To check if you can run hosted hypervisors run:
cat /sys/module/kvm_intel/parameters/nested
If it returns ‘Y’ you are good to go, and actually don’t need this article, if it returns ‘N’ you can enable nested virtualization for the current boot
For intel run as root:
modprobe kvm_intel nested=1
And for AMD run as root:
modprobe kvm_amd nested=1
Or you can enable it in a more permanent manner running
If you have an Intel Processor:
echo "options kvm-intel nested=Y" > /etc/modprobe.d/kvm-nested-intel.conf
If you have an AMD Processor:
echo "options kvm-amd nested=1" > /etc/modprobe.d/kvm-nested-amd.conf
You can always check if it’s working with
cat /sys/module/kvm_intel/parameters/nested
It should return ‘Y’, and you are ready to test new hypervisors without needing a new Test Server, but always remember that when you run a VM inside an VM hypervisor it’s I/O throughput will suffer a lot if you don’t have high end hardware.
Sources:
https://pve.proxmox.com/wiki/Nested_Virtualization
https://www.linuxtechi.com/enable-nested-virtualization-kvm-centos-7-rhel-7/
https://docs.fedoraproject.org/en-US/quick-docs/using-nested-virtualization-in-kvm/
https://www.kernel.org/doc/Documentation/virtual/kvm/nested-vmx.txt
http://www.rdoxenham.com/?p=275