POWER10 Virtualization, Intel SERIALIZE Come For KVM On Linux 5.9

Sent in last week for the Linux 5.9 kernel merge window were the initial batch of changes to the Kernel-based Virtual Machine (KVM) while today some additional interesting changes were sent out.

This latest material for KVM in Linux 5.9 includes:

- Support for the SERIALIZE instruction on KVM x86/x86_64. Intel's SERIALIZE ensures all flags/register/memory modifications are complete and all buffered writes drained before moving on to execute the next instruction. This can be used for stopping speculative execution and prefetching of modified kernel. The first CPUs expected with SERIALIZE are Sapphire Rapids and Alder Lake next year while Linux has already begun preparing for SERIALIZE where relevant.

- Initial support for POWER10 processors. This builds off the initial support in Linux 5.8 for being able to boot POWER10 hardware and further IBM POWER10 code merged this cycle. Now there is initial KVM support ahead of POWER10 systems expected to start shipping in real quantity next year.

- The KVM POWER code also has improvements/fixes for secure VM support yielding better startup time and support for memory hot-plugging.

- The KVM ARM code has support for level-based TLB invalidation, MMU cleanups, and other improvements.

- Fixes for MIPS and other architectures.

More details on the KVM changes for Linux 5.9 via this pull request.