From: Sean Christopherson seanjc@google.com

Explicitly check for present SPTEs when clearing dirty bits in the TDP MMU. This isn't strictly required for correctness, as setting the dirty bit in a defunct SPTE will not change the SPTE from !PRESENT to PRESENT. However, the guarded MMU_WARN_ON() in spte_ad_need_write_protect() would complain if anyone actually turned on KVM's MMU debugging.

Fixes: a6a0b05da9f3 ("kvm: x86/mmu: Support dirty logging for the TDP MMU") Cc: Ben Gardon bgardon@google.com Signed-off-by: Sean Christopherson seanjc@google.com Reviewed-by: Ben Gardon bgardon@google.com Message-Id: 20220226001546.360188-3-seanjc@google.com Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini pbonzini@redhat.com --- arch/x86/kvm/mmu/tdp_mmu.c | 3 +++ 1 file changed, 3 insertions(+)

diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index debf08212f12..4cf0cc04b2a0 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -1468,6 +1468,9 @@ static bool clear_dirty_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root, if (tdp_mmu_iter_cond_resched(kvm, &iter, false, true)) continue;

+ if (!is_shadow_present_pte(iter.old_spte)) + continue; + if (spte_ad_need_write_protect(iter.old_spte)) { if (is_writable_pte(iter.old_spte)) new_spte = iter.old_spte & ~PT_WRITABLE_MASK;