https://www.theregister.co.uk/2017/09/29/google_cloud_nested_virtualization/

In late August 2017 THe Reg's virtualization desk learned that Google was working hard to make KVM better at nested virtualization. And now we know why, as the advertising giant's cloud has just revealed a nested virtualization beta.

The new offering means that you can run a virtual machine inside the virtual machines you rent from the company's infrastructure-as-a-service limb. The service is a beta for now, and requires you to get the KVM hypervisor running inside a Google Cloud VM, which itself runs on KVM. Google's not supporting ESX or Xen but that's not a huge barrier to overcome as KVM can import VMware's VMDK files and plenty of tools let you re-format VMs.