Re: [RFC PATCH 16/21] KVM: x86/mmu: Introduce kvm_split_boundary_leafs() to split boundary leafs

[Edgecombe, Rick P]

On Fri, 2025-05-16 at 19:44 +0800, Yan Zhao wrote:
> > > What do you think about relying on tdp_mmu_split_huge_pages_root() and
> > > moving
> > > this to an optimization patch at the end?
> > > 
> > > Or what about just two calls to tdp_mmu_split_huge_pages_root() at the
> > > boundaries?
> > Though the two generally look like the same, relying on
> > tdp_mmu_split_huge_pages_root() will create several minor changes scattering
> > in tdp_mmu_split_huge_pages_root().
> > 
> > e.g. update flush after tdp_mmu_iter_cond_resched(), check
> > iter_split_required(), set "iter.yielded = true".
> > 
> > So, it may be hard to review as a initial RFC.
> > 
> > I prefer to do that after Paolo and Sean have taken a look of it :)
> 
> Oh, I might misunderstood your meaning.
> Yes, if necessary, we can provide a separate patch at the end to combine code
> of
> tdp_mmu_split_huge_pages_root() and tdp_mmu_split_boundary_leafs().

Hmm, I'm not sure if they will look at this version or wait until Intel folks
work through it a bit. As for reviewability, the log could simply explain that
tdp_mmu_split_huge_pages_root() is the simple option and an optimization patch
will follow. I think it's helpful to separate optimization from implementation.
It can be confusing what is for which purpose.