How to disable nested virtualization?

In some cases, live VM migration cannot be performed if nested virtualization is enabled on the cluster node.

The article describes how to disable nested virtualization on a cluster node.

Diagnostics

1. Connect to the cluster node via SSH.

2. Check whether nested virtualization is enabled:

   cat /sys/module/kvm_*/parameters/nested

    Examples of responses:

   • "Y", "1" — nested virtualization is enabled;
   • "N", "0" — nested virtualization is disabled.

Solution

To disable nested virtualization before the cluster node reboots:

1. Connect to the cluster node via SSH.
2. Run the commands:
   

   • for Intel CPU: 

     modprobe -r kvm_intel

     modprobe kvm_intel nested=0

   • for AMD CPU: 

     modprobe -r kvm_amd

     modprobe kvm_amd nested=0

To completely disable nested virtualization:

1. Connect to the cluster node via SSH.
2. Specify the following in the /etc/modprobe.d/kvm.conf configuration file:
   

   • for Intel CPU:

     options kvm_intel nested=0

   • for AMD CPU:

     options kvm_amd nested=0