docs: add note about stibp CPU feature for spectre v2

[qemu.git] / replay / replay.c

diff --git a/replay/replay.c b/replay/replay.c
index 90f98b749024b583813d415498812628cbc1a37a..8b172b2d1bee57a0ae533b4fcc856b471655fb9d 100644 (file)
--- a/replay/replay.c
+++ b/replay/replay.c
@@ -176,13 +176,24 @@ void replay_shutdown_request(ShutdownCause cause)
 bool replay_checkpoint(ReplayCheckpoint checkpoint)
 {
     bool res = false;
+    static bool in_checkpoint;
     assert(EVENT_CHECKPOINT + checkpoint <= EVENT_CHECKPOINT_LAST);
-    replay_save_instructions();
 
     if (!replay_file) {
         return true;
     }
 
+    if (in_checkpoint) {
+        /* If we are already in checkpoint, then there is no need
+           for additional synchronization.
+           Recursion occurs when HW event modifies timers.
+           Timer modification may invoke the checkpoint and
+           proceed to recursion. */
+        return true;
+    }
+    in_checkpoint = true;
+
+    replay_save_instructions();
 
     if (replay_mode == REPLAY_MODE_PLAY) {
         g_assert(replay_mutex_locked());
@@ -200,10 +211,35 @@ bool replay_checkpoint(ReplayCheckpoint checkpoint)
     } else if (replay_mode == REPLAY_MODE_RECORD) {
         g_assert(replay_mutex_locked());
         replay_put_event(EVENT_CHECKPOINT + checkpoint);
-        replay_save_events(checkpoint);
+        /* This checkpoint belongs to several threads.
+           Processing events from different threads is
+           non-deterministic */
+        if (checkpoint != CHECKPOINT_CLOCK_WARP_START
+            /* FIXME: this is temporary fix, other checkpoints
+                      may also be invoked from the different threads someday.
+                      Asynchronous event processing should be refactored
+                      to create additional replay event kind which is
+                      nailed to the one of the threads and which processes
+                      the event queue. */
+            && checkpoint != CHECKPOINT_CLOCK_VIRTUAL) {
+            replay_save_events(checkpoint);
+        }
         res = true;
     }
 out:
+    in_checkpoint = false;
+    return res;
+}
+
+bool replay_has_checkpoint(void)
+{
+    bool res = false;
+    if (replay_mode == REPLAY_MODE_PLAY) {
+        g_assert(replay_mutex_locked());
+        replay_account_executed_instructions();
+        res = EVENT_CHECKPOINT <= replay_state.data_kind
+              && replay_state.data_kind <= EVENT_CHECKPOINT_LAST;
+    }
     return res;
 }