[Qemu-devel] [RFC PATCH v9 06/23] replay: introduce icount event

[Pavel Dovgalyuk <Pavel.Dovgaluk@ispras.ru>]

This patch adds icount event to the replay subsystem. This event corresponds
to execution of several instructions and used to synchronize input events
in the replay phase.

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>

Signed-off-by: Pavel Dovgalyuk <pavel.dovgaluk@ispras.ru>
---
 replay/replay-internal.c |   21 +++++++++++++++++++++
 replay/replay-internal.h |   24 ++++++++++++++++++++++++
 replay/replay.c          |   46 ++++++++++++++++++++++++++++++++++++++++++++++
 replay/replay.h          |    7 +++++++
 4 files changed, 98 insertions(+), 0 deletions(-)

diff --git a/replay/replay-internal.c b/replay/replay-internal.c
index ce7a1d8..21bb42e 100755
--- a/replay/replay-internal.c
+++ b/replay/replay-internal.c
@@ -10,6 +10,7 @@
  */
 
 #include "qemu-common.h"
+#include "replay.h"
 #include "replay-internal.h"
 
 unsigned int replay_data_kind = -1;
@@ -34,6 +35,7 @@ void replay_put_byte(uint8_t byte)
 
 void replay_put_event(uint8_t event)
 {
+    assert(event < EVENT_COUNT);
     replay_put_byte(event);
 }
 
@@ -145,6 +147,10 @@ void replay_fetch_data_kind(void)
             replay_data_kind = replay_get_byte();
             replay_check_error();
             replay_has_unread_data = 1;
+            if (replay_data_kind >= EVENT_COUNT) {
+                error_report("Replay: unknown event kind %d", replay_data_kind);
+                exit(1);
+            }
         }
     }
 }
@@ -168,3 +174,18 @@ void replay_mutex_unlock(void)
 {
     qemu_mutex_unlock(&lock);
 }
+
+/*! Saves cached instructions. */
+void replay_save_instructions(void)
+{
+    if (replay_file && replay_mode == REPLAY_MODE_RECORD) {
+        int diff = (int)(replay_get_current_step() - replay_state.current_step);
+        if (first_cpu != NULL && diff > 0) {
+            replay_mutex_lock();
+            replay_put_event(EVENT_INSTRUCTION);
+            replay_put_dword(diff);
+            replay_state.current_step += diff;
+            replay_mutex_unlock();
+        }
+    }
+}
diff --git a/replay/replay-internal.h b/replay/replay-internal.h
index d92410e..3588448 100755
--- a/replay/replay-internal.h
+++ b/replay/replay-internal.h
@@ -14,6 +14,20 @@
 
 #include <stdio.h>
 
+enum ReplayEvents {
+    /* for instruction event */
+    EVENT_INSTRUCTION,
+    EVENT_COUNT
+};
+
+typedef struct ReplayState {
+    /*! Current step - number of processed instructions and timer events. */
+    uint64_t current_step;
+    /*! Number of instructions to be executed before other events happen. */
+    int instructions_count;
+} ReplayState;
+extern ReplayState replay_state;
+
 extern unsigned int replay_data_kind;
 extern unsigned int replay_has_unread_data;
 
@@ -48,4 +62,14 @@ void replay_check_error(void);
     replay_data_kind variable. */
 void replay_fetch_data_kind(void);
 
+/*! Saves queued events (like instructions and sound). */
+void replay_save_instructions(void);
+
+/*! Skips async events until some sync event will be found. */
+bool skip_async_events(int stop_event);
+/*! Skips async events invocations from the input,
+    until required data kind is found. If the requested data is not found
+    reports an error and stops the execution. */
+void skip_async_events_until(unsigned int kind);
+
 #endif
diff --git a/replay/replay.c b/replay/replay.c
index 5ce066f..a43bbbc 100755
--- a/replay/replay.c
+++ b/replay/replay.c
@@ -9,6 +9,52 @@
  *
  */
 
+#include "qemu-common.h"
 #include "replay.h"
+#include "replay-internal.h"
+#include "qemu/timer.h"
 
 ReplayMode replay_mode = REPLAY_MODE_NONE;
+
+ReplayState replay_state;
+
+bool skip_async_events(int stop_event)
+{
+    bool res = false;
+
+    /* nothing to skip - not all instructions used */
+    if (replay_state.instructions_count != 0
+        && replay_has_unread_data) {
+        return stop_event == EVENT_INSTRUCTION;
+    }
+
+    while (true) {
+        replay_fetch_data_kind();
+        if (stop_event == replay_data_kind) {
+            res = true;
+        }
+        switch (replay_data_kind) {
+        case EVENT_INSTRUCTION:
+            replay_state.instructions_count = replay_get_dword();
+            return res;
+        default:
+            /* clock, time_t, checkpoint and other events */
+            return res;
+        }
+    }
+    return res;
+}
+
+void skip_async_events_until(unsigned int kind)
+{
+    if (!skip_async_events(kind)) {
+        fprintf(stderr, "%"PRId64": Read data kind %d instead of expected %d\n",
+            replay_get_current_step(), replay_data_kind, kind);
+        exit(1);
+    }
+}
+
+uint64_t replay_get_current_step(void)
+{
+    return cpu_get_icount_raw();
+}
diff --git a/replay/replay.h b/replay/replay.h
index d6b73c3..a03c748 100755
--- a/replay/replay.h
+++ b/replay/replay.h
@@ -12,8 +12,15 @@
  *
  */
 
+#include <stdbool.h>
+#include <stdint.h>
 #include "qapi-types.h"
 
 extern ReplayMode replay_mode;
 
+/* Processing the instructions */
+
+/*! Returns number of executed instructions. */
+uint64_t replay_get_current_step(void);
+
 #endif