Directvisor: Virtualization for bare-metal cloud

Bare-metal cloud platforms allow customers to rent remote physical servers and install their preferred operating systems and software to make the best of servers' raw hardware capabilities. However, this quest for bare-metal performance compromises cloud manageability. To avoid overheads, cloud operators cannot install traditional hypervisors that provide common manageability functions such as live migration and introspection. We aim to bridge this gap between performance, isolation, and manageability for bare-metal clouds. Traditional hypervisors are designed to limit and emulate hardware access by virtual machines (VM). In contrast, we propose Directvisor-a hypervisor that maximizes a VM's ability to directly access hardware for near-native performance, yet retains hardware control and manageability. Directvisor goes beyond traditional direct-Assigned (pass-Through) I/O devices by allowing VMs to directly control and receive hardware timer interrupts and inter-processor interrupts (IPIs) besides eliminating most VM exits. At the same time, Directvisor supports seamless (low-downtime) live migration and introspection for such VMs having direct hardware access.