vduse: Introduce VDUSE - vDPA Device in Userspace

This VDUSE driver enables implementing software-emulated vDPA
devices in userspace. The vDPA device is created by
ioctl(VDUSE_CREATE_DEV) on /dev/vduse/control. Then a char device
interface (/dev/vduse/$NAME) is exported to userspace for device
emulation.

In order to make the device emulation more secure, the device's
control path is handled in kernel. A message mechnism is introduced
to forward some dataplane related control messages to userspace.

And in the data path, the DMA buffer will be mapped into userspace
address space through different ways depending on the vDPA bus to
which the vDPA device is attached. In virtio-vdpa case, the MMU-based
software IOTLB is used to achieve that. And in vhost-vdpa case, the
DMA buffer is reside in a userspace memory region which can be shared
to the VDUSE userspace processs via transferring the shmfd.

For more details on VDUSE design and usage, please see the follow-on
Documentation commit.

NB(mst): when merging this with
b542e383d8c0 ("eventfd: Make signal recursion protection a task bit")
replace eventfd_signal_count with eventfd_signal_allowed,
and drop the previous
("eventfd: Export eventfd_wake_count to modules").

Signed-off-by: Xie Yongji <xieyongji@bytedance.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20210831103634.33-13-xieyongji@bytedance.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

4 files changed, 1662 insertions, 0 deletions

diff --git a/drivers/vdpa/Kconfig b/drivers/vdpa/Kconfig
index e48e2b10ca36..3d91982d8371 100644
--- a/drivers/vdpa/Kconfig
+++ b/drivers/vdpa/Kconfig
@@ -33,6 +33,16 @@ config VDPA_SIM_BLOCK
 	  vDPA block device simulator which terminates IO request in a
 	  memory buffer.
 
+config VDPA_USER
+	tristate "VDUSE (vDPA Device in Userspace) support"
+	depends on EVENTFD && MMU && HAS_DMA
+	select DMA_OPS
+	select VHOST_IOTLB
+	select IOMMU_IOVA
+	help
+	  With VDUSE it is possible to emulate a vDPA Device
+	  in a userspace program.
+
 config IFCVF
 	tristate "Intel IFC VF vDPA driver"
 	depends on PCI_MSI
diff --git a/drivers/vdpa/Makefile b/drivers/vdpa/Makefile
index 67fe7f3d6943..f02ebed33f19 100644
--- a/drivers/vdpa/Makefile
+++ b/drivers/vdpa/Makefile
@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0
 obj-$(CONFIG_VDPA) += vdpa.o
 obj-$(CONFIG_VDPA_SIM) += vdpa_sim/
+obj-$(CONFIG_VDPA_USER) += vdpa_user/
 obj-$(CONFIG_IFCVF)    += ifcvf/
 obj-$(CONFIG_MLX5_VDPA) += mlx5/
 obj-$(CONFIG_VP_VDPA)    += virtio_pci/
diff --git a/drivers/vdpa/vdpa_user/Makefile b/drivers/vdpa/vdpa_user/Makefile
new file mode 100644
index 000000000000..260e0b26af99
--- /dev/null
+++ b/drivers/vdpa/vdpa_user/Makefile
@@ -0,0 +1,5 @@
+# SPDX-License-Identifier: GPL-2.0
+
+vduse-y := vduse_dev.o iova_domain.o
+
+obj-$(CONFIG_VDPA_USER) += vduse.o
diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
new file mode 100644
index 000000000000..b9b2659408e6
--- /dev/null
+++ b/drivers/vdpa/vdpa_user/vduse_dev.c
@@ -0,0 +1,1646 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * VDUSE: vDPA Device in Userspace
+ *
+ * Copyright (C) 2020-2021 Bytedance Inc. and/or its affiliates. All rights reserved.
+ *
+ * Author: Xie Yongji <xieyongji@bytedance.com>
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/cdev.h>
+#include <linux/device.h>
+#include <linux/eventfd.h>
+#include <linux/slab.h>
+#include <linux/wait.h>
+#include <linux/dma-map-ops.h>
+#include <linux/poll.h>
+#include <linux/file.h>
+#include <linux/uio.h>
+#include <linux/vdpa.h>
+#include <linux/nospec.h>
+#include <uapi/linux/vduse.h>
+#include <uapi/linux/vdpa.h>
+#include <uapi/linux/virtio_config.h>
+#include <uapi/linux/virtio_ids.h>
+#include <uapi/linux/virtio_blk.h>
+#include <linux/mod_devicetable.h>
+
+#include "iova_domain.h"
+
+#define DRV_AUTHOR   "Yongji Xie <xieyongji@bytedance.com>"
+#define DRV_DESC     "vDPA Device in Userspace"
+#define DRV_LICENSE  "GPL v2"
+
+#define VDUSE_DEV_MAX (1U << MINORBITS)
+#define VDUSE_BOUNCE_SIZE (64 * 1024 * 1024)
+#define VDUSE_IOVA_SIZE (128 * 1024 * 1024)
+#define VDUSE_MSG_DEFAULT_TIMEOUT 30
+
+struct vduse_virtqueue {
+	u16 index;
+	u16 num_max;
+	u32 num;
+	u64 desc_addr;
+	u64 driver_addr;
+	u64 device_addr;
+	struct vdpa_vq_state state;
+	bool ready;
+	bool kicked;
+	spinlock_t kick_lock;
+	spinlock_t irq_lock;
+	struct eventfd_ctx *kickfd;
+	struct vdpa_callback cb;
+	struct work_struct inject;
+	struct work_struct kick;
+};
+
+struct vduse_dev;
+
+struct vduse_vdpa {
+	struct vdpa_device vdpa;
+	struct vduse_dev *dev;
+};
+
+struct vduse_dev {
+	struct vduse_vdpa *vdev;
+	struct device *dev;
+	struct vduse_virtqueue *vqs;
+	struct vduse_iova_domain *domain;
+	char *name;
+	struct mutex lock;
+	spinlock_t msg_lock;
+	u64 msg_unique;
+	u32 msg_timeout;
+	wait_queue_head_t waitq;
+	struct list_head send_list;
+	struct list_head recv_list;
+	struct vdpa_callback config_cb;
+	struct work_struct inject;
+	spinlock_t irq_lock;
+	int minor;
+	bool broken;
+	bool connected;
+	u64 api_version;
+	u64 device_features;
+	u64 driver_features;
+	u32 device_id;
+	u32 vendor_id;
+	u32 generation;
+	u32 config_size;
+	void *config;
+	u8 status;
+	u32 vq_num;
+	u32 vq_align;
+};
+
+struct vduse_dev_msg {
