Add test for a new backend-transfer migration of virtio-net/tap, with fd
passing through unix socket.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
---
tests/functional/x86_64/meson.build | 1 +
tests/functional/x86_64/test_tap_migration.py | 398 ++++++++++++++++++
2 files changed, 399 insertions(+)
create mode 100644 tests/functional/x86_64/test_tap_migration.py
diff --git a/tests/functional/x86_64/meson.build b/tests/functional/x86_64/meson.build
index f78eec5e6c..d23b0cc727 100644
--- a/tests/functional/x86_64/meson.build
+++ b/tests/functional/x86_64/meson.build
@@ -36,4 +36,5 @@ tests_x86_64_system_thorough = [
'vfio_user_client',
'virtio_balloon',
'virtio_gpu',
+ 'tap_migration',
]
diff --git a/tests/functional/x86_64/test_tap_migration.py b/tests/functional/x86_64/test_tap_migration.py
new file mode 100644
index 0000000000..fd9f706fc3
--- /dev/null
+++ b/tests/functional/x86_64/test_tap_migration.py
@@ -0,0 +1,398 @@
+#!/usr/bin/env python3
+#
+# Functional test that tests TAP local migration
+# with fd passing
+#
+# Copyright (c) Yandex Technologies LLC, 2025
+#
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+import os
+import time
+import subprocess
+from subprocess import run
+import signal
+from typing import Tuple
+
+from qemu_test import (
+ LinuxKernelTest,
+ Asset,
+ exec_command_and_wait_for_pattern,
+)
+from qemu_test.decorators import skipWithoutSudo
+
+GUEST_IP = "10.0.1.2"
+GUEST_IP_MASK = f"{GUEST_IP}/24"
+GUEST_MAC = "d6:0d:75:f8:0f:b7"
+HOST_IP = "10.0.1.1"
+HOST_IP_MASK = f"{HOST_IP}/24"
+TAP_ID = "tap0"
+TAP_ID2 = "tap1"
+TAP_MAC = "e6:1d:44:b5:03:5d"
+
+
+def ip(args, check=True) -> None:
+ """Run ip command with sudo"""
+ run(["sudo", "ip"] + args, check=check)
+
+
+def del_tap(tap_name: str = TAP_ID) -> None:
+ ip(["tuntap", "del", tap_name, "mode", "tap", "multi_queue"], check=False)
+
+
+def init_tap(tap_name: str = TAP_ID, with_ip: bool = True) -> None:
+ ip(["tuntap", "add", "dev", tap_name, "mode", "tap", "multi_queue"])
+ if with_ip:
+ ip(["link", "set", "dev", tap_name, "address", TAP_MAC])
+ ip(["addr", "add", HOST_IP_MASK, "dev", tap_name])
+ ip(["link", "set", tap_name, "up"])
+
+
+def switch_network_to_tap2() -> None:
+ ip(["link", "set", TAP_ID2, "down"])
+ ip(["link", "set", TAP_ID, "down"])
+ ip(["addr", "delete", HOST_IP_MASK, "dev", TAP_ID])
+ ip(["link", "set", "dev", TAP_ID2, "address", TAP_MAC])
+ ip(["addr", "add", HOST_IP_MASK, "dev", TAP_ID2])
+ ip(["link", "set", TAP_ID2, "up"])
+
+
+def parse_ping_line(line: str) -> float:
+ # suspect lines like
+ # [1748524876.590509] 64 bytes from 94.245.155.3 \
+ # (94.245.155.3): icmp_seq=1 ttl=250 time=101 ms
+ spl = line.split()
+ return float(spl[0][1:-1])
+
+
+def parse_ping_output(out) -> Tuple[bool, float, float]:
+ lines = [x for x in out.split("\n") if x.startswith("[")]
+
+ try:
+ first_no_ans = next(
+ (ind for ind in range(len(lines)) if lines[ind][20:26] == "no ans")
+ )
+ except StopIteration:
+ return False, parse_ping_line(lines[0]), parse_ping_line(lines[-1])
+
+ last_no_ans = next(
+ ind
+ for ind in range(len(lines) - 1, -1, -1)
+ if lines[ind][20:26] == "no ans"
+ )
+
+ return (
+ True,
+ parse_ping_line(lines[first_no_ans]),
+ parse_ping_line(lines[last_no_ans]),
+ )
+
+
+def wait_migration_finish(source_vm, target_vm):
+ migr_events = (
+ ("MIGRATION", {"data": {"status": "completed"}}),
+ ("MIGRATION", {"data": {"status": "failed"}}),
+ )
+
+ source_e = source_vm.events_wait(migr_events)["data"]
+ target_e = target_vm.events_wait(migr_events)["data"]
+
+ source_s = source_vm.cmd("query-status")["status"]
+ target_s = target_vm.cmd("query-status")["status"]
+
+ assert (
+ source_e["status"] == "completed"
