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A comment on The dangers of AVX-512 throttling: a 3% impact.

Re:The dangers of AVX-512 throttling: a 3% impact by NightMKoder on Thursday August 16, 2018 @01:10AM (#17772071)
This might be a bit...too far out there, but could there be side channel attacks via cpu heating? Like heating the cpu to near borderline with AVX512 and seeing if a hyperthread causes throttling due to some “heavy” aes instruction. Sounds unlikely to be exploitable though.

Ever since specter I’m thinking of any performance changes by previous instructions might be exploitable. Again thermal throttling might be a bit too far out there since it’s not _that_ deterministic. Fun thought though!

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Re:The dangers of AVX-512 throttling: a 3% impact by greenpenguin on Thursday August 16, 2018 @05:41AM (#17773236)
Not via CPU heating, but a theoretical AVX Spectre attack popped up on HN recently: https://news.ycombinator.com/item?id=17711823
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Re:The dangers of AVX-512 throttling: a 3% impact by dexen on Thursday August 16, 2018 @01:40AM (#17772206)
I remember a paper on a close subject - "Revealing hidden services by their clock skew" [1] tl;dr: performing operations on the hidden Tor nodes causes CPU heating, which causes OS clock drift due changing CPU clock circuit properties.

As for AVX512, I'm not sure - IIRC the Intel CPUs throttle (or lower frequency) automatically around the AVX512 execution for TDP reasons.

[1] https://news.ycombinator.com/item?id=7694612

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