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 "qemu/error-report.h"
  21 #include "trace.h"
  22
  23 static QEMUBH *failover_bh;
  24 static FailoverStatus failover_state;
  25
  26 static void colo_failover_bh(void *opaque)
  27 {
  28     int old_state;
  29
  30     qemu_bh_delete(failover_bh);
  31     failover_bh = NULL;
  32
  33     old_state = failover_set_state(FAILOVER_STATUS_REQUIRE,
  34                                    FAILOVER_STATUS_ACTIVE);
  35     if (old_state != FAILOVER_STATUS_REQUIRE) {
  36         error_report("Unknown error for failover, old_state = %s",
  37                     FailoverStatus_str(old_state));
  38         return;
  39     }
  40
  41     colo_do_failover();
  42 }
  43
  44 void failover_request_active(Error **errp)
  45 {
  46    if (failover_set_state(FAILOVER_STATUS_NONE,
  47         FAILOVER_STATUS_REQUIRE) != FAILOVER_STATUS_NONE) {
  48         error_setg(errp, "COLO failover is already activated");
  49         return;
  50     }
  51     failover_bh = qemu_bh_new(colo_failover_bh, NULL);
  52     qemu_bh_schedule(failover_bh);
  53 }
  54
  55 void failover_init_state(void)
  56 {
  57     failover_state = FAILOVER_STATUS_NONE;
  58 }
  59
  60 FailoverStatus failover_set_state(FailoverStatus old_state,
  61                     FailoverStatus new_state)
  62 {
  63     FailoverStatus old;
  64
  65     old = qatomic_cmpxchg(&failover_state, old_state, new_state);
  66     if (old == old_state) {
  67         trace_colo_failover_set_state(FailoverStatus_str(new_state));
  68     }
  69     return old;
  70 }
  71
  72 FailoverStatus failover_get_state(void)
  73 {
  74     return qatomic_read(&failover_state);
  75 }
  76
  77 void qmp_x_colo_lost_heartbeat(Error **errp)
  78 {
  79     if (get_colo_mode() == COLO_MODE_NONE) {
  80         error_setg(errp, "VM is not in COLO mode");
  81         return;
  82     }
  83
  84     failover_request_active(errp);
  85 }