+	struct vduse_dev_request req;
+	struct vduse_dev_response resp;
+	struct list_head list;
+	wait_queue_head_t waitq;
+	bool completed;
+};
+
+struct vduse_control {
+	u64 api_version;
+};
+
+static DEFINE_MUTEX(vduse_lock);
+static DEFINE_IDR(vduse_idr);
+
+static dev_t vduse_major;
+static struct class *vduse_class;
+static struct cdev vduse_ctrl_cdev;
+static struct cdev vduse_cdev;
+static struct workqueue_struct *vduse_irq_wq;
+
+static u32 allowed_device_id[] = {
+	VIRTIO_ID_BLOCK,
+};
+
+static inline struct vduse_dev *vdpa_to_vduse(struct vdpa_device *vdpa)
+{
+	struct vduse_vdpa *vdev = container_of(vdpa, struct vduse_vdpa, vdpa);
+
+	return vdev->dev;
+}
+
+static inline struct vduse_dev *dev_to_vduse(struct device *dev)
+{
+	struct vdpa_device *vdpa = dev_to_vdpa(dev);
+
+	return vdpa_to_vduse(vdpa);
+}
+
+static struct vduse_dev_msg *vduse_find_msg(struct list_head *head,
+					    uint32_t request_id)
+{
+	struct vduse_dev_msg *msg;
+
+	list_for_each_entry(msg, head, list) {
+		if (msg->req.request_id == request_id) {
+			list_del(&msg->list);
+			return msg;
+		}
+	}
+
+	return NULL;
+}
+
+static struct vduse_dev_msg *vduse_dequeue_msg(struct list_head *head)
+{
+	struct vduse_dev_msg *msg = NULL;
+
+	if (!list_empty(head)) {
+		msg = list_first_entry(head, struct vduse_dev_msg, list);
+		list_del(&msg->list);
+	}
+
+	return msg;
+}
+
+static void vduse_enqueue_msg(struct list_head *head,
+			      struct vduse_dev_msg *msg)
+{
+	list_add_tail(&msg->list, head);
+}
+
+static void vduse_dev_broken(struct vduse_dev *dev)
+{
+	struct vduse_dev_msg *msg, *tmp;
+
+	if (unlikely(dev->broken))
+		return;
+
+	list_splice_init(&dev->recv_list, &dev->send_list);
+	list_for_each_entry_safe(msg, tmp, &dev->send_list, list) {
+		list_del(&msg->list);
+		msg->completed = 1;
+		msg->resp.result = VDUSE_REQ_RESULT_FAILED;
+		wake_up(&msg->waitq);
+	}
+	dev->broken = true;
+	wake_up(&dev->waitq);
+}
+
+static int vduse_dev_msg_sync(struct vduse_dev *dev,
+			      struct vduse_dev_msg *msg)
+{
+	int ret;
+
+	if (unlikely(dev->broken))
+		return -EIO;
+
+	init_waitqueue_head(&msg->waitq);
+	spin_lock(&dev->msg_lock);
+	if (unlikely(dev->broken)) {
+		spin_unlock(&dev->msg_lock);
+		return -EIO;
+	}
+	msg->req.request_id = dev->msg_unique++;
+	vduse_enqueue_msg(&dev->send_list, msg);
+	wake_up(&dev->waitq);
+	spin_unlock(&dev->msg_lock);
+	if (dev->msg_timeout)
+		ret = wait_event_killable_timeout(msg->waitq, msg->completed,
+						  (long)dev->msg_timeout * HZ);
+	else
+		ret = wait_event_killable(msg->waitq, msg->completed);
+
+	spin_lock(&dev->msg_lock);
+	if (!msg->completed) {
+		list_del(&msg->list);
+		msg->resp.result = VDUSE_REQ_RESULT_FAILED;
+		/* Mark the device as malfunction when there is a timeout */
+		if (!ret)
+			vduse_dev_broken(dev);
+	}
+	ret = (msg->resp.result == VDUSE_REQ_RESULT_OK) ? 0 : -EIO;
+	spin_unlock(&dev->msg_lock);
+
+	return ret;
+}
+
+static int vduse_dev_get_vq_state_packed(struct vduse_dev *dev,
+					 struct vduse_virtqueue *vq,
+					 struct vdpa_vq_state_packed *packed)
+{
+	struct vduse_dev_msg msg = { 0 };
+	int ret;
+
+	msg.req.type = VDUSE_GET_VQ_STATE;
+	msg.req.vq_state.index = vq->index;
+
+	ret = vduse_dev_msg_sync(dev, &msg);
+	if (ret)
+		return ret;
+
+	packed->last_avail_counter =
+			msg.resp.vq_state.packed.last_avail_counter & 0x0001;
+	packed->last_avail_idx =
+			msg.resp.vq_state.packed.last_avail_idx & 0x7FFF;
+	packed->last_used_counter =
+			msg.resp.vq_state.packed.last_used_counter & 0x0001;
+	packed->last_used_idx =
+			msg.resp.vq_state.packed.last_used_idx & 0x7FFF;
+
+	return 0;
+}
+
+static int vduse_dev_get_vq_state_split(struct vduse_dev *dev,
+					struct vduse_virtqueue *vq,
+					struct vdpa_vq_state_split *split)
+{
+	struct vduse_dev_msg msg = { 0 };
+	int ret;
+
+	msg.req.type = VDUSE_GET_VQ_STATE;
+	msg.req.vq_state.index = vq->index;
+
+	ret = vduse_dev_msg_sync(dev, &msg);
+	if (ret)
+		return ret;
+
+	split->avail_index = msg.resp.vq_state.split.avail_index;
+
+	return 0;
+}
+
+static int vduse_dev_set_status(struct vduse_dev *dev, u8 status)
+{
+	struct vduse_dev_msg msg = { 0 };
+
+	msg.req.type = VDUSE_SET_STATUS;
+	msg.req.s.status = status;
+
+	return vduse_dev_msg_sync(dev, &msg);
+}
+
+static int vduse_dev_update_iotlb(struct vduse_dev *dev,
+				  u64 start, u64 last)
+{
+	struct vduse_dev_msg msg = { 0 };
+
+	if (last < start)
+		return -EINVAL;
+
+	msg.req.type = VDUSE_UPDATE_IOTLB;
+	msg.req.iova.start = start;
+	msg.req.iova.last = last;
+
+	return vduse_dev_msg_sync(dev, &msg);
+}
+
+static ssize_t vduse_dev_read_iter(struct kiocb *iocb, struct iov_iter *to)
+{
+	struct file *file = iocb->ki_filp;
+	struct vduse_dev *dev = file->private_data;
+	struct vduse_dev_msg *msg;
+	int size = sizeof(struct vduse_dev_request);
+	ssize_t ret;
+
+	if (iov_iter_count(to) < size)
+		return -EINVAL;
+
+	spin_lock(&dev->msg_lock);
+	while (1) {
+		msg = vduse_dequeue_msg(&dev->send_list);
+		if (msg)
+			break;
+
+		ret = -EAGAIN;
+		if (file->f_flags & O_NONBLOCK)
+			goto unlock;
+
+		spin_unlock(&dev->msg_lock);
+		ret = wait_event_interruptible_exclusive(dev->waitq,
+					!list_empty(&dev->send_list));
+		if (ret)
+			return ret;
+
+		spin_lock(&dev->msg_lock);
