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From:   Tiwei Bie <tiwei.bie@intel.com>
To:     mst@redhat.com, jasowang@redhat.com
Cc:     linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
        virtualization@lists.linux-foundation.org, netdev@vger.kernel.org,
        shahafs@mellanox.com, jgg@mellanox.com, rob.miller@broadcom.com,
        haotian.wang@sifive.com, eperezma@redhat.com, lulu@redhat.com,
        parav@mellanox.com, rdunlap@infradead.org, hch@infradead.org,
        jiri@mellanox.com, hanand@xilinx.com, mhabets@solarflare.com,
        maxime.coquelin@redhat.com, lingshan.zhu@intel.com,
        dan.daly@intel.com, cunming.liang@intel.com,
        zhihong.wang@intel.com, tiwei.bie@intel.com
Subject: [PATCH] vhost: introduce vDPA based backend
Date:   Fri, 31 Jan 2020 11:36:51 +0800
Message-Id: <20200131033651.103534-1-tiwei.bie@intel.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

This patch introduces a vDPA based vhost backend. This
backend is built on top of the same interface defined
in virtio-vDPA and provides a generic vhost interface
for userspace to accelerate the virtio devices in guest.

This backend is implemented as a vDPA device driver on
top of the same ops used in virtio-vDPA. It will create
char device entry named vhost-vdpa/$vdpa_device_index
for userspace to use. Userspace can use vhost ioctls on
top of this char device to setup the backend.

Signed-off-by: Tiwei Bie <tiwei.bie@intel.com>
---
This patch depends on below series:
https://lkml.org/lkml/2020/1/16/353

Please note that _SET_MEM_TABLE isn't fully supported yet.
Comments would be appreciated!

Changes since last patch (https://lkml.org/lkml/2019/11/18/1068)
- Switch to the vDPA bus;
- Switch to vhost's own chardev;

 drivers/vhost/Kconfig            |  12 +
 drivers/vhost/Makefile           |   3 +
 drivers/vhost/vdpa.c             | 705 +++++++++++++++++++++++++++++++
 include/uapi/linux/vhost.h       |  21 +
 include/uapi/linux/vhost_types.h |   8 +
 5 files changed, 749 insertions(+)
 create mode 100644 drivers/vhost/vdpa.c

diff --git a/drivers/vhost/Kconfig b/drivers/vhost/Kconfig
index f21c45aa5e07..13e6a94d0243 100644
--- a/drivers/vhost/Kconfig
+++ b/drivers/vhost/Kconfig
@@ -34,6 +34,18 @@ config VHOST_VSOCK
 	To compile this driver as a module, choose M here: the module will be called
 	vhost_vsock.
 
+config VHOST_VDPA
+	tristate "Vhost driver for vDPA based backend"
+	depends on EVENTFD && VDPA
+	select VHOST
+	default n
+	---help---
+	This kernel module can be loaded in host kernel to accelerate
+	guest virtio devices with the vDPA based backends.
+
+	To compile this driver as a module, choose M here: the module
+	will be called vhost_vdpa.
+
 config VHOST
 	tristate
         depends on VHOST_IOTLB
diff --git a/drivers/vhost/Makefile b/drivers/vhost/Makefile
index df99756fbb26..a65e9f4a2c0a 100644
--- a/drivers/vhost/Makefile
+++ b/drivers/vhost/Makefile
@@ -10,6 +10,9 @@ vhost_vsock-y := vsock.o
 
 obj-$(CONFIG_VHOST_RING) += vringh.o
 
+obj-$(CONFIG_VHOST_VDPA) += vhost_vdpa.o
+vhost_vdpa-y := vdpa.o
+
 obj-$(CONFIG_VHOST)	+= vhost.o
 
 obj-$(CONFIG_VHOST_IOTLB) += vhost_iotlb.o
diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
new file mode 100644
index 000000000000..631d994d37ac
--- /dev/null
+++ b/drivers/vhost/vdpa.c
@@ -0,0 +1,705 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2018-2020 Intel Corporation.
