replay: recording and replaying clock ticks

Clock ticks are considered as the sources of non-deterministic data for
virtual machine. This patch implements saving the clock values when they
are acquired (virtual, host clock).
When replaying the execution corresponding values are read from log and
transfered to the module, which wants to read the values.
Such a design required the clock polling to be synchronized. Sometimes
it is not true - e.g. when timeouts for timer lists are checked. In this case
we use a cached value of the clock, passing it to the client code.

Signed-off-by: Pavel Dovgalyuk <pavel.dovgaluk@ispras.ru>
Message-Id: <20150917162427.8676.36558.stgit@PASHA-ISP.def.inno>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgaluk@ispras.ru>

1 files changed, 23 insertions, 0 deletions

diff --git a/include/sysemu/replay.h b/include/sysemu/replay.h
index c2a7651d7a..2398509188 100644
--- a/include/sysemu/replay.h
+++ b/include/sysemu/replay.h
@@ -16,6 +16,16 @@
 #include <stdint.h>
 #include "qapi-types.h"
 
+/* replay clock kinds */
+enum ReplayClockKind {
+    /* host_clock */
+    REPLAY_CLOCK_HOST,
+    /* virtual_rt_clock */
+    REPLAY_CLOCK_VIRTUAL_RT,
+    REPLAY_CLOCK_COUNT
+};
+typedef enum ReplayClockKind ReplayClockKind;
+
 extern ReplayMode replay_mode;
 
 /* Processing the instructions */
@@ -43,6 +53,19 @@ bool replay_interrupt(void);
     Returns true, when interrupt request is pending */
 bool replay_has_interrupt(void);
 
+/* Processing clocks and other time sources */
+
+/*! Save the specified clock */
+int64_t replay_save_clock(ReplayClockKind kind, int64_t clock);
+/*! Read the specified clock from the log or return cached data */
+int64_t replay_read_clock(ReplayClockKind kind);
+/*! Saves or reads the clock depending on the current replay mode. */
+#define REPLAY_CLOCK(clock, value)                                      \
+    (replay_mode == REPLAY_MODE_PLAY ? replay_read_clock((clock))       \
+        : replay_mode == REPLAY_MODE_RECORD                             \
+            ? replay_save_clock((clock), (value))                       \
+        : (value))
+
 /* Asynchronous events queue */
 
 /*! Disables storing events in the queue */