‘Beyond stupid’: Linus Torvalds trashes 5.8 Linux kernel patch over opt-in Intel CPU bug mitigation

AWS engineers given a dressing-down after proposing fix for ‘paranoid’ tasks

Linus Torvalds has removed a patch in the next release of the Linux kernel intended to provide additional opt-in mitigation of attacks against the L1 data (L1D) CPU cache.

The patch from AWS engineer Balbir Singh was to provide “an opt-in (prctl driven) mechanism to flush the L1D cache on context switch. The goal is to allow tasks that are paranoid due to the recent snoop-assisted data sampling vulnerabilities, to flush their L1D on being switched out. This protects their data from being snooped or leaked via side channels after the task has context switched out.” …