Import QEMU upstream snapshot d2e570c

Upstream: https://gitlab.com/qemu-project/qemu.git

Upstream-Commit: d2e570cc0f97b936902a5b1b86b73c0f5998b475

tests/functional/generic/test_monitor_hotplug.py

@@ -0,0 +1,305 @@
+#!/usr/bin/env python3
+#
+# SPDX-License-Identifier: GPL-2.0-or-later
+#
+# Functional test for dynamic QMP monitor hotplug
+#
+# Copyright (c) 2026 Christian Brauner
+
+import asyncio
+import os
+import random
+import threading
+import time
+
+from qemu_test import QemuSystemTest
+
+from qemu.qmp.legacy import QEMUMonitorProtocol
+from qemu.qmp import QMPClient
+
+
+class MonitorHotplug(QemuSystemTest):
+
+    def setUp(self):
+        super().setUp()
+        sock_dir = self.socket_dir()
+        self._sock_path = os.path.join(sock_dir.name, 'hotplug.sock')
+
+    def _add_monitor(self, autodelete=False):
+        """Create a chardev + monitor and return the socket path."""
+        sock = self._sock_path
+        self.vm.cmd('chardev-add', id='hotplug-chr', backend={
+            'type': 'socket',
+            'data': {
+                'addr': {
+                    'type': 'unix',
+                    'data': {'path': sock}
+                },
+                'server': True,
+                'wait': False,
+            }
+        })
+        if autodelete:
+            self.vm.cmd('object-add', id='hotplug-mon',
+                        qom_type='monitor-qmp',
+                        chardev='hotplug-chr',
+                        close_action='delete')
+        else:
+            self.vm.cmd('object-add', id='hotplug-mon',
+                        qom_type='monitor-qmp',
+                        chardev='hotplug-chr')
+        return sock
+
+    def _remove_monitor(self):
+        """Remove the monitor + chardev."""
+        self.vm.cmd('object-del', id='hotplug-mon')
+        self.vm.cmd('chardev-remove', id='hotplug-chr')
+
+    def _connect_and_handshake(self, sock_path):
+        """
+        Connect to the dynamic monitor socket, perform the QMP
+        greeting and capability negotiation, send a command, then
+        disconnect.
+        """
+        qmp = QEMUMonitorProtocol(sock_path)
+
+        # connect(negotiate=True) receives the greeting, validates it,
+        # and sends qmp_capabilities automatically.
+        greeting = qmp.connect(negotiate=True)
+        self.assertIn('QMP', greeting)
+        self.assertIn('version', greeting['QMP'])
+        self.assertIn('capabilities', greeting['QMP'])
+
+        # Send a real command to prove the session is fully functional
+        resp = qmp.cmd_obj({'execute': 'query-version'})
+        self.assertIn('return', resp)
+        self.assertIn('qemu', resp['return'])
+
+        qmp.close()
+
+    def test_hotplug_cycle(self):
+        """
+        Hotplug a monitor, do the full QMP handshake, unplug it,
+        then repeat the whole cycle a second time.
+        """
+        self.set_machine('none')
+        self.vm.add_args('-nodefaults')
+        self.vm.launch()
+
+        # First cycle
+        sock = self._add_monitor()
+        self._connect_and_handshake(sock)
+        self._remove_monitor()
+
+        # Second cycle -- same ids, same path, must work
+        sock = self._add_monitor()
+        self._connect_and_handshake(sock)
+        self._remove_monitor()
+
+    def test_self_removal(self):
+        """
+        A dynamically-added monitor sends object-del targeting
+        itself.  Verify the request is rejected, but the monitor
+        can still be deleted from outside its own context.
+        """
+        self.set_machine('none')
+        self.vm.add_args('-nodefaults')
+        self.vm.launch()
+
+        sock = self._add_monitor()
+
+        qmp = QEMUMonitorProtocol(sock)
+        greeting = qmp.connect(negotiate=True)
+        self.assertIn('QMP', greeting)
+
+        # Self-removal: the dynamic monitor raises error
+        resp = qmp.cmd_obj({'execute': 'object-del',
+                            'arguments': {'id': 'hotplug-mon'}})
+        self.assertIn('error', resp)
+
+        qmp.close()
+
+        resp = self.vm.cmd('object-del', id='hotplug-mon')
+
+        # Clean up the chardev
+        self.vm.cmd('chardev-remove', id='hotplug-chr')
+
+    def test_auto_delete(self):
+        """
+        A dynamically-added monitor configured with 'close-action=delete'
+        should see itself deleted when the client is closed.
+        """
+        self.set_machine('none')
+        self.vm.add_args('-nodefaults')
+        self.vm.launch()
+
+        sock = self._add_monitor(autodelete=True)
+
+        cdevs = [c["label"] for c in self.vm.cmd('query-chardev')]
+        objs = [o["name"] for o in self.vm.cmd('qom-list', path='/objects')]
+        assert ('hotplug-chr' in cdevs)
+        assert ('hotplug-mon' in objs)
+
+        qmp = QEMUMonitorProtocol(sock)
+        greeting = qmp.connect(negotiate=True)
+        self.assertIn('QMP', greeting)
+
+        cdevs = [c["label"] for c in self.vm.cmd('query-chardev')]
+        objs = [o["name"] for o in self.vm.cmd('qom-list', path='/objects')]
+        assert ('hotplug-chr' in cdevs)
+        assert ('hotplug-mon' in objs)
+
+        qmp.close()
+
+        # Wait upto 10 seconds max for chardev to auto-delete, which
+        # is hopefully enough for reliability under high load
+        for i in range(int(10 / 0.2)):
