->offset = find_ram_offset(size);
     if (host) {
         new_block->host = host;