RPUGuard: a Building Block for Next-Generation MPSoCs Hypervisors toward Mixed-Criticality Systems

Abstract The spread of cutting-edge virtualization methods for modern embedded architectures like MultiProcessor Systems on Chip (MPSoCs) opens the door to the development of powerful and dependable hypervisors which might help developers to deal with complexity and heterogeneity of modern technologies while maintaining real-time requirements for critical applications. Following the needs of industrial applications, virtualization has been proven to be among the best approaches for the realization of mixed criticality systems embracing the fog computing paradigm while lowering the space, weight, power and cost (SWaP-C) of the deployment. However, the virtualization support for important hardware accelerators presents on MPSoCs, such as Real-Time Processing Units (RPUs), used for real-time and/or safety-critical workloads, is still overlooked. In this paper we propose the concept of the Omnivisor a software layer that virtualize an entire MPSoC improving the resource utilization while simplifying the implementation of a mixed criticality system over these heterogeneous boards. We identify the RPU virtualization as a building block for its realization. Therefore, as a major contribution for this paper, we design and implement a component, named RPUGuard, which is able to guarantee isolated communication channels with a fixed bandwidth between virtual machines, running on regular Application Processing Units (APUs), and the RPU on the same MPSoC. We evaluated RPUGuard on the Zynq Ultrascale+ board, in the context of a challenging case study concerning the magnetic control system of the ITER experimental nuclear fusion reactor. Results demonstrate how our solution can mitigate the weaknesses of current asymmetric communication techniques, while providing isolation guarantees to critical communication channels.