KVM: x86/mmu: Refactor shadow walk in __direct_map() to reduce indentation

Employ a 'continue' to reduce the indentation for linking a new shadow
page during __direct_map() in preparation for linking private pages.
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <702419686d5700373123f6ea84e7a946c2cad8b4.1625186503.git.isaku.yamahata@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/mmu/mmu.c

@@ -2939,7 +2939,9 @@ static int __direct_map(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code,
 			break;
 
 		drop_large_spte(vcpu, it.sptep);
-		if (!is_shadow_present_pte(*it.sptep)) {
+		if (is_shadow_present_pte(*it.sptep))
+			continue;
+
 		sp = kvm_mmu_get_page(vcpu, base_gfn, it.addr,
 				      it.level - 1, true, ACC_ALL);
 
@@ -2948,7 +2950,6 @@ static int __direct_map(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code,
 		    req_level >= it.level)
 			account_huge_nx_page(vcpu->kvm, sp);
 	}
-	}
 
 	ret = mmu_set_spte(vcpu, it.sptep, ACC_ALL,
 			   write, level, base_gfn, pfn, prefault,