AMD Family 19h CPU microcode 2023-10-19 was added today to Linux-Firmware.Git, the de facto location where CPU microcode/firmware binaries are housed for easy integration by Linux distributions and other software vendors.
The commit updating the CPU microcode simply notes, " Update AMD cpu microcode for processor family 19h " which is standard for the AMD microcode updates with very rarely outlining what fixes, security updates, or other changes are made. The updated CPU microcode is automatically applied at boot-time on Linux systems or can alternatively be late-loaded as well for those wishing to avoid the reboot/down-time.
The new microcode is the first AMD Family 19h update since August when AMD released updated CPU microcode for addressing the Inception vulnerability . Today's microcode push falls outside of Patch Tuesday and there are no new security bulletins from AMD this week on the CPU side, so hopefully this amounts to just a routine update for addressing functional issues or other refinements. In any event I'll be trying out the new CPU microcode on AMD Zen 3/4 servers to look-out for any changes or performance differences.