Memo, I wanna learn more! good post!
KVM needs Qemu (emulator) for full hypervisor functionality. QEMU is self-sufficient and KVM is really a Linux kernel module for exploiting VT-extenstions to act as driver for the physical CPU capabilities.
So, we can say QEMU needs KVM’s performance boost and KVM by itself cannot provide the complete virtualization solution, it needs QEMU.