migration/colo-failover.c

   1 /*
   2  * COarse-grain LOck-stepping Virtual Machines for Non-stop Service (COLO)
   3  * (a.k.a. Fault Tolerance or Continuous Replication)
   4  *
   5  * Copyright (c) 2016 HUAWEI TECHNOLOGIES CO., LTD.
   6  * Copyright (c) 2016 FUJITSU LIMITED
   7  * Copyright (c) 2016 Intel Corporation
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2 or
  10  * later.  See the COPYING file in the top-level directory.
  11  */
  12
  13 #include "qemu/osdep.h"
  14 #include "migration/colo.h"
  15 #include "migration/failover.h"
  16 #include "qemu/main-loop.h"
  17 #include "migration.h"
  18 #include "qapi/error.h"
  19 #include "qapi/qapi-commands-migration.h"
  20 #include "qapi/qmp/qerror.h"
  21 #include "qemu/error-report.h"
  22 #include "trace.h"
  23
  24 static QEMUBH *failover_bh;
  25 static FailoverStatus failover_state;
  26
  27 static void colo_failover_bh(void *opaque)
  28 {
  29     int old_state;
  30
  31     qemu_bh_delete(failover_bh);
  32     failover_bh = NULL;
  33
  34     old_state = failover_set_state(FAILOVER_STATUS_REQUIRE,
  35                                    FAILOVER_STATUS_ACTIVE);
  36     if (old_state != FAILOVER_STATUS_REQUIRE) {
  37         error_report("Unknown error for failover, old_state = %s",
  38                     FailoverStatus_str(old_state));
  39         return;
  40     }
  41
  42     colo_do_failover();
  43 }
  44
  45 void failover_request_active(Error **errp)
  46 {
  47    if (failover_set_state(FAILOVER_STATUS_NONE,
  48         FAILOVER_STATUS_REQUIRE) != FAILOVER_STATUS_NONE) {
  49         error_setg(errp, "COLO failover is already activated");
  50         return;
  51     }
  52     failover_bh = qemu_bh_new(colo_failover_bh, NULL);
  53     qemu_bh_schedule(failover_bh);
  54 }
  55
  56 void failover_init_state(void)
  57 {
  58     failover_state = FAILOVER_STATUS_NONE;
  59 }
  60
  61 FailoverStatus failover_set_state(FailoverStatus old_state,
  62                     FailoverStatus new_state)
  63 {
  64     FailoverStatus old;
  65
  66     old = qatomic_cmpxchg(&failover_state, old_state, new_state);
  67     if (old == old_state) {
  68         trace_colo_failover_set_state(FailoverStatus_str(new_state));
  69     }
  70     return old;
  71 }
  72
  73 FailoverStatus failover_get_state(void)
  74 {
  75     return qatomic_read(&failover_state);
  76 }
  77
  78 void qmp_x_colo_lost_heartbeat(Error **errp)
  79 {
  80     if (get_colo_mode() == COLO_MODE_NONE) {
  81         error_setg(errp, QERR_FEATURE_DISABLED, "colo");
  82         return;
  83     }
  84
  85     failover_request_active(errp);
  86 }