+	}
+	spin_unlock(&dev->msg_lock);
+	ret = copy_to_iter(&msg->req, size, to);
+	spin_lock(&dev->msg_lock);
+	if (ret != size) {
+		ret = -EFAULT;
+		vduse_enqueue_msg(&dev->send_list, msg);
+		goto unlock;
+	}
+	vduse_enqueue_msg(&dev->recv_list, msg);
+unlock:
+	spin_unlock(&dev->msg_lock);
+
+	return ret;
+}
+
+static bool is_mem_zero(const char *ptr, int size)
+{
+	int i;
+
+	for (i = 0; i < size; i++) {
+		if (ptr[i])
+			return false;
+	}
+	return true;
+}
+
+static ssize_t vduse_dev_write_iter(struct kiocb *iocb, struct iov_iter *from)
+{
+	struct file *file = iocb->ki_filp;
+	struct vduse_dev *dev = file->private_data;
+	struct vduse_dev_response resp;
+	struct vduse_dev_msg *msg;
+	size_t ret;
+
+	ret = copy_from_iter(&resp, sizeof(resp), from);
+	if (ret != sizeof(resp))
+		return -EINVAL;
+
+	if (!is_mem_zero((const char *)resp.reserved, sizeof(resp.reserved)))
+		return -EINVAL;
+
+	spin_lock(&dev->msg_lock);
+	msg = vduse_find_msg(&dev->recv_list, resp.request_id);
+	if (!msg) {
+		ret = -ENOENT;
+		goto unlock;
+	}
+
+	memcpy(&msg->resp, &resp, sizeof(resp));
+	msg->completed = 1;
+	wake_up(&msg->waitq);
+unlock:
+	spin_unlock(&dev->msg_lock);
+
+	return ret;
+}
+
+static __poll_t vduse_dev_poll(struct file *file, poll_table *wait)
+{
+	struct vduse_dev *dev = file->private_data;
+	__poll_t mask = 0;
+
+	poll_wait(file, &dev->waitq, wait);
+
+	spin_lock(&dev->msg_lock);
+
+	if (unlikely(dev->broken))
+		mask |= EPOLLERR;
+	if (!list_empty(&dev->send_list))
+		mask |= EPOLLIN | EPOLLRDNORM;
+	if (!list_empty(&dev->recv_list))
+		mask |= EPOLLOUT | EPOLLWRNORM;
+
+	spin_unlock(&dev->msg_lock);
+
+	return mask;
+}
+
+static void vduse_dev_reset(struct vduse_dev *dev)
+{
+	int i;
+	struct vduse_iova_domain *domain = dev->domain;
+
+	/* The coherent mappings are handled in vduse_dev_free_coherent() */
+	if (domain->bounce_map)
+		vduse_domain_reset_bounce_map(domain);
+
+	dev->status = 0;
+	dev->driver_features = 0;
+	dev->generation++;
+	spin_lock(&dev->irq_lock);
+	dev->config_cb.callback = NULL;
+	dev->config_cb.private = NULL;
+	spin_unlock(&dev->irq_lock);
+	flush_work(&dev->inject);
+
+	for (i = 0; i < dev->vq_num; i++) {
+		struct vduse_virtqueue *vq = &dev->vqs[i];
+
+		vq->ready = false;
+		vq->desc_addr = 0;
+		vq->driver_addr = 0;
+		vq->device_addr = 0;
+		vq->num = 0;
+		memset(&vq->state, 0, sizeof(vq->state));
+
+		spin_lock(&vq->kick_lock);
+		vq->kicked = false;
+		if (vq->kickfd)
+			eventfd_ctx_put(vq->kickfd);
+		vq->kickfd = NULL;
+		spin_unlock(&vq->kick_lock);
+
+		spin_lock(&vq->irq_lock);
+		vq->cb.callback = NULL;
+		vq->cb.private = NULL;
+		spin_unlock(&vq->irq_lock);
+		flush_work(&vq->inject);
+		flush_work(&vq->kick);
+	}
+}
+
+static int vduse_vdpa_set_vq_address(struct vdpa_device *vdpa, u16 idx,
+				u64 desc_area, u64 driver_area,
+				u64 device_area)
+{
+	struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+	struct vduse_virtqueue *vq = &dev->vqs[idx];
+
+	vq->desc_addr = desc_area;
+	vq->driver_addr = driver_area;
+	vq->device_addr = device_area;
+
+	return 0;
+}
+
+static void vduse_vq_kick(struct vduse_virtqueue *vq)
+{
+	spin_lock(&vq->kick_lock);
+	if (!vq->ready)
+		goto unlock;
+
+	if (vq->kickfd)
+		eventfd_signal(vq->kickfd, 1);
+	else
+		vq->kicked = true;
+unlock:
+	spin_unlock(&vq->kick_lock);
+}
+
+static void vduse_vq_kick_work(struct work_struct *work)
+{
+	struct vduse_virtqueue *vq = container_of(work,
+					struct vduse_virtqueue, kick);
+
+	vduse_vq_kick(vq);
+}
+
+static void vduse_vdpa_kick_vq(struct vdpa_device *vdpa, u16 idx)
+{
+	struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+	struct vduse_virtqueue *vq = &dev->vqs[idx];
+
+	/*
+	 * TODO: after applying b542e383d8c0 ("eventfd: Make signal recursion protection a task bit")
+	 * replace eventfd_signal_count with eventfd_signal_allowed, and
+	 * drop the previous ("eventfd: Export eventfd_wake_count to modules") 
+	 * */
+	if (eventfd_signal_count()) {
+		schedule_work(&vq->kick);
+		return;
+	}
+	vduse_vq_kick(vq);
+}
+
+static void vduse_vdpa_set_vq_cb(struct vdpa_device *vdpa, u16 idx,
+			      struct vdpa_callback *cb)
+{
+	struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+	struct vduse_virtqueue *vq = &dev->vqs[idx];
+
+	spin_lock(&vq->irq_lock);
+	vq->cb.callback = cb->callback;
+	vq->cb.private = cb->private;
+	spin_unlock(&vq->irq_lock);
+}
+
+static void vduse_vdpa_set_vq_num(struct vdpa_device *vdpa, u16 idx, u32 num)
+{
+	struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+	struct vduse_virtqueue *vq = &dev->vqs[idx];
+
+	vq->num = num;
+}
+
+static void vduse_vdpa_set_vq_ready(struct vdpa_device *vdpa,
+					u16 idx, bool ready)
+{
+	struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+	struct vduse_virtqueue *vq = &dev->vqs[idx];
+
+	vq->ready = ready;
+}
+
+static bool vduse_vdpa_get_vq_ready(struct vdpa_device *vdpa, u16 idx)
+{
+	struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+	struct vduse_virtqueue *vq = &dev->vqs[idx];
+
+	return vq->ready;
+}
+
+static int vduse_vdpa_set_vq_state(struct vdpa_device *vdpa, u16 idx,
+				const struct vdpa_vq_state *state)
+{
+	struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+	struct vduse_virtqueue *vq = &dev->vqs[idx];
