Acceptance Tests: introduce CPU hotplug test

Even though there are qtest based tests for hotplugging CPUs (from
which this test took some inspiration from), this one adds checks
from a Linux guest point of view.

It should also serve as an example for tests that follow a similar
pattern and need to interact with QEMU (via qmp) and with the Linux
guest via SSH.

Signed-off-by: Cleber Rosa <crosa@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Willian Rampazzo <willianr@redhat.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Message-Id: <20210412044644.55083-11-crosa@redhat.com>
Signed-off-by: John Snow <jsnow@redhat.com>

tests/acceptance/hotplug_cpu.py

@@ -0,0 +1,37 @@
+# Functional test that hotplugs a CPU and checks it on a Linux guest
+#
+# Copyright (c) 2021 Red Hat, Inc.
+#
+# Author:
+#  Cleber Rosa <crosa@redhat.com>
+#
+# This work is licensed under the terms of the GNU GPL, version 2 or
+# later.  See the COPYING file in the top-level directory.
+
+from avocado_qemu import LinuxTest
+
+
+class HotPlugCPU(LinuxTest):
+
+    def test(self):
+        """
+        :avocado: tags=arch:x86_64
+        :avocado: tags=machine:q35
+        :avocado: tags=accel:kvm
+        """
+        self.require_accelerator('kvm')
+        self.vm.add_args('-accel', 'kvm')
+        self.vm.add_args('-cpu', 'Haswell')
+        self.vm.add_args('-smp', '1,sockets=1,cores=2,threads=1,maxcpus=2')
+        self.launch_and_wait()
+
+        self.ssh_command('test -e /sys/devices/system/cpu/cpu0')
+        with self.assertRaises(AssertionError):
+            self.ssh_command('test -e /sys/devices/system/cpu/cpu1')
+
+        self.vm.command('device_add',
+                        driver='Haswell-x86_64-cpu',
+                        socket_id=0,
+                        core_id=1,
+                        thread_id=0)
+        self.ssh_command('test -e /sys/devices/system/cpu/cpu1')