Commit 3354ef5a authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

KVM: x86/mmu: Check for present SPTE when clearing dirty bit in TDP MMU 



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: a6a0b05d ("kvm: x86/mmu: Support dirty logging for the TDP MMU")
Cc: Ben Gardon <bgardon@google.com>
Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Reviewed-by: default avatarBen Gardon <bgardon@google.com>
Message-Id: <20220226001546.360188-3-seanjc@google.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 37b2a651

arch/x86/kvm/mmu/tdp_mmu.c

+3 −0
Original line number Diff line number Diff line
@@ -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;