Patchwork [RFC] save/load cpu runstate

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Submitter Hu Tao
Date March 15, 2013, 7:05 a.m.
Message ID <1363331116-22117-1-git-send-email-hutao@cn.fujitsu.com>
Download mbox | patch
Permalink /patch/227858/
State New
Headers show

Comments

Hu Tao - March 15, 2013, 7:05 a.m.
This patch make it aviable to save cpu runstate when do savevm,
and restore it when do loadvm, correspondingly. If qemu is started
with -S, then the saved runstate is ignored.

WARNING: this patch breaks backward migration compatibility, Paolo
thinks it's not worth it. But I'm still posting it for other comments.

Signed-off-by: Hu Tao <hutao@cn.fujitsu.com>
---
 include/sysemu/sysemu.h |  2 ++
 migration.c             |  6 +-----
 monitor.c               |  5 ++---
 savevm.c                |  1 +
 vl.c                    | 34 ++++++++++++++++++++++++++++++++++
 5 files changed, 40 insertions(+), 8 deletions(-)
Markus Armbruster - March 15, 2013, 7:39 a.m.
Hu Tao <hutao@cn.fujitsu.com> writes:

> This patch make it aviable to save cpu runstate when do savevm,
> and restore it when do loadvm, correspondingly. If qemu is started
> with -S, then the saved runstate is ignored.

Why is saving runstate useful?

> WARNING: this patch breaks backward migration compatibility, Paolo
> thinks it's not worth it. But I'm still posting it for other comments.

Patch

diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h
index 6578782..e0ec448 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 185d112..1a6ac7d 100644
--- a/migration.c
+++ b/migration.c
@@ -108,11 +108,7 @@  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 1b5acf8..ebe68fe 100644
--- a/monitor.c
+++ b/monitor.c
@@ -2060,13 +2060,12 @@  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 147e2d2..a6cce75 100644
--- a/savevm.c
+++ b/savevm.c
@@ -2175,6 +2175,7 @@  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 a621aec..aac6659 100644
--- a/vl.c
+++ b/vl.c
@@ -549,6 +549,7 @@  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;
@@ -572,6 +573,7 @@  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 },
@@ -582,6 +584,7 @@  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 },
@@ -611,11 +614,39 @@  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;
@@ -625,6 +656,9 @@  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 */