From 677a3baba4356b91c7acfb5828dd9a598decda6a Mon Sep 17 00:00:00 2001 From: Pavel Dovgalyuk Date: Fri, 22 May 2020 09:35:27 +0300 Subject: [PATCH] replay: synchronize on every virtual timer callback MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sometimes virtual timer callbacks depend on order of virtual timer processing and warping of virtual clock. Therefore every callback should be logged to make replay deterministic. This patch creates a checkpoint before every virtual timer callback. With these checkpoints virtual timers processing and clock warping events order is completely deterministic. Signed-off-by: Pavel Dovgalyuk Acked-by: Alex Bennée -- v2: - remove mutex lock/unlock for virtual clock checkpoint since it is not process any asynchronous events (commit ca9759c2a92f528f256fef0e3922416f7bb47bf9) - bump record/replay log file version Message-Id: <159012932716.27256.8854065545365559921.stgit@pasha-ThinkPad-X280> Signed-off-by: Paolo Bonzini --- replay/replay.c | 2 +- util/qemu-timer.c | 32 +++++++++----------------------- 2 files changed, 10 insertions(+), 24 deletions(-) diff --git a/replay/replay.c b/replay/replay.c index 7d93746c73..83ed9e0e24 100644 --- a/replay/replay.c +++ b/replay/replay.c @@ -22,7 +22,7 @@ /* Current version of the replay mechanism. Increase it when file format changes. */ -#define REPLAY_VERSION 0xe02009 +#define REPLAY_VERSION 0xe0200a /* Size of replay log header */ #define HEADER_SIZE (sizeof(uint32_t) + sizeof(uint64_t)) diff --git a/util/qemu-timer.c b/util/qemu-timer.c index b6575a2cd5..f62b4feecd 100644 --- a/util/qemu-timer.c +++ b/util/qemu-timer.c @@ -501,7 +501,6 @@ bool timerlist_run_timers(QEMUTimerList *timer_list) bool progress = false; QEMUTimerCB *cb; void *opaque; - bool need_replay_checkpoint = false; if (!atomic_read(&timer_list->active_timers)) { return false; @@ -517,16 +516,6 @@ bool timerlist_run_timers(QEMUTimerList *timer_list) break; default: case QEMU_CLOCK_VIRTUAL: - if (replay_mode != REPLAY_MODE_NONE) { - /* Checkpoint for virtual clock is redundant in cases where - * it's being triggered with only non-EXTERNAL timers, because - * these timers don't change guest state directly. - * Since it has conditional dependence on specific timers, it is - * subject to race conditions and requires special handling. - * See below. - */ - need_replay_checkpoint = true; - } break; case QEMU_CLOCK_HOST: if (!replay_checkpoint(CHECKPOINT_CLOCK_HOST)) { @@ -559,19 +548,16 @@ bool timerlist_run_timers(QEMUTimerList *timer_list) */ break; } - if (need_replay_checkpoint - && !(ts->attributes & QEMU_TIMER_ATTR_EXTERNAL)) { - /* once we got here, checkpoint clock only once */ - need_replay_checkpoint = false; + /* Checkpoint for virtual clock is redundant in cases where + * it's being triggered with only non-EXTERNAL timers, because + * these timers don't change guest state directly. + */ + if (replay_mode != REPLAY_MODE_NONE + && timer_list->clock->type == QEMU_CLOCK_VIRTUAL + && !(ts->attributes & QEMU_TIMER_ATTR_EXTERNAL) + && !replay_checkpoint(CHECKPOINT_CLOCK_VIRTUAL)) { qemu_mutex_unlock(&timer_list->active_timers_lock); - if (!replay_checkpoint(CHECKPOINT_CLOCK_VIRTUAL)) { - goto out; - } - qemu_mutex_lock(&timer_list->active_timers_lock); - /* The lock was released; start over again in case the list was - * modified. - */ - continue; + goto out; } /* remove timer from the list before calling the callback */