Azure

Should We Panic About the KPTI/KAISER Intel CPU Design Flaw?

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As a followup to yesterday’s post, I’ve been asked: should we panic about the KPTI/KAISER/F*CKWIT Intel CPU design flaw? My answer was: it depends on a lot of unknowns. There are NDAs around a lot of the fixes so it’s hard to know the scope and effect. We also don’t know how much this will affect particular workloads. The folks over at Sophos have a nice writeup today about the actual problem (link below) but in short, the fix will reduce the effectiveness of the CPU’s speculative execution and on-die caches, forcing it to go out to main memory more. Main memory (what we call RAM) is 20x slower than the CPU’s L2 cache (look below for a good link showing …

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Intel CPU Design Flaw, Performance Degradation, Security Updates

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I was just taking a break and reading some tech news and I saw a wonderfully detailed post from El Reg (link below) about an Intel CPU design flaw and impending crisis-level security updates to fix it. As if that wasn’t bad enough, the fix for the problem is estimated to decrease performance by 5% to 30%, with older systems being the hardest hit. Welcome to 2018, folks. In short, an Intel CPU tries to keep itself busy by speculating about what it’s going to need to work on next. On Intel CPUs (but not AMD) this speculative execution doesn’t properly respect the security boundaries between the OS kernel and userspace applications, so you can trick an Intel processor into letting …

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