Re: [PATCH v11 01/12] iova: Export alloc_iova_fast() and free_iova_fast()

Re: [PATCH v11 01/12] iova: Export alloc_iova_fast() and free_iova_fast()

[Jason Wang]

在 2021/8/18 下午8:06, Xie Yongji 写道:
> Export alloc_iova_fast() and free_iova_fast() so that
> some modules can make use of the per-CPU cache to get
> rid of rbtree spinlock in alloc_iova() and free_iova()
> during IOVA allocation.
>
> Signed-off-by: Xie Yongji <xieyongji@bytedance.com>


Acked-by: Jason Wang <jasowang@redhat.com>

(If we need respin, I'd suggest to put the numbers you measured here)

Thanks


> ---
>   drivers/iommu/iova.c | 2 ++
>   1 file changed, 2 insertions(+)
>
> diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c
> index b6cf5f16123b..3941ed6bb99b 100644
> --- a/drivers/iommu/iova.c
> +++ b/drivers/iommu/iova.c
> @@ -521,6 +521,7 @@ alloc_iova_fast(struct iova_domain *iovad, unsigned long size,
>   
>   	return new_iova->pfn_lo;
>   }
> +EXPORT_SYMBOL_GPL(alloc_iova_fast);
>   
>   /**
>    * free_iova_fast - free iova pfn range into rcache
> @@ -538,6 +539,7 @@ free_iova_fast(struct iova_domain *iovad, unsigned long pfn, unsigned long size)
>   
>   	free_iova(iovad, pfn);
>   }
> +EXPORT_SYMBOL_GPL(free_iova_fast);
>   
>   #define fq_ring_for_each(i, fq) \
>   	for ((i) = (fq)->head; (i) != (fq)->tail; (i) = ((i) + 1) % IOVA_FQ_SIZE)

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Re: [PATCH v11 03/12] vdpa: Fix some coding style issues

[Jason Wang]

在 2021/8/18 下午8:06, Xie Yongji 写道:
> Fix some code indent issues and following checkpatch warning:
>
> WARNING: Prefer 'unsigned int' to bare use of 'unsigned'
> 371: FILE: include/linux/vdpa.h:371:
> +static inline void vdpa_get_config(struct vdpa_device *vdev, unsigned offset,
>
> Signed-off-by: Xie Yongji <xieyongji@bytedance.com>


Acked-by: Jason Wang <jasowang@redhat.com>


> ---
>   include/linux/vdpa.h | 34 +++++++++++++++++-----------------
>   1 file changed, 17 insertions(+), 17 deletions(-)
>
> diff --git a/include/linux/vdpa.h b/include/linux/vdpa.h
> index 954b340f6c2f..8a645f8f4476 100644
> --- a/include/linux/vdpa.h
> +++ b/include/linux/vdpa.h
> @@ -43,17 +43,17 @@ struct vdpa_vq_state_split {
>    * @last_used_idx: used index
>    */
>   struct vdpa_vq_state_packed {
> -        u16	last_avail_counter:1;
> -        u16	last_avail_idx:15;
> -        u16	last_used_counter:1;
> -        u16	last_used_idx:15;
> +	u16	last_avail_counter:1;
> +	u16	last_avail_idx:15;
> +	u16	last_used_counter:1;
> +	u16	last_used_idx:15;
>   };
>   
>   struct vdpa_vq_state {
> -     union {
> -          struct vdpa_vq_state_split split;
> -          struct vdpa_vq_state_packed packed;
> -     };
> +	union {
> +		struct vdpa_vq_state_split split;
> +		struct vdpa_vq_state_packed packed;
> +	};
>   };
>   
>   struct vdpa_mgmt_dev;
> @@ -131,7 +131,7 @@ struct vdpa_iova_range {
>    *				@vdev: vdpa device
>    *				@idx: virtqueue index
>    *				@state: pointer to returned state (last_avail_idx)
> - * @get_vq_notification: 	Get the notification area for a virtqueue
> + * @get_vq_notification:	Get the notification area for a virtqueue
>    *				@vdev: vdpa device
>    *				@idx: virtqueue index
>    *				Returns the notifcation area
> @@ -353,25 +353,25 @@ static inline struct device *vdpa_get_dma_dev(struct vdpa_device *vdev)
>   
>   static inline void vdpa_reset(struct vdpa_device *vdev)
>   {
> -        const struct vdpa_config_ops *ops = vdev->config;
> +	const struct vdpa_config_ops *ops = vdev->config;
>   
>   	vdev->features_valid = false;
> -        ops->set_status(vdev, 0);
> +	ops->set_status(vdev, 0);
>   }
>   
>   static inline int vdpa_set_features(struct vdpa_device *vdev, u64 features)
>   {
> -        const struct vdpa_config_ops *ops = vdev->config;
> +	const struct vdpa_config_ops *ops = vdev->config;
>   
>   	vdev->features_valid = true;
> -        return ops->set_features(vdev, features);
> +	return ops->set_features(vdev, features);
>   }
>   
> -
> -static inline void vdpa_get_config(struct vdpa_device *vdev, unsigned offset,
> -				   void *buf, unsigned int len)
> +static inline void vdpa_get_config(struct vdpa_device *vdev,
> +				   unsigned int offset, void *buf,
> +				   unsigned int len)
>   {
> -        const struct vdpa_config_ops *ops = vdev->config;
> +	const struct vdpa_config_ops *ops = vdev->config;
>   
>   	/*
>   	 * Config accesses aren't supposed to trigger before features are set.