+
+	if (dev->driver_features & BIT_ULL(VIRTIO_F_RING_PACKED)) {
+		vq->state.packed.last_avail_counter =
+				state->packed.last_avail_counter;
+		vq->state.packed.last_avail_idx = state->packed.last_avail_idx;
+		vq->state.packed.last_used_counter =
+				state->packed.last_used_counter;
+		vq->state.packed.last_used_idx = state->packed.last_used_idx;
+	} else
+		vq->state.split.avail_index = state->split.avail_index;
+
+	return 0;
+}
+
+static int vduse_vdpa_get_vq_state(struct vdpa_device *vdpa, u16 idx,
+				struct vdpa_vq_state *state)
+{
+	struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+	struct vduse_virtqueue *vq = &dev->vqs[idx];
+
+	if (dev->driver_features & BIT_ULL(VIRTIO_F_RING_PACKED))
+		return vduse_dev_get_vq_state_packed(dev, vq, &state->packed);
+
+	return vduse_dev_get_vq_state_split(dev, vq, &state->split);
+}
+
+static u32 vduse_vdpa_get_vq_align(struct vdpa_device *vdpa)
+{
+	struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+
+	return dev->vq_align;
+}
+
+static u64 vduse_vdpa_get_features(struct vdpa_device *vdpa)
+{
+	struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+
+	return dev->device_features;
+}
+
+static int vduse_vdpa_set_features(struct vdpa_device *vdpa, u64 features)
+{
+	struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+
+	dev->driver_features = features;
+	return 0;
+}
+
+static void vduse_vdpa_set_config_cb(struct vdpa_device *vdpa,
+				  struct vdpa_callback *cb)
+{
+	struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+
+	spin_lock(&dev->irq_lock);
+	dev->config_cb.callback = cb->callback;
+	dev->config_cb.private = cb->private;
+	spin_unlock(&dev->irq_lock);
+}
+
+static u16 vduse_vdpa_get_vq_num_max(struct vdpa_device *vdpa)
+{
+	struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+	u16 num_max = 0;
+	int i;
+
+	for (i = 0; i < dev->vq_num; i++)
+		if (num_max < dev->vqs[i].num_max)
+			num_max = dev->vqs[i].num_max;
+
+	return num_max;
+}
+
+static u32 vduse_vdpa_get_device_id(struct vdpa_device *vdpa)
+{
+	struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+
+	return dev->device_id;
+}
+
+static u32 vduse_vdpa_get_vendor_id(struct vdpa_device *vdpa)
+{
+	struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+
+	return dev->vendor_id;
+}
+
+static u8 vduse_vdpa_get_status(struct vdpa_device *vdpa)
+{
+	struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+
+	return dev->status;
+}
+
+static void vduse_vdpa_set_status(struct vdpa_device *vdpa, u8 status)
+{
+	struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+
+	if (vduse_dev_set_status(dev, status))
+		return;
+
+	dev->status = status;
+}
+
+static size_t vduse_vdpa_get_config_size(struct vdpa_device *vdpa)
+{
+	struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+
+	return dev->config_size;
+}
+
+static void vduse_vdpa_get_config(struct vdpa_device *vdpa, unsigned int offset,
+				  void *buf, unsigned int len)
+{
+	struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+
+	if (len > dev->config_size - offset)
+		return;
+
+	memcpy(buf, dev->config + offset, len);
+}
+
+static void vduse_vdpa_set_config(struct vdpa_device *vdpa, unsigned int offset,
+			const void *buf, unsigned int len)
+{
+	/* Now we only support read-only configuration space */
+}
+
+static int vduse_vdpa_reset(struct vdpa_device *vdpa)
+{
+	struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+
+	if (vduse_dev_set_status(dev, 0))
+		return -EIO;
+
+	vduse_dev_reset(dev);
+
+	return 0;
+}
+
+static u32 vduse_vdpa_get_generation(struct vdpa_device *vdpa)
+{
+	struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+
+	return dev->generation;
+}
+
+static int vduse_vdpa_set_map(struct vdpa_device *vdpa,
+				struct vhost_iotlb *iotlb)
+{
+	struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+	int ret;
+
+	ret = vduse_domain_set_map(dev->domain, iotlb);
+	if (ret)
+		return ret;
+
+	ret = vduse_dev_update_iotlb(dev, 0ULL, ULLONG_MAX);
+	if (ret) {
+		vduse_domain_clear_map(dev->domain, iotlb);
+		return ret;
+	}
+
+	return 0;
+}
+
+static void vduse_vdpa_free(struct vdpa_device *vdpa)
+{
+	struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+
+	dev->vdev = NULL;
+}
+
+static const struct vdpa_config_ops vduse_vdpa_config_ops = {
+	.set_vq_address		= vduse_vdpa_set_vq_address,
+	.kick_vq		= vduse_vdpa_kick_vq,
+	.set_vq_cb		= vduse_vdpa_set_vq_cb,
+	.set_vq_num             = vduse_vdpa_set_vq_num,
+	.set_vq_ready		= vduse_vdpa_set_vq_ready,
+	.get_vq_ready		= vduse_vdpa_get_vq_ready,
+	.set_vq_state		= vduse_vdpa_set_vq_state,
+	.get_vq_state		= vduse_vdpa_get_vq_state,
+	.get_vq_align		= vduse_vdpa_get_vq_align,
+	.get_features		= vduse_vdpa_get_features,
+	.set_features		= vduse_vdpa_set_features,
+	.set_config_cb		= vduse_vdpa_set_config_cb,
+	.get_vq_num_max		= vduse_vdpa_get_vq_num_max,
+	.get_device_id		= vduse_vdpa_get_device_id,
+	.get_vendor_id		= vduse_vdpa_get_vendor_id,
+	.get_status		= vduse_vdpa_get_status,
+	.set_status		= vduse_vdpa_set_status,
+	.get_config_size	= vduse_vdpa_get_config_size,
+	.get_config		= vduse_vdpa_get_config,
+	.set_config		= vduse_vdpa_set_config,
+	.get_generation		= vduse_vdpa_get_generation,
+	.reset			= vduse_vdpa_reset,
+	.set_map		= vduse_vdpa_set_map,
