util/qemu-timer: refactor deadline calculation for external timers

icount-based record/replay uses qemu_clock_deadline_ns_all to measure
the period until vCPU may be interrupted.
This function takes in account the virtual timers, because they belong
to the virtual devices that may generate interrupt request or affect
the virtual machine state.
However, there are a subset of virtual timers, that are marked with
'external' flag. These do not change the virtual machine state and
only based on virtual clock. Calculating the deadling using the external
timers breaks the determinism, because they do not belong to the replayed
part of the virtual machine.
This patch fixes the deadline calculation for this case by adding
new parameter for skipping the external timers when it is needed.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgaluk@ispras.ru>
--

v2 changes:
 - added new parameter for timer attribute mask
Message-Id: <156404426682.18669.17014100602930969222.stgit@pasha-Precision-3630-Tower>

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/cpus.c b/cpus.c
index f4ad855b774e9a9e357173e60395a1f2556f432e..85cd451a86a9c38718f5ca85581f1f36dfcd1f29 100644 (file)
--- a/cpus.c
+++ b/cpus.c
@@ -556,7 +556,8 @@ void qtest_clock_warp(int64_t dest)
     assert(qtest_enabled());
     aio_context = qemu_get_aio_context();
     while (clock < dest) {
-        int64_t deadline = qemu_clock_deadline_ns_all(QEMU_CLOCK_VIRTUAL);
+        int64_t deadline = qemu_clock_deadline_ns_all(QEMU_CLOCK_VIRTUAL,
+                                                      QEMU_TIMER_ATTR_ALL);
         int64_t warp = qemu_soonest_timeout(dest - clock, deadline);
 
         seqlock_write_lock(&timers_state.vm_clock_seqlock,
@@ -616,7 +617,8 @@ void qemu_start_warp_timer(void)
 
     /* We want to use the earliest deadline from ALL vm_clocks */
     clock = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL_RT);
-    deadline = qemu_clock_deadline_ns_all(QEMU_CLOCK_VIRTUAL);
+    deadline = qemu_clock_deadline_ns_all(QEMU_CLOCK_VIRTUAL,
+                                          ~QEMU_TIMER_ATTR_EXTERNAL);
     if (deadline < 0) {
         static bool notified;
         if (!icount_sleep && !notified) {
@@ -1352,7 +1354,12 @@ static int64_t tcg_get_icount_limit(void)
     int64_t deadline;
 
     if (replay_mode != REPLAY_MODE_PLAY) {
-        deadline = qemu_clock_deadline_ns_all(QEMU_CLOCK_VIRTUAL);
+        /*
+         * Include all the timers, because they may need an attention.
+         * Too long CPU execution may create unnecessary delay in UI.
+         */
+        deadline = qemu_clock_deadline_ns_all(QEMU_CLOCK_VIRTUAL,
+                                              QEMU_TIMER_ATTR_ALL);
 
         /* Maintain prior (possibly buggy) behaviour where if no deadline
          * was set (as there is no QEMU_CLOCK_VIRTUAL timer) or it is more than
@@ -1373,8 +1380,8 @@ static void handle_icount_deadline(void)
 {
     assert(qemu_in_vcpu_thread());
     if (use_icount) {
-        int64_t deadline =
-            qemu_clock_deadline_ns_all(QEMU_CLOCK_VIRTUAL);
+        int64_t deadline = qemu_clock_deadline_ns_all(QEMU_CLOCK_VIRTUAL,
+                                                      QEMU_TIMER_ATTR_ALL);
 
         if (deadline == 0) {
             /* Wake up other AioContexts.  */

diff --git a/include/qemu/timer.h b/include/qemu/timer.h
index 5bcab935f6cd56d17038e4c8c9672a2842976948..85bc6eb00b218e0042549e9e1ddb42d95715fea3 100644 (file)
--- a/include/qemu/timer.h
+++ b/include/qemu/timer.h
@@ -62,13 +62,15 @@ typedef enum {
  * The following attributes are available:
  *
  * QEMU_TIMER_ATTR_EXTERNAL: drives external subsystem
+ * QEMU_TIMER_ATTR_ALL: mask for all existing attributes
  *
  * Timers with this attribute do not recorded in rr mode, therefore it could be
  * used for the subsystems that operate outside the guest core. Applicable only
  * with virtual clock type.
  */
 
-#define QEMU_TIMER_ATTR_EXTERNAL BIT(0)
+#define QEMU_TIMER_ATTR_EXTERNAL ((int)BIT(0))
+#define QEMU_TIMER_ATTR_ALL      0xffffffff
 
 typedef struct QEMUTimerList QEMUTimerList;
 
@@ -177,6 +179,8 @@ bool qemu_clock_use_for_deadline(QEMUClockType type);
 /**
  * qemu_clock_deadline_ns_all:
  * @type: the clock type
+ * @attr_mask: mask for the timer attributes that are included
+ *             in deadline calculation
  *
  * Calculate the deadline across all timer lists associated
  * with a clock (as opposed to just the default one)
@@ -184,7 +188,7 @@ bool qemu_clock_use_for_deadline(QEMUClockType type);
  *
  * Returns: time until expiry in nanoseconds or -1
  */
-int64_t qemu_clock_deadline_ns_all(QEMUClockType type);
+int64_t qemu_clock_deadline_ns_all(QEMUClockType type, int attr_mask);
 