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Re: [PATCH v11 04/12] vdpa: Add reset callback in vdpa_config_ops

[Jason Wang]

在 2021/8/18 下午8:06, Xie Yongji 写道:
> This adds a new callback to support device specific reset
> behavior. The vdpa bus driver will call the reset function
> instead of setting status to zero during resetting if device
> driver supports the new callback.
>
> Signed-off-by: Xie Yongji <xieyongji@bytedance.com>
> ---
>   drivers/vhost/vdpa.c |  9 +++++++--
>   include/linux/vdpa.h | 11 ++++++++++-
>   2 files changed, 17 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
> index b07aa161f7ad..b1c91b4db0ba 100644
> --- a/drivers/vhost/vdpa.c
> +++ b/drivers/vhost/vdpa.c
> @@ -157,7 +157,7 @@ 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, status_old;
> -	int nvqs = v->nvqs;
> +	int ret, nvqs = v->nvqs;
>   	u16 i;
>   
>   	if (copy_from_user(&status, statusp, sizeof(status)))
> @@ -172,7 +172,12 @@ static long vhost_vdpa_set_status(struct vhost_vdpa *v, u8 __user *statusp)
>   	if (status != 0 && (ops->get_status(vdpa) & ~status) != 0)
>   		return -EINVAL;
>   
> -	ops->set_status(vdpa, status);
> +	if (status == 0 && ops->reset) {
> +		ret = ops->reset(vdpa);
> +		if (ret)
> +			return ret;
> +	} else
> +		ops->set_status(vdpa, status);
>   
>   	if ((status & VIRTIO_CONFIG_S_DRIVER_OK) && !(status_old & VIRTIO_CONFIG_S_DRIVER_OK))
>   		for (i = 0; i < nvqs; i++)
> diff --git a/include/linux/vdpa.h b/include/linux/vdpa.h
> index 8a645f8f4476..af7ea5ad795f 100644
> --- a/include/linux/vdpa.h
> +++ b/include/linux/vdpa.h
> @@ -196,6 +196,9 @@ struct vdpa_iova_range {
>    *				@vdev: vdpa device
>    *				Returns the iova range supported by
>    *				the device.
> + * @reset:			Reset device (optional)
> + *				@vdev: vdpa device
> + *				Returns integer: success (0) or error (< 0)


It looks to me we'd better make this mandatory. This help to reduce the 
confusion for the parent driver.

