kyverno/examples/best_practices/policy_validate_host_path.yaml

apiVersion : kyverno.io/v1alpha1
kind: ClusterPolicy
metadata:
  name: validate-host-path
spec:
  rules:
  - name: validate-host-path
    match:
      resources:
        kinds:
        - Pod
    validate:
      message: "Host path '/var/lib/' is not allowed"
      pattern:
        spec:
          volumes:
          - =(hostPath):
              path: "!/var/lib"