KVM/ARM: Experiences Building the Linux ARM Hypervisor

As ARM CPUs become increasingly common in mo-bile devices and servers, there is a growing demand for providing the benefits of virtualization for ARM-based devices. We present our experiences building the Linux ARM hypervisor, KVM/ARM, the first full sys-tem ARM virtualization solution that can run unmodified guest operating systems on ARM multicore hardware. KVM/ARM introduces split-mode virtualization, allow-ing a hypervisor to split its execution across CPU modes to take advantage of CPU mode-specific features. This allows KVM/ARM to leverage Linux kernel services and functionality to simplify hypervisor development and maintainability while utilizing recent ARM hardware virtualization extensions to run application workloads in guest operating systems with comparable performance to native execution. KVM/ARM has been successfully merged into the mainline Linux 3.9 kernel, ensuring that it will gain wide adoption as the virtualization platform of choice for ARM. We provide the first measurements on real hardware of a complete hypervisor using ARM hardware virtualization support. Our results demonstrate that KVM/ARM has modest virtualization performance and power costs, and can achieve lower performance and power costs compared to x86-based Linux virtualization on multicore hardware.