Thanks


>    * @set_map:			Set device memory mapping (optional)
>    *				Needed for device that using device
>    *				specific DMA translation (on-chip IOMMU)
> @@ -263,6 +266,7 @@ struct vdpa_config_ops {
>   			   const void *buf, unsigned int len);
>   	u32 (*get_generation)(struct vdpa_device *vdev);
>   	struct vdpa_iova_range (*get_iova_range)(struct vdpa_device *vdev);
> +	int (*reset)(struct vdpa_device *vdev);
>   
>   	/* DMA ops */
>   	int (*set_map)(struct vdpa_device *vdev, struct vhost_iotlb *iotlb);
> @@ -351,12 +355,17 @@ static inline struct device *vdpa_get_dma_dev(struct vdpa_device *vdev)
>   	return vdev->dma_dev;
>   }
>   
> -static inline void vdpa_reset(struct vdpa_device *vdev)
> +static inline int vdpa_reset(struct vdpa_device *vdev)
>   {
>   	const struct vdpa_config_ops *ops = vdev->config;
>   
>   	vdev->features_valid = false;
> +	if (ops->reset)
> +		return ops->reset(vdev);
> +
>   	ops->set_status(vdev, 0);
> +
> +	return 0;
>   }
>   
>   static inline int vdpa_set_features(struct vdpa_device *vdev, u64 features)

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Re: [PATCH v11 05/12] vhost-vdpa: Handle the failure of vdpa_reset()

[Jason Wang]

在 2021/8/18 下午8:06, Xie Yongji 写道:
> The vdpa_reset() may fail now. This adds check to its return
> value and fail the vhost_vdpa_open().
>
> Signed-off-by: Xie Yongji <xieyongji@bytedance.com>


Acked-by: Jason Wang <jasowang@redhat.com>


> ---
>   drivers/vhost/vdpa.c | 9 ++++++---
>   1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
> index b1c91b4db0ba..d99d75ad30cc 100644
> --- a/drivers/vhost/vdpa.c
> +++ b/drivers/vhost/vdpa.c
> @@ -116,12 +116,13 @@ static void vhost_vdpa_unsetup_vq_irq(struct vhost_vdpa *v, u16 qid)
>   	irq_bypass_unregister_producer(&vq->call_ctx.producer);
>   }
>   
> -static void vhost_vdpa_reset(struct vhost_vdpa *v)
> +static int vhost_vdpa_reset(struct vhost_vdpa *v)
>   {
>   	struct vdpa_device *vdpa = v->vdpa;
>   
> -	vdpa_reset(vdpa);
>   	v->in_batch = 0;
> +
> +	return vdpa_reset(vdpa);
>   }
>   
>   static long vhost_vdpa_get_device_id(struct vhost_vdpa *v, u8 __user *argp)
> @@ -868,7 +869,9 @@ static int vhost_vdpa_open(struct inode *inode, struct file *filep)
>   		return -EBUSY;
>   
>   	nvqs = v->nvqs;
> -	vhost_vdpa_reset(v);
> +	r = vhost_vdpa_reset(v);
> +	if (r)
> +		goto err;
>   
>   	vqs = kmalloc_array(nvqs, sizeof(*vqs), GFP_KERNEL);
>   	if (!vqs) {

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Re: [PATCH v11 11/12] vduse: Introduce VDUSE - vDPA Device in Userspace

[Jason Wang]

在 2021/8/18 下午8:06, Xie Yongji 写道:
> 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.
>
> Signed-off-by: Xie Yongji <xieyongji@bytedance.com>


Acked-by: Jason Wang <jasowang@redhat.com>


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Re: [PATCH v11 12/12] Documentation: Add documentation for VDUSE

[Jason Wang]

在 2021/8/18 下午8:06, Xie Yongji 写道:
> VDUSE (vDPA Device in Userspace) is a framework to support
> implementing software-emulated vDPA devices in userspace. This
> document is intended to clarify the VDUSE design and usage.
>
> Signed-off-by: Xie Yongji <xieyongji@bytedance.com>


