[Qemu-devel] [RFC PATCH v2 32/49] replay: checkpoints

[Pavel Dovgalyuk <Pavel.Dovgaluk@ispras.ru>]

This patch introduces checkpoints that synchronize cpu thread and iothread.
When checkpoint is met in the code all asynchronous events from the queue
are executed.

Signed-off-by: Pavel Dovgalyuk <pavel.dovgaluk@ispras.ru>
---
 block.c                  |   11 +++++++++++
 cpus.c                   |    2 +-
 include/qemu/timer.h     |    6 ++++--
 qemu-timer.c             |   41 +++++++++++++++++++++++++++++++++--------
 replay/replay-internal.h |    3 +++
 replay/replay.c          |   28 ++++++++++++++++++++++++++++
 replay/replay.h          |    6 ++++++
 stubs/replay.c           |   11 +++++++++++
 vl.c                     |    3 ++-
 9 files changed, 99 insertions(+), 12 deletions(-)

diff --git a/block.c b/block.c
index 3ff1052..fb6c849 100644
--- a/block.c
+++ b/block.c
@@ -1914,6 +1914,11 @@ void bdrv_drain_all(void)
     BlockDriverState *bs;
 
     while (busy) {
+        if (!replay_checkpoint(8)) {
+            /* Do not wait anymore, we stopped at some place in 
+               the middle of execution during replay */
+            return;
+        }
         busy = false;
 
         QTAILQ_FOREACH(bs, &bdrv_states, device_list) {
@@ -1930,6 +1935,12 @@ void bdrv_drain_all(void)
             busy |= bs_busy;
         }
     }
+    if (replay_mode == REPLAY_PLAY) {
+        /* Skip checkpoints from the log */
+        while (replay_checkpoint(8)) {
+            /* Nothing */
+        }
+    }
 }
 
 /* make a BlockDriverState anonymous by removing from bdrv_state and
diff --git a/cpus.c b/cpus.c
index 15a2106..4f517ee 100644
--- a/cpus.c
+++ b/cpus.c
@@ -363,7 +363,7 @@ void qtest_clock_warp(int64_t dest)
         qemu_icount_bias += warp;
         seqlock_write_unlock(&timers_state.vm_clock_seqlock);
 
-        qemu_clock_run_timers(QEMU_CLOCK_VIRTUAL);
+        qemu_clock_run_timers(QEMU_CLOCK_VIRTUAL, false);
         clock = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
     }
     qemu_clock_notify(QEMU_CLOCK_VIRTUAL);
diff --git a/include/qemu/timer.h b/include/qemu/timer.h
index 9eaed56..6b00341 100644
--- a/include/qemu/timer.h
+++ b/include/qemu/timer.h
@@ -232,13 +232,14 @@ void qemu_clock_unregister_reset_notifier(QEMUClockType type,
 /**
  * qemu_clock_run_timers:
  * @type: clock on which to operate
+ * @run_all: true, when called from qemu_clock_run_all_timers
  *
  * Run all the timers associated with the default timer list
  * of a clock.
  *
  * Returns: true if any timer ran.
  */
-bool qemu_clock_run_timers(QEMUClockType type);
+bool qemu_clock_run_timers(QEMUClockType type, bool run_all);
 
 /**
  * qemu_clock_run_all_timers:
@@ -329,12 +330,13 @@ QEMUClockType timerlist_get_clock(QEMUTimerList *timer_list);
 /**
  * timerlist_run_timers:
  * @timer_list: the timer list to use
+ * @run_all: true, when called from qemu_clock_run_all_timers
  *
  * Call all expired timers associated with the timer list.
  *
  * Returns: true if any timer expired
  */
-bool timerlist_run_timers(QEMUTimerList *timer_list);
+bool timerlist_run_timers(QEMUTimerList *timer_list, bool run_all);
 
 /**
  * timerlist_notify:
diff --git a/qemu-timer.c b/qemu-timer.c
index 00a5d35..dcf9b14 100644
--- a/qemu-timer.c
+++ b/qemu-timer.c
@@ -457,7 +457,7 @@ bool timer_expired(QEMUTimer *timer_head, int64_t current_time)
     return timer_expired_ns(timer_head, current_time * timer_head->scale);
 }
 
-bool timerlist_run_timers(QEMUTimerList *timer_list)
+bool timerlist_run_timers(QEMUTimerList *timer_list, bool run_all)
 {
     QEMUTimer *ts;
     int64_t current_time;
@@ -465,6 +465,24 @@ bool timerlist_run_timers(QEMUTimerList *timer_list)
     QEMUTimerCB *cb;
     void *opaque;
 
+    switch (timer_list->clock->type) {
+    case QEMU_CLOCK_REALTIME:
+        break;
+    default:
+    case QEMU_CLOCK_VIRTUAL:
+        if ((replay_mode != REPLAY_NONE && !runstate_is_running()) 
+            || !replay_checkpoint(run_all ? 2 : 3)) {
+            return false;
+        }
+        break;
+    case QEMU_CLOCK_HOST:
+        if ((replay_mode != REPLAY_NONE && !runstate_is_running()) 
+            || !replay_checkpoint(run_all ? 5 : 6)) {
+            return false;
+        }
+        break;
+    }
+
     qemu_event_reset(&timer_list->timers_done_ev);
     if (!timer_list->clock->enabled) {
         goto out;
@@ -497,9 +515,9 @@ out:
     return progress;
 }
 