 /**
  * qemu_clock_get_main_loop_timerlist:

diff --git a/qtest.c b/qtest.c
index 59df1b66148e4288a19ee7c5b9aa892b8094a5cd..d8b4857c743bfa698b0d795dce0de1215a1089cd 100644 (file)
--- a/qtest.c
+++ b/qtest.c
@@ -654,7 +654,8 @@ static void qtest_process_command(CharBackend *chr, gchar **words)
             int ret = qemu_strtoi64(words[1], NULL, 0, &ns);
             g_assert(ret == 0);
         } else {
-            ns = qemu_clock_deadline_ns_all(QEMU_CLOCK_VIRTUAL);
+            ns = qemu_clock_deadline_ns_all(QEMU_CLOCK_VIRTUAL,
+                                            QEMU_TIMER_ATTR_ALL);
         }
         qtest_clock_warp(qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + ns);
         qtest_send_prefix(chr);

diff --git a/tests/ptimer-test-stubs.c b/tests/ptimer-test-stubs.c
index 54b3fd26f61e651e3ee70c5d993b067426e287f6..ed393d9082e4e6177fa5ca528e48fd12833fde0c 100644 (file)
--- a/tests/ptimer-test-stubs.c
+++ b/tests/ptimer-test-stubs.c
@@ -88,9 +88,9 @@ int64_t qemu_clock_get_ns(QEMUClockType type)
     return ptimer_test_time_ns;
 }
 
-int64_t qemu_clock_deadline_ns_all(QEMUClockType type)
+int64_t qemu_clock_deadline_ns_all(QEMUClockType type, int attr_mask)
 {
-    QEMUTimerList *timer_list = main_loop_tlg.tl[type];
+    QEMUTimerList *timer_list = main_loop_tlg.tl[QEMU_CLOCK_VIRTUAL];
     QEMUTimer *t = timer_list->active_timers.next;
     int64_t deadline = -1;
 

diff --git a/tests/ptimer-test.c b/tests/ptimer-test.c
index b30aad0737239f840335b4b973fc0c376b48fe04..5b20e91599e54f7f3f464af710316b7bb3b3ce87 100644 (file)
--- a/tests/ptimer-test.c
+++ b/tests/ptimer-test.c
@@ -50,13 +50,15 @@ static void ptimer_test_set_qemu_time_ns(int64_t ns)
 
 static void qemu_clock_step(uint64_t ns)
 {
-    int64_t deadline = qemu_clock_deadline_ns_all(QEMU_CLOCK_VIRTUAL);
+    int64_t deadline = qemu_clock_deadline_ns_all(QEMU_CLOCK_VIRTUAL,
+                                                  QEMU_TIMER_ATTR_ALL);
     int64_t advanced_time = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + ns;
 
     while (deadline != -1 && deadline <= advanced_time) {
         ptimer_test_set_qemu_time_ns(deadline);
         ptimer_test_expire_qemu_timers(deadline, QEMU_CLOCK_VIRTUAL);
-        deadline = qemu_clock_deadline_ns_all(QEMU_CLOCK_VIRTUAL);
+        deadline = qemu_clock_deadline_ns_all(QEMU_CLOCK_VIRTUAL,
+                                              QEMU_TIMER_ATTR_ALL);
     }
 
     ptimer_test_set_qemu_time_ns(advanced_time);

diff --git a/util/qemu-timer.c b/util/qemu-timer.c
index 37ecfe31e854481965887220c63388eac462c2fd..d428fec5677258b18f0d2d4bb1923a80fac69d94 100644 (file)
--- a/util/qemu-timer.c
+++ b/util/qemu-timer.c
@@ -247,14 +247,38 @@ int64_t timerlist_deadline_ns(QEMUTimerList *timer_list)
  * ignore whether or not the clock should be used in deadline
  * calculations.
  */
-int64_t qemu_clock_deadline_ns_all(QEMUClockType type)
+int64_t qemu_clock_deadline_ns_all(QEMUClockType type, int attr_mask)
 {
     int64_t deadline = -1;
+    int64_t delta;
+    int64_t expire_time;
+    QEMUTimer *ts;
     QEMUTimerList *timer_list;
     QEMUClock *clock = qemu_clock_ptr(type);
+
+    if (!clock->enabled) {
+        return -1;
+    }
+
     QLIST_FOREACH(timer_list, &clock->timerlists, list) {
-        deadline = qemu_soonest_timeout(deadline,
-                                        timerlist_deadline_ns(timer_list));
+        qemu_mutex_lock(&timer_list->active_timers_lock);
+        ts = timer_list->active_timers;
+        /* Skip all external timers */
+        while (ts && (ts->attributes & ~attr_mask)) {
+            ts = ts->next;
+        }
+        if (!ts) {
+            qemu_mutex_unlock(&timer_list->active_timers_lock);
+            continue;
+        }
+        expire_time = ts->expire_time;
+        qemu_mutex_unlock(&timer_list->active_timers_lock);
+
+        delta = expire_time - qemu_clock_get_ns(type);
+        if (delta <= 0) {
+            delta = 0;
+        }
+        deadline = qemu_soonest_timeout(deadline, delta);
     }
     return deadline;
 }