KVM: MMU: fix apf prefault if nested guest is enabled

If apf is generated in L2 guest and is completed in L1 guest, it will
prefault this apf in L1 guest's mmu context.

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 116dac5..f1e8d5b 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -600,6 +600,7 @@
 struct kvm_arch_async_pf {
 	u32 token;
 	gfn_t gfn;
+	bool direct_map;
 };
 
 extern struct kvm_x86_ops *kvm_x86_ops;
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index db0fd55..ab100a7 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -2609,6 +2609,7 @@
 	struct kvm_arch_async_pf arch;
 	arch.token = (vcpu->arch.apf.id++ << 12) | vcpu->vcpu_id;
 	arch.gfn = gfn;
+	arch.direct_map = vcpu->arch.mmu.direct_map;
 
 	return kvm_setup_async_pf(vcpu, gva, gfn, &arch);
 }
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 9b875ff..c673e72 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6168,7 +6168,8 @@
 {
 	int r;
 
-	if (!vcpu->arch.mmu.direct_map || is_error_page(work->page))
+	if (!vcpu->arch.mmu.direct_map || !work->arch.direct_map ||
+	      is_error_page(work->page))
 		return;
 
 	r = kvm_mmu_reload(vcpu);