Acked-by: Jason Wang <jasowang@redhat.com>


> ---
>   Documentation/userspace-api/index.rst |   1 +
>   Documentation/userspace-api/vduse.rst | 233 ++++++++++++++++++++++++++++++++++
>   2 files changed, 234 insertions(+)
>   create mode 100644 Documentation/userspace-api/vduse.rst
>
> diff --git a/Documentation/userspace-api/index.rst b/Documentation/userspace-api/index.rst
> index 0b5eefed027e..c432be070f67 100644
> --- a/Documentation/userspace-api/index.rst
> +++ b/Documentation/userspace-api/index.rst
> @@ -27,6 +27,7 @@ place where this information is gathered.
>      iommu
>      media/index
>      sysfs-platform_profile
> +   vduse
>   
>   .. only::  subproject and html
>   
> diff --git a/Documentation/userspace-api/vduse.rst b/Documentation/userspace-api/vduse.rst
> new file mode 100644
> index 000000000000..42ef59ea5314
> --- /dev/null
> +++ b/Documentation/userspace-api/vduse.rst
> @@ -0,0 +1,233 @@
> +==================================
> +VDUSE - "vDPA Device in Userspace"
> +==================================
> +
> +vDPA (virtio data path acceleration) device is a device that uses a
> +datapath which complies with the virtio specifications with vendor
> +specific control path. vDPA devices can be both physically located on
> +the hardware or emulated by software. VDUSE is a framework that makes it
> +possible to implement software-emulated vDPA devices in userspace. And
> +to make the device emulation more secure, the emulated vDPA device's
> +control path is handled in the kernel and only the data path is
> +implemented in the userspace.
> +
> +Note that only virtio block device is supported by VDUSE framework now,
> +which can reduce security risks when the userspace process that implements
> +the data path is run by an unprivileged user. The support for other device
> +types can be added after the security issue of corresponding device driver
> +is clarified or fixed in the future.
> +
> +Create/Destroy VDUSE devices
> +------------------------
> +
> +VDUSE devices are created as follows:
> +
> +1. Create a new VDUSE instance with ioctl(VDUSE_CREATE_DEV) on
> +   /dev/vduse/control.
> +
> +2. Setup each virtqueue with ioctl(VDUSE_VQ_SETUP) on /dev/vduse/$NAME.
> +
> +3. Begin processing VDUSE messages from /dev/vduse/$NAME. The first
> +   messages will arrive while attaching the VDUSE instance to vDPA bus.
> +
> +4. Send the VDPA_CMD_DEV_NEW netlink message to attach the VDUSE
> +   instance to vDPA bus.
> +
> +VDUSE devices are destroyed as follows:
> +
> +1. Send the VDPA_CMD_DEV_DEL netlink message to detach the VDUSE
> +   instance from vDPA bus.
> +
> +2. Close the file descriptor referring to /dev/vduse/$NAME.
> +
> +3. Destroy the VDUSE instance with ioctl(VDUSE_DESTROY_DEV) on
> +   /dev/vduse/control.
> +
> +The netlink messages can be sent via vdpa tool in iproute2 or use the
> +below sample codes:
> +
> +.. code-block:: c
> +
> +	static int netlink_add_vduse(const char *name, enum vdpa_command cmd)
> +	{
> +		struct nl_sock *nlsock;
> +		struct nl_msg *msg;
> +		int famid;
> +
> +		nlsock = nl_socket_alloc();
> +		if (!nlsock)
> +			return -ENOMEM;
> +
> +		if (genl_connect(nlsock))
> +			goto free_sock;
> +
> +		famid = genl_ctrl_resolve(nlsock, VDPA_GENL_NAME);
> +		if (famid < 0)
> +			goto close_sock;
> +
> +		msg = nlmsg_alloc();
> +		if (!msg)
> +			goto close_sock;
> +
> +		if (!genlmsg_put(msg, NL_AUTO_PORT, NL_AUTO_SEQ, famid, 0, 0, cmd, 0))
> +			goto nla_put_failure;
> +
> +		NLA_PUT_STRING(msg, VDPA_ATTR_DEV_NAME, name);
> +		if (cmd == VDPA_CMD_DEV_NEW)
> +			NLA_PUT_STRING(msg, VDPA_ATTR_MGMTDEV_DEV_NAME, "vduse");
> +
> +		if (nl_send_sync(nlsock, msg))
> +			goto close_sock;
> +
> +		nl_close(nlsock);
> +		nl_socket_free(nlsock);
