Virtualization has been a key technology in enhancing interoperability and in making systems more secure. However, the question remains whether virtualization can be used in the context of real-time systems because of efficiency and schedulability issues. This question is even more controversial when recursive virtualization is considered.
In this paper, we explore one of the biggest challenges of bringing recursive virtualization to the real-time systems community, namely bounding the time for interrupt and exception forward- ing across the hierarchy of hypervisors. We analyze the problem and propose non-paravirtualized algorithms in the context of the x86 architecture, both with and without the latest hardware virtualization support. Though the performance is severely limited by the current hardware features, we show that a simple hardware extension could speed up recursive interrupt and exception delivery significantly.
Wing-Chi Poon, Aloysius K. Mok