Commit 966da62a authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

KVM: x86/mmu: WARN if old _or_ new SPTE is REMOVED in non-atomic path 



WARN if the new_spte being set by __tdp_mmu_set_spte() is a REMOVED_SPTE,
which is called out by the comment as being disallowed but not actually
checked.  Keep the WARN on the old_spte as well, because overwriting a
REMOVED_SPTE in the non-atomic path is also disallowed (as evidence by
lack of splats with the existing WARN).

Fixes: 08f07c80 ("KVM: x86/mmu: Flush TLBs after zap in TDP MMU PF handler")
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: <20220226001546.360188-12-seanjc@google.com>
Reviewed-by: default avatarMingwei Zhang <mizhang@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 0e587aa7

arch/x86/kvm/mmu/tdp_mmu.c

+2 −2
Original line number Diff line number Diff line
@@ -626,13 +626,13 @@ static inline void __tdp_mmu_set_spte(struct kvm *kvm, struct tdp_iter *iter, 
	lockdep_assert_held_write(&kvm->mmu_lock);



	/*

	 * No thread should be using this function to set SPTEs to the

	 * No thread should be using this function to set SPTEs to or from the

	 * temporary removed SPTE value.

	 * If operating under the MMU lock in read mode, tdp_mmu_set_spte_atomic

	 * should be used. If operating under the MMU lock in write mode, the

	 * use of the removed SPTE should not be necessary.

	 */

	WARN_ON(is_removed_spte(iter->old_spte));

	WARN_ON(is_removed_spte(iter->old_spte) || is_removed_spte(new_spte));



	kvm_tdp_mmu_write_spte(iter->sptep, new_spte);