A key tenet in KVM is to reuse as much Linux infrastructure as possible
and focus specifically on processor virtualization. Back in 2007, this
meant a smaller code base and less friction with the other kernel
subsystems, especially when compared with other virtualization technologies
such as Xen. This led to KVM being merged into the mainline with relative
ease. A talk at this year’s KVM Forum looks at ways to better protect
guests, perhaps by moving away from that tenet.

Source: LWN.net – [$] Enhancing KVM for guest protection and security