exec: always call qemu_get_ram_ptr within rcu_read_lock

Simplify the code and document the assumption.  The only caller
that is not within rcu_read_lock is memory_region_get_ram_ptr.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 7 insertions, 2 deletions

diff --git a/include/exec/memory.h b/include/exec/memory.h
index 0f07159bb4..9bbd247c38 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -656,8 +656,13 @@ int memory_region_get_fd(MemoryRegion *mr);
  * memory_region_get_ram_ptr: Get a pointer into a RAM memory region.
  *
  * Returns a host pointer to a RAM memory region (created with
- * memory_region_init_ram() or memory_region_init_ram_ptr()).  Use with
- * care.
+ * memory_region_init_ram() or memory_region_init_ram_ptr()).
+ *
+ * Use with care; by the time this function returns, the returned pointer is
+ * not protected by RCU anymore.  If the caller is not within an RCU critical
+ * section and does not hold the iothread lock, it must have other means of
+ * protecting the pointer, such as a reference to the region that includes
+ * the incoming ram_addr_t.
  *
  * @mr: the memory region being queried.
  */