chore(vm): e2e test for CPU hotplug

test/e2e/internal/object/cloud_config.go

@@ -49,6 +49,7 @@ type WriteFile struct {
 	Permissions string `json:"permissions,omitempty"`
 	Content     string `json:"content,omitempty"`
 	Append      bool   `json:"append,omitempty"`
+	Owner       string `json:"owner,omitempty"`
 }
 
 const defaultSSHPublicKey = "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIFxcXHmwaGnJ8scJaEN5RzklBPZpVSic4GdaAsKjQoeA your_email@example.com"

test/e2e/internal/object/const.go

@@ -82,11 +82,23 @@ BPZpVSic4GdaAsKjQoeAAAAAFnlvdXJfZW1haWxAZXhhbXBsZS5jb20BAgMEBQYH
 	DefaultPassword = "cloud"
 )
 
+var HotplugCPUUdevRule = WriteFile{
+	Path:    "/etc/udev/rules.d/99-hotplug-cpu.rules",
+	Content: `SUBSYSTEM=="cpu",ACTION=="add",RUN+="/bin/sh -c '[ ! -e /sys$devpath/online ] || echo 1 > /sys$devpath/online'"`,
+	Owner:   "root:root",
+}
+
 var AlpineCloudInit = CloudConfig{
 	PackageUpdate: true,
-	Packages:      append(basePackages, "iputils"),
+	Packages:      append(basePackages, "eudev", "iputils"),
 	Users:         []CloudConfigUser{DefaultCloudUser()},
-	Runcmd:        []string{"rc-update add qemu-guest-agent && rc-service qemu-guest-agent start"},
+	Runcmd: []string{
+		"rc-update add qemu-guest-agent && rc-service qemu-guest-agent start",
+		"rc-update add udev && rc-service udev start",
+	},
+	WriteFiles: []WriteFile{
+		HotplugCPUUdevRule,
+	},
 }.Render()
 
