[PATCH V3 10/13] migration: stop vm for cpr

[Steve Sistare <steven.sistare@oracle.com>]

When migration for cpr is initiated, stop the vm and set state
RUN_STATE_FINISH_MIGRATE before ram is saved.  This eliminates the
possibility of ram and device state being out of sync, and guarantees
that a guest in the suspended state remains suspended, because qmp_cont
rejects a cont command in the RUN_STATE_FINISH_MIGRATE state.

Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
---
 include/migration/misc.h |  1 +
 migration/migration.c    | 32 +++++++++++++++++++++++++-------
 2 files changed, 26 insertions(+), 7 deletions(-)

diff --git a/include/migration/misc.h b/include/migration/misc.h
index 6dc234b..54c99a3 100644
--- a/include/migration/misc.h
+++ b/include/migration/misc.h
@@ -60,6 +60,7 @@ void migration_object_init(void);
 void migration_shutdown(void);
 bool migration_is_idle(void);
 bool migration_is_active(MigrationState *);
+bool migrate_mode_is_cpr(MigrationState *);
 
 typedef enum MigrationEventType {
     MIG_EVENT_PRECOPY_SETUP,
diff --git a/migration/migration.c b/migration/migration.c
index d1fce9e..fc5c587 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -1603,6 +1603,11 @@ bool migration_is_active(MigrationState *s)
             s->state == MIGRATION_STATUS_POSTCOPY_ACTIVE);
 }
 
+bool migrate_mode_is_cpr(MigrationState *s)
+{
+    return s->parameters.mode == MIG_MODE_CPR_REBOOT;
+}
+
 int migrate_init(MigrationState *s, Error **errp)
 {
     int ret;
@@ -2651,13 +2656,14 @@ static int migration_completion_precopy(MigrationState *s,
     bql_lock();
     migration_downtime_start(s);
 
-    s->vm_old_state = runstate_get();
-    global_state_store();
-
-    ret = migration_stop_vm(RUN_STATE_FINISH_MIGRATE);
-    trace_migration_completion_vm_stop(ret);
-    if (ret < 0) {
-        goto out_unlock;
+    if (!migrate_mode_is_cpr(s)) {
+        s->vm_old_state = runstate_get();
+        global_state_store();
+        ret = migration_stop_vm(RUN_STATE_FINISH_MIGRATE);
+        trace_migration_completion_vm_stop(ret);
+        if (ret < 0) {
+            goto out_unlock;
+        }
     }
 
     ret = migration_maybe_pause(s, current_active_state,
@@ -3576,6 +3582,7 @@ void migrate_fd_connect(MigrationState *s, Error *error_in)
     Error *local_err = NULL;
     uint64_t rate_limit;
     bool resume = s->state == MIGRATION_STATUS_POSTCOPY_PAUSED;
+    int ret;
 
     /*
      * If there's a previous error, free it and prepare for another one.
@@ -3651,6 +3658,17 @@ void migrate_fd_connect(MigrationState *s, Error *error_in)
         goto fail;
     }
 
+    if (migrate_mode_is_cpr(s)) {
+        s->vm_old_state = runstate_get();
+        global_state_store();
+        ret = migration_stop_vm(RUN_STATE_FINISH_MIGRATE);
+        trace_migration_completion_vm_stop(ret);
+        if (ret < 0) {
+            error_setg(&local_err, "migration_stop_vm failed, error %d", -ret);
+            goto fail;
+        }
+    }
+
     if (migrate_background_snapshot()) {
         qemu_thread_create(&s->thread, "bg_snapshot",
                 bg_migration_thread, s, QEMU_THREAD_JOINABLE);
-- 
1.8.3.1