This VDUSE driver enables implementing vDPA devices in userspace.
The vDPA device's control path is handled in kernel and the data
path is handled in userspace.

A message mechnism is used by VDUSE driver to forward some control
messages such as starting/stopping datapath to userspace. Userspace
can use read()/write() to receive/reply those control messages.

And some ioctls are introduced to help userspace to implement the
data path. VDUSE_IOTLB_GET_FD ioctl can be used to get the file
descriptors referring to vDPA device's iova regions. Then userspace
can use mmap() to access those iova regions. VDUSE_DEV_GET_FEATURES
and VDUSE_VQ_GET_INFO ioctls are used to get the negotiated features
and metadata of virtqueues. VDUSE_INJECT_VQ_IRQ and VDUSE_VQ_SETUP_KICKFD
ioctls can be used to inject interrupt and setup the kickfd for
virtqueues. VDUSE_DEV_UPDATE_CONFIG ioctl is used to update the
configuration space and inject a config interrupt.

Signed-off-by: Xie Yongji <xieyon...@bytedance.com>
---
 Documentation/userspace-api/ioctl/ioctl-number.rst |    1 +
 drivers/vdpa/Kconfig                               |   10 +
 drivers/vdpa/Makefile                              |    1 +
 drivers/vdpa/vdpa_user/Makefile                    |    5 +
 drivers/vdpa/vdpa_user/vduse_dev.c                 | 1453 ++++++++++++++++++++
 include/uapi/linux/vduse.h                         |  143 ++
 6 files changed, 1613 insertions(+)
 create mode 100644 drivers/vdpa/vdpa_user/Makefile
 create mode 100644 drivers/vdpa/vdpa_user/vduse_dev.c
 create mode 100644 include/uapi/linux/vduse.h

diff --git a/Documentation/userspace-api/ioctl/ioctl-number.rst 
b/Documentation/userspace-api/ioctl/ioctl-number.rst
index 9bfc2b510c64..acd95e9dcfe7 100644
--- a/Documentation/userspace-api/ioctl/ioctl-number.rst
+++ b/Documentation/userspace-api/ioctl/ioctl-number.rst
@@ -300,6 +300,7 @@ Code  Seq#    Include File                                  
         Comments
 'z'   10-4F  drivers/s390/crypto/zcrypt_api.h                        conflict!
 '|'   00-7F  linux/media.h
 0x80  00-1F  linux/fb.h
+0x81  00-1F  linux/vduse.h
 0x89  00-06  arch/x86/include/asm/sockios.h
 0x89  0B-DF  linux/sockios.h
 0x89  E0-EF  linux/sockios.h                                         
SIOCPROTOPRIVATE range
diff --git a/drivers/vdpa/Kconfig b/drivers/vdpa/Kconfig
index a503c1b2bfd9..6e23bce6433a 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..5271cbd15e28
--- /dev/null
+++ b/drivers/vdpa/vdpa_user/vduse_dev.c
@@ -0,0 +1,1453 @@
+// 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 <xieyon...@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 <xieyon...@bytedance.com>"
+#define DRV_DESC     "vDPA Device in Userspace"
+#define DRV_LICENSE  "GPL v2"
+
+#define VDUSE_DEV_MAX (1U << MINORBITS)
+#define VDUSE_MAX_BOUNCE_SIZE (64 * 1024 * 1024)
+#define VDUSE_IOVA_SIZE (128 * 1024 * 1024)
+#define VDUSE_REQUEST_TIMEOUT 30
+
+struct vduse_virtqueue {
+       u16 index;
+       u32 num;
+       u32 avail_idx;
+       u64 desc_addr;
+       u64 driver_addr;
+       u64 device_addr;
+       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 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;
+       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 connected;
+       bool started;
+       u64 api_version;
+       u64 user_features;
+       u64 features;
+       u32 device_id;
+       u32 vendor_id;
+       u32 generation;
+       u32 config_size;
+       void *config;
+       u8 status;
+       u16 vq_size_max;
+       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 int vduse_dev_msg_send(struct vduse_dev *dev,
+                             struct vduse_dev_msg *msg, bool no_reply)
+{
+       init_waitqueue_head(&msg->waitq);
+       spin_lock(&dev->msg_lock);
+       msg->req.request_id = dev->msg_unique++;
+       vduse_enqueue_msg(&dev->send_list, msg);
+       wake_up(&dev->waitq);
+       spin_unlock(&dev->msg_lock);
+       if (no_reply)
+               return 0;
+
+       wait_event_killable_timeout(msg->waitq, msg->completed,
+                                   VDUSE_REQUEST_TIMEOUT * HZ);
+       spin_lock(&dev->msg_lock);
+       if (!msg->completed) {
+               list_del(&msg->list);
+               msg->resp.result = VDUSE_REQ_RESULT_FAILED;
+       }