+            cdevs = [c["label"] for c in self.vm.cmd('query-chardev')]
+            if 'hotplug-chr' not in cdevs:
+                break
+            # Wait a little more then try again
+            time.sleep(0.2)
+
+        cdevs = [c["label"] for c in self.vm.cmd('query-chardev')]
+        objs = [o["name"] for o in self.vm.cmd('qom-list', path='/objects')]
+        assert ('hotplug-chr' not in cdevs)
+        assert ('hotplug-mon' not in objs)
+
+    def test_reconnect(self):
+        """
+        A dynamically-added monitor configured without 'close-action'
+        should allow reconnects after the client is closed.
+        """
+        self.set_machine('none')
+        self.vm.add_args('-nodefaults')
+        self.vm.launch()
+
+        sock = self._add_monitor()
+
+        qmp = QEMUMonitorProtocol(sock)
+        qmp.connect(negotiate=True)
+
+        resp = qmp.cmd_obj({'execute': 'query-chardev'})
+        self.assertIn('return', resp)
+
+        qmp.close()
+
+        qmp = QEMUMonitorProtocol(sock)
+        qmp.connect(negotiate=True)
+
+        resp = qmp.cmd_obj({'execute': 'query-chardev'})
+        self.assertIn('return', resp)
+
+        qmp.close()
+        self._remove_monitor()
+
+    def test_large_response(self):
+        """
+        Send a command with a large response (query-qmp-schema) on a
+        dynamically-added monitor to exercise the output buffer flush
+        path.
+        """
+        self.set_machine('none')
+        self.vm.add_args('-nodefaults')
+        self.vm.launch()
+
+        sock = self._add_monitor()
+
+        qmp = QEMUMonitorProtocol(sock)
+        qmp.connect(negotiate=True)
+
+        resp = qmp.cmd_obj({'execute': 'query-qmp-schema'})
+        self.assertIn('return', resp)
+        self.assertIsInstance(resp['return'], list)
+        self.assertGreater(len(resp['return']), 0)
+
+        qmp.close()
+        self._remove_monitor()
+
+    def test_events_after_negotiation(self):
+        """
+        Verify that QMP events are delivered on a dynamically-added
+        monitor after capability negotiation completes.
+        """
+        self.set_machine('none')
+        self.vm.add_args('-nodefaults')
+        self.vm.launch()
+
+        sock = self._add_monitor()
+
+        qmp = QEMUMonitorProtocol(sock)
+        qmp.connect(negotiate=True)
+
+        # Trigger a STOP event via the main monitor, then read it
+        # from the dynamic monitor.
+        self.vm.cmd('stop')
+        resp = qmp.pull_event(wait=True)
+        self.assertEqual(resp['event'], 'STOP')
+
+        self.vm.cmd('cont')
+        resp = qmp.pull_event(wait=True)
+        self.assertEqual(resp['event'], 'RESUME')
+
+        qmp.close()
+        self._remove_monitor()
+
+    def stress_mon(self, sock):
+        async def main():
+            qmp = QMPClient('testvm')
+            await qmp.connect(sock)
+            # Run query-version in a tight loop so that the
+            # monitor thread/dispatcher is very busy at the
+            # time we try to delete the monitor
+            while True:
+                try:
+                    # A command which returns a lot of data to make
+                    # it more likely we're in the I/O reply path
+                    # when deleting the monitor
+                    res = await qmp.execute('query-qmp-schema')
+                    # Some commands which generate async events
+                    # as those can trigger different code paths
+                    res = await qmp.execute('stop')
+                    res = await qmp.execute('cont')
+                except:
+                    # we'll get here if the monitor is terminated
+                    # by QEMU in which case we must disconnect
+                    # out side, but....
+                    try:
+                        await qmp.disconnect()
+                    except (ConnectionResetError, EOFError, BrokenPipeError):
+                        # ... disconnect() will probably see
+                        # errors too, but we must try to call it
+                        # regardless to cleanup asyncio state
+                        # and prevent python warnings at GC time
+                        pass
+                    return
+        asyncio.run(main())
+
+    def test_hotplug_stress(self):
+        """
+        Repeatedly hotplug and unplug a monitor, while another thread
+        concurrently issues commands on that monitor. This stresses
+        the synchronization with the monitor thread during cleanup
+        """
+        self.set_machine('none')
+        self.vm.add_args('-nodefaults')
+        self.vm.launch()
+
+        # Each loop sleeps at most 0.5 seconds, so this should
+        # give an upper bound of approx 5 seconds execution
+        # time which is reasonable to run by default
+        repeat = 10
+        for i in range(repeat):
+            # First cycle
+            sock = self._add_monitor()
+            print ("# stress cycle %02d/%02d" % (i, repeat))
+            stress = threading.Thread(target=self.stress_mon, args=[sock])
+            stress.start()
+            # Sleep upto 1/2 second to vary the races
+            time.sleep(random.random() / 2)
+            self._remove_monitor()
+            stress.join()
+
+
+if __name__ == '__main__':
+    QemuSystemTest.main()