KVM: x86/xen: Move KVM_XEN_HVM_CONFIG handling to xen.c

This is already more complex than the simple memcpy it originally had.
Move it to xen.c with the rest of the Xen support.
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>

arch/x86/kvm/x86.c

@@ -5627,19 +5627,7 @@ long kvm_arch_vm_ioctl(struct file *filp,
 		r = -EFAULT;
 		if (copy_from_user(&xhc, argp, sizeof(xhc)))
 			goto out;
-		r = -EINVAL;
-		if (xhc.flags & ~KVM_XEN_HVM_CONFIG_INTERCEPT_HCALL)
-			goto out;
-		/*
-		 * With hypercall interception the kernel generates its own
-		 * hypercall page so it must not be provided.
-		 */
-		if ((xhc.flags & KVM_XEN_HVM_CONFIG_INTERCEPT_HCALL) &&
-		    (xhc.blob_addr_32 || xhc.blob_addr_64 ||
-		     xhc.blob_size_32 || xhc.blob_size_64))
-			goto out;
-		memcpy(&kvm->arch.xen_hvm_config, &xhc, sizeof(xhc));
-		r = 0;
+		r = kvm_xen_hvm_config(kvm, &xhc);
 		break;
 	}
 	case KVM_SET_CLOCK: {

arch/x86/kvm/xen.c

@@ -79,6 +79,24 @@ int kvm_xen_write_hypercall_page(struct kvm_vcpu *vcpu, u64 data)
 	return 0;
 }
 
+int kvm_xen_hvm_config(struct kvm *kvm, struct kvm_xen_hvm_config *xhc)
+{
+	if (xhc->flags & ~KVM_XEN_HVM_CONFIG_INTERCEPT_HCALL)
+		return -EINVAL;
+
+	/*
+	 * With hypercall interception the kernel generates its own
+	 * hypercall page so it must not be provided.
+	 */
+	if ((xhc->flags & KVM_XEN_HVM_CONFIG_INTERCEPT_HCALL) &&
+	    (xhc->blob_addr_32 || xhc->blob_addr_64 ||
+	     xhc->blob_size_32 || xhc->blob_size_64))
+		return -EINVAL;
+
+	memcpy(&kvm->arch.xen_hvm_config, xhc, sizeof(*xhc));
+	return 0;
+}
+
 static int kvm_xen_hypercall_set_result(struct kvm_vcpu *vcpu, u64 result)
 {
 	kvm_rax_write(vcpu, result);

arch/x86/kvm/xen.h

@@ -11,6 +11,7 @@
 
 int kvm_xen_hypercall(struct kvm_vcpu *vcpu);
 int kvm_xen_write_hypercall_page(struct kvm_vcpu *vcpu, u64 data);
+int kvm_xen_hvm_config(struct kvm *kvm, struct kvm_xen_hvm_config *xhc);
 
 static inline bool kvm_xen_hypercall_enabled(struct kvm *kvm)
 {