[Qemu-devel] [RFC PATCH v10 08/24] cpu: replay instructions sequence

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

This patch adds calls to replay functions into the icount setup block.
In record mode number of executed instructions is written to the log.
In replay mode number of istructions to execute is taken from the replay log.
When replayed instructions counter is expired qemu_notify_event()
function is called to wake up the iothread.

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

Signed-off-by: Pavel Dovgalyuk <pavel.dovgaluk@ispras.ru>
---
 cpus.c          |   38 +++++++++++++++++++++++++-------------
 replay/replay.c |   31 ++++++++++++++++++++++++++++++-
 replay/replay.h |    4 ++++
 3 files changed, 59 insertions(+), 14 deletions(-)

diff --git a/cpus.c b/cpus.c
index 04124ca..511a0c5 100644
--- a/cpus.c
+++ b/cpus.c
@@ -41,6 +41,7 @@
 #include "qemu/seqlock.h"
 #include "qapi-event.h"
 #include "hw/nmi.h"
+#include "replay/replay.h"
 
 #ifndef _WIN32
 #include "qemu/compatfd.h"
@@ -1306,6 +1307,28 @@ int vm_stop_force_state(RunState state)
     }
 }
 
+static int64_t tcg_get_icount_limit(void)
+{
+    int64_t deadline;
+
+    if (replay_mode != REPLAY_MODE_PLAY) {
+        deadline = qemu_clock_deadline_ns_all(QEMU_CLOCK_VIRTUAL);
+
+        /* Maintain prior (possibly buggy) behaviour where if no deadline
+         * was set (as there is no QEMU_CLOCK_VIRTUAL timer) or it is more than
+         * INT32_MAX nanoseconds ahead, we still use INT32_MAX
+         * nanoseconds.
+         */
+        if ((deadline < 0) || (deadline > INT32_MAX)) {
+            deadline = INT32_MAX;
+        }
+
+        return qemu_icount_round(deadline);
+    } else {
+        return replay_get_instructions();
+    }
+}
+
 static int tcg_cpu_exec(CPUArchState *env)
 {
     CPUState *cpu = ENV_GET_CPU(env);
@@ -1319,24 +1342,12 @@ static int tcg_cpu_exec(CPUArchState *env)
 #endif
     if (use_icount) {
         int64_t count;
-        int64_t deadline;
         int decr;
         timers_state.qemu_icount -= (cpu->icount_decr.u16.low
                                     + cpu->icount_extra);
         cpu->icount_decr.u16.low = 0;
         cpu->icount_extra = 0;
-        deadline = qemu_clock_deadline_ns_all(QEMU_CLOCK_VIRTUAL);
-
-        /* Maintain prior (possibly buggy) behaviour where if no deadline
-         * was set (as there is no QEMU_CLOCK_VIRTUAL timer) or it is more than
-         * INT32_MAX nanoseconds ahead, we still use INT32_MAX
-         * nanoseconds.
-         */
-        if ((deadline < 0) || (deadline > INT32_MAX)) {
-            deadline = INT32_MAX;
-        }
-
-        count = qemu_icount_round(deadline);
+        count = tcg_get_icount_limit();
         timers_state.qemu_icount += count;
         decr = (count > 0xffff) ? 0xffff : count;
         count -= decr;
@@ -1354,6 +1365,7 @@ static int tcg_cpu_exec(CPUArchState *env)
                         + cpu->icount_extra);
         cpu->icount_decr.u32 = 0;
         cpu->icount_extra = 0;
+        replay_account_executed_instructions();
     }
     return ret;
 }
diff --git a/replay/replay.c b/replay/replay.c
index 8b0fee5..bf0e27e 100755
--- a/replay/replay.c
+++ b/replay/replay.c
@@ -29,7 +29,6 @@ bool replay_next_event_is(int event)
     }
 
     while (true) {
-        replay_fetch_data_kind();
         if (event == replay_data_kind) {
             res = true;
         }
@@ -49,3 +48,33 @@ uint64_t replay_get_current_step(void)
 {
     return cpu_get_icount_raw();
 }
+
+int replay_get_instructions(void)
+{
+    int res = 0;
+    replay_mutex_lock();
+    if (replay_next_event_is(EVENT_INSTRUCTION)) {
+        res = replay_state.instructions_count;
+    }
+    replay_mutex_unlock();
+    return res;
+}
+
+void replay_account_executed_instructions(void)
+{
+    if (replay_mode == REPLAY_MODE_PLAY
+        && replay_state.instructions_count > 0) {
+        int count = (int)(replay_get_current_step()
+                          - replay_state.current_step);
+        replay_state.instructions_count -= count;
+        replay_state.current_step += count;
+        if (replay_state.instructions_count == 0) {
+            assert(replay_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();
+        }
+    }
+}
diff --git a/replay/replay.h b/replay/replay.h
index a03c748..d19715f 100755
--- a/replay/replay.h
+++ b/replay/replay.h
@@ -22,5 +22,9 @@ extern ReplayMode replay_mode;
 
 /*! Returns number of executed instructions. */
 uint64_t replay_get_current_step(void);
+/*! Returns number of instructions to execute in replay mode. */
+int replay_get_instructions(void);
+/*! Updates instructions counter in replay mode. */
+void replay_account_executed_instructions(void);
 
 #endif