+	.free			= vduse_vdpa_free,
+};
+
+static dma_addr_t vduse_dev_map_page(struct device *dev, struct page *page,
+				     unsigned long offset, size_t size,
+				     enum dma_data_direction dir,
+				     unsigned long attrs)
+{
+	struct vduse_dev *vdev = dev_to_vduse(dev);
+	struct vduse_iova_domain *domain = vdev->domain;
+
+	return vduse_domain_map_page(domain, page, offset, size, dir, attrs);
+}
+
+static void vduse_dev_unmap_page(struct device *dev, dma_addr_t dma_addr,
+				size_t size, enum dma_data_direction dir,
+				unsigned long attrs)
+{
+	struct vduse_dev *vdev = dev_to_vduse(dev);
+	struct vduse_iova_domain *domain = vdev->domain;
+
+	return vduse_domain_unmap_page(domain, dma_addr, size, dir, attrs);
+}
+
+static void *vduse_dev_alloc_coherent(struct device *dev, size_t size,
+					dma_addr_t *dma_addr, gfp_t flag,
+					unsigned long attrs)
+{
+	struct vduse_dev *vdev = dev_to_vduse(dev);
+	struct vduse_iova_domain *domain = vdev->domain;
+	unsigned long iova;
+	void *addr;
+
+	*dma_addr = DMA_MAPPING_ERROR;
+	addr = vduse_domain_alloc_coherent(domain, size,
+				(dma_addr_t *)&iova, flag, attrs);
+	if (!addr)
+		return NULL;
+
+	*dma_addr = (dma_addr_t)iova;
+
+	return addr;
+}
+
+static void vduse_dev_free_coherent(struct device *dev, size_t size,
+					void *vaddr, dma_addr_t dma_addr,
+					unsigned long attrs)
+{
+	struct vduse_dev *vdev = dev_to_vduse(dev);
+	struct vduse_iova_domain *domain = vdev->domain;
+
+	vduse_domain_free_coherent(domain, size, vaddr, dma_addr, attrs);
+}
+
+static size_t vduse_dev_max_mapping_size(struct device *dev)
+{
+	struct vduse_dev *vdev = dev_to_vduse(dev);
+	struct vduse_iova_domain *domain = vdev->domain;
+
+	return domain->bounce_size;
+}
+
+static const struct dma_map_ops vduse_dev_dma_ops = {
+	.map_page = vduse_dev_map_page,
+	.unmap_page = vduse_dev_unmap_page,
+	.alloc = vduse_dev_alloc_coherent,
+	.free = vduse_dev_free_coherent,
+	.max_mapping_size = vduse_dev_max_mapping_size,
+};
+
+static unsigned int perm_to_file_flags(u8 perm)
+{
+	unsigned int flags = 0;
+
+	switch (perm) {
+	case VDUSE_ACCESS_WO:
+		flags |= O_WRONLY;
+		break;
+	case VDUSE_ACCESS_RO:
+		flags |= O_RDONLY;
+		break;
+	case VDUSE_ACCESS_RW:
+		flags |= O_RDWR;
+		break;
+	default:
+		WARN(1, "invalidate vhost IOTLB permission\n");
+		break;
+	}
+
+	return flags;
+}
+
+static int vduse_kickfd_setup(struct vduse_dev *dev,
+			struct vduse_vq_eventfd *eventfd)
+{
+	struct eventfd_ctx *ctx = NULL;
+	struct vduse_virtqueue *vq;
+	u32 index;
+
+	if (eventfd->index >= dev->vq_num)
+		return -EINVAL;
+
+	index = array_index_nospec(eventfd->index, dev->vq_num);
+	vq = &dev->vqs[index];
+	if (eventfd->fd >= 0) {
+		ctx = eventfd_ctx_fdget(eventfd->fd);
+		if (IS_ERR(ctx))
+			return PTR_ERR(ctx);
+	} else if (eventfd->fd != VDUSE_EVENTFD_DEASSIGN)
+		return 0;
+
+	spin_lock(&vq->kick_lock);
+	if (vq->kickfd)
+		eventfd_ctx_put(vq->kickfd);
+	vq->kickfd = ctx;
+	if (vq->ready && vq->kicked && vq->kickfd) {
+		eventfd_signal(vq->kickfd, 1);
+		vq->kicked = false;
+	}
+	spin_unlock(&vq->kick_lock);
+
+	return 0;
+}
+
+static bool vduse_dev_is_ready(struct vduse_dev *dev)
+{
+	int i;
+
+	for (i = 0; i < dev->vq_num; i++)
+		if (!dev->vqs[i].num_max)
+			return false;
+
+	return true;
+}
+
+static void vduse_dev_irq_inject(struct work_struct *work)
+{
+	struct vduse_dev *dev = container_of(work, struct vduse_dev, inject);
+
+	spin_lock_irq(&dev->irq_lock);
+	if (dev->config_cb.callback)
+		dev->config_cb.callback(dev->config_cb.private);
+	spin_unlock_irq(&dev->irq_lock);
+}
+
+static void vduse_vq_irq_inject(struct work_struct *work)
+{
+	struct vduse_virtqueue *vq = container_of(work,
+					struct vduse_virtqueue, inject);
+
+	spin_lock_irq(&vq->irq_lock);
+	if (vq->ready && vq->cb.callback)
+		vq->cb.callback(vq->cb.private);
+	spin_unlock_irq(&vq->irq_lock);
+}
+
+static long vduse_dev_ioctl(struct file *file, unsigned int cmd,
+			    unsigned long arg)
+{
+	struct vduse_dev *dev = file->private_data;
+	void __user *argp = (void __user *)arg;
+	int ret;
+
+	if (unlikely(dev->broken))
+		return -EPERM;
+
+	switch (cmd) {
+	case VDUSE_IOTLB_GET_FD: {
+		struct vduse_iotlb_entry entry;
+		struct vhost_iotlb_map *map;
+		struct vdpa_map_file *map_file;
+		struct vduse_iova_domain *domain = dev->domain;
+		struct file *f = NULL;
+
+		ret = -EFAULT;
+		if (copy_from_user(&entry, argp, sizeof(entry)))
+			break;
+
+		ret = -EINVAL;
+		if (entry.start > entry.last)
+			break;
+
+		spin_lock(&domain->iotlb_lock);
+		map = vhost_iotlb_itree_first(domain->iotlb,
+					      entry.start, entry.last);
+		if (map) {
+			map_file = (struct vdpa_map_file *)map->opaque;
+			f = get_file(map_file->file);
+			entry.offset = map_file->offset;
+			entry.start = map->start;
+			entry.last = map->last;
+			entry.perm = map->perm;
+		}
+		spin_unlock(&domain->iotlb_lock);
+		ret = -EINVAL;
+		if (!f)
+			break;
+
+		ret = -EFAULT;
+		if (copy_to_user(argp, &entry, sizeof(entry))) {
+			fput(f);
+			break;
+		}
+		ret = receive_fd(f, perm_to_file_flags(entry.perm));
+		fput(f);
+		break;
+	}
+	case VDUSE_DEV_GET_FEATURES:
+		/*
+		 * Just mirror what driver wrote here.
+		 * The driver is expected to check FEATURE_OK later.
