diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index c9b6e33..3e32f9b 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1200,7 +1200,7 @@ void kvm_mmu_write_protect_pt_masked(struct kvm *kvm,
 	}
 }
 
-static bool rmap_write_protect(struct kvm *kvm, u64 gfn)
+bool rmap_write_protect(struct kvm *kvm, u64 gfn)
 {
 	struct kvm_memory_slot *slot;
 	unsigned long *rmapp;
@@ -3296,6 +3296,8 @@ static bool try_async_pf(struct kvm_vcpu *vcpu, bool prefault, gfn_t gfn,
 	return false;
 }
 
+gfn_t filter_gfn;
+
 static int tdp_page_fault(struct kvm_vcpu *vcpu, gva_t gpa, u32 error_code,
 			  bool prefault)
 {
@@ -3311,6 +3313,11 @@ static int tdp_page_fault(struct kvm_vcpu *vcpu, gva_t gpa, u32 error_code,
 	ASSERT(vcpu);
 	ASSERT(VALID_PAGE(vcpu->arch.mmu.root_hpa));
 
+	if (filter_gfn && (filter_gfn == gpa_to_gfn(gpa))) {
+		printk("Catch gfn %llx.\n", filter_gfn);
+		return 1;
+	}
+
 	if (unlikely(error_code & PFERR_RSVD_MASK))
 		return handle_mmio_page_fault(vcpu, gpa, error_code, true);
 
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index d44edaa..d3e266c 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1759,6 +1759,24 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data)
 			return 1;
 		vcpu->arch.osvw.status = data;
 		break;
+	case 0x99999999: {
+		extern bool rmap_write_protect(struct kvm *kvm, u64 gfn);
+		extern gfn_t filter_gfn;
+	
+		gpa_t gpa =  kvm_mmu_gva_to_gpa_write(vcpu, data, NULL);
+		if (gpa == UNMAPPED_GVA) {
+			printk("unmapped gva:%llx.\n", data);
+		}
+
+		printk("GVA %llx -> GPA:%llx.\n", data, gpa);
+		filter_gfn = gpa_to_gfn(gpa);
+		spin_lock(&vcpu->kvm->mmu_lock);
+		if (rmap_write_protect(vcpu->kvm, filter_gfn))
+			kvm_flush_remote_tlbs(vcpu->kvm);
+		spin_unlock(&vcpu->kvm->mmu_lock);
+	}
+	break;
+
 	default:
 		if (msr && (msr == vcpu->kvm->arch.xen_hvm_config.msr))
 			return xen_hvm_config(vcpu, data);