CubeVisor: A Multi-realm Architecture Design for Running VM with ARM CCA

Cloud computing nowadays provides flexible and scalable computing services, using different hardware platforms, including ARM. Virtualization allows multiple virtual machines (VMs) to share the physical resources of a host machine. However, these technologies have security risks. The hypervisor is the software that controls VMs, and it can be exploited or manipulated by hackers or untrusted providers. ARM CCA, a novel feature of ARMv9-A, allows confidential VMs to run in a new security state called realm. However, the current CCA prototype still has some problems, including risks brought by external libraries, single point of failure, highly privileged TF-RMM and costly world switch. In this paper, we introduce CubeVisor, a new secure virtualization architecture based on ARM CCA. It uses the idea of the Cube, which is a combination of a hypervisor and a VM, protecting each Cube from other Cubes or components. The CubeVisor also improves performance by optimizing memory allocation and world-switching processes. We implement prototypes on both software-based ARM FVP platform and hardware-based ARM Cortex-A platform for evaluations. The results show that the CubeVisor can protect VMs well and has very low overhead compared to the CCA based virtualization methods.