+		 */
+		ret = put_user(dev->driver_features, (u64 __user *)argp);
+		break;
+	case VDUSE_DEV_SET_CONFIG: {
+		struct vduse_config_data config;
+		unsigned long size = offsetof(struct vduse_config_data,
+					      buffer);
+
+		ret = -EFAULT;
+		if (copy_from_user(&config, argp, size))
+			break;
+
+		ret = -EINVAL;
+		if (config.length == 0 ||
+		    config.length > dev->config_size - config.offset)
+			break;
+
+		ret = -EFAULT;
+		if (copy_from_user(dev->config + config.offset, argp + size,
+				   config.length))
+			break;
+
+		ret = 0;
+		break;
+	}
+	case VDUSE_DEV_INJECT_CONFIG_IRQ:
+		ret = 0;
+		queue_work(vduse_irq_wq, &dev->inject);
+		break;
+	case VDUSE_VQ_SETUP: {
+		struct vduse_vq_config config;
+		u32 index;
+
+		ret = -EFAULT;
+		if (copy_from_user(&config, argp, sizeof(config)))
+			break;
+
+		ret = -EINVAL;
+		if (config.index >= dev->vq_num)
+			break;
+
+		if (!is_mem_zero((const char *)config.reserved,
+				 sizeof(config.reserved)))
+			break;
+
+		index = array_index_nospec(config.index, dev->vq_num);
+		dev->vqs[index].num_max = config.max_size;
+		ret = 0;
+		break;
+	}
+	case VDUSE_VQ_GET_INFO: {
+		struct vduse_vq_info vq_info;
+		struct vduse_virtqueue *vq;
+		u32 index;
+
+		ret = -EFAULT;
+		if (copy_from_user(&vq_info, argp, sizeof(vq_info)))
+			break;
+
+		ret = -EINVAL;
+		if (vq_info.index >= dev->vq_num)
+			break;
+
+		index = array_index_nospec(vq_info.index, dev->vq_num);
+		vq = &dev->vqs[index];
+		vq_info.desc_addr = vq->desc_addr;
+		vq_info.driver_addr = vq->driver_addr;
+		vq_info.device_addr = vq->device_addr;
+		vq_info.num = vq->num;
+
+		if (dev->driver_features & BIT_ULL(VIRTIO_F_RING_PACKED)) {
+			vq_info.packed.last_avail_counter =
+				vq->state.packed.last_avail_counter;
+			vq_info.packed.last_avail_idx =
+				vq->state.packed.last_avail_idx;
+			vq_info.packed.last_used_counter =
+				vq->state.packed.last_used_counter;
+			vq_info.packed.last_used_idx =
+				vq->state.packed.last_used_idx;
+		} else
+			vq_info.split.avail_index =
+				vq->state.split.avail_index;
+
+		vq_info.ready = vq->ready;
+
+		ret = -EFAULT;
+		if (copy_to_user(argp, &vq_info, sizeof(vq_info)))
+			break;
+
+		ret = 0;
+		break;
+	}
+	case VDUSE_VQ_SETUP_KICKFD: {
+		struct vduse_vq_eventfd eventfd;
+
+		ret = -EFAULT;
+		if (copy_from_user(&eventfd, argp, sizeof(eventfd)))
+			break;
+
+		ret = vduse_kickfd_setup(dev, &eventfd);
+		break;
+	}
+	case VDUSE_VQ_INJECT_IRQ: {
+		u32 index;
+
+		ret = -EFAULT;
+		if (get_user(index, (u32 __user *)argp))
+			break;
+
+		ret = -EINVAL;
+		if (index >= dev->vq_num)
+			break;
+
+		ret = 0;
+		index = array_index_nospec(index, dev->vq_num);
+		queue_work(vduse_irq_wq, &dev->vqs[index].inject);
+		break;
+	}
+	default:
+		ret = -ENOIOCTLCMD;
+		break;
+	}
+
+	return ret;
+}
+
+static int vduse_dev_release(struct inode *inode, struct file *file)
+{
+	struct vduse_dev *dev = file->private_data;
+
+	spin_lock(&dev->msg_lock);
+	/* Make sure the inflight messages can processed after reconncection */
+	list_splice_init(&dev->recv_list, &dev->send_list);
+	spin_unlock(&dev->msg_lock);
+	dev->connected = false;
+
+	return 0;
+}
+
+static struct vduse_dev *vduse_dev_get_from_minor(int minor)
+{
+	struct vduse_dev *dev;
+
+	mutex_lock(&vduse_lock);
+	dev = idr_find(&vduse_idr, minor);
+	mutex_unlock(&vduse_lock);
+
+	return dev;
+}
+
+static int vduse_dev_open(struct inode *inode, struct file *file)
+{
+	int ret;
+	struct vduse_dev *dev = vduse_dev_get_from_minor(iminor(inode));
+
+	if (!dev)
+		return -ENODEV;
+
+	ret = -EBUSY;
+	mutex_lock(&dev->lock);
+	if (dev->connected)
+		goto unlock;
+
+	ret = 0;
+	dev->connected = true;
+	file->private_data = dev;
+unlock:
+	mutex_unlock(&dev->lock);
+
+	return ret;
+}
+
+static const struct file_operations vduse_dev_fops = {
+	.owner		= THIS_MODULE,
+	.open		= vduse_dev_open,
+	.release	= vduse_dev_release,
+	.read_iter	= vduse_dev_read_iter,
+	.write_iter	= vduse_dev_write_iter,
+	.poll		= vduse_dev_poll,
+	.unlocked_ioctl	= vduse_dev_ioctl,
+	.compat_ioctl	= compat_ptr_ioctl,
+	.llseek		= noop_llseek,
+};
+
+static struct vduse_dev *vduse_dev_create(void)
+{
+	struct vduse_dev *dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+
+	if (!dev)
+		return NULL;
+
+	mutex_init(&dev->lock);
+	spin_lock_init(&dev->msg_lock);
+	INIT_LIST_HEAD(&dev->send_list);
+	INIT_LIST_HEAD(&dev->recv_list);
+	spin_lock_init(&dev->irq_lock);
+
+	INIT_WORK(&dev->inject, vduse_dev_irq_inject);
+	init_waitqueue_head(&dev->waitq);
+
+	return dev;
+}
+
+static void vduse_dev_destroy(struct vduse_dev *dev)
+{
+	kfree(dev);
+}
+
+static struct vduse_dev *vduse_find_dev(const char *name)
+{
+	struct vduse_dev *dev;
+	int id;
+
+	idr_for_each_entry(&vduse_idr, dev, id)
+		if (!strcmp(dev->name, name))
+			return dev;
+
+	return NULL;
+}
+
+static int vduse_destroy_dev(char *name)
+{
+	struct vduse_dev *dev = vduse_find_dev(name);
+
+	if (!dev)
+		return -EINVAL;
+
+	mutex_lock(&dev->lock);
+	if (dev->vdev || dev->connected) {
+		mutex_unlock(&dev->lock);
+		return -EBUSY;
+	}
+	dev->connected = true;
+	mutex_unlock(&dev->lock);
+
+	vduse_dev_reset(dev);
