Using UEFI mode for virtual machines

You can boot a virtual machine (VM) in Unified Extensible Firmware Interface (UEFI) mode for faster boot times, the ability to boot to larger disks, and added security features.

About UEFI mode for virtual machines

Unified Extensible Firmware Interface (UEFI), like legacy BIOS, initializes hardware components and operating system image files when a computer starts. UEFI supports more modern features and customization options than BIOS, enabling faster boot times.

It stores all the information about initialization and startup in a file with a .efi extension, which is stored on a special partition called EFI System Partition (ESP). The ESP also contains the boot loader programs for the operating system that is installed on the computer.

Booting virtual machines in UEFI mode

You can configure a virtual machine to boot in UEFI mode by editing the VirtualMachine manifest.

Prerequisites

• Install the OpenShift CLI (oc).

Procedure

1. To boot a virtual machine (VM) in UEFI mode with secure boot active, edit or create a VirtualMachine manifest file. Use the spec.firmware.bootloader stanza to configure UEFI mode:

   apiversion: kubevirt.io/v1
   kind: VirtualMachine
   metadata:
     labels:
       special: vm-secureboot
     name: vm-secureboot
   spec:
     template:
       metadata:
         labels:
           special: vm-secureboot
       spec:
         domain:
           devices:
             disks:
             - disk:
                 bus: virtio
               name: containerdisk
           features:
             acpi: {}
             smm:
               enabled: true
           firmware:
             bootloader:
               efi:
                 secureBoot: true
   # ...
   

   • You must set spec.template.spec.domain.features.ssm.enabled to have a value of true.
   • If spec.template.spec.domain.firmware.bootloader.efi.secureBoot is set to true, then UEFI mode is required. However, you can enable UEFI mode without using Secure Boot.

2. Apply the manifest to your cluster by running the following command:

   $ oc create -f <file_name>.yaml
   

Configuring VMs with persistent EFI

You can configure a VM to have EFI persistence enabled by editing its manifest file.

Procedure

• Edit the VM manifest file and save to apply settings.

  apiVersion: kubevirt.io/v1
  kind: VirtualMachine
  metadata:
    name: vm
  spec:
    template:
      spec:
        domain:
          firmware:
            bootloader:
              efi:
                persistent: true
  # ...