KVM: x86/mmu: Use common TDP MMU zap helper for MMU notifier unmap hook

Use the common TDP MMU zap helper when handling an MMU notifier unmap
event, the two flows are semantically identical.  Consolidate the code in
preparation for a future bug fix, as both kvm_tdp_mmu_unmap_gfn_range()
and __kvm_tdp_mmu_zap_gfn_range() are guilty of not zapping SPTEs in
invalid roots.

No functional change intended.

Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211215011557.399940-2-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/mmu/tdp_mmu.c

@@ -1032,13 +1032,8 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
 bool kvm_tdp_mmu_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range,
 				 bool flush)
 {
-	struct kvm_mmu_page *root;
-
-	for_each_tdp_mmu_root_yield_safe(kvm, root, range->slot->as_id, false)
-		flush = zap_gfn_range(kvm, root, range->start, range->end,
-				      range->may_block, flush, false);
-
-	return flush;
+	return __kvm_tdp_mmu_zap_gfn_range(kvm, range->slot->as_id, range->start,
+					   range->end, range->may_block, flush);
 }
 
 typedef bool (*tdp_handler_t)(struct kvm *kvm, struct tdp_iter *iter,