+ *
+ * Author: Tiwei Bie <tiwei.bie@intel.com>
+ *
+ * Thanks to Jason Wang and Michael S. Tsirkin for the valuable
+ * comments and suggestions.  And thanks to Cunming Liang and
+ * Zhihong Wang for all their supports.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/cdev.h>
+#include <linux/device.h>
+#include <linux/uuid.h>
+#include <linux/vdpa.h>
+#include <linux/nospec.h>
+#include <linux/vhost.h>
+#include <linux/virtio_net.h>
+
+#include "vhost.h"
+
+enum {
+	VHOST_VDPA_FEATURES =
+		(1ULL << VIRTIO_F_NOTIFY_ON_EMPTY) |
+		(1ULL << VIRTIO_F_ANY_LAYOUT) |
+		(1ULL << VIRTIO_F_VERSION_1) |
+		(1ULL << VIRTIO_F_IOMMU_PLATFORM) |
+		(1ULL << VIRTIO_F_RING_PACKED) |
+		(1ULL << VIRTIO_F_ORDER_PLATFORM) |
+		(1ULL << VIRTIO_RING_F_INDIRECT_DESC) |
+		(1ULL << VIRTIO_RING_F_EVENT_IDX),
+
+	VHOST_VDPA_NET_FEATURES = VHOST_VDPA_FEATURES |
+		(1ULL << VIRTIO_NET_F_CSUM) |
+		(1ULL << VIRTIO_NET_F_GUEST_CSUM) |
+		(1ULL << VIRTIO_NET_F_MTU) |
+		(1ULL << VIRTIO_NET_F_MAC) |
+		(1ULL << VIRTIO_NET_F_GUEST_TSO4) |
+		(1ULL << VIRTIO_NET_F_GUEST_TSO6) |
+		(1ULL << VIRTIO_NET_F_GUEST_ECN) |
+		(1ULL << VIRTIO_NET_F_GUEST_UFO) |
+		(1ULL << VIRTIO_NET_F_HOST_TSO4) |
+		(1ULL << VIRTIO_NET_F_HOST_TSO6) |
+		(1ULL << VIRTIO_NET_F_HOST_ECN) |
+		(1ULL << VIRTIO_NET_F_HOST_UFO) |
+		(1ULL << VIRTIO_NET_F_MRG_RXBUF) |
+		(1ULL << VIRTIO_NET_F_STATUS) |
+		(1ULL << VIRTIO_NET_F_SPEED_DUPLEX),
+};
+
+/* Currently, only network backend w/o multiqueue is supported. */
+#define VHOST_VDPA_VQ_MAX	2
+
+struct vhost_vdpa {
+	/* The lock is to protect this structure. */
+	struct mutex mutex;
+	struct vhost_dev vdev;
+	struct vhost_virtqueue *vqs;
+	struct vdpa_device *vdpa;
+	struct device *dev;
+	atomic_t opened;
+	int nvqs;
+	int virtio_id;
+	int minor;
+};
+
+static struct {
+	/* The lock is to protect this structure. */
+	struct mutex mutex;
+	struct class *class;
+	struct idr idr;
+	struct cdev cdev;
+	dev_t devt;
+	wait_queue_head_t release_q;
+} vhost_vdpa;
+
+static const u64 vhost_vdpa_features[] = {
+	[VIRTIO_ID_NET] = VHOST_VDPA_NET_FEATURES,
+};
+
+static int vhost_vdpa_alloc_minor(struct vhost_vdpa *v)
