Re: [PATCH 0/2] KVM: x86/mmu: Micro-optimize TDP MMU cond_resched()

From: Sean Christopherson
Date: Tue Nov 05 2024 - 01:02:54 EST


On Thu, 31 Oct 2024 10:06:31 -0700, Sean Christopherson wrote:
> Invert the order of checks in tdp_mmu_iter_cond_resched() so that the common
> case (no resched needed) is checked first, and opportunsitically clean up a
> wart where the helper would return "yielded" in an error path, even if that
> invocation didn't actually yield. The latter cleanup allows extracting the
> base "need resched" logic to a separate helper.
>
> Note, I "speculatively" pushed these patches to kvm-x86 mmu, as they are
> effectively needed for David's series to optimize hugepage recovery when
> disabling dirty logging. I'll rework the commits sometime next weeks, e.g.
> fix a few changelog typos (I found two, so far), to capture reviews, and
> add Links. And if there are problems, I'll yank you the entire series
> (David's and mine).
>
> [...]

"Officially" applied to kvm-x86 mmu.

[1/2] KVM: x86/mmu: Check yielded_gfn for forward progress iff resched is needed
https://github.com/kvm-x86/linux/commit/e287e4316713
[2/2] KVM: x86/mmu: Demote the WARN on yielded in xxx_cond_resched() to KVM_MMU_WARN_ON
https://github.com/kvm-x86/linux/commit/38b0ac47169b

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https://github.com/kvm-x86/linux/tree/next