+ and target_e["status"] == "completed"
+ and source_s == "postmigrate"
+ and target_s == "paused"
+ ), f"""Migration failed:
+ SRC status: {source_s}
+ SRC event: {source_e}
+ TGT status: {target_s}
+ TGT event:{target_e}"""
+
+
+@skipWithoutSudo()
+class VhostUserBlkFdMigration(LinuxKernelTest):
+
+ ASSET_KERNEL = Asset(
+ (
+ "https://archives.fedoraproject.org/pub/archive/fedora/linux/releases"
+ "/31/Server/x86_64/os/images/pxeboot/vmlinuz"
+ ),
+ "d4738d03dbbe083ca610d0821d0a8f1488bebbdccef54ce33e3adb35fda00129",
+ )
+
+ ASSET_INITRD = Asset(
+ (
+ "https://archives.fedoraproject.org/pub/archive/fedora/linux/releases"
+ "/31/Server/x86_64/os/images/pxeboot/initrd.img"
+ ),
+ "277cd6c7adf77c7e63d73bbb2cded8ef9e2d3a2f100000e92ff1f8396513cd8b",
+ )
+
+ ASSET_ALPINE_ISO = Asset(
+ (
+ "https://dl-cdn.alpinelinux.org/"
+ "alpine/v3.22/releases/x86_64/alpine-standard-3.22.1-x86_64.iso"
+ ),
+ "96d1b44ea1b8a5a884f193526d92edb4676054e9fa903ad2f016441a0fe13089",
+ )
+
+ def setUp(self):
+ super().setUp()
+
+ init_tap()
+
+ self.outer_ping_proc = None
+ self.shm_path = None
+
+ def tearDown(self):
+ try:
+ del_tap(TAP_ID)
+ del_tap(TAP_ID2)
+
+ if self.outer_ping_proc:
+ self.stop_outer_ping()
+
+ if self.shm_path:
+ os.unlink(self.shm_path)
+ finally:
+ super().tearDown()
+
+ def start_outer_ping(self) -> None:
+ assert self.outer_ping_proc is None
+ self.outer_ping_log = self.scratch_file("ping.log")
+ with open(self.outer_ping_log, "w") as f:
+ self.outer_ping_proc = subprocess.Popen(
+ ["ping", "-i", "0", "-O", "-D", GUEST_IP],
+ text=True,
+ stdout=f,
+ )
+
+ def stop_outer_ping(self) -> str:
+ assert self.outer_ping_proc
+ self.outer_ping_proc.send_signal(signal.SIGINT)
+
+ self.outer_ping_proc.communicate(timeout=5)
+ self.outer_ping_proc = None
+
+ with open(self.outer_ping_log) as f:
+ return f.read()
+
+ def stop_ping_and_check(self, stop_time, resume_time):
+ ping_res = self.stop_outer_ping()
+
+ discon, a, b = parse_ping_output(ping_res)
+
+ if not discon:
+ text = (
+ f"STOP: {stop_time}, RESUME: {resume_time}," f"PING: {a} - {b}"
+ )
+ if a > stop_time or b < resume_time:
+ self.fail(f"PING failed: {text}")
+ self.log.info(f"PING: no packets lost: {text}")
+ return
+
+ text = (
+ f"STOP: {stop_time}, RESUME: {resume_time},"
+ f"PING: disconnect: {a} - {b}"
+ )
+ self.log.info(text)
+ eps = 0.01
+ if a < stop_time - eps or b > resume_time + eps:
+ self.fail(text)
+
+ def one_ping_from_guest(self, vm) -> None:
+ exec_command_and_wait_for_pattern(
+ self,
+ f"ping -c 1 -W 1 {HOST_IP}",
+ "1 packets transmitted, 1 packets received",
+ "1 packets transmitted, 0 packets received",
+ vm=vm,
+ )
+ self.wait_for_console_pattern("# ", vm=vm)
+
+ def one_ping_from_host(self) -> None:
+ run(["ping", "-c", "1", "-W", "1", GUEST_IP])
+
+ def setup_shared_memory(self):
+ self.shm_path = f"/dev/shm/qemu_test_{os.getpid()}"
+
+ try:
+ with open(self.shm_path, "wb") as f:
+ f.write(b"\0" * (1024 * 1024 * 1024)) # 1GB
+ except Exception as e:
+ self.fail(f"Failed to create shared memory file: {e}")
+
+ def prepare_and_launch_vm(
+ self, shm_path, vhost, incoming=False, vm=None, backend_transfer=True
+ ):
+ if not vm:
+ vm = self.vm
+
+ vm.set_console()
+ vm.add_args("-accel", "kvm")
+ vm.add_args("-device", "pcie-pci-bridge,id=pci.1,bus=pcie.0")
+ vm.add_args("-m", "1G")
+
+ vm.add_args(
+ "-object",
+ f"memory-backend-file,id=ram0,size=1G,mem-path={shm_path},share=on",
+ )
+ vm.add_args("-machine", "memory-backend=ram0")
+
+ vm.add_args(
+ "-drive",
+ f"file={self.ASSET_ALPINE_ISO.fetch()},media=cdrom,format=raw",
+ )
+
+ vm.add_args("-S")
+
+ if incoming:
+ vm.add_args("-incoming", "defer")
+
+ vm_s = "target" if incoming else "source"
