COSMOS: A Fault Injection Framework to Assess Hardware-Assisted Hypervisors

Hardware-assisted virtualization represents a pillar technology for large-scale clusters and cloud-based applications. Hardware faults are still frequent as technology advances, potentially resulting in serious reliability concerns. This paper introduces COSMOS, a fault injection framework tailored for testing hardware-assisted hypervisors. By exploiting nested virtualization, COSMOS does not require instrumentation of the target and enables the assessment of multiple hypervisors. We performed an extensive fault injection campaign to assess popular hardware-assisted hypervisors like KVM, Xen, and Jailhouse. The results show a non-negligible percentage of non–fail-stop behaviors, with notable differences in hypervisors’ ability to log failures and prevent fault propagation with a timely recovery.