Support limitations for nested virtualization

In most environments, nested virtualization is only available as a Technology Preview in RHEL 10.

However, you can use a Windows virtual machine (VM) with the Windows Subsystem for Linux (WSL2) to create a virtual Linux environment inside the Windows VM. This use case is fully supported on RHEL 10 under specific conditions.

To learn more about the relevant terminology for nested virtualization, see What is nested virtualization?

Supported environments

To create a supported deployment of nested virtualization, create an L1 Windows VM on a RHEL 9 or RHEL 10 L0 host and use WSL2 to create a virtual Linux environment inside the L1 Windows VM. Currently, this is the only supported nested environment.

Important

The L0 host must be an Intel or AMD system. Other architectures, such as ARM or IBM Z, are currently not supported.

You must use only the following operating system versions:

On the L0 host: On the L1 VMs:

RHEL 10.0 and later

Windows Server 2019 and later with WSL2

Windows 10 and later with WSL2

See Microsoft documentation for instructions on installing WSL2 and choosing supported Linux distributions.

To create a supported nested environment, use one of the following procedures:

Technology Preview environments

These nested environments are available only as a Technology Preview and are not supported.

Important

The L0 host must be an Intel, AMD, or IBM Z system. Nested virtualization currently does not work on other architectures, such as ARM.

You must use only the following operating system versions for the deployment to work:

On the L0 host: On the L1 VMs: On the L2 VMs:

RHEL 10.0 and later

RHEL 9.6 and later

RHEL 9.6 and later

RHEL 10.0 and later

RHEL 10.0 and later

Windows Server 2016 and later with Hyper-V

Windows Server 2019 and later

Windows 10 and later with Hyper-V
Note

Creating RHEL L1 VMs is not tested when used in other Red Hat virtualization offerings. These include:

  • Red Hat Virtualization
  • Red Hat OpenStack Platform
  • OpenShift Virtualization

To create a Technology Preview nested environment, use one of the following procedures:

Hypervisor limitations

  • Currently, Red Hat tests nesting only on RHEL-KVM. When RHEL is used as the L0 hypervisor, you can use RHEL or Windows as the L1 hypervisor.
  • When using an L1 RHEL VM on a non-KVM L0 hypervisor, such as VMware ESXi or Amazon Web Services (AWS), creating L2 VMs in the RHEL guest operating system has not been tested and might not work.

Feature limitations

  • Use of L2 VMs as hypervisors and creating L3 guests has not been properly tested and is not expected to work.
  • Migrating VMs currently does not work on AMD systems if nested virtualization has been enabled on the L0 host.
  • On an IBM Z system, huge-page backing storage and nested virtualization cannot be used at the same time. 
    # modprobe kvm hpage=1 nested=1
modprobe: ERROR: could not insert 'kvm': Invalid argument
# dmesg |tail -1
[90226.508366] kvm-s390: A KVM host that supports nesting cannot back its KVM guests with huge pages
  • Some features available on the L0 host might be unavailable on the L1 hypervisor.