Linux 6.3 To Support Making Use Of Intel's New LKGS Instruction (Part Of FRED)

As part of Intel's forthcoming Flexible Return and Event Delivery (FRED) specification is the new LKGS instruction for managing the state of the GS segment register in a more flexible manner. With Linux 6.3 the kernel will allow making use of the LKGS instruction where supported on future Intel CPUs.

Intel engineers have been working on Linux support for FRED and that remains in-development while the new LKGS instruction can be used outside of FRED. This week the kernel patches to allow making use of LKGS were queued up via TIP's "x86/cpu" branch ahead of the Linux 6.3 merge window. So barring any last minute issues from coming about in this relatively straight-forward code, that LKGS use will land with the Linux 6.3 cycle kicking off in February.

There is the new LKGS feature bit and using the new instruction for Linux's load_gs_index() function, among other related patches for enabling its use.

Intel hasn't yet publicly confirmed which generation of processors will ship with FRED and LKGS support.