[Qemu-devel] [RFC PATCH v4 24/25] replay: command line options

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

This patch introduces command line options for enabling recording or replaying
virtual machine behavior. "-record" option starts recording of the execution
and saves it into the log, specified with "fname" parameter. "-replay" option
is intended for replaying previously saved log.

Signed-off-by: Pavel Dovgalyuk <pavel.dovgaluk@ispras.ru>
---
 cpus.c          |   15 ++++++++--
 qemu-options.hx |   27 +++++++++++++++++++
 vl.c            |   79 ++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 3 files changed, 116 insertions(+), 5 deletions(-)

diff --git a/cpus.c b/cpus.c
index 6adff2b..de8276b 100644
--- a/cpus.c
+++ b/cpus.c
@@ -933,12 +933,21 @@ static void qemu_wait_io_event_common(CPUState *cpu)
 static void qemu_tcg_wait_io_event(void)
 {
     CPUState *cpu;
+    GMainContext *context = g_main_context_default();
 
-    while (all_cpu_threads_idle()) {
-       /* Start accounting real time to the virtual clock if the CPUs
-          are idle.  */
+    if (replay_mode == REPLAY_MODE_PLAY
+        && all_cpu_threads_idle() && first_cpu->halted) {
+        /* wakeup iothread when there is no code to execute in replay mode */
         qemu_clock_warp(QEMU_CLOCK_VIRTUAL);
+        g_main_context_wakeup(context);
         qemu_cond_wait(tcg_halt_cond, &qemu_global_mutex);
+    } else {
+        while (all_cpu_threads_idle()) {
+            /* Start accounting real time to the virtual clock if the CPUs
+              are idle.  */
+            qemu_clock_warp(QEMU_CLOCK_VIRTUAL);
+            qemu_cond_wait(tcg_halt_cond, &qemu_global_mutex);
+        }
     }
 
     while (iothread_requesting_mutex) {
diff --git a/qemu-options.hx b/qemu-options.hx
index 22cf3b9..44ad8fc 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -3380,6 +3380,33 @@ Dump json-encoded vmstate information for current machine type to file
 in @var{file}
 ETEXI
 
+DEF("record", HAS_ARG, QEMU_OPTION_record,
+    "-record fname=<filename>[,suffix=<suffix>,snapshot=<on/off>]\n"
+    "                writes replay file for latter replaying\n",
+    QEMU_ARCH_ALL)
+STEXI
+@item -record fname=@var{file}[,suffix=@var{suffix},snapshot=@var{snapshot}]
+Writes compact execution trace into @var{file}.
+Changes for disk images are written
+into separate files with @var{suffix} added. If no @var{suffix} is
+specified, "replay_qcow" is used as suffix.
+If @var{snapshot} parameter is set as off, then original disk image will be
+modified. Default value is on.
+ETEXI
+
+DEF("replay", HAS_ARG, QEMU_OPTION_replay,
+    "-replay fname=<filename>[,suffix=<suffix>,snapshot=<on/off>]\n"
+    "                plays saved replay file\n", QEMU_ARCH_ALL)
+STEXI
+@item -replay fname=@var{filename}[,suffix=@var{suffix},snapshot=@var{snapshot}]
+Plays compact execution trace from @var{filename}.
+Changes for disk images and VM states are read
+from separate files with @var{suffix} added. If no @var{suffix} is
+specified, "replay_qcow" is used as suffix.
+If @var{snapshot} parameter is set as off, then original disk image will be
+modified. Default value is on.
+ETEXI
+
 HXCOMM This is the last statement. Insert new options before this line!
 STEXI
 @end table
diff --git a/vl.c b/vl.c
index 877a77c..fb5003e 100644
--- a/vl.c
+++ b/vl.c
@@ -548,6 +548,42 @@ static QemuOptsList qemu_icount_opts = {
     },
 };
 
+static QemuOptsList qemu_record_opts = {
+    .name = "record",
+    .head = QTAILQ_HEAD_INITIALIZER(qemu_record_opts.head),
+    .desc = {
+        {
+            .name = "fname",
+            .type = QEMU_OPT_STRING,
+        },{
+            .name = "suffix",
+            .type = QEMU_OPT_STRING,
+        },{
+            .name = "snapshot",
+            .type = QEMU_OPT_BOOL,
+        },
+        { /* end of list */ }
+    },
+};
+
+static QemuOptsList qemu_replay_opts = {
+    .name = "replay",
+    .head = QTAILQ_HEAD_INITIALIZER(qemu_replay_opts.head),
+    .desc = {
+        {
+            .name = "fname",
+            .type = QEMU_OPT_STRING,
+        },{
+            .name = "suffix",
+            .type = QEMU_OPT_STRING,
+        },{
+            .name = "snapshot",
+            .type = QEMU_OPT_BOOL,
+        },
+        { /* end of list */ }
+    },
+};
+
 /**
  * Get machine options
  *
@@ -2711,7 +2747,9 @@ out:
 int main(int argc, char **argv, char **envp)
 {
     int i;
-    int snapshot, linux_boot;
+    int snapshot, linux_boot, replay_snapshot;
+    int not_compatible_replay_param = 0;
+    const char *icount_option = NULL;
     const char *initrd_filename;
     const char *kernel_filename, *kernel_cmdline;
     const char *boot_order;
@@ -2784,6 +2822,8 @@ int main(int argc, char **argv, char **envp)
     qemu_add_opts(&qemu_name_opts);
     qemu_add_opts(&qemu_numa_opts);
     qemu_add_opts(&qemu_icount_opts);
+    qemu_add_opts(&qemu_replay_opts);
+    qemu_add_opts(&qemu_record_opts);
 
     runstate_init();
 
