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, 62 insertions, 0 deletions

diff --git a/migration/yank_functions.c b/migration/yank_functions.c
new file mode 100644
index 000000000..8c08aef14
--- /dev/null
+++ b/migration/yank_functions.c
@@ -0,0 +1,62 @@
+/*
+ * migration yank functions
+ *
+ * Copyright (c) Lukas Straub <lukasstraub2@web.de>
+ *
+ * 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 "qapi/error.h"
+#include "io/channel.h"
+#include "yank_functions.h"
+#include "qemu/yank.h"
+#include "io/channel-socket.h"
+#include "io/channel-tls.h"
+#include "qemu-file.h"
+
+void migration_yank_iochannel(void *opaque)
+{
+    QIOChannel *ioc = QIO_CHANNEL(opaque);
+
+    qio_channel_shutdown(ioc, QIO_CHANNEL_SHUTDOWN_BOTH, NULL);
+}
+
+/* Return whether yank is supported on this ioc */
+static bool migration_ioc_yank_supported(QIOChannel *ioc)
+{
+    return object_dynamic_cast(OBJECT(ioc), TYPE_QIO_CHANNEL_SOCKET) ||
+        object_dynamic_cast(OBJECT(ioc), TYPE_QIO_CHANNEL_TLS);
+}
+
+void migration_ioc_register_yank(QIOChannel *ioc)
+{
+    if (migration_ioc_yank_supported(ioc)) {
+        yank_register_function(MIGRATION_YANK_INSTANCE,
+                               migration_yank_iochannel,
+                               QIO_CHANNEL(ioc));
+    }
+}
+
+void migration_ioc_unregister_yank(QIOChannel *ioc)
+{
+    if (migration_ioc_yank_supported(ioc)) {
+        yank_unregister_function(MIGRATION_YANK_INSTANCE,
+                                 migration_yank_iochannel,
+                                 QIO_CHANNEL(ioc));
+    }
+}
+
+void migration_ioc_unregister_yank_from_file(QEMUFile *file)
+{
+    QIOChannel *ioc = qemu_file_get_ioc(file);
+
+    if (ioc) {
+        /*
+         * For migration qemufiles, we'll always reach here.  Though we'll skip
+         * calls from e.g. savevm/loadvm as they don't use yank.
+         */
+        migration_ioc_unregister_yank(ioc);
+    }
+}