migration: let MigrationState be a qdev

Let the old man "MigrationState" join the object family. Direct benefit
is that we can start to use all the property features derived from
current QDev, like: HW_COMPAT_* bits, command line setup for migration
parameters (so will never need to set them up each time using HMP/QMP,
this is really, really attractive for test writters), etc.

I see no reason to disallow this happen yet. So let's start from this
one, to see whether it would be anything good.

Now we init the MigrationState struct statically in main() to make sure
it's initialized after global properties are applied, since we'll use
them during creation of the object.

No functional change at all.

Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <1498536619-14548-5-git-send-email-peterx@redhat.com>
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>

include/migration/misc.h

@@ -45,6 +45,7 @@ void savevm_skip_section_footers(void);
 void savevm_skip_configuration(void);
 
 /* migration/migration.c */
+void migration_object_init(void);
 void qemu_start_incoming_migration(const char *uri, Error **errp);
 bool migration_is_idle(void);
 void add_migration_state_change_notifier(Notifier *notify);

migration/migration.c

@@ -98,32 +98,21 @@ enum mig_rp_message_type {
    migrations at once.  For now we don't need to add
    dynamic creation of migration */
 
+static MigrationState *current_migration;
+
+void migration_object_init(void)
+{
+    /* This can only be called once. */
+    assert(!current_migration);
+    current_migration = MIGRATION_OBJ(object_new(TYPE_MIGRATION));
+}
+
 /* For outgoing */
 MigrationState *migrate_get_current(void)
 {
-    static bool once;
-    static MigrationState current_migration = {
-        .state = MIGRATION_STATUS_NONE,
-        .xbzrle_cache_size = DEFAULT_MIGRATE_CACHE_SIZE,
-        .mbps = -1,
-        .parameters = {
-            .compress_level = DEFAULT_MIGRATE_COMPRESS_LEVEL,
-            .compress_threads = DEFAULT_MIGRATE_COMPRESS_THREAD_COUNT,
-            .decompress_threads = DEFAULT_MIGRATE_DECOMPRESS_THREAD_COUNT,
-            .cpu_throttle_initial = DEFAULT_MIGRATE_CPU_THROTTLE_INITIAL,
-            .cpu_throttle_increment = DEFAULT_MIGRATE_CPU_THROTTLE_INCREMENT,
-            .max_bandwidth = MAX_THROTTLE,
-            .downtime_limit = DEFAULT_MIGRATE_SET_DOWNTIME,
-            .x_checkpoint_delay = DEFAULT_MIGRATE_X_CHECKPOINT_DELAY,
-        },
-    };
-
-    if (!once) {
-        current_migration.parameters.tls_creds = g_strdup("");
-        current_migration.parameters.tls_hostname = g_strdup("");
-        once = true;
-    }
-    return &current_migration;
+    /* This can only be called after the object created. */
+    assert(current_migration);
+    return current_migration;
 }
 
 MigrationIncomingState *migration_incoming_get_current(void)
@@ -1987,3 +1976,46 @@ void migrate_fd_connect(MigrationState *s)
     s->migration_thread_running = true;
 }
 
+static void migration_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+
+    dc->user_creatable = false;
+}
+
+static void migration_instance_init(Object *obj)
+{
+    MigrationState *ms = MIGRATION_OBJ(obj);
+
+    ms->state = MIGRATION_STATUS_NONE;
+    ms->xbzrle_cache_size = DEFAULT_MIGRATE_CACHE_SIZE;
+    ms->mbps = -1;
+    ms->parameters = (MigrationParameters) {
+        .compress_level = DEFAULT_MIGRATE_COMPRESS_LEVEL,
+        .compress_threads = DEFAULT_MIGRATE_COMPRESS_THREAD_COUNT,
+        .decompress_threads = DEFAULT_MIGRATE_DECOMPRESS_THREAD_COUNT,
+        .cpu_throttle_initial = DEFAULT_MIGRATE_CPU_THROTTLE_INITIAL,
+        .cpu_throttle_increment = DEFAULT_MIGRATE_CPU_THROTTLE_INCREMENT,
+        .max_bandwidth = MAX_THROTTLE,
+        .downtime_limit = DEFAULT_MIGRATE_SET_DOWNTIME,
+        .x_checkpoint_delay = DEFAULT_MIGRATE_X_CHECKPOINT_DELAY,
+    };
+    ms->parameters.tls_creds = g_strdup("");
+    ms->parameters.tls_hostname = g_strdup("");
+}
+
+static const TypeInfo migration_type = {
+    .name = TYPE_MIGRATION,
+    .parent = TYPE_DEVICE,
+    .class_init = migration_class_init,
+    .class_size = sizeof(MigrationClass),
+    .instance_size = sizeof(MigrationState),
+    .instance_init = migration_instance_init,
+};
+
+static void register_migration_types(void)
+{
+    type_register_static(&migration_type);
+}
+
+type_init(register_migration_types);

migration/migration.h

@@ -19,6 +19,7 @@
 #include "qapi-types.h"
 #include "exec/cpu-common.h"
 #include "qemu/coroutine_int.h"
+#include "hw/qdev.h"
 
 /* State for the incoming migration */
 struct MigrationIncomingState {
@@ -62,8 +63,26 @@ struct MigrationIncomingState {
 MigrationIncomingState *migration_incoming_get_current(void);
 void migration_incoming_state_destroy(void);
 
+#define TYPE_MIGRATION "migration"
+
+#define MIGRATION_CLASS(klass) \
+    OBJECT_CLASS_CHECK(MigrationClass, (klass), TYPE_MIGRATION)
+#define MIGRATION_OBJ(obj) \
+    OBJECT_CHECK(MigrationState, (obj), TYPE_MIGRATION)
+#define MIGRATION_GET_CLASS(obj) \
+    OBJECT_GET_CLASS(MigrationClass, (obj), TYPE_MIGRATION)
+
+typedef struct MigrationClass {
+    /*< private >*/
+    DeviceClass parent_class;
+} MigrationClass;
+
 struct MigrationState
 {
+    /*< private >*/
+    DeviceState parent_obj;
+
+    /*< public >*/
     size_t bytes_xfer;
     size_t xfer_limit;
     QemuThread thread;

vl.c

@@ -4596,6 +4596,12 @@ int main(int argc, char **argv, char **envp)
      */
     register_global_properties(current_machine);
 
+    /*
+     * Migration object can only be created after global properties
+     * are applied correctly.
+     */
+    migration_object_init();
+
     /* This checkpoint is required by replay to separate prior clock
        reading from the other reads, because timer polling functions query
        clock values from the log. */