Linux 5.14 POWERs Up The Microwatt Soft CPU Core

The POWER architecture updates have been submitted for the ongoing Linux 5.14 merge window with a few changes worth pointing out this round.

First up, Linux 5.14 adds support for the OpenPOWER Microwatt soft CPU core. This is the OpenPOWER FPGA-based soft CPU design that is built on Power ISA 3.0 and the first open-source POWER design written from scratch. With Linux 5.14 there is preliminary support for the OpenPOWER Microwatt but not yet any SMP capabilities nor other advanced CPU capabilities.

POWER in Linux 5.14 also has a big refactoring to its KVM code, optimizations for its 64-bit interrupt return path, support for user-space access to the POWER10 CPU's NX GZIP accelerator, and other small changes.

At this stage it appears IBM has most of the POWER10 support all squared away for Linux.

The full list of POWER processor changes for Linux 5.14 can be found via this PR that has already been merged to mainline.