Introduce Virtio-loopback epsilon release:

Epsilon release introduces a new compatibility layer which make virtio-loopback
design to work with QEMU and rust-vmm vhost-user backend without require any
changes.

Signed-off-by: Timos Ampelikiotis <t.ampelikiotis@virtualopensystems.com>
Change-Id: I52e57563e08a7d0bdc002f8e928ee61ba0c53dd9

1 files changed, 86 insertions, 0 deletions

diff --git a/migration/colo-failover.c b/migration/colo-failover.c
new file mode 100644
index 000000000..42453481c
--- /dev/null
+++ b/migration/colo-failover.c
@@ -0,0 +1,86 @@
+/*
+ * COarse-grain LOck-stepping Virtual Machines for Non-stop Service (COLO)
+ * (a.k.a. Fault Tolerance or Continuous Replication)
+ *
+ * Copyright (c) 2016 HUAWEI TECHNOLOGIES CO., LTD.
+ * Copyright (c) 2016 FUJITSU LIMITED
+ * Copyright (c) 2016 Intel Corporation
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or
+ * later.  See the COPYING file in the top-level directory.
+ */
+
+#include "qemu/osdep.h"
+#include "migration/colo.h"
+#include "migration/failover.h"
+#include "qemu/main-loop.h"
+#include "migration.h"
+#include "qapi/error.h"
+#include "qapi/qapi-commands-migration.h"
+#include "qapi/qmp/qerror.h"
+#include "qemu/error-report.h"
+#include "trace.h"
+
+static QEMUBH *failover_bh;
+static FailoverStatus failover_state;
+
+static void colo_failover_bh(void *opaque)
+{
+    int old_state;
+
+    qemu_bh_delete(failover_bh);
+    failover_bh = NULL;
+
+    old_state = failover_set_state(FAILOVER_STATUS_REQUIRE,
+                                   FAILOVER_STATUS_ACTIVE);
+    if (old_state != FAILOVER_STATUS_REQUIRE) {
+        error_report("Unknown error for failover, old_state = %s",
+                    FailoverStatus_str(old_state));
+        return;
+    }
+
+    colo_do_failover();
+}
+
+void failover_request_active(Error **errp)
+{
+   if (failover_set_state(FAILOVER_STATUS_NONE,
+        FAILOVER_STATUS_REQUIRE) != FAILOVER_STATUS_NONE) {
+        error_setg(errp, "COLO failover is already activated");
+        return;
+    }
+    failover_bh = qemu_bh_new(colo_failover_bh, NULL);
+    qemu_bh_schedule(failover_bh);
+}
+
+void failover_init_state(void)
+{
+    failover_state = FAILOVER_STATUS_NONE;
+}
+
+FailoverStatus failover_set_state(FailoverStatus old_state,
+                    FailoverStatus new_state)
+{
+    FailoverStatus old;
+
+    old = qatomic_cmpxchg(&failover_state, old_state, new_state);
+    if (old == old_state) {
+        trace_colo_failover_set_state(FailoverStatus_str(new_state));
+    }
+    return old;
+}
+
+FailoverStatus failover_get_state(void)
+{
+    return qatomic_read(&failover_state);
+}
+
+void qmp_x_colo_lost_heartbeat(Error **errp)
+{
+    if (get_colo_mode() == COLO_MODE_NONE) {
+        error_setg(errp, QERR_FEATURE_DISABLED, "colo");
+        return;
+    }
+
+    failover_request_active(errp);
+}