linux-kernel - Re: [PATCH v5 4/4] KVM: mmu: remove over-aggressive warnings

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Date:   Tue, 11 Jan 2022 08:47:47 +0900
From:   David Stevens <stevensd@...omium.org>
To:     Sean Christopherson <seanjc@...gle.com>
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,
        Chia-I Wu <olv@...omium.org>
Subject: Re: [PATCH v5 4/4] KVM: mmu: remove over-aggressive warnings

> The best thing to do is probably to wait for for kvm_vcpu_map() to be eliminated,
> as described in the changelogs for commits:
>
>   357a18ad230f ("KVM: Kill kvm_map_gfn() / kvm_unmap_gfn() and gfn_to_pfn_cache")
>   7e2175ebd695 ("KVM: x86: Fix recording of guest steal time / preempted status")
>
> Once that is done, everything in KVM will either access guest memory through the
> userspace hva, or via a mechanism that is tied into the mmu_notifier, at which
> point accessing non-refcounted struct pages is safe and just needs to worry about
> not corrupting _refcount.

That does sound like the best approach. I'll put this patch series on
hold until that work is done.