[lmz]

Wouldn't KVM be part of the kernel interface to userspace? The emulated devices aren't really part of KVM, are they?

[CommanderData]

I was thinking due to modified code and copyleft/GPL it could force copyleft on Workstation, but I may have misunderstood how it works.

[bityard]

Yes, you probably misunderstand. KVM is part of the Linux kernel, which is GPL licensed. The GPL only prohibits derivations of a GPL'd projects from using a difference license. (Actually, copyright law prohibits this.) Using one piece of software alongside another does not count as a derivation. It has always been possible to run proprietary software on the Linux kernel, for example. This is no different.