Re: [PATCH v6 0/5] x86: Enable LKGS instruction

[Ingo Molnar <mingo@kernel.org>]

* Xin Li <xin3.li@intel.com> wrote:

> LKGS instruction is introduced with Intel FRED (flexible return and event 
> delivery) specification. As LKGS is independent of FRED, we enable it as 
> a standalone CPU feature.
> 
> LKGS behaves like the MOV to GS instruction except that it loads the base 
> address into the IA32_KERNEL_GS_BASE MSR instead of the GS segment’s 
> descriptor cache, which is exactly what Linux kernel does to load user 
> level GS base.  Thus, with LKGS, there is no need to SWAPGS away from the 
> kernel GS base.

Ok, this looks good to me.

I've applied the first 4 patches to tip:x86/cpu, as the instruction exists 
in a public document and these patches are fine stand-alone as well, such 
as the factoring out of load_gs_index() methods from a high-use low level 
header into a new header file.

Planning to apply the final, LKGS enabler patch as well, unless there's any 
objections from others?

Thanks,

	Ingo