memory: Fix incorrect calls of log_global_start/stop

We should only call the log_global_start/stop when the global dirty track
bitmask changes from zero<->non-zero.

No real issue reported for this yet probably because no immediate user to
enable both dirty rate measurement and migration at the same time.  However
it'll be good to be prepared for it.

Fixes: 63b41db4bc ("memory: make global_dirty_tracking a bitmask")
Cc: [email protected]
Cc: Hyman Huang <[email protected]>
Cc: Paolo Bonzini <[email protected]>
Cc: Dr. David Alan Gilbert <[email protected]>
Cc: Juan Quintela <[email protected]>
Cc: David Hildenbrand <[email protected]>
Signed-off-by: Peter Xu <[email protected]>
Reviewed-by: David Hildenbrand <[email protected]>
Message-Id: <20211130080028[email protected]>
Signed-off-by: Philippe Mathieu-Daudé <[email protected]>

diff --git a/softmmu/memory.c b/softmmu/memory.c
index e37a4b8ae39e2ba8a6f8537666f2543ffbc7c09e..678dc62f0697bb253685b2f2d60b7c97ab2483a7 100644 (file)
--- a/softmmu/memory.c
+++ b/softmmu/memory.c
@@ -2794,6 +2794,8 @@ static VMChangeStateEntry *vmstate_change;
 
 void memory_global_dirty_log_start(unsigned int flags)
 {
+    unsigned int old_flags = global_dirty_tracking;
+
     if (vmstate_change) {
         qemu_del_vm_change_state_handler(vmstate_change);
         vmstate_change = NULL;
@@ -2802,15 +2804,14 @@ void memory_global_dirty_log_start(unsigned int flags)
     assert(flags && !(flags & (~GLOBAL_DIRTY_MASK)));
     assert(!(global_dirty_tracking & flags));
     global_dirty_tracking |= flags;
-
     trace_global_dirty_changed(global_dirty_tracking);
 
-    MEMORY_LISTENER_CALL_GLOBAL(log_global_start, Forward);
-
-    /* Refresh DIRTY_MEMORY_MIGRATION bit.  */
-    memory_region_transaction_begin();
-    memory_region_update_pending = true;
-    memory_region_transaction_commit();
+    if (!old_flags) {
+        MEMORY_LISTENER_CALL_GLOBAL(log_global_start, Forward);
+        memory_region_transaction_begin();
+        memory_region_update_pending = true;
+        memory_region_transaction_commit();
+    }
 }
 
 static void memory_global_dirty_log_do_stop(unsigned int flags)
@@ -2821,12 +2822,12 @@ static void memory_global_dirty_log_do_stop(unsigned int flags)
 
     trace_global_dirty_changed(global_dirty_tracking);
 
-    /* Refresh DIRTY_MEMORY_MIGRATION bit.  */
-    memory_region_transaction_begin();
-    memory_region_update_pending = true;
-    memory_region_transaction_commit();
-
-    MEMORY_LISTENER_CALL_GLOBAL(log_global_stop, Reverse);
+    if (!global_dirty_tracking) {
+        memory_region_transaction_begin();
+        memory_region_update_pending = true;
+        memory_region_transaction_commit();
+        MEMORY_LISTENER_CALL_GLOBAL(log_global_stop, Reverse);
+    }
 }
 
 static void memory_vm_change_state_handler(void *opaque, bool running,