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

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Date:   Thu, 24 Jun 2021 11:06:27 +0100
From:   Marc Zyngier <maz@...nel.org>
To:     Nicholas Piggin <npiggin@...il.com>
Cc:     Aleksandar Markovic <aleksandar.qemu.devel@...il.com>,
        Huacai Chen <chenhuacai@...nel.org>,
        Paul Mackerras <paulus@...abs.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        David Stevens <stevensd@...omium.org>,
        Zhenyu Wang <zhenyuw@...ux.intel.com>,
        Zhi Wang <zhi.a.wang@...el.com>,
        Alexandru Elisei <alexandru.elisei@....com>,
        dri-devel@...ts.freedesktop.org, intel-gfx@...ts.freedesktop.org,
        intel-gvt-dev@...ts.freedesktop.org,
        James Morse <james.morse@....com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvmarm@...ts.cs.columbia.edu,
        kvm-ppc@...r.kernel.org, kvm@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-mips@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        Sean Christopherson <seanjc@...gle.com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Will Deacon <will@...nel.org>
Subject: Re: [PATCH 3/6] KVM: x86/mmu: avoid struct page in MMU

On Thu, 24 Jun 2021 09:58:00 +0100,
Nicholas Piggin <npiggin@...il.com> wrote:
> 
> Excerpts from David Stevens's message of June 24, 2021 1:57 pm:
> > From: David Stevens <stevensd@...omium.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()'.

	M.

-- 
Without deviation from the norm, progress is not possible.