replay: fix replay of the interrupts

Sometimes interrupt event comes at the same time with
the virtual timers. In this case replay tries to proceed
the timers, because deadline for them is zero.
This patch allows processing interrupts and exceptions
by entering the vCPU execution loop, when deadline is zero,
but checkpoint associated with virtual timers is not ready
to be replayed.

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

Message-Id: <161216312794.2030770.1709657858900983160.stgit@pasha-ThinkPad-X280>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

accel/tcg/tcg-accel-ops-icount.c

@@ -81,7 +81,13 @@ void icount_handle_deadline(void)
     int64_t deadline = qemu_clock_deadline_ns_all(QEMU_CLOCK_VIRTUAL,
                                                   QEMU_TIMER_ATTR_ALL);
 
-    if (deadline == 0) {
+    /*
+     * Instructions, interrupts, and exceptions are processed in cpu-exec.
+     * Don't interrupt cpu thread, when these events are waiting
+     * (i.e., there is no checkpoint)
+     */
+    if (deadline == 0
+        && (replay_mode != REPLAY_MODE_PLAY || replay_has_checkpoint())) {
         icount_notify_aio_contexts();
     }
 }