-bool qemu_clock_run_timers(QEMUClockType type)
+bool qemu_clock_run_timers(QEMUClockType type, bool run_all)
 {
-    return timerlist_run_timers(main_loop_tlg.tl[type]);
+    return timerlist_run_timers(main_loop_tlg.tl[type], run_all);
 }
 
 void timerlistgroup_init(QEMUTimerListGroup *tlg,
@@ -524,7 +542,7 @@ bool timerlistgroup_run_timers(QEMUTimerListGroup *tlg)
     QEMUClockType type;
     bool progress = false;
     for (type = 0; type < QEMU_CLOCK_MAX; type++) {
-        progress |= timerlist_run_timers(tlg->tl[type]);
+        progress |= timerlist_run_timers(tlg->tl[type], false);
     }
     return progress;
 }
@@ -533,11 +551,18 @@ int64_t timerlistgroup_deadline_ns(QEMUTimerListGroup *tlg)
 {
     int64_t deadline = -1;
     QEMUClockType type;
+    bool play = replay_mode == REPLAY_PLAY;
     for (type = 0; type < QEMU_CLOCK_MAX; type++) {
         if (qemu_clock_use_for_deadline(tlg->tl[type]->clock->type)) {
-            deadline = qemu_soonest_timeout(deadline,
-                                            timerlist_deadline_ns(
-                                                tlg->tl[type]));
+            if (!play || tlg->tl[type]->clock->type == QEMU_CLOCK_REALTIME) {
+                deadline = qemu_soonest_timeout(deadline,
+                                                timerlist_deadline_ns(
+                                                    tlg->tl[type]));
+            } else {
+                /* Read clock from the replay file and 
+                   do not calculate the deadline, based on virtual clock. */
+                qemu_clock_get_ns(tlg->tl[type]->clock->type);
+            }
         }
     }
     return deadline;
@@ -605,7 +630,7 @@ bool qemu_clock_run_all_timers(void)
     QEMUClockType type;
 
     for (type = 0; type < QEMU_CLOCK_MAX; type++) {
-        progress |= qemu_clock_run_timers(type);
+        progress |= qemu_clock_run_timers(type, true);
     }
 
     return progress;
diff --git a/replay/replay-internal.h b/replay/replay-internal.h
index 033dbdc..95cbde6 100755
--- a/replay/replay-internal.h
+++ b/replay/replay-internal.h
@@ -34,6 +34,9 @@
 #define EVENT_CLOCK                 64
 /* some of grteater codes are reserved for clocks */
 
+/* for checkpoint event */
+#define EVENT_CHECKPOINT            96
+
 /* Asynchronous events IDs */
 
 #define REPLAY_ASYNC_COUNT             0
diff --git a/replay/replay.c b/replay/replay.c
index 2067d6b..225d8ec 100755
--- a/replay/replay.c
+++ b/replay/replay.c
@@ -212,3 +212,31 @@ void replay_shutdown_request(void)
         replay_put_event(EVENT_SHUTDOWN);
     }
 }
+
+/* Used checkpoints: 2 3 5 6 7 8 9 */
+int replay_checkpoint(unsigned int checkpoint)
+{
+    replay_save_instructions();
+
+    if (replay_file) {
+        if (replay_mode == REPLAY_PLAY) {
+            if (!skip_async_events(EVENT_CHECKPOINT + checkpoint)) {
+                if (replay_data_kind == EVENT_ASYNC_OPT) {
+                    replay_read_events(checkpoint);
+                    replay_fetch_data_kind();
+                    return replay_data_kind != EVENT_ASYNC_OPT;
+                }
+                return 0;
+            }
+            replay_has_unread_data = 0;
+            replay_read_events(checkpoint);
+            replay_fetch_data_kind();
+            return replay_data_kind != EVENT_ASYNC_OPT;
+        } else if (replay_mode == REPLAY_SAVE) {
+            replay_put_event(EVENT_CHECKPOINT + checkpoint);
+            replay_save_events(checkpoint);
+        }
+    }
+
+    return 1;
+}
diff --git a/replay/replay.h b/replay/replay.h
index a84c57c..69a20af 100755
--- a/replay/replay.h
+++ b/replay/replay.h
@@ -87,6 +87,12 @@ void replay_read_tm(struct tm *tm);
 
 /*! Called when qemu shutdown is requested. */
 void replay_shutdown_request(void);
+/*! Should be called at check points in the execution.
+    These check points are skipped, if they were not met.
+    Saves checkpoint in the SAVE mode and validates in the PLAY mode.
+    Returns 0 in PLAY mode if checkpoint was not found.
+    Returns 1 in all other cases. */
+int replay_checkpoint(unsigned int checkpoint);
 
 /* Asynchronous events queue */
 
diff --git a/stubs/replay.c b/stubs/replay.c
index 3b88b1a..1b0b78f 100755
--- a/stubs/replay.c
+++ b/stubs/replay.c
@@ -1,4 +1,5 @@
 #include "replay/replay.h"
+#include "sysemu/sysemu.h"
 
 int replay_mode;
 int replay_icount;
@@ -16,3 +17,13 @@ int64_t replay_read_clock(unsigned int kind)
 {
     return 0;
 }
+
+int replay_checkpoint(unsigned int checkpoint)
+{
+    return 0;
+}
+
+int runstate_is_running(void)
+{
+    return 0;
+}
diff --git a/vl.c b/vl.c
index 1a837e6..053b2ba 100644
--- a/vl.c
+++ b/vl.c
@@ -1984,7 +1984,8 @@ static bool main_loop_should_exit(void)
             return true;
         }
     }
-    if (qemu_reset_requested()) {
+    if (qemu_reset_requested_get() && replay_checkpoint(7)) {
+        qemu_reset_requested();
         pause_all_vcpus();
         cpu_synchronize_all_states();
         qemu_system_reset(VMRESET_REPORT);