source/kernel: Add kvm availability

This commit adds a feature to check kvm availability.

Signed-off-by: Seunguk Shin <[email protected]>
Reviewed-by: Nick Connolly <[email protected]>

Author: seungukshin

deployment/base/nfd-crds/cr-sample.yaml

@@ -47,6 +47,9 @@ spec:
         - feature: kernel.selinux
           matchExpressions:
             enabled: {op: IsFalse}
+        - feature: kernel.kvm
+          matchExpressions:
+            enabled: {op: IsFalse}
         - feature: kernel.version
           matchExpressions:
             major: {op: In, value: ["5"]}

deployment/components/worker-config/nfd-worker.conf.example

@@ -116,6 +116,9 @@
 #        - feature: kernel.selinux
 #          matchExpressions:
 #            enabled: {op: IsFalse}
+#        - feature: kernel.kvm
+#          matchExpressions:
+#            enabled: {op: IsFalse}
 #        - feature: kernel.version
 #          matchExpressions:
 #            major: {op: In, value: ["5"]}

deployment/helm/node-feature-discovery/values.yaml

@@ -464,6 +464,9 @@ worker:
     #        - feature: kernel.selinux
     #          matchExpressions:
     #            enabled: {op: IsFalse}
+    #        - feature: kernel.kvm
+    #          matchExpressions:
+    #            enabled: {op: IsFalse}
     #        - feature: kernel.version
     #          matchExpressions:
     #            major: {op: In, value: ["5"]}

docs/usage/customization-guide.md

@@ -962,6 +962,8 @@ The following features are available for matching:
 |                  |              | **`mod-name`** |      | Kernel module `<mod-name>` is loaded |
 | **`kernel.selinux`** | attribute |         |            | Kernel SELinux related features |
 |                  |              | **`enabled`** | bool  | `true` if SELinux has been enabled and is in enforcing mode, otherwise `false` |
+| **`kernel.kvm`** | attribute |         |            | Kernel KVM related features |
+|                  |              | **`enabled`** | bool  | `true` if KVM has been enabled, otherwise `false` |
 | **`kernel.version`** | attribute |          |           | Kernel version information |
 |                  |              | **`full`** | string   | Full kernel version (e.g. ‘4.5.6-7-g123abcde') |
 |                  |              | **`major`** | int     | First component of the kernel version (e.g. ‘4') |

source/kernel/kernel.go

@@ -36,6 +36,7 @@ const (
 	SelinuxFeature       = "selinux"
 	VersionFeature       = "version"
 	EnabledModuleFeature = "enabledmodule"
+	KvmFeature           = "kvm"
 )
 
 // Configuration file options
@@ -159,6 +160,13 @@ func (s *kernelSource) Discover() error {
 		s.features.Attributes[SelinuxFeature].Elements["enabled"] = strconv.FormatBool(selinux)
 	}
 
+	if kvm, err := KvmEnabled(); err != nil {
+		klog.ErrorS(err, "failed to detect kvm status")
+	} else {
+		s.features.Attributes[KvmFeature] = nfdv1alpha1.NewAttributeFeatures(nil)
+		s.features.Attributes[KvmFeature].Elements["enabled"] = strconv.FormatBool(kvm)
+	}
+
 	klog.V(3).InfoS("discovered features", "featureSource", s.Name(), "features", utils.DelayedDumper(s.features))
 
 	return nil

source/kernel/kvm.go

@@ -0,0 +1,38 @@
+/*
+Copyright 2017-2025 The Kubernetes Authors.
+
+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 kernel
+
+import (
+	"os"
+
+	"k8s.io/klog/v2"
+
+	"sigs.k8s.io/node-feature-discovery/pkg/utils/hostpath"
+)
+
+// KvmEnabled detects if kvm has been enabled in the kernel
+func KvmEnabled() (bool, error) {
+	_, err := os.Stat(hostpath.SysfsDir.Path("devices/virtual/misc/kvm"))
+	if err != nil {
+		if os.IsNotExist(err) {
+			klog.V(1).InfoS("kvm not available on the system")
+			return false, nil
+		}
+		return false, err
+	}
+	return true, nil
+}

test/e2e/e2e-test-config.example.yaml

@@ -52,6 +52,7 @@ defaultFeatures:
     - "feature.node.kubernetes.io/kernel-config.NO_HZ_IDLE"
     - "feature.node.kubernetes.io/kernel-config.PREEMPT"
     - "feature.node.kubernetes.io/kernel-selinux.enabled"
+    - "feature.node.kubernetes.io/kernel-kvm.enabled"
     - "feature.node.kubernetes.io/kernel-version.full"
     - "feature.node.kubernetes.io/kernel-version.major"
     - "feature.node.kubernetes.io/kernel-version.minor"