+       spin_unlock(&dev->msg_lock);
+
+       return (msg->resp.result == VDUSE_REQ_RESULT_OK) ? 0 : -EIO;
+}
+
+static void vduse_dev_msg_cleanup(struct vduse_dev *dev)
+{
+       struct vduse_dev_msg *msg;
+
+       spin_lock(&dev->msg_lock);
+       while ((msg = vduse_dequeue_msg(&dev->send_list))) {
+               if (msg->req.flags & VDUSE_REQ_FLAGS_NO_REPLY)
+                       kfree(msg);
+               else
+                       vduse_enqueue_msg(&dev->recv_list, msg);
+       }
+       while ((msg = vduse_dequeue_msg(&dev->recv_list))) {
+               msg->resp.result = VDUSE_REQ_RESULT_FAILED;
+               msg->completed = 1;
+               wake_up(&msg->waitq);
+       }
+       spin_unlock(&dev->msg_lock);
+}
+
+static void vduse_dev_start_dataplane(struct vduse_dev *dev)
+{
+       struct vduse_dev_msg *msg = kzalloc(sizeof(*msg),
+                                           GFP_KERNEL | __GFP_NOFAIL);
+
+       msg->req.type = VDUSE_START_DATAPLANE;
+       msg->req.flags |= VDUSE_REQ_FLAGS_NO_REPLY;
+       vduse_dev_msg_send(dev, msg, true);
+}
+
+static void vduse_dev_stop_dataplane(struct vduse_dev *dev)
+{
+       struct vduse_dev_msg *msg = kzalloc(sizeof(*msg),
+                                           GFP_KERNEL | __GFP_NOFAIL);
+
+       msg->req.type = VDUSE_STOP_DATAPLANE;
+       msg->req.flags |= VDUSE_REQ_FLAGS_NO_REPLY;
+       vduse_dev_msg_send(dev, msg, true);
+}
+
+static int vduse_dev_get_vq_state(struct vduse_dev *dev,
+                                 struct vduse_virtqueue *vq,
+                                 struct vdpa_vq_state *state)
+{
+       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_send(dev, &msg, false);
+       if (ret)
+               return ret;
+
+       state->avail_index = msg.resp.vq_state.avail_idx;
+       return 0;
+}
+
+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_send(dev, &msg, false);
+}
+
+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;
+       }
+       if (msg->req.flags & VDUSE_REQ_FLAGS_NO_REPLY)
+               kfree(msg);
+       else
+               vduse_enqueue_msg(&dev->recv_list, msg);
+unlock:
+       spin_unlock(&dev->msg_lock);
+
+       return ret;
+}
+
+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;
+
+       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);
+
+       if (!list_empty(&dev->send_list))
+               mask |= EPOLLIN | EPOLLRDNORM;
+       if (!list_empty(&dev->recv_list))
+               mask |= EPOLLOUT | EPOLLWRNORM;
+
+       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->features = 0;
+       dev->generation++;
+       spin_lock(&dev->irq_lock);
+       dev->config_cb.callback = NULL;
+       dev->config_cb.private = NULL;
+       spin_unlock(&dev->irq_lock);
+
+       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->avail_idx = 0;
+               vq->num = 0;
+
+               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);
+       }
+}
+
+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_vdpa_kick_vq(struct vdpa_device *vdpa, u16 idx)
+{
+       struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+       struct vduse_virtqueue *vq = &dev->vqs[idx];
+
+       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_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];
+
+       vq->avail_idx = state->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];
+
+       return vduse_dev_get_vq_state(dev, vq, state);
+}
+
+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->user_features;
+}
+
+static int vduse_vdpa_set_features(struct vdpa_device *vdpa, u64 features)
+{
+       struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+
+       dev->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);
+
+       return dev->vq_size_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);
+       bool started = !!(status & VIRTIO_CONFIG_S_DRIVER_OK);
+
+       dev->status = status;
+
+       if (dev->started == started)
+               return;
+
+       dev->started = started;
+       if (dev->started) {
+               vduse_dev_start_dataplane(dev);
+       } else {
+               vduse_dev_reset(dev);
+               vduse_dev_stop_dataplane(dev);
+       }
+}
+
+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);
+