 var UbuntuCloudInit = CloudConfig{

test/e2e/vm/hotplug_cpu.go

@@ -0,0 +1,148 @@
+/*
+Copyright 2026 Flant JSC
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+     http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package vm
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"strings"
+
+	. "github.com/onsi/ginkgo/v2"
+	. "github.com/onsi/gomega"
+	"k8s.io/apimachinery/pkg/api/resource"
+	"k8s.io/apimachinery/pkg/types"
+	"k8s.io/utils/ptr"
+	crclient "sigs.k8s.io/controller-runtime/pkg/client"
+
+	vdbuilder "github.com/deckhouse/virtualization-controller/pkg/builder/vd"
+	vmbuilder "github.com/deckhouse/virtualization-controller/pkg/builder/vm"
+	"github.com/deckhouse/virtualization/api/core/v1alpha2"
+	"github.com/deckhouse/virtualization/test/e2e/internal/framework"
+	"github.com/deckhouse/virtualization/test/e2e/internal/object"
+	"github.com/deckhouse/virtualization/test/e2e/internal/util"
+)
+
+var _ = Describe("HotplugCPU", func() {
+	var (
+		f *framework.Framework
+		t *cpuHotplugTest
+	)
+
+	BeforeEach(func() {
+		Skip("Hotplug CPU requires enabled feature gates in ModuleConfig. Skip until prechecks are implemented.")
+		f = framework.NewFramework("cpu-hotplug")
+		DeferCleanup(f.After)
+		f.Before()
+		t = newCPUHotplugTest(f)
+	})
+
+	DescribeTable("should apply cpu core changes without restart", func(initialCores, changedCores int) {
+		By("Environment preparation")
+		vmName := fmt.Sprintf("vm-%d-%d", initialCores, changedCores)
+		t.generateResources(vmName, initialCores)
+		err := f.CreateWithDeferredDeletion(context.Background(), t.VM, t.VD)
+		Expect(err).NotTo(HaveOccurred())
+
+		By("Waiting for VM agent to be ready")
+		util.UntilSSHReady(f, t.VM, framework.MiddleTimeout)
+
+		By("Checking initial CPU configuration")
+		err = f.Clients.GenericClient().Get(context.Background(), crclient.ObjectKeyFromObject(t.VM), t.VM)
+		Expect(err).NotTo(HaveOccurred())
+		Expect(t.VM.Status.Resources.CPU.Cores).To(Equal(initialCores))
+
+		guestCPUCount, err := t.getGuestCPUCount()
+		Expect(err).NotTo(HaveOccurred())
+		Expect(guestCPUCount).To(Equal(initialCores))
+
+		By("Applying CPU core changes")
+		patch, err := json.Marshal([]map[string]interface{}{{
+			"op":    "replace",
+			"path":  "/spec/cpu/cores",
+			"value": changedCores,
+		}})
+		Expect(err).NotTo(HaveOccurred())
+		err = f.GenericClient().Patch(context.Background(), t.VM, crclient.RawPatch(types.JSONPatchType, patch))
+		Expect(err).NotTo(HaveOccurred())
+
+		By("Waiting until CPU configuration is applied without restart")
+		util.UntilVMMigrationSucceeded(crclient.ObjectKeyFromObject(t.VM), framework.MaxTimeout)
+		util.UntilSSHReady(f, t.VM, framework.MiddleTimeout)
+
+		By("Checking changed CPU configuration")
+		err = f.Clients.GenericClient().Get(context.Background(), crclient.ObjectKeyFromObject(t.VM), t.VM)
+		Expect(err).NotTo(HaveOccurred())
+		Expect(t.VM.Status.Resources.CPU.Cores).To(Equal(changedCores))
+
+		guestCPUCount, err = t.getGuestCPUCount()
+		Expect(err).NotTo(HaveOccurred())
+		Expect(guestCPUCount).To(Equal(changedCores))
+	},
+		Entry("one socket topology, change cores from 1 to 3", 1, 3),
+		Entry("one socket topology, change cores to maximum 16", 4, 16),
+	)
+})
+
+type cpuHotplugTest struct {
+	Framework *framework.Framework
+
+	VM *v1alpha2.VirtualMachine
+	VD *v1alpha2.VirtualDisk
+}
+
+func newCPUHotplugTest(f *framework.Framework) *cpuHotplugTest {
+	return &cpuHotplugTest{Framework: f}
+}
+
+func (t *cpuHotplugTest) generateResources(vmName string, cores int) {
+	vdName := fmt.Sprintf("vd-%s-root", vmName)
+	t.VD = object.NewVDFromCVI(vdName, t.Framework.Namespace().Name, object.PrecreatedCVIAlpineBIOS,
+		vdbuilder.WithSize(ptr.To(resource.MustParse("350Mi"))),
+	)
+
+	t.VM = vmbuilder.New(
+		vmbuilder.WithName(vmName),
+		vmbuilder.WithNamespace(t.Framework.Namespace().Name),
+		vmbuilder.WithCPU(cores, ptr.To("10%")),
+		vmbuilder.WithMemory(*resource.NewQuantity(object.Mi256, resource.BinarySI)),
+		vmbuilder.WithLiveMigrationPolicy(v1alpha2.AlwaysSafeMigrationPolicy),
+		vmbuilder.WithProvisioningUserData(object.AlpineCloudInit),
+		vmbuilder.WithBlockDeviceRefs(
+			v1alpha2.BlockDeviceSpecRef{
+				Kind: v1alpha2.DiskDevice,
+				Name: t.VD.Name,
+			},
+		),
+		vmbuilder.WithRestartApprovalMode(v1alpha2.Automatic),
+	)
+}
+
+func (t *cpuHotplugTest) getGuestCPUCount() (int, error) {
+	cmdOut, err := t.Framework.SSHCommand(t.VM.Name, t.VM.Namespace, "nproc")
+	if err != nil {
+		return 0, err
+	}
+
+	var cpuCount int
+	_, err = fmt.Sscanf(strings.TrimSpace(cmdOut), "%d", &cpuCount)
+	if err != nil {
+		return 0, fmt.Errorf("parse guest cpu count from %q: %w", cmdOut, err)
+	}
+
+	return cpuCount, nil
+}