KVM/nSVM: properly map nested VMCB

Commit 8c5fbf1a ("KVM/nSVM: Use the new mapping API for mapping guest
memory") broke nested SVM completely: kvm_vcpu_map()'s second parameter is
GFN so vmcb_gpa needs to be converted with gpa_to_gfn(), not the other way
around.

Fixes: 8c5fbf1a ("KVM/nSVM: Use the new mapping API for mapping guest memory")
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: NSean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/svm.c

@@ -3293,7 +3293,7 @@ static int nested_svm_vmexit(struct vcpu_svm *svm)
 				       vmcb->control.exit_int_info_err,
 				       KVM_ISA_SVM);
 
-	rc = kvm_vcpu_map(&svm->vcpu, gfn_to_gpa(svm->nested.vmcb), &map);
+	rc = kvm_vcpu_map(&svm->vcpu, gpa_to_gfn(svm->nested.vmcb), &map);
 	if (rc) {
 		if (rc == -EINVAL)
 			kvm_inject_gp(&svm->vcpu, 0);
@@ -3583,7 +3583,7 @@ static bool nested_svm_vmrun(struct vcpu_svm *svm)
 
 	vmcb_gpa = svm->vmcb->save.rax;
 
-	rc = kvm_vcpu_map(&svm->vcpu, gfn_to_gpa(vmcb_gpa), &map);
+	rc = kvm_vcpu_map(&svm->vcpu, gpa_to_gfn(vmcb_gpa), &map);
 	if (rc) {
 		if (rc == -EINVAL)
 			kvm_inject_gp(&svm->vcpu, 0);