migration-test: cpr-transfer

Add a migration test for cpr-transfer mode.  Defer the connection to the
target monitor, else the test hangs because in cpr-transfer mode QEMU does
not listen for monitor connections until we send the migrate command to
source QEMU.

To test -incoming defer, send a migrate incoming command to the target,
after sending the migrate command to the source, as required by
cpr-transfer mode.

Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Link: https://lore.kernel.org/r/1736967650-129648-24-git-send-email-steven.sistare@oracle.com
[only allocate in_channels when needed]
Signed-off-by: Fabiano Rosas <farosas@suse.de>

tests/qtest/migration/cpr-tests.c

@@ -44,6 +44,62 @@ static void test_mode_reboot(void)
     test_file_common(&args, true);
 }
 
+static void *test_mode_transfer_start(QTestState *from, QTestState *to)
+{
+    migrate_set_parameter_str(from, "mode", "cpr-transfer");
+    return NULL;
+}
+
+/*
+ * cpr-transfer mode cannot use the target monitor prior to starting the
+ * migration, and cannot connect synchronously to the monitor, so defer
+ * the target connection.
+ */
+static void test_mode_transfer_common(bool incoming_defer)
+{
+    g_autofree char *cpr_path = g_strdup_printf("%s/cpr.sock", tmpfs);
+    g_autofree char *mig_path = g_strdup_printf("%s/migsocket", tmpfs);
+    g_autofree char *uri = g_strdup_printf("unix:%s", mig_path);
+
+    const char *opts = "-machine aux-ram-share=on -nodefaults";
+    g_autofree const char *cpr_channel = g_strdup_printf(
+        "cpr,addr.transport=socket,addr.type=unix,addr.path=%s",
+        cpr_path);
+    g_autofree char *opts_target = g_strdup_printf("-incoming %s %s",
+                                                   cpr_channel, opts);
+
+    g_autofree char *connect_channels = g_strdup_printf(
+        "[ { 'channel-type': 'main',"
+        "    'addr': { 'transport': 'socket',"
+        "              'type': 'unix',"
+        "              'path': '%s' } } ]",
+        mig_path);
+
+    MigrateCommon args = {
+        .start.opts_source = opts,
+        .start.opts_target = opts_target,
+        .start.defer_target_connect = true,
+        .start.memory_backend = "-object memory-backend-memfd,id=pc.ram,size=%s"
+                                " -machine memory-backend=pc.ram",
+        .listen_uri = incoming_defer ? "defer" : uri,
+        .connect_channels = connect_channels,
+        .cpr_channel = cpr_channel,
+        .start_hook = test_mode_transfer_start,
+    };
+
+    test_precopy_common(&args);
+}
+
+static void test_mode_transfer(void)
+{
+    test_mode_transfer_common(NULL);
+}
+
+static void test_mode_transfer_defer(void)
+{
+    test_mode_transfer_common(true);
+}
+
 void migration_test_add_cpr(MigrationTestEnv *env)
 {
     tmpfs = env->tmpfs;
@@ -55,4 +111,10 @@ void migration_test_add_cpr(MigrationTestEnv *env)
     if (getenv("QEMU_TEST_FLAKY_TESTS")) {
         migration_test_add("/migration/mode/reboot", test_mode_reboot);
     }
+
+    if (env->has_kvm) {
+        migration_test_add("/migration/mode/transfer", test_mode_transfer);
+        migration_test_add("/migration/mode/transfer/defer",
+                           test_mode_transfer_defer);
+    }
 }

tests/qtest/migration/framework.c

@@ -420,6 +420,7 @@ void migrate_end(QTestState *from, QTestState *to, bool test_dest)
     qtest_quit(to);
 
     cleanup("migsocket");
+    cleanup("cpr.sock");
     cleanup("src_serial");
     cleanup("dest_serial");
     cleanup(FILE_TEST_FILENAME);
@@ -707,8 +708,11 @@ void test_precopy_common(MigrateCommon *args)
 {
     QTestState *from, *to;
     void *data_hook = NULL;
+    QObject *in_channels = NULL;
     QObject *out_channels = NULL;
 
+    g_assert(!args->cpr_channel || args->connect_channels);
+
     if (migrate_start(&from, &to, args->listen_uri, &args->start)) {
         return;
     }
@@ -740,8 +744,24 @@ void test_precopy_common(MigrateCommon *args)
         }
     }
 
+    /*
+     * The cpr channel must be included in outgoing channels, but not in
+     * migrate-incoming channels.
+     */
     if (args->connect_channels) {
+        if (args->start.defer_target_connect &&
+            !strcmp(args->listen_uri, "defer")) {
+            in_channels = qobject_from_json(args->connect_channels,
+                                            &error_abort);
+        }
         out_channels = qobject_from_json(args->connect_channels, &error_abort);
+
+        if (args->cpr_channel) {
+            QList *channels_list = qobject_to(QList, out_channels);
+            QObject *obj = migrate_str_to_channel(args->cpr_channel);
+
+            qlist_append(channels_list, obj);
+        }
     }
 
     if (args->result == MIG_TEST_QMP_ERROR) {
@@ -754,6 +774,9 @@ void test_precopy_common(MigrateCommon *args)
     if (args->start.defer_target_connect) {
         qtest_connect(to);
         qtest_qmp_handshake(to, NULL);
+        if (!strcmp(args->listen_uri, "defer")) {
+            migrate_incoming_qmp(to, args->connect_uri, in_channels, "{}");
+        }
     }
 
     if (args->result != MIG_TEST_SUCCEED) {

tests/qtest/migration/framework.h

@@ -154,6 +154,9 @@ typedef struct {
      */
     const char *connect_channels;
 
+    /* Optional: the cpr migration channel, in JSON or dotted keys format */
+    const char *cpr_channel;
+
     /* Optional: callback to run at start to set migration parameters */
     TestMigrateStartHook start_hook;
     /* Optional: callback to run at finish to cleanup */