linux-kernel - Re: [PATCH v5 2/4] KVM: x86/mmu: use gfn_to_pfn

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Message-ID: <Yc4I8DNgQjomsfrc@google.com>
Date:   Thu, 30 Dec 2021 19:30:56 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     David Stevens <stevensd@...omium.org>
Cc:     Marc Zyngier <maz@...nel.org>, Paolo Bonzini <pbonzini@...hat.com>,
        James Morse <james.morse@....com>,
        Alexandru Elisei <alexandru.elisei@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Will Deacon <will@...nel.org>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Subject: Re: [PATCH v5 2/4] KVM: x86/mmu: use gfn_to_pfn_page

On Mon, Nov 29, 2021, David Stevens wrote:
> From: David Stevens <stevensd@...omium.org>
> 
> Covert usages of the deprecated gfn_to_pfn functions to the new
> gfn_to_pfn_page functions.
> 
> Signed-off-by: David Stevens <stevensd@...omium.org>
> ---
>  arch/x86/kvm/mmu.h             |  1 +
>  arch/x86/kvm/mmu/mmu.c         | 18 +++++++++++-------
>  arch/x86/kvm/mmu/paging_tmpl.h |  9 ++++++---
>  arch/x86/kvm/x86.c             |  6 ++++--
>  4 files changed, 22 insertions(+), 12 deletions(-)
> 
> diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
> index 9ae6168d381e..97d94a9612b6 100644
> --- a/arch/x86/kvm/mmu.h
> +++ b/arch/x86/kvm/mmu.h
> @@ -164,6 +164,7 @@ struct kvm_page_fault {
>  	/* Outputs of kvm_faultin_pfn.  */
>  	kvm_pfn_t pfn;
>  	hva_t hva;
> +	struct page *page;
>  	bool map_writable;
>  };
>  
> diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> index 04c00c34517e..0626395ff1d9 100644
> --- a/arch/x86/kvm/mmu/mmu.c
> +++ b/arch/x86/kvm/mmu/mmu.c
> @@ -2891,6 +2891,9 @@ void kvm_mmu_hugepage_adjust(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault
>  	if (unlikely(fault->max_level == PG_LEVEL_4K))
>  		return;
>  
> +	if (!fault->page)
> +		return;
> +
>  	if (is_error_noslot_pfn(fault->pfn) || kvm_is_reserved_pfn(fault->pfn))

These two checks can go away as they're made obsolete by the new !fault->page check.

>  		return;
>