Re: [PATCH 0/4] KVM: x86/mmu: Fix TDP MMU dirty logging bug L2 running with EPT disabled

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On Tue, Apr 9, 2024 at 5:20 PM Sean Christopherson <seanjc@xxxxxxxxxx> wrote:
>
> On Fri, 15 Mar 2024 16:05:37 -0700, David Matlack wrote:
> > Fix a bug in the TDP MMU caught by syzkaller and CONFIG_KVM_PROVE_MMU
> > that causes writes made by L2 to no be reflected in the dirty log when
> > L1 has disabled EPT.
> >
> > Patch 1 contains the fix. Patch 2 and 3 fix comments related to clearing
> > dirty bits in the TDP MMU. Patch 4 adds selftests coverage of dirty
> > logging of L2 when L1 has disabled EPT. i.e.  a regression test for this
> > bug.
> >
> > [...]
>
> Applied to kvm-x86 fixes, with the various tweaks mentioned in reply, and the
> s/READ_ONCE/WRITE_ONCE fixup.  A sanity check would be nice though, I botched
> the first attempt at the fixup (the one time I _should_ have copy+pasted code...).
>
> Thanks!
>
> [1/4] KVM: x86/mmu: Check kvm_mmu_page_ad_need_write_protect() when clearing TDP MMU dirty bits
>       https://github.com/kvm-x86/linux/commit/b44914b27e6b
> [2/4] KVM: x86/mmu: Remove function comments above clear_dirty_{gfn_range,pt_masked}()
>       https://github.com/kvm-x86/linux/commit/d0adc4ce20e8
> [3/4] KVM: x86/mmu: Fix and clarify comments about clearing D-bit vs. write-protecting
>       https://github.com/kvm-x86/linux/commit/5709b14d1cea
> [4/4] KVM: selftests: Add coverage of EPT-disabled to vmx_dirty_log_test
>       https://github.com/kvm-x86/linux/commit/1d24b536d85b

This commit does not have the WRITE_ONCE() fixup, but when I look at
the commits in the fixes branch itself I see [1] which is correct.

The other commits look good as well, thanks for the various fixups.

[1] https://github.com/kvm-x86/linux/commit/f1ef5c343399ec5e21eb1e1e0093e731dce2fa1e

>
> --
> https://github.com/kvm-x86/linux/tree/next





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