s390x: smp: Add restart when running test

Let's make sure we can restart a cpu that is already running.
Restarting it if it is stopped is implicitely tested by the the other
restart calls in the smp test.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Message-Id: <20200429143518.1360468-10-frankja@linux.ibm.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
diff --git a/s390x/smp.c b/s390x/smp.c
index f2319c4..ad30e3c 100644
--- a/s390x/smp.c
+++ b/s390x/smp.c
@@ -52,6 +52,34 @@
 	report(1, "start");
 }
 
+/*
+ * Does only test restart when the target is running.
+ * The other tests do restarts when stopped multiple times already.
+ */
+static void test_restart(void)
+{
+	struct cpu *cpu = smp_cpu_from_addr(1);
+	struct lowcore *lc = cpu->lowcore;
+
+	lc->restart_new_psw.mask = extract_psw_mask();
+	lc->restart_new_psw.addr = (unsigned long)test_func;
+
+	/* Make sure cpu is running */
+	smp_cpu_stop(0);
+	set_flag(0);
+	smp_cpu_restart(1);
+	wait_for_flag();
+
+	/*
+	 * Wait until cpu 1 has set the flag because it executed the
+	 * restart function.
+	 */
+	set_flag(0);
+	smp_cpu_restart(1);
+	wait_for_flag();
+	report(1, "restart while running");
+}
+
 static void test_stop(void)
 {
 	smp_cpu_stop(1);
@@ -305,6 +333,7 @@
 	smp_cpu_stop(1);
 
 	test_start();
+	test_restart();
 	test_stop();
 	test_stop_store_status();
 	test_store_status();