replay: fix icount request when replaying clock access

Record/replay provides REPLAY_CLOCK_LOCKED macro to access
the clock when vm_clock_seqlock is locked. This macro is
needed because replay internals operate icount. In locked case
replay use icount_get_raw_locked for icount request, which prevents
excess locking which leads to deadlock. But previously only
record code used *_locked function and replay did not.
Therefore sometimes clock access lead to deadlocks.
This patch fixes clock access for replay too and uses *_locked
icount access function.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
Message-Id: <161347990483.1313189.8371838968343494161.stgit@pasha-ThinkPad-X280>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

include/sysemu/replay.h

@@ -128,18 +128,20 @@ bool replay_has_interrupt(void);
 int64_t replay_save_clock(ReplayClockKind kind, int64_t clock,
                           int64_t raw_icount);
 /*! Read the specified clock from the log or return cached data */
-int64_t replay_read_clock(ReplayClockKind kind);
+int64_t replay_read_clock(ReplayClockKind kind, int64_t raw_icount);
 /*! 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_PLAY                                    \
+        ? replay_read_clock((clock), icount_get_raw())                  \
         : replay_mode == REPLAY_MODE_RECORD                             \
-            ? replay_save_clock((clock), (value), icount_get_raw()) \
-        : (value))
+            ? replay_save_clock((clock), (value), icount_get_raw())     \
+            : (value))
 #define REPLAY_CLOCK_LOCKED(clock, value)                               \
-    (replay_mode == REPLAY_MODE_PLAY ? replay_read_clock((clock))       \
+    (replay_mode == REPLAY_MODE_PLAY                                    \
+        ? replay_read_clock((clock), icount_get_raw_locked())           \
         : replay_mode == REPLAY_MODE_RECORD                             \
             ? replay_save_clock((clock), (value), icount_get_raw_locked()) \
-        : (value))
+            : (value))
 
 /* Processing data from random generators */
 

replay/replay-internal.c

@@ -247,10 +247,31 @@ void replay_advance_current_icount(uint64_t current_icount)
     /* Time can only go forward */
     assert(diff >= 0);
 
-    if (diff > 0) {
-        replay_put_event(EVENT_INSTRUCTION);
-        replay_put_dword(diff);
-        replay_state.current_icount += diff;
+    if (replay_mode == REPLAY_MODE_RECORD) {
+        if (diff > 0) {
+            replay_put_event(EVENT_INSTRUCTION);
+            replay_put_dword(diff);
+            replay_state.current_icount += diff;
+        }
+    } else if (replay_mode == REPLAY_MODE_PLAY) {
+        if (diff > 0) {
+            replay_state.instruction_count -= diff;
+            replay_state.current_icount += diff;
+            if (replay_state.instruction_count == 0) {
+                assert(replay_state.data_kind == EVENT_INSTRUCTION);
+                replay_finish_event();
+                /* Wake up iothread. This is required because
+                    timers will not expire until clock counters
+                    will be read from the log. */
+                qemu_notify_event();
+            }
+        }
+        /* Execution reached the break step */
+        if (replay_break_icount == replay_state.current_icount) {
+            /* Cannot make callback directly from the vCPU thread */
+            timer_mod_ns(replay_break_timer,
+                qemu_clock_get_ns(QEMU_CLOCK_REALTIME));
+        }
     }
 }
 

replay/replay-time.c

@@ -46,12 +46,12 @@ void replay_read_next_clock(ReplayClockKind kind)
 }
 
 /*! Reads next clock event from the input. */
-int64_t replay_read_clock(ReplayClockKind kind)
+int64_t replay_read_clock(ReplayClockKind kind, int64_t raw_icount)
 {
     int64_t ret;
     g_assert(replay_file && replay_mutex_locked());
 
-    replay_account_executed_instructions();
+    replay_advance_current_icount(raw_icount);
 
     if (replay_next_event_is(EVENT_CLOCK + kind)) {
         replay_read_next_clock(kind);

replay/replay.c

@@ -94,28 +94,7 @@ void replay_account_executed_instructions(void)
     if (replay_mode == REPLAY_MODE_PLAY) {
         g_assert(replay_mutex_locked());
         if (replay_state.instruction_count > 0) {
-            int count = (int)(replay_get_current_icount()
-                              - replay_state.current_icount);
-
-            /* Time can only go forward */
-            assert(count >= 0);
-
-            replay_state.instruction_count -= count;
-            replay_state.current_icount += count;
-            if (replay_state.instruction_count == 0) {
-                assert(replay_state.data_kind == EVENT_INSTRUCTION);
-                replay_finish_event();
-                /* Wake up iothread. This is required because
-                   timers will not expire until clock counters
-                   will be read from the log. */
-                qemu_notify_event();
-            }
-            /* Execution reached the break step */
-            if (replay_break_icount == replay_state.current_icount) {
-                /* Cannot make callback directly from the vCPU thread */
-                timer_mod_ns(replay_break_timer,
-                    qemu_clock_get_ns(QEMU_CLOCK_REALTIME));
-            }
+            replay_advance_current_icount(replay_get_current_icount());
         }
     }
 }

stubs/replay-tools.c

@@ -13,7 +13,7 @@ int64_t replay_save_clock(unsigned int kind, int64_t clock, int64_t raw_icount)
     return 0;
 }
 
-int64_t replay_read_clock(unsigned int kind)
+int64_t replay_read_clock(unsigned int kind, int64_t raw_icount)
 {
     abort();
     return 0;