+{
+	return idr_alloc(&vhost_vdpa.idr, v, 0, MINORMASK + 1,
+			 GFP_KERNEL);
+}
+
+static void vhost_vdpa_free_minor(int minor)
+{
+	idr_remove(&vhost_vdpa.idr, minor);
+}
+
+static struct vhost_vdpa *vhost_vdpa_get_from_minor(int minor)
+{
+	struct vhost_vdpa *v;
+
+	mutex_lock(&vhost_vdpa.mutex);
+	v = idr_find(&vhost_vdpa.idr, minor);
+	mutex_unlock(&vhost_vdpa.mutex);
+
+	return v;
+}
+
+static void handle_vq_kick(struct vhost_work *work)
+{
+	struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
+						  poll.work);
+	struct vhost_vdpa *v = container_of(vq->dev, struct vhost_vdpa, vdev);
+	const struct vdpa_config_ops *ops = v->vdpa->config;
+
+	ops->kick_vq(v->vdpa, vq - v->vqs);
+}
+
+static irqreturn_t vhost_vdpa_virtqueue_cb(void *private)
+{
+	struct vhost_virtqueue *vq = private;
+	struct eventfd_ctx *call_ctx = vq->call_ctx;
+
+	if (call_ctx)
+		eventfd_signal(call_ctx, 1);
+
+	return IRQ_HANDLED;
+}
+
+static void vhost_vdpa_reset(struct vhost_vdpa *v)
+{
+	struct vdpa_device *vdpa = v->vdpa;
+	const struct vdpa_config_ops *ops = vdpa->config;
+
+	ops->set_status(vdpa, 0);
+}
+
+static long vhost_vdpa_get_device_id(struct vhost_vdpa *v, u8 __user *argp)
+{
+	struct vdpa_device *vdpa = v->vdpa;
+	const struct vdpa_config_ops *ops = vdpa->config;
+	u32 device_id;
+
+	device_id = ops->get_device_id(vdpa);
+
+	if (copy_to_user(argp, &device_id, sizeof(device_id)))
+		return -EFAULT;
+
+	return 0;
+}
+
+static long vhost_vdpa_get_status(struct vhost_vdpa *v, u8 __user *statusp)
+{
+	struct vdpa_device *vdpa = v->vdpa;
+	const struct vdpa_config_ops *ops = vdpa->config;
+	u8 status;
+
+	status = ops->get_status(vdpa);
+
+	if (copy_to_user(statusp, &status, sizeof(status)))
+		return -EFAULT;
+
+	return 0;
+}
+
+static long vhost_vdpa_set_status(struct vhost_vdpa *v, u8 __user *statusp)
+{
+	struct vdpa_device *vdpa = v->vdpa;
+	const struct vdpa_config_ops *ops = vdpa->config;
+	u8 status;
+
+	if (copy_from_user(&status, statusp, sizeof(status)))
+		return -EFAULT;
+
+	/*
+	 * Userspace shouldn't remove status bits unless reset the
+	 * status to 0.
