AMD CPU Microcode Loading On Linux Being Fixed Up To Be Per-Thread

Up to this point loading updated CPU microcode on AMD processors under Linux has checked just to ensure every physical CPU core was loaded with the new microcode but not sibling threads for SMT processors. While logically that makes sense, it turns out some AMD microcode updates do carry out per-thread modifications that means the microcode updating needs to be carried out on every thread. A Linux fix is on its way to the kernel to adjust that behavior...