expose_host_mtu: add test case of expose host mtu to guest

Signed-off-by: NXiyue Wang <xiywang@redhat.com>

qemu/tests/cfg/expose_host_mtu.cfg

+- expose_host_mtu: install setup image_copy unattended_install.cdrom
+    no RHEL.6 RHEL.5 RHEL.4 RHEL.3
+    no Windows
+    requires_root = yes
+    type = expose_host_mtu
+    kill_vm = yes
+    only virtio_net
+    start_vm = no
+    mtu_value = 4000
+    nic_extra_params = ",host_mtu=${mtu_value}"
+    nm_stop_cmd = systemctl stop NetworkManager
+    check_guest_mtu_cmd = "ifconfig %s"
+    set_guest_mtu_cmd = "ifconfig %s mtu ${mtu_value}"
+    bridge_get_if_cmd = "bridge link show | awk '{print $2}'"
+    Windows:
+        # TBD, will support later
+        check_guest_mtu_cmd = "netsh interface ipv4 show subinterface "%s""

qemu/tests/expose_host_mtu.py

+import logging
+import re
+
+from avocado.utils import process
+from virttest import error_context
+from virttest import utils_net
+from virttest import utils_test
+from virttest import env_process
+
+
+@error_context.context_aware
+def run(test, params, env):
+    """
+    Expose host MTU to guest test
+
+    1) Boot up guest with param 'host_mtu=4000' in nic part
+    2) Disable NetworkManager in guest
+    3) set mtu of guest tap (eg: tap0) and physical nic (eg: eno1) to
+       4000 in host
+    4) check the mtu in guest
+    5) ping from guest to external host with packet size 3972
+
+    :param test: kvm test object
+    :param params: Dictionary with the test parameters
+    :param env: Dictionary with test environment
+    """
+
+    def get_ovs_ports(ovs):
+        """
+        Get ovs ports
+
+        :param ovs: ovs bridge name
+        """
+
+        cmd = "ovs-vsctl list-ports %s" % ovs
+        return process.system_output(cmd, shell=True).decode()
+
+    def is_ovs_backend(netdst):
+        """
+        Check whether the host is OVS backend
+
+        :param netdst: netdst get from command line
+        """
+
+        return netdst in process.system_output("ovs-vsctl list-br",
+                                               ignore_status=True,
+                                               shell=True).decode()
+
+    def cleanup_ovs_ports(netdst, ports):
+        """
+        Clean up created ovs ports in this case
+
+        :param netdst: netdst get from command line
+        :param ports: existing ports need to be remain before this test
+        """
+
+        if is_ovs_backend(netdst) is True:
+            ports = set(get_ovs_ports(netdst).splitlines()) - \
+                set(ports.splitlines())
+            for p in ports:
+                process.system("ovs-vsctl del-port %s %s" % (netdst, p))
+
+    netdst = params.get("netdst", "switch")
+    if netdst in utils_net.Bridge().list_br():
+        cmd = params["bridge_get_if_cmd"]
+        host_hw_interface = process.system_output(
+                cmd, shell=True).decode().strip(':')
+    elif is_ovs_backend(netdst) is True:
+        host_hw_interface = get_ovs_ports(netdst)
+        tmp_ports = re.findall(r"t[0-9]-[a-zA-Z0-9]{6}", host_hw_interface)
+        if tmp_ports:
+            for p in tmp_ports:
+                process.system_output("ovs-vsctl del-port %s %s" %
+                                      (netdst, p))
+            host_hw_interface = get_ovs_ports(netdst)
+    else:
+        test.cancel("The host is using Macvtap backend, which is not"
+                    " supported by now!")
+
+    params["start_vm"] = "yes"
+    env_process.preprocess_vm(test, params, env, params["main_vm"])
+
+    vm = env.get_vm(params["main_vm"])
+    vm.verify_alive()
+
+    device_mac = vm.virtnet[0].mac
+    vm_iface = vm.get_ifname()
+    # TODO, will support windows later
+    process.system_output(params["nm_stop_cmd"])
+    process.system_output(params["set_guest_mtu_cmd"] % host_hw_interface)
+    process.system_output(params["set_guest_mtu_cmd"] % vm_iface)
+
+    os_type = params.get("os_type", "linux")
+    login_timeout = float(params.get("login_timeout", 360))
+    session = vm.wait_for_login(timeout=login_timeout)
+
+    host_ip = utils_net.get_ip_address_by_interface(params["netdst"])
+    if os_type == "linux":  # TODO, will support windows later
+        session.cmd_output_safe(params["nm_stop_cmd"])
+        guest_ifname = utils_net.get_linux_ifname(session,
+                                                  vm.get_mac_address())
+        output = session.cmd_output_safe(
+                params["check_guest_mtu_cmd"] % guest_ifname)
+        error_context.context(output, logging.info)
+        match_string = "mtu %s" % params["mtu_value"]
+        if match_string in output:
+            logging.info("Host mtu %s exposed to guest as expected!" %
+                         params["mtu_value"])
+            logging.info("Ping from guest to host with packet size 3972")
+            status, output = utils_test.ping(host_ip, 10, packetsize=3972,
+                                             timeout=30, session=session)
+            ratio = utils_test.get_loss_ratio(output)
+            if ratio != 0:
+                test.fail("Loss ratio is %s", ratio)
+        else:
+            test.fail("host mtu %s not exposed to guest" % params["mtu_value"])
+    cleanup_ovs_ports(netdst, host_hw_interface)
+    session.close()