Re-architecting VMMs for Multicore Systems: The Sidecore Approach

Future many-core platforms present scalability challenges to VMMs, including the need to efficiently utilize their processor and cache resources. Focusing on platform virtualization, we address these challenges by devising new virtualization methods that not only work with, but actually exploit the many-core nature of future processors. Specifically, we utilize the fact that cores will differ with respect to their current internal processor and memory states. The hypervisor, or VMM, then leverages these differences to substantially improve VMM performance and better utilize these cores. The key idea underlying this work is simple: to carry out some privileged VMM operation, rather than forcing a core to undergo an expensive internal state change via traps, such as VMexit in Intel's VT architecture, why not have the operation carried out by a remote core that is already in the appropriate state? Termed the sidecore approach to running VMM-level functionality, it can be used to run VMM services more efficiently on remote cores that are already in VMM state. This paper demonstrates the viability and utility of the sidecore approach for two VMM-level classes of functionality: (1) efficient VM-VMM communication in VT-enabled processors and (2) interrupt virtualization for self- virtualized devices.