replay: save/load initial state

This patch implements initial vmstate creation or loading at the start
of record/replay. It is needed for rewinding the execution in the replay mode.

v4 changes:
 - snapshots are not created by default anymore

v3 changes:
 - added rrsnapshot option

Signed-off-by: Pavel Dovgalyuk <pavel.dovgaluk@ispras.ru>
Message-Id: <20170124071746.4572.61449.stgit@PASHA-ISP>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

2 files changed, 22 insertions, 0 deletions

diff --git a/replay/replay-snapshot.c b/replay/replay-snapshot.c
index 498059734d..65e2d375c2 100644
--- a/replay/replay-snapshot.c
+++ b/replay/replay-snapshot.c
@@ -59,3 +59,20 @@ void replay_vmstate_register(void)
 {
     vmstate_register(NULL, 0, &vmstate_replay, &replay_state);
 }
+
+void replay_vmstate_init(void)
+{
+    if (replay_snapshot) {
+        if (replay_mode == REPLAY_MODE_RECORD) {
+            if (save_vmstate(cur_mon, replay_snapshot) != 0) {
+                error_report("Could not create snapshot for icount record");
+                exit(1);
+            }
+        } else if (replay_mode == REPLAY_MODE_PLAY) {
+            if (load_vmstate(replay_snapshot) != 0) {
+                error_report("Could not load snapshot for icount replay");
+                exit(1);
+            }
+        }
+    }
+}
diff --git a/replay/replay.c b/replay/replay.c
index 7f27cf17b0..1835b9902e 100644
--- a/replay/replay.c
+++ b/replay/replay.c
@@ -26,6 +26,7 @@
 #define HEADER_SIZE                 (sizeof(uint32_t) + sizeof(uint64_t))
 
 ReplayMode replay_mode = REPLAY_MODE_NONE;
+char *replay_snapshot;
 
 /* Name of replay file  */
 static char *replay_filename;
@@ -292,6 +293,7 @@ void replay_configure(QemuOpts *opts)
         exit(1);
     }
 
+    replay_snapshot = g_strdup(qemu_opt_get(opts, "rrsnapshot"));
     replay_vmstate_register();
     replay_enable(fname, mode);
 
@@ -346,6 +348,9 @@ void replay_finish(void)
         replay_filename = NULL;
     }
 
+    g_free(replay_snapshot);
+    replay_snapshot = NULL;
+
     replay_finish_events();
     replay_mutex_destroy();
 }