Re: [PATCH] KVM: x86/mmu: Add "never" option to allow sticky disabling of nx_huge_pages

[Luiz Capitulino]

On 2023-06-13 19:21, Sean Christopherson wrote:

> On Thu, 01 Jun 2023 17:58:59 -0700, Sean Christopherson wrote:
> > Add a "never" option to the nx_huge_pages module param to allow userspace
> > to do a one-way hard disabling of the mitigation, and don't create the
> > per-VM recovery threads when the mitigation is hard disabled.  Letting
> > userspace pinky swear that userspace doesn't want to enable NX mitigation
> > (without reloading KVM) allows certain use cases to avoid the latency
> > problems associated with spawning a kthread for each VM.
> >
> > [...]
>
> Applied to kvm-x86 mmu.  I kept the default as "auto" for now, as that can go on
> top and I don't want to introduce that change this late in the cycle.  If no one
> beats me to the punch (hint, hint ;-) ), I'll post a patch to make "never" the
> default for unaffected hosts so that we can discuss/consider that change for 6.6.

Thanks Sean, I agree with the plan. I could give a try on the patch if you'd like.

- Luiz

> Thanks for the reviews!
>
> [1/1] KVM: x86/mmu: Add "never" option to allow sticky disabling of nx_huge_pages
>        https://github.com/kvm-x86/linux/commit/0b210faf3373
>
> --
> https://github.com/kvm-x86/linux/tree/next
> https://github.com/kvm-x86/linux/tree/fixes