| Message ID | 20240315230541.1635322-1-dmatlack@google.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | KVM: x86/mmu: Fix TDP MMU dirty logging bug L2 running with EPT disabled | expand |
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 -- https://github.com/kvm-x86/linux/tree/next
On Tue, Apr 9, 2024 at 5:20 PM Sean Christopherson <seanjc@google.com> 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
On Wed, Apr 10, 2024, David Matlack wrote: > On Tue, Apr 9, 2024 at 5:20 PM Sean Christopherson <seanjc@google.com> 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. Argh, I must have forgot to copy+paste in the correct hashes (like I said above, it took me a few tries to get things right). For posterity... [1/4] KVM: x86/mmu: Write-protect L2 SPTEs in TDP MMU when clearing dirty status 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/f1ef5c343399
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. David Matlack (4): KVM: x86/mmu: Check kvm_mmu_page_ad_need_write_protect() when clearing TDP MMU dirty bits KVM: x86/mmu: Remove function comments above clear_dirty_{gfn_range,pt_masked}() KVM: x86/mmu: Fix and clarify comments about clearing D-bit vs. write-protecting KVM: selftests: Add coverage of EPT-disabled to vmx_dirty_log_test arch/x86/kvm/mmu/tdp_mmu.c | 51 +++++++--------- .../selftests/kvm/x86_64/vmx_dirty_log_test.c | 60 ++++++++++++++----- 2 files changed, 68 insertions(+), 43 deletions(-) base-commit: 687d8f4c3dea0758afd748968d91288220bbe7e3