KVM: x86/mmu: Use is_removed_spte() instead of open coded equivalents

Use the is_removed_spte() helper instead of open coding the check.

No functional change intended.

Cc: Ben Gardon <bgardon@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210225204749.1512652-23-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/mmu/tdp_mmu.c

@@ -488,7 +488,7 @@ static inline bool tdp_mmu_set_spte_atomic(struct kvm *kvm,
 	 * Do not change removed SPTEs. Only the thread that froze the SPTE
 	 * may modify it.
 	 */
-	if (iter->old_spte == REMOVED_SPTE)
+	if (is_removed_spte(iter->old_spte))
 		return false;
 
 	if (cmpxchg64(rcu_dereference(iter->sptep), iter->old_spte,
@@ -563,7 +563,7 @@ static inline void __tdp_mmu_set_spte(struct kvm *kvm, struct tdp_iter *iter,
 	 * should be used. If operating under the MMU lock in write mode, the
 	 * use of the removed SPTE should not be necessary.
 	 */
-	WARN_ON(iter->old_spte == REMOVED_SPTE);
+	WARN_ON(is_removed_spte(iter->old_spte));
 
 	WRITE_ONCE(*rcu_dereference(iter->sptep), new_spte);