+	 */
+	if (status != 0 && (ops->get_status(vdpa) & ~status) != 0)
+		return -EINVAL;
+
+	ops->set_status(vdpa, status);
+
+	return 0;
+}
+
+static int vhost_vdpa_config_validate(struct vhost_vdpa *v,
+				      struct vhost_vdpa_config *c)
+{
+	long size = 0;
+
+	switch (v->virtio_id) {
+	case VIRTIO_ID_NET:
+		size = sizeof(struct virtio_net_config);
+		break;
+	}
+
+	if (c->len == 0)
+		return -EINVAL;
+
+	if (c->len > size - c->off)
+		return -E2BIG;
+
+	return 0;
+}
+
+static long vhost_vdpa_get_config(struct vhost_vdpa *v,
+				  struct vhost_vdpa_config __user *c)
+{
+	struct vdpa_device *vdpa = v->vdpa;
+	const struct vdpa_config_ops *ops = vdpa->config;
+	struct vhost_vdpa_config config;
+	unsigned long size = offsetof(struct vhost_vdpa_config, buf);
+	u8 *buf;
+
+	if (copy_from_user(&config, c, size))
+		return -EFAULT;
+	if (vhost_vdpa_config_validate(v, &config))
+		return -EINVAL;
+	buf = kvzalloc(config.len, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	ops->get_config(vdpa, config.off, buf, config.len);
+
+	if (copy_to_user(c->buf, buf, config.len)) {
+		kvfree(buf);
+		return -EFAULT;
+	}
+
+	kvfree(buf);
+	return 0;
+}
+
+static long vhost_vdpa_set_config(struct vhost_vdpa *v,
+				  struct vhost_vdpa_config __user *c)
+{
+	struct vdpa_device *vdpa = v->vdpa;
+	const struct vdpa_config_ops *ops = vdpa->config;
+	struct vhost_vdpa_config config;
+	unsigned long size = offsetof(struct vhost_vdpa_config, buf);
+	u8 *buf;
+
+	if (copy_from_user(&config, c, size))
+		return -EFAULT;
+	if (vhost_vdpa_config_validate(v, &config))
+		return -EINVAL;
+	buf = kvzalloc(config.len, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	if (copy_from_user(buf, c->buf, config.len)) {
+		kvfree(buf);
+		return -EFAULT;
+	}
+
+	ops->set_config(vdpa, config.off, buf, config.len);
+
+	kvfree(buf);
+	return 0;
+}
+
+static long vhost_vdpa_get_features(struct vhost_vdpa *v, u64 __user *featurep)
+{
+	struct vdpa_device *vdpa = v->vdpa;
+	const struct vdpa_config_ops *ops = vdpa->config;
+	u64 features;
+
+	features = ops->get_features(vdpa);
+	features &= vhost_vdpa_features[v->virtio_id];
+
+	if (copy_to_user(featurep, &features, sizeof(features)))
+		return -EFAULT;
+
+	return 0;
+}
+
+static long vhost_vdpa_set_features(struct vhost_vdpa *v, u64 __user *featurep)
+{
+	struct vdpa_device *vdpa = v->vdpa;
+	const struct vdpa_config_ops *ops = vdpa->config;
+	u64 features;
+
+	/*
+	 * It's not allowed to change the features after they have
+	 * been negotiated.
+	 */
+	if (ops->get_status(vdpa) & VIRTIO_CONFIG_S_FEATURES_OK)
+		return -EBUSY;
+
+	if (copy_from_user(&features, featurep, sizeof(features)))
+		return -EFAULT;
+
+	if (features & ~vhost_vdpa_features[v->virtio_id])
+		return -EINVAL;
+
+	if (ops->set_features(vdpa, features))
+		return -EINVAL;
+
+	return 0;
+}
+
+static long vhost_vdpa_get_vring_num(struct vhost_vdpa *v, u16 __user *argp)
+{
+	struct vdpa_device *vdpa = v->vdpa;
+	const struct vdpa_config_ops *ops = vdpa->config;
+	u16 num;
+
+	num = ops->get_vq_num_max(vdpa);
+
+	if (copy_to_user(argp, &num, sizeof(num)))
+		return -EFAULT;
+
+	return 0;
+}
+
+static long vhost_vdpa_vring_ioctl(struct vhost_vdpa *v, unsigned int cmd,
+				   void __user *argp)
+{
+	struct vdpa_device *vdpa = v->vdpa;
+	const struct vdpa_config_ops *ops = vdpa->config;
+	struct vdpa_callback cb;
+	struct vhost_virtqueue *vq;
+	struct vhost_vring_state s;
+	u8 status;
+	u32 idx;
+	long r;
+
+	r = get_user(idx, (u32 __user *)argp);
+	if (r < 0)
+		return r;
+	if (idx >= v->nvqs)
+		return -ENOBUFS;
+
+	idx = array_index_nospec(idx, v->nvqs);
+	vq = &v->vqs[idx];
+
+	status = ops->get_status(vdpa);
+
+	/*
+	 * It's not allowed to detect and program vqs before
+	 * features negotiation or after enabling driver.
