RE: [patch 13/31] x86/fpu: Move KVMs FPU swapping to FPU core

Thomas Gleixner
2021-10-13T15:12:19Z

Jing,

On Wed, Oct 13 2021 at 06:15, Jing2 Liu wrote:
>> On 12/10/21 02:00, Thomas Gleixner wrote:
> When looking into the tglx/devel.git x86/fpu for the full #1-#4
> series and the KVM AMX support, I'd like to talk two things
> as follows,
>
> 1. KVM dynamic allocation API:
> Since KVM also uses dynamic allocation, after KVM detects guest
> requesting AMX by #NM trap, KVM need alloc extra buffer for
> this vcpu's current->thread.fpu.fpstate and guest_fpu related.
> So far, the kernel itself has such API like fpstate_realloc(), but it's
> static. How about making a common function usable for KVM?

Just making that function usable without a proper design how this should
work at all does not solve anything.

We first need a conclusion vs. buffer reallocation.

Once that is sorted then we can create proper infrastructure for that in
the FPU core code and not just expose a random function to KVM and hack
it into submssion.

Thanks,

tglx