From: KONRAD Frederic <fred.kon...@greensocs.com>
We don't want to warp on host clock as it is not deterministic for replay.
So this patch warp icount on the next QEMU_VIRTUAL_CLOCK event if reverse
execution is enabled.
The normal behaviour is kept when reverse execution is disabled.
Signed-off-by: KONRAD Frederic <fred.kon...@greensocs.com>
---
cpus.c | 19 +++++++++++++++++--
include/qemu/timer.h | 8 ++++++++
include/reverse-execution.h | 2 ++
main-loop.c | 10 ++++++++++
stubs/Makefile.objs | 1 +
stubs/cpu-get-icount.c | 8 ++++++++
stubs/reverse-execution-stub.c | 32 ++++++++++++++++++++++++++++++++
7 files changed, 78 insertions(+), 2 deletions(-)
create mode 100644 stubs/reverse-execution-stub.c
diff --git a/cpus.c b/cpus.c
index 39f4e98..742fc84 100644
--- a/cpus.c
+++ b/cpus.c
@@ -341,8 +341,10 @@ static int64_t qemu_icount_round(int64_t count)
return (count + (1 << icount_time_shift) - 1) >> icount_time_shift;
}
-static void icount_warp_rt(void *opaque)
+void icount_warp_rt(void *opaque)
{
+ int64_t next_vm_deadline = -1;
+
/* The icount_warp_timer is rescheduled soon after vm_clock_warp_start
* changes from -1 to another value, so the race here is okay.
*/
@@ -350,6 +352,13 @@ static void icount_warp_rt(void *opaque)
return;
}
+ if (rexec_is_enabled()) {
+ /*
+ * We need this because the standard warp_delta is not deterministic.
+ */
+ next_vm_deadline = qemu_clock_deadline_ns_all(QEMU_CLOCK_VIRTUAL);
+ }
+
seqlock_write_lock(&timers_state.vm_clock_seqlock);
if (runstate_is_running()) {
int64_t clock = qemu_clock_get_ns(QEMU_CLOCK_REALTIME);
@@ -366,7 +375,13 @@ static void icount_warp_rt(void *opaque)
int64_t delta = cur_time - cur_icount;
warp_delta = MIN(warp_delta, delta);
}
- timers_state.qemu_icount_bias += warp_delta;
+ if (rexec_is_enabled()) {
+ if (next_vm_deadline > 0) {
+ timers_state.qemu_icount_bias += next_vm_deadline;
+ }
+ } else {
+ timers_state.qemu_icount_bias += warp_delta;
+ }
}
vm_clock_warp_start = -1;
seqlock_write_unlock(&timers_state.vm_clock_seqlock);
diff --git a/include/qemu/timer.h b/include/qemu/timer.h
index 16bafde..74f3d94 100644
--- a/include/qemu/timer.h
+++ b/include/qemu/timer.h
@@ -755,6 +755,14 @@ int64_t cpu_get_clock(void);
int64_t cpu_get_clock_offset(void);
int64_t cpu_icount_to_ns(int64_t icount);
+/**
+ * void icount_warp_rt:
+ *
+ * Move icount to the realtime clock or to the next QEMU_VIRTUAL_CLOCK event
+ * when reverse execution is enabled.
+ */
+void icount_warp_rt(void *opaque);
+
/*******************************************/
/* host CPU ticks (if available) */
diff --git a/include/reverse-execution.h b/include/reverse-execution.h
index 9951549..871d5ee 100644
--- a/include/reverse-execution.h
+++ b/include/reverse-execution.h
@@ -25,6 +25,8 @@
#ifndef REVERSE_EXECUTION
#define REVERSE_EXECUTION
+#include "qom/cpu.h"
+
void rexec_setup(void);
void rexec_step_backward(CPUState *cpu, uint64_t steps);
void rexec_stop_stepping_back_mode(void);
diff --git a/main-loop.c b/main-loop.c
index 3cc79f8..44ae29a 100644
--- a/main-loop.c
+++ b/main-loop.c
@@ -34,6 +34,8 @@
#include "qemu/compatfd.h"
+#include "reverse-execution.h"
+
/* If we have signalfd, we mask out the signals we want to handle and then
* use signalfd to listen for them. We rely on whatever the current signal
* handler is to dispatch the signals when we receive them.
@@ -489,6 +491,14 @@ int main_loop_wait(int nonblocking)
qemu_clock_run_all_timers();
+ /*
+ * Sometimes deadlock can appears because there is no pending event on
+ * virtual clock.
+ */
+ if (rexec_is_enabled()) {
+ icount_warp_rt(NULL);
+ }
+
return ret;
}
diff --git a/stubs/Makefile.objs b/stubs/Makefile.objs
index 5e347d0..aa42bca 100644
--- a/stubs/Makefile.objs
+++ b/stubs/Makefile.objs
@@ -40,3 +40,4 @@ stub-obj-$(CONFIG_WIN32) += fd-register.o
stub-obj-y += cpus.o
stub-obj-y += kvm.o
stub-obj-y += qmp_pc_dimm_device_list.o
+stub-obj-y += reverse-execution-stub.o
diff --git a/stubs/cpu-get-icount.c b/stubs/cpu-get-icount.c
index 1968de7..d35948f 100644
--- a/stubs/cpu-get-icount.c
+++ b/stubs/cpu-get-icount.c
@@ -7,3 +7,11 @@ int64_t cpu_get_icount(int with_bias)
{
abort();
}
+
+void icount_warp_rt(void *opaque)
+{
+ /*
+ * Should not happen, as rexec_is_enabled() always return false.
+ */
+ abort();
+}
diff --git a/stubs/reverse-execution-stub.c b/stubs/reverse-execution-stub.c
new file mode 100644
index 0000000..e417d31
--- /dev/null
+++ b/stubs/reverse-execution-stub.c
@@ -0,0 +1,32 @@
+/*
+ * reverse-execution-stub.c
+ *
+ * Copyright (C) 2014 : GreenSocs Ltd
+ * http://www.greensocs.com/ , email: i...@greensocs.com
+ *
+ * Developed by :
+ * Frederic Konrad <fred.kon...@greensocs.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <stdbool.h>
+
+bool rexec_is_enabled(void);
+
+bool rexec_is_enabled(void)
+{
+ return false;
+}
--
1.9.0
