Which component is NOT part of the KVM virtualization architecture?

In the context of KVM (Kernel-based Virtual Machine) virtualization architecture, the correct answer is the Xen hypervisor, as it is not a component of KVM. KVM is a Linux kernel module that allows the Linux kernel to function as a hypervisor, enabling the host system to run multiple guest virtual machines.

KVM modules are essential components because they integrate directly with the Linux kernel, providing the necessary interfaces for virtualization. QEMU serves as a user-space emulator that works alongside KVM to provide hardware virtualization capabilities and manage virtual machine instances. Libvirt is a toolkit and API that helps manage different virtualization technologies, including KVM, by providing a standardized interface for operations.

The Xen hypervisor, however, is an entirely different virtualization technology and architectural framework. It is not directly related to KVM and functions independently, using its own architecture for managing virtualization tasks. Therefore, it does not belong to the KVM virtualization architecture, making it the correct answer in this context.