+	 */
+	if (!(status & VIRTIO_CONFIG_S_FEATURES_OK) ||
+	    (status & VIRTIO_CONFIG_S_DRIVER_OK))
+		return -EBUSY;
+
+	if (cmd == VHOST_VDPA_SET_VRING_ENABLE) {
+		if (copy_from_user(&s, argp, sizeof(s)))
+			return -EFAULT;
+		ops->set_vq_ready(vdpa, idx, s.num);
+		return 0;
+	}
+
+	/*
+	 * It's not allowed to detect and program vqs with
+	 * vqs enabled.
+	 */
+	if (ops->get_vq_ready(vdpa, idx))
+		return -EBUSY;
+
+	if (cmd == VHOST_GET_VRING_BASE)
+		vq->last_avail_idx = ops->get_vq_state(v->vdpa, idx);
+
+	r = vhost_vring_ioctl(&v->vdev, cmd, argp);
+	if (r)
+		return r;
+
+	switch (cmd) {
+	case VHOST_SET_VRING_ADDR:
+		if (ops->set_vq_address(vdpa, idx, (u64)vq->desc,
+					(u64)vq->avail, (u64)vq->used))
+			r = -EINVAL;
+		break;
+
+	case VHOST_SET_VRING_BASE:
+		if (ops->set_vq_state(vdpa, idx, vq->last_avail_idx))
+			r = -EINVAL;
+		break;
+
+	case VHOST_SET_VRING_CALL:
+		if (vq->call_ctx) {
+			cb.callback = vhost_vdpa_virtqueue_cb;
+			cb.private = vq;
+		} else {
+			cb.callback = NULL;
+			cb.private = NULL;
+		}
+		ops->set_vq_cb(vdpa, idx, &cb);
+		break;
+
+	case VHOST_SET_VRING_NUM:
+		ops->set_vq_num(vdpa, idx, vq->num);
+		break;
+	}
+
+	return r;
+}
+
+static long vhost_vdpa_do_dma_mapping(struct vhost_vdpa *v)
+{
+	/* TODO: fix this */
+	return -ENOTSUPP;
+}
+
+static int vhost_vdpa_open(struct inode *inode, struct file *filep)
+{
+	struct vhost_vdpa *v;
+	struct vhost_dev *dev;
+	struct vhost_virtqueue **vqs;
+	int nvqs, i, r, opened;
+
+	v = vhost_vdpa_get_from_minor(iminor(inode));
+	if (!v)
+		return -ENODEV;
+
+	opened = atomic_cmpxchg(&v->opened, 0, 1);
+	if (opened) {
+		r = -EBUSY;
+		goto err;
+	}
+
+	nvqs = v->nvqs;
+	vhost_vdpa_reset(v);
+
+	vqs = kmalloc_array(nvqs, sizeof(*vqs), GFP_KERNEL);
+	if (!vqs) {
+		r = -ENOMEM;
+		goto err;
+	}
+
+	dev = &v->vdev;
+	for (i = 0; i < nvqs; i++) {
+		vqs[i] = &v->vqs[i];
+		vqs[i]->handle_kick = handle_vq_kick;
+	}
+	vhost_dev_init(dev, vqs, nvqs, 0, 0, 0);
+
+	filep->private_data = v;
+
+	return 0;
+
+err:
+	atomic_dec(&v->opened);
+	return r;
+}
+
+static int vhost_vdpa_release(struct inode *inode, struct file *filep)
+{
+	struct vhost_vdpa *v = filep->private_data;
+
+	mutex_lock(&v->mutex);
+	filep->private_data = NULL;
+	vhost_vdpa_reset(v);
+	vhost_dev_stop(&v->vdev);
+	vhost_dev_cleanup(&v->vdev);
+	kfree(v->vdev.vqs);
+	mutex_unlock(&v->mutex);
+
+	atomic_dec(&v->opened);
+	wake_up(&vhost_vdpa.release_q);
+
+	return 0;
+}
+
+static long vhost_vdpa_unlocked_ioctl(struct file *filep,
