> The threat resides in the chips’ data memory-dependent prefetcher, a hardware optimization that predicts the memory addresses of data that running code is likely to access in the near future. Are we nearing any sort of consensus that any form of speculation is bad? Is there a fundamentally secure way to do it?
At the hardware level any optimizations that change performance characteristics locally (how long the crypto operation directly takes) or non locally (in this case the secrets leak via observation of cache timings in the attacker's untrusted code) are unsafe.
Intel DMPs already have a flag to turn off the same behavior that was exploited on the M1/M2. Which may suggest that the risk of this type of optimization was understood previously.
Mixing crypto operations with general purpose computation and memory accesses is a fragile balance. Where possible try utilizing HSMs, yubikeys, secure enclaves - any specialized hardware that has been hardened to protect key material.