Lightweight Shadow Paging for Efficient Memory Isolation in Gandalf VMM

Demands are increasing for consolidating multiple OSes on a single multi-core CPU rather than using multiple sets of an OS and a CPU. A VMM enables multiple guest OSes to run concurrently on one CPU while providing separate security domains. We have developed Gandalf a lightweight VMM targeting embedded systems with multi-core CPUs. This paper focuses on the shadow paging mechanism of Gandalf which enables physical memory isolation among guest OSes by separating guest page tables from CPUs, because shadow paging significantly affects VMM overheads and is a key to make a VMM lightweight. We designed and implemented two models of shadow paging, single shadow model and multiple shadow model. The measurement results show that they are realized lightweight.