[PATCH v2 2/9] replay: notify vCPU when BH is scheduled

[Pavel Dovgalyuk <pavel.dovgalyuk@ispras.ru>]

vCPU execution should be suspended when new BH is scheduled.
This is needed to avoid guest timeouts caused by the long cycles
of the execution. In replay mode execution may hang when
vCPU sleeps and block event comes to the queue.
This patch adds notification which wakes up vCPU or interrupts
execution of guest code.

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

--

v2: changed first_cpu to current_cpu (suggested by Richard Henderson)
---
 include/sysemu/cpu-timers.h |    1 +
 softmmu/icount.c            |    8 ++++++++
 stubs/icount.c              |    4 ++++
 util/async.c                |    8 ++++++++
 4 files changed, 21 insertions(+)

diff --git a/include/sysemu/cpu-timers.h b/include/sysemu/cpu-timers.h
index ed6ee5c46c..2e786fe7fb 100644
--- a/include/sysemu/cpu-timers.h
+++ b/include/sysemu/cpu-timers.h
@@ -59,6 +59,7 @@ int64_t icount_round(int64_t count);
 /* if the CPUs are idle, start accounting real time to virtual clock. */
 void icount_start_warp_timer(void);
 void icount_account_warp_timer(void);
+void icount_notify_exit(void);
 
 /*
  * CPU Ticks and Clock
diff --git a/softmmu/icount.c b/softmmu/icount.c
index 5ca271620d..1cafec5014 100644
--- a/softmmu/icount.c
+++ b/softmmu/icount.c
@@ -486,3 +486,11 @@ void icount_configure(QemuOpts *opts, Error **errp)
                    qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) +
                    NANOSECONDS_PER_SECOND / 10);
 }
+
+void icount_notify_exit(void)
+{
+    if (icount_enabled() && current_cpu) {
+        qemu_cpu_kick(current_cpu);
+        qemu_clock_notify(QEMU_CLOCK_VIRTUAL);
+    }
+}
diff --git a/stubs/icount.c b/stubs/icount.c
index f13c43568b..6df8c2bf7d 100644
--- a/stubs/icount.c
+++ b/stubs/icount.c
@@ -43,3 +43,7 @@ void icount_account_warp_timer(void)
 {
     abort();
 }
+
+void icount_notify_exit(void)
+{
+}
diff --git a/util/async.c b/util/async.c
index 2ea1172f3e..c376b6c2b4 100644
--- a/util/async.c
+++ b/util/async.c
@@ -33,6 +33,7 @@
 #include "block/raw-aio.h"
 #include "qemu/coroutine_int.h"
 #include "qemu/coroutine-tls.h"
+#include "sysemu/cpu-timers.h"
 #include "trace.h"
 
 /***********************************************************/
@@ -185,6 +186,13 @@ void qemu_bh_schedule_idle(QEMUBH *bh)
 void qemu_bh_schedule(QEMUBH *bh)
 {
     aio_bh_enqueue(bh, BH_SCHEDULED);
+    /*
+     * Workaround for record/replay.
+     * vCPU execution should be suspended when new BH is set.
+     * This is needed to avoid guest timeouts caused
+     * by the long cycles of the execution.
+     */
+    icount_notify_exit();
 }
 
 /* This func is async.