Create functional integration tests for hotplugging

Create some functional integration tests for hotplugging. Covering
positive and negative cases, as well as onlining of vCPUs

Signed-off-by: James Curtis <[email protected]>

Author: JamesC1305

tests/integration_tests/functional/test_vcpu_hotplug.py

@@ -0,0 +1,99 @@
+# Copyright 2024 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+# SPDX-License-Identifier: Apache-2.0
+
+"""Integration tests for hotplugging vCPUs"""
+
+import re
+
+import pytest
+
+from framework import microvm
+from framework.defs import MAX_SUPPORTED_VCPUS
+from framework.microvm import Serial
+from framework.utils_cpuid import check_guest_cpuid_output
+
+
+@pytest.mark.parametrize("vcpu_count", [1, MAX_SUPPORTED_VCPUS - 1])
+def test_hotplug_vcpus(uvm_plain_rw, vcpu_count):
+    """Test hotplugging works as intended"""
+    vm = uvm_plain_rw
+    vm.jailer.extra_args.update({"no-seccomp": None})
+    vm.spawn()
+    vm.basic_config(vcpu_count=1, mem_size_mib=128)
+    vm.add_net_iface()
+    vm.start()
+
+    vm.api.hotplug.put(Vcpu={"add": vcpu_count})
+
+    check_guest_cpuid_output(
+        vm,
+        "lscpu",
+        None,
+        ":",
+        {
+            "CPU(s)": str(1 + vcpu_count),
+            "Off-line CPU(s) list": "1" if vcpu_count == 1 else f"1-{vcpu_count}",
+        },
+    )
+
+
+@pytest.mark.parametrize(
+    "vcpu_count", [-1, 0, MAX_SUPPORTED_VCPUS, MAX_SUPPORTED_VCPUS + 1]
+)
+def test_negative_hotplug_vcpus(uvm_plain, vcpu_count):
+    """Test cases where hotplugging should fail."""
+    uvm_plain.jailer.extra_args.update({"no-seccomp": None})
+    uvm_plain.spawn()
+    uvm_plain.basic_config(vcpu_count=1, mem_size_mib=128)
+    uvm_plain.add_net_iface()
+    uvm_plain.start()
+
+    if vcpu_count == 0:
+        with pytest.raises(
+            RuntimeError,
+            match="Hotplug error: Vcpu hotplugging error: The number of vCPUs added must be greater than 0.",
+        ):
+            uvm_plain.api.hotplug.put(Vcpu={"add": vcpu_count})
+    elif vcpu_count < 0:
+        with pytest.raises(
+            RuntimeError,
+            match=re.compile(
+                f"An error occurred when deserializing the json body of a request: invalid value: integer `-\\d+`, expected u8+"
+            ),
+        ):
+            uvm_plain.api.hotplug.put(Vcpu={"add": vcpu_count})
+    elif vcpu_count > 31:
+        with pytest.raises(
+            RuntimeError,
+            match="Hotplug error: Vcpu hotplugging error: The number of vCPUs added must be less than 32.",
+        ):
+            uvm_plain.api.hotplug.put(Vcpu={"add": vcpu_count})
+
+
+@pytest.mark.parametrize("vcpu_count", [1, MAX_SUPPORTED_VCPUS - 1])
+def test_online_hotplugged_vcpus(uvm_plain, vcpu_count):
+    """Test that hotplugged CPUs can be onlined"""
+    uvm_plain.jailer.extra_args.update({"no-seccomp": None})
+    uvm_plain.spawn()
+    uvm_plain.basic_config(vcpu_count=1, mem_size_mib=128)
+    uvm_plain.add_net_iface()
+    uvm_plain.start()
+
+    uvm_plain.api.hotplug.put(Vcpu={"add": vcpu_count})
+
+    _, _, stderr = uvm_plain.ssh.run(
+        f"for i in {{1..{vcpu_count}}}; do echo 1 > /sys/devices/cpu/cpu$i/online; done"
+    )
+
+    assert stderr == ""
+
+    check_guest_cpuid_output(
+        uvm_plain,
+        "lscpu",
+        None,
+        ":",
+        {
+            "CPU(s)": str(1 + vcpu_count),
+            "On-line CPU(s) list": "0,1" if vcpu_count == 1 else f"0-{vcpu_count}",
+        },
+    )