+				      unsigned int cmd, unsigned long arg)
+{
+	struct vhost_vdpa *v = filep->private_data;
+	struct vdpa_device *vdpa = v->vdpa;
+	const struct vdpa_config_ops *ops = vdpa->config;
+	void __user *argp = (void __user *)arg;
+	long r;
+
+	mutex_lock(&v->mutex);
+
+	switch (cmd) {
+	case VHOST_VDPA_GET_DEVICE_ID:
+		r = vhost_vdpa_get_device_id(v, argp);
+		break;
+	case VHOST_VDPA_GET_STATUS:
+		r = vhost_vdpa_get_status(v, argp);
+		break;
+	case VHOST_VDPA_SET_STATUS:
+		r = vhost_vdpa_set_status(v, argp);
+		break;
+	case VHOST_VDPA_GET_CONFIG:
+		r = vhost_vdpa_get_config(v, argp);
+		break;
+	case VHOST_VDPA_SET_CONFIG:
+		r = vhost_vdpa_set_config(v, argp);
+		break;
+	case VHOST_GET_FEATURES:
+		r = vhost_vdpa_get_features(v, argp);
+		break;
+	case VHOST_SET_FEATURES:
+		r = vhost_vdpa_set_features(v, argp);
+		break;
+	case VHOST_VDPA_GET_VRING_NUM:
+		r = vhost_vdpa_get_vring_num(v, argp);
+		break;
+	case VHOST_SET_LOG_BASE:
+	case VHOST_SET_LOG_FD:
+		r = -ENOIOCTLCMD;
+		break;
+	default:
+		mutex_lock(&v->vdev.mutex);
+		r = vhost_dev_ioctl(&v->vdev, cmd, argp);
+		if (r == -ENOIOCTLCMD)
+			r = vhost_vdpa_vring_ioctl(v, cmd, argp);
+		mutex_unlock(&v->vdev.mutex);
+		break;
+	}
+
+	if (r)
+		goto out;
+
+	switch (cmd) {
+	case VHOST_SET_MEM_TABLE:
+		if (ops->set_map)
+			r = ops->set_map(vdpa, v->vdev.umem);
+		else
+			r = vhost_vdpa_do_dma_mapping(v);
+		break;
+	}
+
+out:
+	mutex_unlock(&v->mutex);
+	return r;
+}
+
+static const struct file_operations vhost_vdpa_fops = {
+	.owner		= THIS_MODULE,
+	.open		= vhost_vdpa_open,
+	.release	= vhost_vdpa_release,
+	.unlocked_ioctl	= vhost_vdpa_unlocked_ioctl,
+	.compat_ioctl	= compat_ptr_ioctl,
+};
+
+static int vhost_vdpa_probe(struct device *dev)
+{
+	struct vdpa_device *vdpa = dev_to_vdpa(dev);
+	const struct vdpa_config_ops *ops = vdpa->config;
+	struct vhost_vdpa *v;
+	struct device *d;
+	int minor, nvqs;
+	int r;
+
+	/* Currently, we only accept the network devices. */
+	if (ops->get_device_id(vdpa) != VIRTIO_ID_NET) {
+		r = -ENOTSUPP;
+		goto err;
+	}
+
+	v = kzalloc(sizeof(*v), GFP_KERNEL | __GFP_RETRY_MAYFAIL);
+	if (!v) {
+		r = -ENOMEM;
+		goto err;
+	}
+
+	nvqs = VHOST_VDPA_VQ_MAX;
+
+	v->vqs = kmalloc_array(nvqs, sizeof(struct vhost_virtqueue),
+			       GFP_KERNEL);
+	if (!v->vqs) {
+		r = -ENOMEM;
+		goto err_alloc_vqs;
+	}
+
+	mutex_init(&v->mutex);
+	atomic_set(&v->opened, 0);
+
+	v->vdpa = vdpa;
+	v->nvqs = nvqs;
