linux-kernel - Re: [Patch v3 2/7] KVM: x86/mmu: Atomically clear SPTE dirty state in the clear-dirty-log flow

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Message-ID: <CAHVum0dKw-i5v+m8xgD=8bqs3tajFbJoSnZadjYtXSORKcuF0g@mail.gmail.com>
Date:   Fri, 17 Mar 2023 16:50:11 -0700
From:   Vipin Sharma <vipinsh@...gle.com>
To:     Sean Christopherson <seanjc@...gle.com>
Cc:     pbonzini@...hat.com, bgardon@...gle.com, dmatlack@...gle.com,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [Patch v3 2/7] KVM: x86/mmu: Atomically clear SPTE dirty state in
 the clear-dirty-log flow

On Fri, Mar 17, 2023 at 3:59 PM Sean Christopherson <seanjc@...gle.com> wrote:
>
> On Fri, Feb 10, 2023, Vipin Sharma wrote:
> > @@ -1677,8 +1670,13 @@ bool kvm_tdp_mmu_clear_dirty_slot(struct kvm *kvm,
> >  static void clear_dirty_pt_masked(struct kvm *kvm, struct kvm_mmu_page *root,
> >                                 gfn_t gfn, unsigned long mask, bool wrprot)
> >  {
> > +     /*
> > +      * Either all SPTEs in TDP MMU will need write protection or none. This
> > +      * contract will not be modified for TDP MMU pages.
> > +      */
> > +     u64 clear_bit = (wrprot || !kvm_ad_enabled()) ? PT_WRITABLE_MASK :
> > +                                                     shadow_dirty_mask;
>
> Switching from spte_ad_need_write_protect() to kvm_ad_enabled() belongs in a
> separate.  In the unlikely event that the above assertion/contracts is invalid,
> then any issues should bisect to the switch, not to a much more complex patch.
>
> I'll make that happen when applying.

Make sense, thanks!