+       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 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,
+       .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 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;
+
+       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:
+               ret = put_user(dev->features, (u64 __user *)argp);
+               break;
+       case VDUSE_DEV_UPDATE_CONFIG: {
+               struct vduse_config_update config;
+               unsigned long size = offsetof(struct vduse_config_update,
+                                             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;
+               queue_work(vduse_irq_wq, &dev->inject);
+               break;
+       }
+       case VDUSE_VQ_GET_INFO: {
+               struct vduse_vq_info vq_info;
+               u32 vq_index;
+
+               ret = -EFAULT;
+               if (copy_from_user(&vq_info, argp, sizeof(vq_info)))
+                       break;
+
+               ret = -EINVAL;
+               if (vq_info.index >= dev->vq_num)
+                       break;
+
+               vq_index = array_index_nospec(vq_info.index, dev->vq_num);
+               vq_info.desc_addr = dev->vqs[vq_index].desc_addr;
+               vq_info.driver_addr = dev->vqs[vq_index].driver_addr;
+               vq_info.device_addr = dev->vqs[vq_index].device_addr;
+               vq_info.num = dev->vqs[vq_index].num;
+               vq_info.avail_idx = dev->vqs[vq_index].avail_idx;
+               vq_info.ready = dev->vqs[vq_index].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 vq_index;
+
+               ret = -EFAULT;
+               if (get_user(vq_index, (u32 __user *)argp))
+                       break;
+
+               ret = -EINVAL;
+               if (vq_index >= dev->vq_num)
+                       break;
+
+               ret = 0;
+               vq_index = array_index_nospec(vq_index, dev->vq_num);
+               queue_work(vduse_irq_wq, &dev->vqs[vq_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_msg_cleanup(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 (config->bounce_size > VDUSE_MAX_BOUNCE_SIZE)
+               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 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->user_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,
+                                         config->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_size_max = config->vq_size_max;
+       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);
+               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->dev = device_create(vduse_class, NULL,
+                                MKDEV(MAJOR(vduse_major), dev->minor),
+                                NULL, "%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;
+               }
+               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;
+
+               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 (!vdev)
+               return -ENOMEM;
+
+       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) {
+               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;
+
+       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);
diff --git a/include/uapi/linux/vduse.h b/include/uapi/linux/vduse.h
new file mode 100644
index 000000000000..f21b2e51b5c8
--- /dev/null
+++ b/include/uapi/linux/vduse.h
@@ -0,0 +1,143 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+#ifndef _UAPI_VDUSE_H_
+#define _UAPI_VDUSE_H_
+
+#include <linux/types.h>
+
+#define VDUSE_API_VERSION      0
+
+#define VDUSE_NAME_MAX 256
+
+/* the control messages definition for read/write */
+
+enum vduse_req_type {
+       /* Get the state for virtqueue from userspace */
+       VDUSE_GET_VQ_STATE,
+       /* Notify userspace to start the dataplane, no reply */
+       VDUSE_START_DATAPLANE,
+       /* Notify userspace to stop the dataplane, no reply */
+       VDUSE_STOP_DATAPLANE,
+       /* Notify userspace to update the memory mapping in device IOTLB */
+       VDUSE_UPDATE_IOTLB,
+};
+
+struct vduse_vq_state {
+       __u32 index; /* virtqueue index */
+       __u32 avail_idx; /* virtqueue state (last_avail_idx) */
+};
+
+struct vduse_iova_range {
+       __u64 start; /* start of the IOVA range */
+       __u64 last; /* end of the IOVA range */
