Initial Benchmarks Of The Spectre "SWAPGS" Mitigation Performance Impact

Yesterday the SWAPGS vulnerability was made public as a new variant of Spectre V1 that affects all operating systems and is believed to affect only Intel CPUs. The SWAPGS discovery by Bitdefender was quietly mitigated by Microsoft for Windows 10 last month while yesterday the patches were posted for the mainline Linux kernel as the Grand Schemozzle. As soon as learning of this SWAPGS vulnerability and seeing the kernel code, I began running some preliminary performance tests to look at the impact of this latest CPU mitigation.