+	device_destroy(vduse_class, MKDEV(MAJOR(vduse_major), dev->minor));
+	idr_remove(&vduse_idr, dev->minor);
+	kvfree(dev->config);
+	kfree(dev->vqs);
+	vduse_domain_destroy(dev->domain);
+	kfree(dev->name);
+	vduse_dev_destroy(dev);
+	module_put(THIS_MODULE);
+
+	return 0;
+}
+
+static bool device_is_allowed(u32 device_id)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(allowed_device_id); i++)
+		if (allowed_device_id[i] == device_id)
+			return true;
+
+	return false;
+}
+
+static bool features_is_valid(u64 features)
+{
+	if (!(features & (1ULL << VIRTIO_F_ACCESS_PLATFORM)))
+		return false;
+
+	/* Now we only support read-only configuration space */
+	if (features & (1ULL << VIRTIO_BLK_F_CONFIG_WCE))
+		return false;
+
+	return true;
+}
+
+static bool vduse_validate_config(struct vduse_dev_config *config)
+{
+	if (!is_mem_zero((const char *)config->reserved,
+			 sizeof(config->reserved)))
+		return false;
+
+	if (config->vq_align > PAGE_SIZE)
+		return false;
+
+	if (config->config_size > PAGE_SIZE)
+		return false;
+
+	if (!device_is_allowed(config->device_id))
+		return false;
+
+	if (!features_is_valid(config->features))
+		return false;
+
+	return true;
+}
+
+static ssize_t msg_timeout_show(struct device *device,
+				struct device_attribute *attr, char *buf)
+{
+	struct vduse_dev *dev = dev_get_drvdata(device);
+
+	return sysfs_emit(buf, "%u\n", dev->msg_timeout);
+}
+
+static ssize_t msg_timeout_store(struct device *device,
+				 struct device_attribute *attr,
+				 const char *buf, size_t count)
+{
+	struct vduse_dev *dev = dev_get_drvdata(device);
+	int ret;
+
+	ret = kstrtouint(buf, 10, &dev->msg_timeout);
+	if (ret < 0)
+		return ret;
+
+	return count;
+}
+
+static DEVICE_ATTR_RW(msg_timeout);
+
+static struct attribute *vduse_dev_attrs[] = {
+	&dev_attr_msg_timeout.attr,
+	NULL
+};
+
+ATTRIBUTE_GROUPS(vduse_dev);
+
+static int vduse_create_dev(struct vduse_dev_config *config,
+			    void *config_buf, u64 api_version)
+{
+	int i, ret;
+	struct vduse_dev *dev;
+
+	ret = -EEXIST;
+	if (vduse_find_dev(config->name))
+		goto err;
+
+	ret = -ENOMEM;
+	dev = vduse_dev_create();
+	if (!dev)
+		goto err;
+
+	dev->api_version = api_version;
+	dev->device_features = config->features;
+	dev->device_id = config->device_id;
+	dev->vendor_id = config->vendor_id;
+	dev->name = kstrdup(config->name, GFP_KERNEL);
+	if (!dev->name)
+		goto err_str;
+
+	dev->domain = vduse_domain_create(VDUSE_IOVA_SIZE - 1,
+					  VDUSE_BOUNCE_SIZE);
+	if (!dev->domain)
+		goto err_domain;
+
+	dev->config = config_buf;
+	dev->config_size = config->config_size;
+	dev->vq_align = config->vq_align;
+	dev->vq_num = config->vq_num;
+	dev->vqs = kcalloc(dev->vq_num, sizeof(*dev->vqs), GFP_KERNEL);
+	if (!dev->vqs)
+		goto err_vqs;
+
+	for (i = 0; i < dev->vq_num; i++) {
+		dev->vqs[i].index = i;
+		INIT_WORK(&dev->vqs[i].inject, vduse_vq_irq_inject);
+		INIT_WORK(&dev->vqs[i].kick, vduse_vq_kick_work);
+		spin_lock_init(&dev->vqs[i].kick_lock);
+		spin_lock_init(&dev->vqs[i].irq_lock);
+	}
+
+	ret = idr_alloc(&vduse_idr, dev, 1, VDUSE_DEV_MAX, GFP_KERNEL);
+	if (ret < 0)
+		goto err_idr;
+
+	dev->minor = ret;
+	dev->msg_timeout = VDUSE_MSG_DEFAULT_TIMEOUT;
+	dev->dev = device_create(vduse_class, NULL,
+				 MKDEV(MAJOR(vduse_major), dev->minor),
+				 dev, "%s", config->name);
+	if (IS_ERR(dev->dev)) {
+		ret = PTR_ERR(dev->dev);
+		goto err_dev;
+	}
+	__module_get(THIS_MODULE);
+
+	return 0;
+err_dev:
+	idr_remove(&vduse_idr, dev->minor);
+err_idr:
+	kfree(dev->vqs);
+err_vqs:
+	vduse_domain_destroy(dev->domain);
+err_domain:
+	kfree(dev->name);
+err_str:
+	vduse_dev_destroy(dev);
+err:
+	kvfree(config_buf);
+	return ret;
+}
+
+static long vduse_ioctl(struct file *file, unsigned int cmd,
+			unsigned long arg)
+{
+	int ret;
+	void __user *argp = (void __user *)arg;
+	struct vduse_control *control = file->private_data;
+
+	mutex_lock(&vduse_lock);
+	switch (cmd) {
+	case VDUSE_GET_API_VERSION:
+		ret = put_user(control->api_version, (u64 __user *)argp);
+		break;
+	case VDUSE_SET_API_VERSION: {
+		u64 api_version;
+
+		ret = -EFAULT;
+		if (get_user(api_version, (u64 __user *)argp))
+			break;
+
+		ret = -EINVAL;
+		if (api_version > VDUSE_API_VERSION)
+			break;
+
+		ret = 0;
+		control->api_version = api_version;
+		break;
+	}
+	case VDUSE_CREATE_DEV: {
+		struct vduse_dev_config config;
+		unsigned long size = offsetof(struct vduse_dev_config, config);
+		void *buf;
+
+		ret = -EFAULT;
+		if (copy_from_user(&config, argp, size))
+			break;
+
+		ret = -EINVAL;
+		if (vduse_validate_config(&config) == false)
+			break;
+
+		buf = vmemdup_user(argp + size, config.config_size);
+		if (IS_ERR(buf)) {
+			ret = PTR_ERR(buf);
+			break;
+		}
+		config.name[VDUSE_NAME_MAX - 1] = '\0';
+		ret = vduse_create_dev(&config, buf, control->api_version);
+		break;
+	}
+	case VDUSE_DESTROY_DEV: {
+		char name[VDUSE_NAME_MAX];
+
+		ret = -EFAULT;
+		if (copy_from_user(name, argp, VDUSE_NAME_MAX))
+			break;
+
+		name[VDUSE_NAME_MAX - 1] = '\0';
+		ret = vduse_destroy_dev(name);
+		break;
+	}
+	default:
+		ret = -EINVAL;
+		break;
+	}
+	mutex_unlock(&vduse_lock);
+
+	return ret;