+};
+
+struct vduse_dev_request {
+       __u32 type; /* request type */
+       __u32 request_id; /* request id */
+#define VDUSE_REQ_FLAGS_NO_REPLY       (1 << 0) /* No need to reply */
+       __u32 flags; /* request flags */
+       __u32 reserved; /* for future use */
+       union {
+               struct vduse_vq_state vq_state; /* virtqueue state */
+               struct vduse_iova_range iova; /* iova range for updating */
+               __u32 padding[16]; /* padding */
+       };
+};
+
+struct vduse_dev_response {
+       __u32 request_id; /* corresponding request id */
+#define VDUSE_REQ_RESULT_OK    0x00
+#define VDUSE_REQ_RESULT_FAILED        0x01
+       __u32 result; /* the result of request */
+       __u32 reserved[2]; /* for future use */
+       union {
+               struct vduse_vq_state vq_state; /* virtqueue state */
+               __u32 padding[16]; /* padding */
+       };
+};
+
+/* ioctls */
+
+struct vduse_dev_config {
+       char name[VDUSE_NAME_MAX]; /* vduse device name */
+       __u32 vendor_id; /* virtio vendor id */
+       __u32 device_id; /* virtio device id */
+       __u64 features; /* device features */
+       __u64 bounce_size; /* bounce buffer size for iommu */
+       __u16 vq_size_max; /* the max size of virtqueue */
+       __u16 padding; /* padding */
+       __u32 vq_num; /* the number of virtqueues */
+       __u32 vq_align; /* the allocation alignment of virtqueue's metadata */
+       __u32 config_size; /* the size of the configuration space */
+       __u32 reserved[15]; /* for future use */
+       __u8 config[0]; /* the buffer of the configuration space */
+};
+
+struct vduse_iotlb_entry {
+       __u64 offset; /* the mmap offset on fd */
+       __u64 start; /* start of the IOVA range */
+       __u64 last; /* last of the IOVA range */
+#define VDUSE_ACCESS_RO 0x1
+#define VDUSE_ACCESS_WO 0x2
+#define VDUSE_ACCESS_RW 0x3
+       __u8 perm; /* access permission of this range */
+};
+
+struct vduse_config_update {
+       __u32 offset; /* offset from the beginning of configuration space */
+       __u32 length; /* the length to write to configuration space */
+       __u8 buffer[0]; /* buffer used to write from */
+};
+
+struct vduse_vq_info {
+       __u32 index; /* virtqueue index */
+       __u32 avail_idx; /* virtqueue state (last_avail_idx) */
+       __u64 desc_addr; /* address of desc area */
+       __u64 driver_addr; /* address of driver area */
+       __u64 device_addr; /* address of device area */
+       __u32 num; /* the size of virtqueue */
+       __u8 ready; /* ready status of virtqueue */
+};
+
+struct vduse_vq_eventfd {
+       __u32 index; /* virtqueue index */
+#define VDUSE_EVENTFD_DEASSIGN -1
+       int fd; /* eventfd, -1 means de-assigning the eventfd */
+};
+
+#define VDUSE_BASE     0x81
+
+/* Get the version of VDUSE API. This is used for future extension */
+#define VDUSE_GET_API_VERSION  _IOR(VDUSE_BASE, 0x00, __u64)
+
+/* Set the version of VDUSE API. */
+#define VDUSE_SET_API_VERSION  _IOW(VDUSE_BASE, 0x01, __u64)
+
+/* Create a vduse device which is represented by a char device 
(/dev/vduse/<name>) */
+#define VDUSE_CREATE_DEV       _IOW(VDUSE_BASE, 0x02, struct vduse_dev_config)
+
+/* Destroy a vduse device. Make sure there are no references to the char 
device */
+#define VDUSE_DESTROY_DEV      _IOW(VDUSE_BASE, 0x03, char[VDUSE_NAME_MAX])
+
+/*
+ * Get a file descriptor for the first overlapped iova region,
+ * -EINVAL means the iova region doesn't exist.
+ */
+#define VDUSE_IOTLB_GET_FD     _IOWR(VDUSE_BASE, 0x04, struct 
vduse_iotlb_entry)
+
+/* Get the negotiated features */
+#define VDUSE_DEV_GET_FEATURES _IOR(VDUSE_BASE, 0x05, __u64)
+
+/* Update the configuration space */
+#define VDUSE_DEV_UPDATE_CONFIG        _IOW(VDUSE_BASE, 0x06, struct 
vduse_config_update)
+
+/* Get the specified virtqueue's information */
+#define VDUSE_VQ_GET_INFO      _IOWR(VDUSE_BASE, 0x07, struct vduse_vq_info)
+
+/* Setup an eventfd to receive kick for virtqueue */
+#define VDUSE_VQ_SETUP_KICKFD  _IOW(VDUSE_BASE, 0x08, struct vduse_vq_eventfd)
+
+/* Inject an interrupt for specific virtqueue */
+#define VDUSE_VQ_INJECT_IRQ    _IOW(VDUSE_BASE, 0x09, __u32)
+
+#endif /* _UAPI_VDUSE_H_ */
-- 
2.11.0


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