@@ -2797,6 +2837,7 @@ int main(int argc, char **argv, char **envp)
     cpu_model = NULL;
     ram_size = default_ram_size;
     snapshot = 0;
+    replay_snapshot = 1;
     cyls = heads = secs = 0;
     translation = BIOS_ATA_TRANSLATION_AUTO;
 
@@ -2914,6 +2955,7 @@ int main(int argc, char **argv, char **envp)
                 break;
             case QEMU_OPTION_pflash:
                 drive_add(IF_PFLASH, -1, optarg, PFLASH_OPTS);
+                not_compatible_replay_param++;
                 break;
             case QEMU_OPTION_snapshot:
                 snapshot = 1;
@@ -3070,6 +3112,7 @@ int main(int argc, char **argv, char **envp)
 #endif
             case QEMU_OPTION_bt:
                 add_device_config(DEV_BT, optarg);
+                not_compatible_replay_param++;
                 break;
             case QEMU_OPTION_audio_help:
                 AUD_help ();
@@ -3284,6 +3327,7 @@ int main(int argc, char **argv, char **envp)
                 if (!opts) {
                     exit(1);
                 }
+                not_compatible_replay_param++;
                 break;
             case QEMU_OPTION_fsdev:
                 olist = qemu_find_opts("fsdev");
@@ -3412,6 +3456,7 @@ int main(int argc, char **argv, char **envp)
                 if (strncmp(optarg, "mon:", 4) == 0) {
                     default_monitor = 0;
                 }
+                not_compatible_replay_param++;
                 break;
             case QEMU_OPTION_debugcon:
                 add_device_config(DEV_DEBUGCON, optarg);
@@ -3532,6 +3577,7 @@ int main(int argc, char **argv, char **envp)
                 if (!qemu_opts_parse(qemu_find_opts("smp-opts"), optarg, 1)) {
                     exit(1);
                 }
+                not_compatible_replay_param++;
                 break;
 	    case QEMU_OPTION_vnc:
 #ifdef CONFIG_VNC
@@ -3770,6 +3816,24 @@ int main(int argc, char **argv, char **envp)
                     exit(1);
                 }
                 break;
+            case QEMU_OPTION_record:
+                opts = qemu_opts_parse(qemu_find_opts("record"), optarg, 0);
+                if (!opts) {
+                    fprintf(stderr, "Invalid record options: %s\n", optarg);
+                    exit(1);
+                }
+                replay_configure(opts, REPLAY_MODE_RECORD);
+                replay_snapshot = qemu_opt_get_bool(opts, "snapshot", 1);
+                break;
+            case QEMU_OPTION_replay:
+                opts = qemu_opts_parse(qemu_find_opts("replay"), optarg, 0);
+                if (!opts) {
+                    fprintf(stderr, "Invalid replay options: %s\n", optarg);
+                    exit(1);
+                }
+                replay_configure(opts, REPLAY_MODE_PLAY);
+                replay_snapshot = qemu_opt_get_bool(opts, "snapshot", 1);
+                break;
             default:
                 os_parse_cmd_args(popt->index, optarg);
             }
@@ -3784,6 +3848,12 @@ int main(int argc, char **argv, char **envp)
         exit(1);
     }
 
+    if (not_compatible_replay_param && (replay_mode != REPLAY_MODE_NONE)) {
+        fprintf(stderr, "options -smp, -pflash, -chardev, -bt, -parallel "
+                        "are not compatible with record/replay\n");
+        exit(1);
+    }
+
     if (qemu_opts_foreach(qemu_find_opts("sandbox"), parse_sandbox, NULL, 0)) {
         exit(1);
     }
@@ -4125,6 +4195,11 @@ int main(int argc, char **argv, char **envp)
         qemu_opts_del(icount_opts);
     }
 
+    if (replay_mode != REPLAY_MODE_NONE && !use_icount) {
+        fprintf(stderr, "Please enable icount to use record/replay\n");
+        exit(1);
+    }
+
     /* clean up network at qemu process termination */
     atexit(&net_cleanup);
 
@@ -4161,7 +4236,7 @@ int main(int argc, char **argv, char **envp)
     }
 
     /* open the virtual block devices */
-    if (snapshot)
+    if (snapshot || (replay_mode != REPLAY_MODE_NONE && replay_snapshot))
         qemu_opts_foreach(qemu_find_opts("drive"), drive_enable_snapshot, NULL, 0);
     if (qemu_opts_foreach(qemu_find_opts("drive"), drive_init_func,
                           &machine_class->block_default_type, 1) != 0) {