[PATCH v13 1/8] save/load cpu runstate

[Hu Tao]

This patch enables preservation of cpu runstate during save/load vm.
So when a vm is restored from snapshot, the cpu runstate is restored,
too.

See following example:

# save two vms: one is running, the other is paused
(qemu) info status
VM status: running
(qemu) savevm running
(qemu) stop
(qemu) info status
VM status: paused
(qemu) savevm paused

# restore the one running
(qemu) info status
VM status: paused
(qemu) loadvm running
(qemu) info status
VM status: running

# restore the one paused
(qemu) loadvm paused
(qemu) info status
VM status: paused
(qemu) cont
(qemu)info status
VM status: running

Signed-off-by: Hu Tao <hutao@xxxxxxxxxxxxxx>
---
 include/sysemu/sysemu.h |  2 ++
 migration.c             |  6 +-----
 monitor.c               |  5 ++---
 savevm.c                |  1 +
 vl.c                    | 34 ++++++++++++++++++++++++++++++++++
 5 files changed, 40 insertions(+), 8 deletions(-)

diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h
index b19ec95..f121213 100644
--- a/include/sysemu/sysemu.h
+++ b/include/sysemu/sysemu.h
@@ -19,6 +19,8 @@ extern uint8_t qemu_uuid[];
 int qemu_uuid_parse(const char *str, uint8_t *uuid);
 #define UUID_FMT "%02hhx%02hhx%02hhx%02hhx-%02hhx%02hhx-%02hhx%02hhx-%02hhx%02hhx-%02hhx%02hhx%02hhx%02hhx%02hhx%02hhx"
 
+void save_run_state(void);
+void load_run_state(void);
 bool runstate_check(RunState state);
 void runstate_set(RunState new_state);
 int runstate_is_running(void);
diff --git a/migration.c b/migration.c
index 11725ae..c29830e 100644
--- a/migration.c
+++ b/migration.c
@@ -107,11 +107,7 @@ static void process_incoming_migration_co(void *opaque)
     /* Make sure all file formats flush their mutable metadata */
     bdrv_invalidate_cache_all();
 
-    if (autostart) {
-        vm_start();
-    } else {
-        runstate_set(RUN_STATE_PAUSED);
-    }
+    load_run_state();
 }
 
 void process_incoming_migration(QEMUFile *f)
diff --git a/monitor.c b/monitor.c
index 32a6e74..bf974b4 100644
--- a/monitor.c
+++ b/monitor.c
@@ -2059,13 +2059,12 @@ void qmp_closefd(const char *fdname, Error **errp)
 
 static void do_loadvm(Monitor *mon, const QDict *qdict)
 {
-    int saved_vm_running  = runstate_is_running();
     const char *name = qdict_get_str(qdict, "name");
 
     vm_stop(RUN_STATE_RESTORE_VM);
 
-    if (load_vmstate(name) == 0 && saved_vm_running) {
-        vm_start();
+    if (load_vmstate(name) == 0) {
+        load_run_state();
     }
 }
 
diff --git a/savevm.c b/savevm.c
index a8a53ef..aa631eb 100644
--- a/savevm.c
+++ b/savevm.c
@@ -2143,6 +2143,7 @@ void do_savevm(Monitor *mon, const QDict *qdict)
     }
 
     saved_vm_running = runstate_is_running();
+    save_run_state();
     vm_stop(RUN_STATE_SAVE_VM);
 
     memset(sn, 0, sizeof(*sn));
diff --git a/vl.c b/vl.c
index febd2ea..7991f2e 100644
--- a/vl.c
+++ b/vl.c
@@ -523,6 +523,7 @@ static int default_driver_check(QemuOpts *opts, void *opaque)
 /* QEMU state */
 
 static RunState current_run_state = RUN_STATE_PRELAUNCH;
+static RunState saved_run_state = RUN_STATE_RUNNING;
 
 typedef struct {
     RunState from;
@@ -546,6 +547,7 @@ static const RunStateTransition runstate_transitions_def[] = {
     { RUN_STATE_PAUSED, RUN_STATE_FINISH_MIGRATE },
 
     { RUN_STATE_POSTMIGRATE, RUN_STATE_RUNNING },
+    { RUN_STATE_POSTMIGRATE, RUN_STATE_PAUSED },
     { RUN_STATE_POSTMIGRATE, RUN_STATE_FINISH_MIGRATE },
 
     { RUN_STATE_PRELAUNCH, RUN_STATE_RUNNING },
@@ -556,6 +558,7 @@ static const RunStateTransition runstate_transitions_def[] = {
     { RUN_STATE_FINISH_MIGRATE, RUN_STATE_POSTMIGRATE },
 
     { RUN_STATE_RESTORE_VM, RUN_STATE_RUNNING },
+    { RUN_STATE_RESTORE_VM, RUN_STATE_PAUSED },
 
     { RUN_STATE_RUNNING, RUN_STATE_DEBUG },
     { RUN_STATE_RUNNING, RUN_STATE_INTERNAL_ERROR },
@@ -585,11 +588,39 @@ static const RunStateTransition runstate_transitions_def[] = {
 
 static bool runstate_valid_transitions[RUN_STATE_MAX][RUN_STATE_MAX];
 
+void save_run_state(void)
+{
+    saved_run_state = current_run_state;
+}
+
+void load_run_state(void)
+{
+    if (saved_run_state == RUN_STATE_RUNNING) {
+        vm_start();
+    } else if (!runstate_check(saved_run_state)) {
+        runstate_set(saved_run_state);
+    } else {
+        ; /* leave unchanged */
+    }
+}
+
 bool runstate_check(RunState state)
 {
     return current_run_state == state;
 }
 
+static void runstate_save(QEMUFile *f, void *opaque)
+{
+    qemu_put_byte(f, saved_run_state);
+}
+
+static int runstate_load(QEMUFile *f, void *opaque, int version_id)
+{
+    saved_run_state = qemu_get_byte(f);
+
+    return 0;
+}
+
 static void runstate_init(void)
 {
     const RunStateTransition *p;
@@ -599,6 +630,9 @@ static void runstate_init(void)
     for (p = &runstate_transitions_def[0]; p->from != RUN_STATE_MAX; p++) {
         runstate_valid_transitions[p->from][p->to] = true;
     }
+
+    register_savevm(NULL, "runstate", 0, 1,
+                    runstate_save, runstate_load, NULL);
 }
 
 /* This function will abort() on invalid state transitions */
-- 
1.8.1.4

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