replay: record and replay random number sources

Record/replay feature of icount allows deterministic running of execution
scenarios. Some CPUs and peripheral devices read random numbers from
external sources making deterministic execution impossible.
This patch adds recording and replaying of random read operations
into guest-random module, which is used by the virtual hardware.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgaluk@ispras.ru>
Message-Id: <157675984852.14505.15709141760677102489.stgit@pasha-Precision-3630-Tower>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

4 files changed, 49 insertions, 2 deletions

diff --git a/replay/Makefile.objs b/replay/Makefile.objs
index cee6539a23..939be964a9 100644
--- a/replay/Makefile.objs
+++ b/replay/Makefile.objs
@@ -6,4 +6,5 @@ common-obj-y += replay-input.o
 common-obj-y += replay-char.o
 common-obj-y += replay-snapshot.o
 common-obj-y += replay-net.o
-common-obj-y += replay-audio.o
\ No newline at end of file
+common-obj-y += replay-audio.o
+common-obj-y += replay-random.o
diff --git a/replay/replay-internal.h b/replay/replay-internal.h
index 55fca1ac6b..33ac551e78 100644
--- a/replay/replay-internal.h
+++ b/replay/replay-internal.h
@@ -34,6 +34,8 @@ enum ReplayEvents {
     EVENT_AUDIO_OUT,
     /* for audio in event */
     EVENT_AUDIO_IN,
+    /* for random number generator */
+    EVENT_RANDOM,
     /* for clock read/writes */
     /* some of greater codes are reserved for clocks */
     EVENT_CLOCK,
diff --git a/replay/replay-random.c b/replay/replay-random.c
new file mode 100644
index 0000000000..afc7a0fccc
--- /dev/null
+++ b/replay/replay-random.c
@@ -0,0 +1,44 @@
+/*
+ * replay-random.c
+ *
+ * Copyright (c) 2010-2020 Institute for System Programming
+ *                         of the Russian Academy of Sciences.
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ *
+ */
+
+#include "qemu/osdep.h"
+#include "qemu/error-report.h"
+#include "sysemu/replay.h"
+#include "replay-internal.h"
+
+void replay_save_random(int ret, void *buf, size_t len)
+{
+    g_assert(replay_mutex_locked());
+
+    replay_save_instructions();
+    replay_put_event(EVENT_RANDOM);
+    replay_put_dword(ret);
+    replay_put_array(buf, len);
+}
+
+int replay_read_random(void *buf, size_t len)
+{
+    int ret = 0;
+    g_assert(replay_mutex_locked());
+
+    replay_account_executed_instructions();
+    if (replay_next_event_is(EVENT_RANDOM)) {
+        size_t buf_size = 0;
+        ret = replay_get_dword();
+        replay_get_array(buf, &buf_size);
+        replay_finish_event();
+        g_assert(buf_size == len);
+    } else {
+        error_report("Missing random event in the replay log");
+        exit(1);
+    }
+    return ret;
+}
diff --git a/replay/replay.c b/replay/replay.c
index 5cc25bd2f8..706c7b4f4b 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              0xe02008
+#define REPLAY_VERSION              0xe02009
 /* Size of replay log header */
 #define HEADER_SIZE                 (sizeof(uint32_t) + sizeof(uint64_t))