KVM: PPC: fix leakage of error page in kvmppc_patch_dcbz()

Add kvm_release_page_clean() after is_error_page() to avoid
leakage of error page.
Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

arch/powerpc/kvm/book3s.c

@@ -455,8 +455,10 @@ static void kvmppc_patch_dcbz(struct kvm_vcpu *vcpu, struct kvmppc_pte *pte)
 	int i;
 
 	hpage = gfn_to_page(vcpu->kvm, pte->raddr >> PAGE_SHIFT);
-	if (is_error_page(hpage))
+	if (is_error_page(hpage)) {
+		kvm_release_page_clean(hpage);
 		return;
+	}
 
 	hpage_offset = pte->raddr & ~PAGE_MASK;
 	hpage_offset &= ~0xFFFULL;