+	v->virtio_id = ops->get_device_id(vdpa);
+
+	mutex_lock(&vhost_vdpa.mutex);
+
+	minor = vhost_vdpa_alloc_minor(v);
+	if (minor < 0) {
+		r = minor;
+		goto err_alloc_minor;
+	}
+
+	d = device_create(vhost_vdpa.class, NULL,
+			  MKDEV(MAJOR(vhost_vdpa.devt), minor),
+			  v, "%d", vdpa->index);
+	if (IS_ERR(d)) {
+		r = PTR_ERR(d);
+		goto err_device_create;
+	}
+
+	mutex_unlock(&vhost_vdpa.mutex);
+
+	v->dev = d;
+	v->minor = minor;
+	dev_set_drvdata(dev, v);
+
+	return 0;
+
+err_device_create:
+	vhost_vdpa_free_minor(minor);
+err_alloc_minor:
+	mutex_unlock(&vhost_vdpa.mutex);
+	kfree(v->vqs);
+err_alloc_vqs:
+	kfree(v);
+err:
+	return r;
+}
+
+static void vhost_vdpa_remove(struct device *dev)
+{
+	DEFINE_WAIT_FUNC(wait, woken_wake_function);
+	struct vhost_vdpa *v = dev_get_drvdata(dev);
+	int opened;
+
+	add_wait_queue(&vhost_vdpa.release_q, &wait);
+
+	do {
+		opened = atomic_cmpxchg(&v->opened, 0, 1);
+		if (!opened)
+			break;
+		wait_woken(&wait, TASK_UNINTERRUPTIBLE, HZ * 10);
+	} while (1);
+
+	remove_wait_queue(&vhost_vdpa.release_q, &wait);
+
+	mutex_lock(&vhost_vdpa.mutex);
+	device_destroy(vhost_vdpa.class,
+		       MKDEV(MAJOR(vhost_vdpa.devt), v->minor));
+	vhost_vdpa_free_minor(v->minor);
+	mutex_unlock(&vhost_vdpa.mutex);
+	kfree(v->vqs);
+	kfree(v);
+}
+
+static struct vdpa_driver vhost_vdpa_driver = {
+	.drv = {
+		.name	= "vhost_vdpa",
+	},
+	.probe	= vhost_vdpa_probe,
+	.remove	= vhost_vdpa_remove,
+};
+
+static char *vhost_vdpa_devnode(struct device *dev, umode_t *mode)
+{
+	return kasprintf(GFP_KERNEL, "vhost-vdpa/%s", dev_name(dev));
+}
+
+static int __init vhost_vdpa_init(void)
+{
+	int r;
+
+	idr_init(&vhost_vdpa.idr);
+	mutex_init(&vhost_vdpa.mutex);
+	init_waitqueue_head(&vhost_vdpa.release_q);
+
+	/* /dev/vhost-vdpa/$vdpa_device_index */
+	vhost_vdpa.class = class_create(THIS_MODULE, "vhost-vdpa");
+	if (IS_ERR(vhost_vdpa.class)) {
+		r = PTR_ERR(vhost_vdpa.class);
+		goto err_class;
+	}
+
+	vhost_vdpa.class->devnode = vhost_vdpa_devnode;
+
+	r = alloc_chrdev_region(&vhost_vdpa.devt, 0, MINORMASK + 1,
+				"vhost-vdpa");
+	if (r)
+		goto err_alloc_chrdev;
+
+	cdev_init(&vhost_vdpa.cdev, &vhost_vdpa_fops);
+	r = cdev_add(&vhost_vdpa.cdev, vhost_vdpa.devt, MINORMASK + 1);
+	if (r)
+		goto err_cdev_add;
+
+	r = register_vdpa_driver(&vhost_vdpa_driver);
+	if (r)
+		goto err_register_vdpa_driver;
+
+	return 0;
+
+err_register_vdpa_driver:
+	cdev_del(&vhost_vdpa.cdev);
+err_cdev_add:
+	unregister_chrdev_region(vhost_vdpa.devt, MINORMASK + 1);
