hostmem: add property to map memory with MAP_SHARED

A new "share" property can be used with the "memory-file" backend to
map memory with MAP_SHARED instead of MAP_PRIVATE.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Hu Tao <hutao@cn.fujitsu.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
diff --git a/memory.c b/memory.c
index e7f1160..b91a60a 100644
--- a/memory.c
+++ b/memory.c
@@ -1038,6 +1038,7 @@
                                       struct Object *owner,
                                       const char *name,
                                       uint64_t size,
+                                      bool share,
                                       const char *path,
                                       Error **errp)
 {
@@ -1045,7 +1046,7 @@
     mr->ram = true;
     mr->terminates = true;
     mr->destructor = memory_region_destructor_ram;
-    mr->ram_addr = qemu_ram_alloc_from_file(size, mr, path, errp);
+    mr->ram_addr = qemu_ram_alloc_from_file(size, mr, share, path, errp);
 }
 #endif