Nested Virtualization: VMs inside VMs

Nested Virtualization | Microsoft Docs
"Nested virtualization is a feature that allows you to run Hyper-V inside of a Hyper-V virtual machine. In other words, with nested virtualization, a Hyper-V host itself can be virtualized. Some use cases for nested virtualization would be to run a Hyper-V Container in a virtualized container host, set-up a Hyper-V lab in a virtualized environment, or to test multi-machine scenarios without the need for individual hardware. Prerequisites:

• A Hyper-V host running Windows Server 2016 or Windows 10 Anniversary Update.
• A Hyper-V VM running Windows Server 2016 or Windows 10 Anniversary Update.
• A Hyper-V VM with configuration version 8.0 or greater.
• An Intel processor with VT-x and EPT technology."

Can you run a virtual machine inside another virtual machine? Would this make you safe from viruses that can migrate outside virtual machines? - Quora
"With VMware vSphere, yes, you can and it works very well - no speed penalty. VMware calls it Nested VMs."

Nested Virtualization in Xen - Xen

"Nested virtualization is the ability to run a hypervisor inside of a virtual machine. The hypervisor that runs on the real hardware is called a level 0 or L0; the hypervisor that runs as a guest on L0 is called level 1 or L1; a guest that runs on the L1 hypervisor is called a level 2 or L2."

Amazon Elastic Compute Cloud - Wikipedia

"EC2 uses Xen virtualization."