Hardware Security
Which statement about countermeasures to speculative-execution vulnerabilities is generally correct?
- ACountermeasures have no effect on performance at all
- BThe more speculation and cache sharing are restricted, the safer it gets, but performance drops, so the choice balances security and performance
- CRemoving speculation makes CPUs faster
Show answer and explanation
Answer: B. The more speculation and cache sharing are restricted, the safer it gets, but performance drops, so the choice balances security and performance
Speculative execution, branch prediction and shared caches underpin modern CPU performance. Restricting them reduces leakage but costs performance. So OS, compiler and CPU designers choose how far to go based on the information at stake and the severity of the threat. Newer CPUs increasingly build in countermeasures with little performance impact.
- A. Some workloads slow noticeably.
- B. Correct. The very features that boost performance are the cause.
- C. Speculation exists to raise performance.