memory: add memory_region_set_size

Add API to change MR size.
Will be used internally for RAM resize.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>

2 files changed, 26 insertions, 0 deletions

diff --git a/include/exec/memory.h b/include/exec/memory.h
index f64ab5e3e5..0882221395 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -878,6 +878,16 @@ void memory_region_set_enabled(MemoryRegion *mr, bool enabled);
 void memory_region_set_address(MemoryRegion *mr, hwaddr addr);
 
 /*
+ * memory_region_set_size: dynamically update the size of a region.
+ *
+ * Dynamically updates the size of a region.
+ *
+ * @mr: the region to be updated
+ * @size: used size of the region.
+ */
+void memory_region_set_size(MemoryRegion *mr, uint64_t size);
+
+/*
  * memory_region_set_alias_offset: dynamically update a memory alias's offset
  *
  * Dynamically updates the offset into the target region that an alias points
diff --git a/memory.c b/memory.c
index 15cf9ebd84..618470bc4f 100644
--- a/memory.c
+++ b/memory.c
@@ -1707,6 +1707,22 @@ void memory_region_set_enabled(MemoryRegion *mr, bool enabled)
     memory_region_transaction_commit();
 }
 
+void memory_region_set_size(MemoryRegion *mr, uint64_t size)
+{
+    Int128 s = int128_make64(size);
+
+    if (size == UINT64_MAX) {
+        s = int128_2_64();
+    }
+    if (int128_eq(s, mr->size)) {
+        return;
+    }
+    memory_region_transaction_begin();
+    mr->size = s;
+    memory_region_update_pending = true;
+    memory_region_transaction_commit();
+}
+
 static void memory_region_readd_subregion(MemoryRegion *mr)
 {
     MemoryRegion *container = mr->container;