diff --git a/Documentation/vfio-mdev/Makefile b/Documentation/vfio-mdev/Makefile
index ff6f8a3..721daf0 100644
--- a/Documentation/vfio-mdev/Makefile
+++ b/Documentation/vfio-mdev/Makefile
@@ -8,6 +8,9 @@ obj-m:=mtty.o
 default:
 	$(MAKE) -C $(KDIR) SUBDIRS=$(PWD) modules
 
+modules_install:
+	$(MAKE) -C $(KDIR) SUBDIRS=$(PWD) modules_install
+
 clean:
 	@rm -rf .*.cmd *.mod.c *.o *.ko .tmp*
 	@rm -rf Module.* Modules.* modules.* .tmp_versions
diff --git a/Documentation/vfio-mdev/mtty.c b/Documentation/vfio-mdev/mtty.c
index 497c90e..05ab40d 100644
--- a/Documentation/vfio-mdev/mtty.c
+++ b/Documentation/vfio-mdev/mtty.c
@@ -141,8 +141,11 @@ struct mdev_state {
 	struct serial_port s[2];
 	struct mutex rxtx_lock;
 	struct vfio_device_info dev_info;
+	int nr_ports;
 };
 
+#define MAX_MTTYS 24
+
 struct mutex mdev_list_lock;
 struct list_head mdev_devices_list;
 
@@ -723,6 +726,11 @@ int mtty_create(struct kobject *kobj, struct mdev_device *mdev)
 	if (mdev_state == NULL)
 		return -ENOMEM;
 
+	if (!strcmp(kobj->name, "mtty1"))
+		mdev_state->nr_ports = 1;
+	else if (!strcmp(kobj->name, "mtty2"))
+		mdev_state->nr_ports = 2;
+
 	mdev_state->irq_index = -1;
 	mdev_state->s[0].max_fifo_size = MAX_FIFO_SIZE;
 	mdev_state->s[1].max_fifo_size = MAX_FIFO_SIZE;
@@ -1224,7 +1232,12 @@ const struct attribute_group *mdev_dev_groups[] = {
 static ssize_t
 name_show(struct kobject *kobj, struct device *dev, char *buf)
 {
-	return sprintf(buf, "Dual-port-serial\n");
+	if (!strcmp(kobj->name, "mtty1"))
+		return sprintf(buf, "Single-port-serial\n");
+	if (!strcmp(kobj->name, "mtty2"))
+		return sprintf(buf, "Dual-port-serial\n");
+
+	return -EINVAL;
 }
 
 MDEV_TYPE_ATTR_RO(name);
@@ -1232,7 +1245,20 @@ MDEV_TYPE_ATTR_RO(name);
 static ssize_t
 available_instances_show(struct kobject *kobj, struct device *dev, char *buf)
 {
-	return sprintf(buf, "1\n");
+	struct mdev_state *mds;
+	int ports, used = 0;
+
+	if (!strcmp(kobj->name, "mtty1"))
+		ports = 1;
+	else if (!strcmp(kobj->name, "mtty2"))
+		ports = 2;
+	else
+		return -EINVAL;
+
+	list_for_each_entry(mds, &mdev_devices_list, next) {
+		used += mds->nr_ports;
+	}
+	return sprintf(buf, "%d\n", (MAX_MTTYS - used)/ports);
 }
 
 MDEV_TYPE_ATTR_RO(available_instances);
@@ -1243,13 +1269,19 @@ static struct attribute *mdev_types_attrs[] = {
 	NULL,
 };
 
-static struct attribute_group mdev_type_group = {
+static struct attribute_group mdev_type_group1 = {
 	.name  = "mtty1",
 	.attrs = mdev_types_attrs,
 };
 
+static struct attribute_group mdev_type_group2 = {
+	.name  = "mtty2",
+	.attrs = mdev_types_attrs,
+};
+
 struct attribute_group *mdev_type_groups[] = {
-	&mdev_type_group,
+	&mdev_type_group1,
+	&mdev_type_group2,
 	NULL,
 };