+ self.log.info(f"Launching {vm_s} VM")
+ vm.launch()
+
+ if not backend_transfer:
+ tap_name = TAP_ID2 if incoming else TAP_ID
+ else:
+ tap_name = TAP_ID
+
+ self.add_virtio_net(vm, vhost, tap_name)
+
+ self.set_migration_capabilities(vm, backend_transfer)
+
+ def add_virtio_net(self, vm, vhost: bool, tap_name: str = "tap0"):
+ netdev_params = {
+ "id": "netdev.1",
+ "vhost": vhost,
+ "type": "tap",
+ "ifname": tap_name,
+ "script": "no",
+ "downscript": "no",
+ "queues": 4,
+ "vnet_hdr": True,
+ }
+
+ vm.cmd("netdev_add", netdev_params)
+
+ vm.cmd(
+ "device_add",
+ driver="virtio-net-pci",
+ romfile="",
+ id="vnet.1",
+ netdev="netdev.1",
+ mq=True,
+ vectors=18,
+ bus="pci.1",
+ mac=GUEST_MAC,
+ disable_legacy="off",
+ )
+
+ def set_migration_capabilities(self, vm, backend_transfer=True):
+ capabilities = [
+ {"capability": "events", "state": True},
+ {"capability": "x-ignore-shared", "state": True},
+ ]
+ vm.cmd("migrate-set-capabilities", {"capabilities": capabilities})
+ if backend_transfer:
+ res = vm.cmd("query-backend-transfer-support")
+ path = "/machine/peripheral/vnet.1/virtio-backend"
+ self.assertEqual(res, [{"path": path}])
+ vm.cmd("migrate-set-parameters", {"backend-transfer": [path]})
+
+ def setup_guest_network(self) -> None:
+ exec_command_and_wait_for_pattern(self, "ip addr", "# ")
+ exec_command_and_wait_for_pattern(
+ self,
+ f"ip addr add {GUEST_IP_MASK} dev eth0 && "
+ "ip link set eth0 up && echo OK",
+ "OK",
+ )
+ self.wait_for_console_pattern("# ")
+
+ def do_test_tap_fd_migration(self, vhost, backend_transfer=True):
+ self.require_accelerator("kvm")
+ self.set_machine("q35")
+
+ socket_dir = self.socket_dir()
+ migration_socket = os.path.join(socket_dir.name, "migration.sock")
+
+ self.setup_shared_memory()
+
+ # Setup second TAP if needed
+ if not backend_transfer:
+ del_tap(TAP_ID2)
+ init_tap(TAP_ID2, with_ip=False)
+
+ self.prepare_and_launch_vm(
+ self.shm_path, vhost, backend_transfer=backend_transfer
+ )
+ self.vm.cmd("cont")
+ self.wait_for_console_pattern("login:")
+ exec_command_and_wait_for_pattern(self, "root", "# ")
+
+ self.setup_guest_network()
+
+ self.one_ping_from_guest(self.vm)
+ self.one_ping_from_host()
+ self.start_outer_ping()
+
+ # Get some successful pings before migration
+ time.sleep(0.5)
+
+ target_vm = self.get_vm(name="target")
+ self.prepare_and_launch_vm(
+ self.shm_path,
+ vhost,
+ incoming=True,
+ vm=target_vm,
+ backend_transfer=backend_transfer,
+ )
+
+ target_vm.cmd("migrate-incoming", {"uri": f"unix:{migration_socket}"})
+
+ self.log.info("Starting migration")
+ freeze_start = time.time()
+ self.vm.cmd("migrate", {"uri": f"unix:{migration_socket}"})
+
+ self.log.info("Waiting for migration completion")
+ wait_migration_finish(self.vm, target_vm)
+
+ # Switch network to tap1 if not using backend transfer
+ if not backend_transfer:
+ switch_network_to_tap2()
+
+ target_vm.cmd("cont")
+ freeze_end = time.time()
+
+ self.vm.shutdown()
+
+ self.log.info("Verifying PING on target VM after migration")
+ self.one_ping_from_guest(target_vm)
+ self.one_ping_from_host()
+
+ # And a bit more pings after source shutdown
+ time.sleep(0.3)
+ self.stop_ping_and_check(freeze_start, freeze_end)
+
+ target_vm.shutdown()
+
+ def test_tap_fd_migration(self):
+ self.do_test_tap_fd_migration(False)
+
+ def test_tap_fd_migration_vhost(self):
+ self.do_test_tap_fd_migration(True)
+
+ def test_tap_new_tap_migration(self):
+ self.do_test_tap_fd_migration(False, backend_transfer=False)
+
+ def test_tap_new_tap_migration_vhost(self):
+ self.do_test_tap_fd_migration(True, backend_transfer=False)
+
+
+if __name__ == "__main__":
+ LinuxKernelTest.main()
--
2.48.1© 2016 - 2025 Red Hat, Inc.