22.5. Creating a nested virtual machine on IBM Z

Prerequisites

• An L0 RHEL 10 host running an L1 virtual machine (VM).
• The hypervisor CPU must support nested virtualization. To verify this is the case, use the cat /proc/cpuinfo command on the L0 hypervisor. If the output of the command includes the sie flag, creating L2 VMs is possible.

• Ensure that nested virtualization is enabled on the L0 host:

  # cat /sys/module/kvm/parameters/nested

  • If the command returns 1 or Y, the feature is enabled. Skip the remaining prerequisite steps, and continue with the Procedure section.

  • If the command returns 0 or N, use the following steps to enable the feature.

    1. Stop all running VMs on the L0 host.

    2. Unload the kvm module:

       # modprobe -r kvm

    3. Activate the nesting feature:

       # modprobe kvm nested=1

    4. The nesting feature is now enabled, but only until the next reboot of the L0 host. To enable it permanently, add the following line to the /etc/modprobe.d/kvm.conf file:

       options kvm nested=1

Procedure

• Create an L2 VM within the L1 VM. To do this, follow the same procedure as when creating the L1 VM.