KVM: MMU: support apf for nonpaing guest

Let's support apf for nonpaing guest
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

arch/x86/kvm/mmu.c

@@ -2286,7 +2286,11 @@ static int kvm_handle_bad_page(struct kvm *kvm, gfn_t gfn, pfn_t pfn)
 	return 1;
 }
 
-static int nonpaging_map(struct kvm_vcpu *vcpu, gva_t v, int write, gfn_t gfn)
+static bool try_async_pf(struct kvm_vcpu *vcpu, bool no_apf, gfn_t gfn,
+			 gva_t gva, pfn_t *pfn, bool write, bool *writable);
+
+static int nonpaging_map(struct kvm_vcpu *vcpu, gva_t v, int write, gfn_t gfn,
+			 bool no_apf)
 {
 	int r;
 	int level;
@@ -2307,7 +2311,9 @@ static int nonpaging_map(struct kvm_vcpu *vcpu, gva_t v, int write, gfn_t gfn)
 
 	mmu_seq = vcpu->kvm->mmu_notifier_seq;
 	smp_rmb();
-	pfn = gfn_to_pfn_prot(vcpu->kvm, gfn, write, &map_writable);
+
+	if (try_async_pf(vcpu, no_apf, gfn, v, &pfn, write, &map_writable))
+		return 0;
 
 	/* mmio */
 	if (is_error_pfn(pfn))
@@ -2595,7 +2601,7 @@ static int nonpaging_page_fault(struct kvm_vcpu *vcpu, gva_t gva,
 	gfn = gva >> PAGE_SHIFT;
 
 	return nonpaging_map(vcpu, gva & PAGE_MASK,
-			     error_code & PFERR_WRITE_MASK, gfn);
+			     error_code & PFERR_WRITE_MASK, gfn, no_apf);
 }
 
 static int kvm_arch_setup_async_pf(struct kvm_vcpu *vcpu, gva_t gva, gfn_t gfn)