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>

1 files changed, 44 insertions, 0 deletions

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;
+}