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 "qmp-commands.h"
  17 #include "qapi/qmp/qerror.h"
  18 #include "qemu/error-report.h"
  19 #include "trace.h"
  20
  21 static QEMUBH *failover_bh;
  22 static FailoverStatus failover_state;
  23
  24 static void colo_failover_bh(void *opaque)
  25 {
  26     int old_state;
  27
  28     qemu_bh_delete(failover_bh);
  29     failover_bh = NULL;
  30
  31     old_state = failover_set_state(FAILOVER_STATUS_REQUIRE,
  32                                    FAILOVER_STATUS_ACTIVE);
  33     if (old_state != FAILOVER_STATUS_REQUIRE) {
  34         error_report("Unknown error for failover, old_state = %s",
  35                     FailoverStatus_lookup[old_state]);
  36         return;
  37     }
  38
  39     colo_do_failover(NULL);
  40 }
  41
  42 void failover_request_active(Error **errp)
  43 {
  44    if (failover_set_state(FAILOVER_STATUS_NONE,
  45         FAILOVER_STATUS_REQUIRE) != FAILOVER_STATUS_NONE) {
  46         error_setg(errp, "COLO failover is already actived");
  47         return;
  48     }
  49     failover_bh = qemu_bh_new(colo_failover_bh, NULL);
  50     qemu_bh_schedule(failover_bh);
  51 }
  52
  53 void failover_init_state(void)
  54 {
  55     failover_state = FAILOVER_STATUS_NONE;
  56 }
  57
  58 FailoverStatus failover_set_state(FailoverStatus old_state,
  59                     FailoverStatus new_state)
  60 {
  61     FailoverStatus old;
  62
  63     old = atomic_cmpxchg(&failover_state, old_state, new_state);
  64     if (old == old_state) {
  65         trace_colo_failover_set_state(FailoverStatus_lookup[new_state]);
  66     }
  67     return old;
  68 }
  69
  70 FailoverStatus failover_get_state(void)
  71 {
  72     return atomic_read(&failover_state);
  73 }
  74
  75 void qmp_x_colo_lost_heartbeat(Error **errp)
  76 {
  77     if (get_colo_mode() == COLO_MODE_UNKNOWN) {
  78         error_setg(errp, QERR_FEATURE_DISABLED, "colo");
  79         return;
  80     }
  81
  82     failover_request_active(errp);
  83 }