qemu.tests: cfg for checking clock offset after hotplug vcpu

Signed-off-by: NXu Tian <xutian@redhat.com>

qemu/tests/cfg/cpu_add.cfg

@@ -102,3 +102,27 @@
             vcpu_need_hotplug = 100
             offline = 1-100
             online = 1-100
+        - check_clock:
+            # check guest clock offset before switch vcpus status
+            only Linux
+            requires_root = yes
+            smp = 1
+            repeat_time = 1
+            acceptable_offset = 5
+            vcpu_need_hotplug = 1
+            online = 1
+            offline = 1
+            vcpu_num_rechek = no
+            ntp_server = "clock.redhat.com"
+            pre_command = "ntpdate ${ntp_server}"
+            ntp_sync_cmd = "ntpdate ${ntp_server}"
+            ntp_query_cmd = "ntpdate -q ${ntp_server}"
+            ntp_service_stop_cmd = "service chronyd stop || service ntpdate stop"
+            variants:
+                - after_10mins:
+                    # seconds switch vcpus between online and offline
+                    onoff_iterations = 600
+                - after_20mins:
+                    onoff_iterations = 1200
+                - after_30mins:
+                    onoff_iterations = 1800