AMD 4th Gen EPYC "Genoa" To Enjoy Slightly Better Performance With Linux 6.3

Expected to be squared away in time for the Linux 6.3 kernel cycle, which is kicking off in February, is Automatic IBRS as a new feature of Zen 4 processors. The patches already have been queued up into TIP's x86/cpu branch so barring any issues will be all wired up for this next kernel version. Automatic IBRS can provide better performance than the Retpolines implementation used currently on Zen 4 and prior CPUs as part of the Spectre V2 mitigations. With the switch over to Automatic IBRS for Zen 4, it means better performance in some areas as shown by these benchmarks today with AMD 4th Gen EPYC "Genoa" processors.