[kvm-unit-tests PATCH v2 1/4] lib: add function to request migration

[Nico Boehr <nrb@linux.ibm.com>]

Migration tests can ask migrate_cmd to migrate them to a new QEMU
process. Requesting migration and waiting for completion is hence a
common pattern which is repeated all over the code base. Add a function
which does all of that to avoid repeating the same pattern.

Since migrate_cmd currently can only migrate exactly once, this function
is called migrate_once() and is a no-op when it has been called before.
This can simplify the control flow, especially when tests are skipped.

Suggested-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Signed-off-by: Nico Boehr <nrb@linux.ibm.com>
---
 lib/migrate.h |  9 +++++++++
 lib/migrate.c | 34 ++++++++++++++++++++++++++++++++++
 2 files changed, 43 insertions(+)
 create mode 100644 lib/migrate.h
 create mode 100644 lib/migrate.c

diff --git a/lib/migrate.h b/lib/migrate.h
new file mode 100644
index 000000000000..3c94e6af761c
--- /dev/null
+++ b/lib/migrate.h
@@ -0,0 +1,9 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Migration-related functions
+ *
+ * Copyright IBM Corp. 2022
+ * Author: Nico Boehr <nrb@linux.ibm.com>
+ */
+
+void migrate_once(void);
diff --git a/lib/migrate.c b/lib/migrate.c
new file mode 100644
index 000000000000..527e63ae189b
--- /dev/null
+++ b/lib/migrate.c
@@ -0,0 +1,34 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Migration-related functions
+ *
+ * Copyright IBM Corp. 2022
+ * Author: Nico Boehr <nrb@linux.ibm.com>
+ */
+#include <libcflat.h>
+#include "migrate.h"
+
+/* static for now since we only support migrating exactly once per test. */
+static void migrate(void)
+{
+	puts("Now migrate the VM, then press a key to continue...\n");
+	(void)getchar();
+	report_info("Migration complete");
+}
+
+/*
+ * Initiate migration and wait for it to complete.
+ * If this function is called more than once, it is a no-op.
+ * Since migrate_cmd can only migrate exactly once this function can
+ * simplify the control flow, especially when skipping tests.
+ */
+void migrate_once(void)
+{
+	static bool migrated;
+
+	if (migrated)
+		return;
+
+	migrated = true;
+	migrate();
+}
-- 
2.36.1