Virtual Switching Without a Hypervisor for a More Secure Cloud

Cloud computing leverages virtualization to offer resources on demand to multiple “tenants”. However, sharing the server and network infrastructure creates new vulnerabilities, where one tenant can attack another by compromising the underlying hypervisor. We design a system that supports virtualized networking using software switches without a hypervisor. In our architecture, the software switch runs in a Switch Domain (DomS) that is separate from the control VM. Both the guest VMs and DomS run directly on the server hardware, with processing and memory resources allocated in advance. Each guest VM interacts with the software switch through a shared memory region using periodic polling to detect network packets. The communication does not involve the hypervisor or the control VM. In addition, any software bugs that crash the software switch do not crash the rest of the system, and a crashed switch can be easily rebooted. Experiments with our initial prototype, built using Xen and Open vSwitch, show that the combination of shared pages and polling offers reasonable performance compared to conventional hypervisor-based solutions.