  Microprocessors enable aggressive hardware virtualization by means of which
multiple processes temporally execute on the system. These security-critical
and ordinary processes interact with each other to assure application progress.
However, temporal sharing of hardware resources exposes the processor to
various microarchitecture state attacks. State-of-the-art secure processors,
such as MI6 adopt Intel's SGX enclave execution model. MI6 architects strong
isolation by statically isolating shared memory state, and purging the
microarchitecture state of private core, cache, and TLB resources on every
enclave entry and exit. The purging overhead significantly impacts performance
as the interactivity across the secure and insecure processes increases. This
paper proposes IRONHIDE that implements strong isolation in the context of
multicores to form spatially isolated secure and insecure clusters of cores.
For an interactive application comprising of secure and insecure processes,
IRONHIDE pins the secure process(es) to the secure cluster, where they execute
and interact with the insecure process(es) without incurring the
microarchitecture state purging overheads on every interaction event. IRONHIDE
improves performance by 2.1x over the MI6 baseline for a set of user and OS
interactive applications. Moreover, IRONHIDE improves performance by 20% over
an SGX-like baseline, while also ensuring strong isolation guarantees against
microarchitecture state attacks.
