The Big Set Of x86 Changes Hit The Linux 5.6 Kernel

As part of the Linux 5.6 development dance, Ingo Molnar began sending in all of the pull requests this morning for the different areas of the Linux kernel he oversees.

On the x86/asm front for x86 Assembly changes to the kernel, there has been some code clean-ups as well as a micro-optimization/simplification to the 32-bit boot code. Most interesting though on the Assembly side is Linux 5.6 will now use Intel Ice Lake's Fast Short REP MOV instruction for faster memmove() performance. The FSRM instruction with Ice Lake should offer faster memory movements from one location to another. It will be interesting to see on the Ice Lake Core i7-1065G7 system if this ends up having any meaningful performance difference in the real-world.

On the x86/cache front is now a cpu_resctrl_groups file exposed under procfs for each PID to help navigate from tasks to resctrl groups.

Not part of Ingo's x86 pulls, but related x86 work is yesterday Thomas Gleixner sending in the x86/pti updates. The only item worth mentioning there is white-listing of new Zhaoxin x86 CPUs now that their 7-series CPUs are mitigated for Spectre V2 and SWAPGS. (There isn't any new kernel patches pertaining to Intel's newest security disclosures but on that front it sounds like Intel will be mitigating with microcode updates rather than kernel changes.)

Various code cleanups came with x86/cleanups and some minor improvements within x86/core. Meanwhile x86/cpu has a clean-up to the handling of VMX feature code that also makes it better future-proofed. Lastly the x86/fpu code has a fix for possible FPU corruption.