The KVM Changes Aren't Too Notable For Linux 5.1, But Many x86 Cleanups

Paolo Bonzini submitted the Kernel-based Virtual Machine (KVM) changes for the Linux 5.1 kernel on Friday, much later in the cycle than normal. This isn't due to some big ticket features landing but rather "some ugly factors" in the form of tracking down some bugs and ended up dropping some premature optimizations.

So for Linux 5.1 the KVM virtualization work isn't the most exciting but there are some clean-ups for the ARM code, similar work on the S390 front, bug fixes and improvements to the POWER code, and "many, many cleanups" on the x86 front. Along with the many x86/x86_64 cleanups to the KVM code, a number of unnecessary MMU code optimizations were removed.

One little bit of additional KVM x86 news to pass along is that MOVDIRI and MOVDIR64B CPU features are now exposed to the VMs when supported by the host processor. MOVDIR/MOVDIR64B are some of the new instructions coming to Intel's 10nm Tremont CPU cores as the successor to Goldmont Plus. These are new direct store instructions for Intel CPUs and now with Linux 5.1+, guests will be able to use those instructions when running on the next-generation Intel hardware.

The complete list of KVM changes for the Linux 5.1 merge window are outlined via this pull request that has already been merged to mainline.