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Nested Virtualization on AMD PCs Now Available in Windows 10 Preview

• By Kurt Mackie
• 06/11/2020

The latest Windows 10 preview now has support for nested virtualization on machines using AMD processors, Microsoft announced this week.

Nested virtualization entails running a Hyper-V hypervisor within a Hyper-V-based virtual machine, according to Microsoft's definition in this document. Nested virtualization is the kind of thing that might be used when "testing configurations that ordinarily require several hosts," it added.

IT pros might use nested virtualization to create lab environments or to use Hyper-V containers.

"If you want to use a Hyper-V Containers inside a VM, you guessed it: this is enabled with Nested Virtualization," Microsoft's announcement indicated.

Nested virtualization is also used in application building. Microsoft MVP Brien Posey, for instance, used nested virtualization to set up the Windows 10X emulator solution on a Windows 10 machine, as described in this Redmondmag.com article.

Typically, a virtual machine doesn't expose hardware virtualization to the guest operating system. However, "with nesting enabled, a guest virtual machine can install its own hypervisor and run its own guest VMs," Microsoft's document clarified.

Nested virtualization was first released as preview in Windows 10 machines back in 2015, when it was described as being available for machines having Intel VT-x or AMD-V processors. However, nested virtualization apparently didn't happen on the AMD side.

Here's how Microsoft characterized it:

There is one group of users that was unable to take advantage of Nested Virtualization on Windows. These were our users with AMD hardware. Not a week goes by where the team doesn't get a request for Nested Virtualization support for AMD from our community or from within Microsoft. In fact, it is the number 1 ask on Windows Server's uservoice page. At the time of this blog post, it was almost 5x more than the next feedback item.

The new nested virtualization preview requires using Windows 10 build 19636 or higher. Microsoft this week announced that build 19645 for Windows Insider Program participants is now available, which contains support for nested virtualization on AMD-based machines. That build is also notable for supporting updates to the Linux kernel in Windows Subsystem for Linux 2 via the Microsoft Update service.

The nested virtualization capability has so far been tested on "AMD's first generation Ryzen/Epyc or newer processors," the announcement indicated.

Microsoft hinted that it'll be possible to use Linux-based virtual machines with nested virtualization, stating that "Linux KVM [kernel-based virtual machine] guest support will be coming in the future."