linux-kernel - Re: [PATCH v7 04/11] KVM: pfncache: base offset check on khva rather than gpa

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Message-ID: <b47e82a4-2c01-4207-b4f8-296243061202@xen.org>
Date:   Thu, 2 Nov 2023 18:11:59 +0000
From:   Paul Durrant <xadimgnik@...il.com>
To:     Sean Christopherson <seanjc@...gle.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Paul Durrant <pdurrant@...zon.com>,
        David Woodhouse <dwmw@...zon.co.uk>,
        David Woodhouse <dwmw2@...radead.org>,
        Paolo Bonzini <pbonzini@...hat.com>
Subject: Re: [PATCH v7 04/11] KVM: pfncache: base offset check on khva rather
 than gpa

On 31/10/2023 23:40, Sean Christopherson wrote:
> On Mon, Oct 02, 2023, Paul Durrant wrote:
>> From: Paul Durrant <pdurrant@...zon.com>
>>
>> After a subsequent patch, the gpa may not always be set whereas khva will
>> (as long as the cache valid flag is also set).
> 
> This holds true only because there are no users of KVM_GUEST_USES_PFN, and
> because hva_to_pfn_retry() rather oddly adds the offset to a NULL khva.
> 
> I think it's time to admit using this to map PFNs into the guest is a bad idea
> and rip out KVM_GUEST_USES_PFN before fully relying on khva.
> 
> https://lore.kernel.org/all/ZQiR8IpqOZrOpzHC@google.com

Is this something you want me to fix?

   Paul