linux-kernel - Re: [PATCH 04/10] KVM: Avoid pfn_to_page() and vice versa when releasing pages

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Message-ID: <e793f8f4-69dd-1824-7bb1-048428d977f4@redhat.com>
Date:   Thu, 16 Jun 2022 17:00:22 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Sean Christopherson <seanjc@...gle.com>
Cc:     Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 04/10] KVM: Avoid pfn_to_page() and vice versa when
 releasing pages

On 4/29/22 03:04, Sean Christopherson wrote:
> -
> +/*
> + * Note, checking for an error/noslot pfn is the caller's responsibility when
> + * directly marking a page dirty/accessed.  Unlike the "release" helpers, the
> + * "set" helpers are not to be unused when the pfn might point at garbage.
> + */

s/unused/unused/

But while at it, I'd rather add a WARN_ON(is_error_noslot_pfn(pfn)).

Paolo

>   void kvm_set_pfn_dirty(kvm_pfn_t pfn)
>   {
> -	if (kvm_is_ad_tracked_pfn(pfn))
> -		SetPageDirty(pfn_to_page(pfn));
> +	if (pfn_valid(pfn))
> +		kvm_set_page_dirty(pfn_to_page(pfn));
>   }
>   EXPORT_SYMBOL_GPL(kvm_set_pfn_dirty);
>   
>   void kvm_set_pfn_accessed(kvm_pfn_t pfn)
>   {
> -	if (kvm_is_ad_tracked_pfn(pfn))
> -		mark_page_accessed(pfn_to_page(pfn));
> +	if (pfn_valid(pfn))
> +		kvm_set_page_accessed(pfn_to_page(pfn));
>   }
>   EXPORT_SYMBOL_GPL(kvm_set_pfn_accessed);