I don't think I've landed here before: QEMU Emulator User Documentation. It references 2.10 Direct Linux Boot for fast Linux Kernel testing. The documentation is referenced from QEMU: processor emulator.
libVirt is a virtualization API.
Daniel P. Berrangé is a prolific writer on all things KVM / QEMU / Virtualization / libvirt.
While using Planet Virt Tools as a jumping off point for 'blogging about open source virtualization", I came across Virtio 1.0 and Windows Guests.
Last but not least, we have the KVM - Kernel Virtual Machine.