migration: Switch to COLO process after finishing loadvm

Switch from normal migration loadvm process into COLO checkpoint process if
COLO mode is enabled.

We add three new members to struct MigrationIncomingState,
'have_colo_incoming_thread' and 'colo_incoming_thread' record the COLO
related thread for secondary VM, 'migration_incoming_co' records the
original migration incoming coroutine.
Signed-off-by: Nzhanghailiang <zhang.zhanghailiang@huawei.com>
Signed-off-by: NLi Zhijian <lizhijian@cn.fujitsu.com>
Reviewed-by: NDr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: NAmit Shah <amit.shah@redhat.com>
Signed-off-by: NAmit Shah <amit@amitshah.net>

include/migration/colo.h

@@ -15,6 +15,8 @@
 
 #include "qemu-common.h"
 #include "migration/migration.h"
+#include "qemu/coroutine_int.h"
+#include "qemu/thread.h"
 
 bool colo_supported(void);
 void colo_info_init(void);
@@ -22,4 +24,9 @@ void colo_info_init(void);
 void migrate_start_colo_process(MigrationState *s);
 bool migration_in_colo_state(void);
 
+/* loadvm */
+bool migration_incoming_enable_colo(void);
+void migration_incoming_exit_colo(void);
+void *colo_process_incoming_thread(void *opaque);
+bool migration_incoming_in_colo_state(void);
 #endif

include/migration/migration.h

@@ -21,6 +21,7 @@
 #include "migration/vmstate.h"
 #include "qapi-types.h"
 #include "exec/cpu-common.h"
+#include "qemu/coroutine_int.h"
 
 #define QEMU_VM_FILE_MAGIC           0x5145564d
 #define QEMU_VM_FILE_VERSION_COMPAT  0x00000002
@@ -107,6 +108,12 @@ struct MigrationIncomingState {
     QEMUBH *bh;
 
     int state;
+
+    bool have_colo_incoming_thread;
+    QemuThread colo_incoming_thread;
+    /* The coroutine we should enter (back) after failover */
+    Coroutine *migration_incoming_co;
+
     /* See savevm.c */
     LoadStateEntry_Head loadvm_handlers;
 };

migration/colo-comm.c

@@ -49,3 +49,13 @@ void colo_info_init(void)
 {
     vmstate_register(NULL, 0, &colo_state, &colo_info);
 }
+
+bool migration_incoming_enable_colo(void)
+{
+    return colo_info.colo_requested;
+}
+
+void migration_incoming_exit_colo(void)
+{
+    colo_info.colo_requested = false;
+}

migration/colo.c

@@ -27,6 +27,13 @@ bool migration_in_colo_state(void)
     return (s->state == MIGRATION_STATUS_COLO);
 }
 
+bool migration_incoming_in_colo_state(void)
+{
+    MigrationIncomingState *mis = migration_incoming_get_current();
+
+    return mis && (mis->state == MIGRATION_STATUS_COLO);
+}
+
 static void colo_process_checkpoint(MigrationState *s)
 {
     qemu_mutex_lock_iothread();
@@ -46,3 +53,17 @@ void migrate_start_colo_process(MigrationState *s)
     colo_process_checkpoint(s);
     qemu_mutex_lock_iothread();
 }
+
+void *colo_process_incoming_thread(void *opaque)
+{
+    MigrationIncomingState *mis = opaque;
+
+    migrate_set_state(&mis->state, MIGRATION_STATUS_ACTIVE,
+                      MIGRATION_STATUS_COLO);
+
+    /* TODO: COLO checkpoint restore loop */
+
+    migration_incoming_exit_colo();
+
+    return NULL;
+}

migration/migration.c

@@ -407,6 +407,18 @@ static void process_incoming_migration_co(void *opaque)
         /* Else if something went wrong then just fall out of the normal exit */
     }
 
+    /* we get COLO info, and know if we are in COLO mode */
+    if (!ret && migration_incoming_enable_colo()) {
+        mis->migration_incoming_co = qemu_coroutine_self();
+        qemu_thread_create(&mis->colo_incoming_thread, "COLO incoming",
+             colo_process_incoming_thread, mis, QEMU_THREAD_JOINABLE);
+        mis->have_colo_incoming_thread = true;
+        qemu_coroutine_yield();
+
+        /* Wait checkpoint incoming thread exit before free resource */
+        qemu_thread_join(&mis->colo_incoming_thread);
+    }
+
     qemu_fclose(f);
     free_xbzrle_decoded_buf();
 

stubs/migration-colo.c

@@ -23,6 +23,16 @@ bool migration_in_colo_state(void)
     return false;
 }
 
+bool migration_incoming_in_colo_state(void)
+{
+    return false;
+}
+
 void migrate_start_colo_process(MigrationState *s)
 {
 }
+
+void *colo_process_incoming_thread(void *opaque)
+{
+    return NULL;
+}