Hervé Debar

Nested virtualization [1] provides an extra layer of virtualization to enhance security with fairly reasonable performance impact. User-centric vision of cloud computing gives a high-level of control on the whole infrastructure [2], such as untrusted dom0 [3, 4]. This paper introduces RetroVisor, a security architecture to seam-lessly run a virtual machine (VM) on multiple hypervisors simulta-neously. We argue that this approach delivers high-availability and provides strong guarantees on multi IaaS infrastructures. The user can perform detection and remediation against potential hypervi-sors weaknesses, unexpected behaviors and exploits. 1. ARCHITECTURE The physical host is running a minimal hypervisor (L0) with nested virtualization enabled. L0 hypervisor controls, monitors and runs multiple guest hypervisors (L1) in isolated environments. Each L1 hypervisor deals with its own VM image and VM execution. Th