Recently, VUSec, the security group at VU Amsterdam, discovered a new BHI Spectre v2 vulnerability in Intel and ARM CPUs. With the mitigation patch put in place, it was found that even modern 11th Gen and 12th Gen Intel processors were losing a lot of performance with the new patch.
Although AMD CPUs appear to be impervious to this new Spectre-BHB threat, the IPAS STORM security team over at Intel discovered that the LFENCE/JMP mitigation for Spectre v2 used in AMD CPUs wasn't helping much. As a result, AMD now recommends either the "generic retpoline" or the Indirect Branch Restricted Speculation (IBRS) mitigation methods.
To see how the new generic retpoline impacts the performance of AMD chips, Phoronix decided to test three newly patched systems powered by three different eligible AMD CPUs.
First, we have the 16 core Ryzen 9 5950X desktop CPU, and outside of the Stress-NG synthetic stress test, the performance loss is much lower compared to what we were seeing on the Core i9-12900K after it was patched.
After that, we have the 8-core Ryzen 9 5900HX mobile chip, and this time the performance loss was slightly bigger, though still, it was far lower than what was observed on the Tiger Lake Core i7-1185G7.
Finally, we also have an EPYC CPU in the form of the 8-core EPYC 72F3, and in this instance, the results were mixed as the EPYC chip even performed better in certain benchmarks post-retpoline patch.
You can read about the full test setup and such in the original article linked at source below.
Source and images: Phoronix