+}
+
+static int vduse_release(struct inode *inode, struct file *file)
+{
+	struct vduse_control *control = file->private_data;
+
+	kfree(control);
+	return 0;
+}
+
+static int vduse_open(struct inode *inode, struct file *file)
+{
+	struct vduse_control *control;
+
+	control = kmalloc(sizeof(struct vduse_control), GFP_KERNEL);
+	if (!control)
+		return -ENOMEM;
+
+	control->api_version = VDUSE_API_VERSION;
+	file->private_data = control;
+
+	return 0;
+}
+
+static const struct file_operations vduse_ctrl_fops = {
+	.owner		= THIS_MODULE,
+	.open		= vduse_open,
+	.release	= vduse_release,
+	.unlocked_ioctl	= vduse_ioctl,
+	.compat_ioctl	= compat_ptr_ioctl,
+	.llseek		= noop_llseek,
+};
+
+static char *vduse_devnode(struct device *dev, umode_t *mode)
+{
+	return kasprintf(GFP_KERNEL, "vduse/%s", dev_name(dev));
+}
+
+static void vduse_mgmtdev_release(struct device *dev)
+{
+}
+
+static struct device vduse_mgmtdev = {
+	.init_name = "vduse",
+	.release = vduse_mgmtdev_release,
+};
+
+static struct vdpa_mgmt_dev mgmt_dev;
+
+static int vduse_dev_init_vdpa(struct vduse_dev *dev, const char *name)
+{
+	struct vduse_vdpa *vdev;
+	int ret;
+
+	if (dev->vdev)
+		return -EEXIST;
+
+	vdev = vdpa_alloc_device(struct vduse_vdpa, vdpa, dev->dev,
+				 &vduse_vdpa_config_ops, name, true);
+	if (IS_ERR(vdev))
+		return PTR_ERR(vdev);
+
+	dev->vdev = vdev;
+	vdev->dev = dev;
+	vdev->vdpa.dev.dma_mask = &vdev->vdpa.dev.coherent_dma_mask;
+	ret = dma_set_mask_and_coherent(&vdev->vdpa.dev, DMA_BIT_MASK(64));
+	if (ret) {
+		put_device(&vdev->vdpa.dev);
+		return ret;
+	}
+	set_dma_ops(&vdev->vdpa.dev, &vduse_dev_dma_ops);
+	vdev->vdpa.dma_dev = &vdev->vdpa.dev;
+	vdev->vdpa.mdev = &mgmt_dev;
+
+	return 0;
+}
+
+static int vdpa_dev_add(struct vdpa_mgmt_dev *mdev, const char *name)
+{
+	struct vduse_dev *dev;
+	int ret;
+
+	mutex_lock(&vduse_lock);
+	dev = vduse_find_dev(name);
+	if (!dev || !vduse_dev_is_ready(dev)) {
+		mutex_unlock(&vduse_lock);
+		return -EINVAL;
+	}
+	ret = vduse_dev_init_vdpa(dev, name);
+	mutex_unlock(&vduse_lock);
+	if (ret)
+		return ret;
+
+	ret = _vdpa_register_device(&dev->vdev->vdpa, dev->vq_num);
+	if (ret) {
+		put_device(&dev->vdev->vdpa.dev);
+		return ret;
+	}
+
+	return 0;
+}
+
+static void vdpa_dev_del(struct vdpa_mgmt_dev *mdev, struct vdpa_device *dev)
+{
+	_vdpa_unregister_device(dev);
+}
+
+static const struct vdpa_mgmtdev_ops vdpa_dev_mgmtdev_ops = {
+	.dev_add = vdpa_dev_add,
+	.dev_del = vdpa_dev_del,
+};
+
+static struct virtio_device_id id_table[] = {
+	{ VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID },
+	{ 0 },
+};
+
+static struct vdpa_mgmt_dev mgmt_dev = {
+	.device = &vduse_mgmtdev,
+	.id_table = id_table,
+	.ops = &vdpa_dev_mgmtdev_ops,
+};
+
+static int vduse_mgmtdev_init(void)
+{
+	int ret;
+
+	ret = device_register(&vduse_mgmtdev);
+	if (ret)
+		return ret;
+
+	ret = vdpa_mgmtdev_register(&mgmt_dev);
+	if (ret)
+		goto err;
+
+	return 0;
+err:
+	device_unregister(&vduse_mgmtdev);
+	return ret;
+}
+
+static void vduse_mgmtdev_exit(void)
+{
+	vdpa_mgmtdev_unregister(&mgmt_dev);
+	device_unregister(&vduse_mgmtdev);
+}
+
+static int vduse_init(void)
+{
+	int ret;
+	struct device *dev;
+
+	vduse_class = class_create(THIS_MODULE, "vduse");
+	if (IS_ERR(vduse_class))
+		return PTR_ERR(vduse_class);
+
+	vduse_class->devnode = vduse_devnode;
+	vduse_class->dev_groups = vduse_dev_groups;
+
+	ret = alloc_chrdev_region(&vduse_major, 0, VDUSE_DEV_MAX, "vduse");
+	if (ret)
+		goto err_chardev_region;
+
+	/* /dev/vduse/control */
+	cdev_init(&vduse_ctrl_cdev, &vduse_ctrl_fops);
+	vduse_ctrl_cdev.owner = THIS_MODULE;
+	ret = cdev_add(&vduse_ctrl_cdev, vduse_major, 1);
+	if (ret)
+		goto err_ctrl_cdev;
+
+	dev = device_create(vduse_class, NULL, vduse_major, NULL, "control");
+	if (IS_ERR(dev)) {
+		ret = PTR_ERR(dev);
+		goto err_device;
+	}
+
+	/* /dev/vduse/$DEVICE */
+	cdev_init(&vduse_cdev, &vduse_dev_fops);
+	vduse_cdev.owner = THIS_MODULE;
+	ret = cdev_add(&vduse_cdev, MKDEV(MAJOR(vduse_major), 1),
+		       VDUSE_DEV_MAX - 1);
+	if (ret)
+		goto err_cdev;
+
+	vduse_irq_wq = alloc_workqueue("vduse-irq",
+				WQ_HIGHPRI | WQ_SYSFS | WQ_UNBOUND, 0);
+	if (!vduse_irq_wq)
+		goto err_wq;
+
+	ret = vduse_domain_init();
+	if (ret)
+		goto err_domain;
+
+	ret = vduse_mgmtdev_init();
+	if (ret)
+		goto err_mgmtdev;
+
+	return 0;
+err_mgmtdev:
+	vduse_domain_exit();
+err_domain:
+	destroy_workqueue(vduse_irq_wq);
+err_wq:
+	cdev_del(&vduse_cdev);
+err_cdev:
+	device_destroy(vduse_class, vduse_major);
+err_device:
+	cdev_del(&vduse_ctrl_cdev);
+err_ctrl_cdev:
+	unregister_chrdev_region(vduse_major, VDUSE_DEV_MAX);
+err_chardev_region:
+	class_destroy(vduse_class);
+	return ret;
+}
+module_init(vduse_init);
+
+static void vduse_exit(void)
+{
+	vduse_mgmtdev_exit();
+	vduse_domain_exit();
+	destroy_workqueue(vduse_irq_wq);
+	cdev_del(&vduse_cdev);
+	device_destroy(vduse_class, vduse_major);
+	cdev_del(&vduse_ctrl_cdev);
+	unregister_chrdev_region(vduse_major, VDUSE_DEV_MAX);
+	class_destroy(vduse_class);
+}
+module_exit(vduse_exit);
+
+MODULE_LICENSE(DRV_LICENSE);
+MODULE_AUTHOR(DRV_AUTHOR);
+MODULE_DESCRIPTION(DRV_DESC);