In the past, we've seen tests timing out because some/all cores were stuck in WFE state.

Ideally, the tests should be implemented in a robust manner that prevents this situation to occur. As a safeguard, we might want to enable the ARM architected timer event stream generation. This is a feature of the ARM architected timer (enabled through the CNTKCTL_EL1.EVNTEN bit) which makes it generate a WFE-wake up event at a fixed frequency (represented as a power-of-2 divisor of the clock rate).