Re: [Intel-gfx] [PATCH 3/6] KVM: x86/mmu: avoid struct page in MMU

Paolo Bonzini
2021-06-24T10:17:46Z

On 24/06/21 12:06, Marc Zyngier wrote:
> On Thu, 24 Jun 2021 09:58:00 +0100,
> Nicholas Piggin <npiggin@gmail.com> wrote:
>>
>> Excerpts from David Stevens's message of June 24, 2021 1:57 pm:
>>> From: David Stevens <stevensd@chromium.org>
>>> out_unlock:
>>> if (is_tdp_mmu_root(vcpu->kvm, vcpu->arch.mmu->root_hpa))
>>> read_unlock(&vcpu->kvm->mmu_lock);
>>> else
>>> write_unlock(&vcpu->kvm->mmu_lock);
>>> - kvm_release_pfn_clean(pfn);
>>> + if (pfnpg.page)
>>> + put_page(pfnpg.page);
>>> return r;
>>> }
>>
>> How about
>>
>> kvm_release_pfn_page_clean(pfnpg);
>
> I'm not sure. I always found kvm_release_pfn_clean() ugly, because it
> doesn't mark the page 'clean'. I find put_page() more correct.
>
> Something like 'kvm_put_pfn_page()' would make more sense, but I'm so
> bad at naming things that I could just as well call it 'bob()'.

The best way to go would be to get rid of kvm_release_pfn_clean() and
always go through a pfn_page. Then we could or could not introduce
wrappers kvm_put_pfn_page{,_dirty}.

I think for now it's best to limit the churn since these patches will go
in the stable releases too, and clean up the resulting API once we have
a clear idea of how all architectures are using kvm_pfn_page.

Paolo