+err_alloc_chrdev:
+	class_destroy(vhost_vdpa.class);
+err_class:
+	idr_destroy(&vhost_vdpa.idr);
+	return r;
+}
+module_init(vhost_vdpa_init);
+
+static void __exit vhost_vdpa_exit(void)
+{
+	unregister_vdpa_driver(&vhost_vdpa_driver);
+	cdev_del(&vhost_vdpa.cdev);
+	unregister_chrdev_region(vhost_vdpa.devt, MINORMASK + 1);
+	class_destroy(vhost_vdpa.class);
+	idr_destroy(&vhost_vdpa.idr);
+}
+module_exit(vhost_vdpa_exit);
+
+MODULE_VERSION("0.0.1");
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Intel Corporation");
+MODULE_DESCRIPTION("vDPA based vhost backend for virtio");
diff --git a/include/uapi/linux/vhost.h b/include/uapi/linux/vhost.h
index 40d028eed645..23f6db2106f5 100644
--- a/include/uapi/linux/vhost.h
+++ b/include/uapi/linux/vhost.h
@@ -116,4 +116,25 @@
 #define VHOST_VSOCK_SET_GUEST_CID	_IOW(VHOST_VIRTIO, 0x60, __u64)
 #define VHOST_VSOCK_SET_RUNNING		_IOW(VHOST_VIRTIO, 0x61, int)
 
+/* VHOST_VDPA specific defines */
+
+/* Get the device id. The device ids follow the same definition of
+ * the device id defined in virtio-spec. */
+#define VHOST_VDPA_GET_DEVICE_ID	_IOR(VHOST_VIRTIO, 0x70, __u32)
+/* Get and set the status. The status bits follow the same definition
+ * of the device status defined in virtio-spec. */
+#define VHOST_VDPA_GET_STATUS		_IOR(VHOST_VIRTIO, 0x71, __u8)
+#define VHOST_VDPA_SET_STATUS		_IOW(VHOST_VIRTIO, 0x72, __u8)
+/* Get and set the device config. The device config follows the same
+ * definition of the device config defined in virtio-spec. */
+#define VHOST_VDPA_GET_CONFIG		_IOR(VHOST_VIRTIO, 0x73, \
+					     struct vhost_vdpa_config)
+#define VHOST_VDPA_SET_CONFIG		_IOW(VHOST_VIRTIO, 0x74, \
+					     struct vhost_vdpa_config)
+/* Enable/disable the ring. */
+#define VHOST_VDPA_SET_VRING_ENABLE	_IOW(VHOST_VIRTIO, 0x75, \
+					     struct vhost_vring_state)
+/* Get the max ring size. */
+#define VHOST_VDPA_GET_VRING_NUM	_IOR(VHOST_VIRTIO, 0x76, __u16)
+
 #endif
diff --git a/include/uapi/linux/vhost_types.h b/include/uapi/linux/vhost_types.h
index c907290ff065..669457ce5c48 100644
--- a/include/uapi/linux/vhost_types.h
+++ b/include/uapi/linux/vhost_types.h
@@ -119,6 +119,14 @@ struct vhost_scsi_target {
 	unsigned short reserved;
 };
 
+/* VHOST_VDPA specific definitions */
+
+struct vhost_vdpa_config {
+	__u32 off;
+	__u32 len;
+	__u8 buf[0];
+};
+
 /* Feature bits */
 /* Log all write descriptors. Can be changed while device is active. */
 #define VHOST_F_LOG_ALL 26
-- 
2.24.1