Hector Martin

TL;DR on ZombieLoad: this is like L1TF, where the CPU is using "garbage" data during a fault instead of coercing to zero (except here it's data instead of addresses). It seems this is pervasive problem class across the design of Intel CPUs, not just a single instance.

Basically it seems their engineering teams have, until now, considered it acceptable to have known-to-fault instructions operate on *complete garbage*, ignoring *all* privilege rules, as long as they will never retire.

This is, of course, completely insane from a security perspective, and given that we're now acutely aware of speculation attacks, represents *many* different opportunities for leakage. L1TF and ZombieLoad are on a completely different class from Spectre/Meltdown.

So my recommendation at this point would be to avoid Intel CPUs for several years if you care about this sort of thing, and OSes *need* to implement hyperthread pair privilege boundary separation, since that's most of the attack surface.

I am lucky enough to have non-hyperthread, four core Intel CPUs on both of my desktops (Linux and Windows), an i5-4590T and an i5-7500T. Though not that common, they exist. Not saying this solves every Intel problem, of course. But some people need to buy Intel for other reasons.

Well if losing all performance (that you paid for...) provided by hyperthreading is an option, then most BIOSes allow you to disable hyperthreading AFAICT.