MI6: secure enclaves in a speculative out-of-order processor

MI6 is an aggressive, speculative out-of-order processor to support Secure Enclaves, which restore the process isolation guarantees broken by recent attacks exploiting microarchitectural sidechannels.Our threat model includes an untrusted OS and an attacker capable of mounting any software attack currently considered practical, including control flow speculation attacks such as Spectre. We model the performance impact of the hardware and software mechanisms added to support enclaves in MI6 through FPGA emulation on AWS F1 FPGAs by running SPEC CINT2006 benchmarks on top of an untrusted Linux OS. Security comes at the cost of 16.7% average slowdown for protected programs (MICRO 2019). Our open-source implementation will be auditable by the architecture and the security communities down to the hardware source code