> +
> +		return 0;
> +	nla_put_failure:
> +		nlmsg_free(msg);
> +	close_sock:
> +		nl_close(nlsock);
> +	free_sock:
> +		nl_socket_free(nlsock);
> +		return -1;
> +	}
> +
> +How VDUSE works
> +---------------
> +
> +As mentioned above, a VDUSE device is created by ioctl(VDUSE_CREATE_DEV) on
> +/dev/vduse/control. With this ioctl, userspace can specify some basic configuration
> +such as device name (uniquely identify a VDUSE device), virtio features, virtio
> +configuration space, the number of virtqueues and so on for this emulated device.
> +Then a char device interface (/dev/vduse/$NAME) is exported to userspace for device
> +emulation. Userspace can use the VDUSE_VQ_SETUP ioctl on /dev/vduse/$NAME to
> +add per-virtqueue configuration such as the max size of virtqueue to the device.
> +
> +After the initialization, the VDUSE device can be attached to vDPA bus via
> +the VDPA_CMD_DEV_NEW netlink message. Userspace needs to read()/write() on
> +/dev/vduse/$NAME to receive/reply some control messages from/to VDUSE kernel
> +module as follows:
> +
> +.. code-block:: c
> +
> +	static int vduse_message_handler(int dev_fd)
> +	{
> +		int len;
> +		struct vduse_dev_request req;
> +		struct vduse_dev_response resp;
> +
> +		len = read(dev_fd, &req, sizeof(req));
> +		if (len != sizeof(req))
> +			return -1;
> +
> +		resp.request_id = req.request_id;
> +
> +		switch (req.type) {
> +
> +		/* handle different types of messages */
> +
> +		}
> +
> +		len = write(dev_fd, &resp, sizeof(resp));
> +		if (len != sizeof(resp))
> +			return -1;
> +
> +		return 0;
> +	}
> +
> +There are now three types of messages introduced by VDUSE framework:
> +
> +- VDUSE_GET_VQ_STATE: Get the state for virtqueue, userspace should return
> +  avail index for split virtqueue or the device/driver ring wrap counters and
> +  the avail and used index for packed virtqueue.
> +
> +- VDUSE_SET_STATUS: Set the device status, userspace should follow
> +  the virtio spec: https://docs.oasis-open.org/virtio/virtio/v1.1/virtio-v1.1.html
> +  to process this message. For example, fail to set the FEATURES_OK device
> +  status bit if the device can not accept the negotiated virtio features
> +  get from the VDUSE_DEV_GET_FEATURES ioctl.
> +
> +- VDUSE_UPDATE_IOTLB: Notify userspace to update the memory mapping for specified
> +  IOVA range, userspace should firstly remove the old mapping, then setup the new
> +  mapping via the VDUSE_IOTLB_GET_FD ioctl.
> +
> +After DRIVER_OK status bit is set via the VDUSE_SET_STATUS message, userspace is
> +able to start the dataplane processing as follows:
> +
> +1. Get the specified virtqueue's information with the VDUSE_VQ_GET_INFO ioctl,
> +   including the size, the IOVAs of descriptor table, available ring and used ring,
> +   the state and the ready status.
> +
> +2. Pass the above IOVAs to the VDUSE_IOTLB_GET_FD ioctl so that those IOVA regions
> +   can be mapped into userspace. Some sample codes is shown below:
> +
> +.. code-block:: c
> +
> +	static int perm_to_prot(uint8_t perm)
> +	{
> +		int prot = 0;
> +
> +		switch (perm) {
> +		case VDUSE_ACCESS_WO:
> +			prot |= PROT_WRITE;
> +			break;
> +		case VDUSE_ACCESS_RO:
> +			prot |= PROT_READ;
> +			break;
> +		case VDUSE_ACCESS_RW:
> +			prot |= PROT_READ | PROT_WRITE;
> +			break;
> +		}
> +
> +		return prot;
> +	}
> +
> +	static void *iova_to_va(int dev_fd, uint64_t iova, uint64_t *len)
> +	{
> +		int fd;
> +		void *addr;
> +		size_t size;
> +		struct vduse_iotlb_entry entry;
> +
> +		entry.start = iova;
> +		entry.last = iova;
> +
> +		/*
> +		 * Find the first IOVA region that overlaps with the specified
> +		 * range [start, last] and return the corresponding file descriptor.
> +		 */
> +		fd = ioctl(dev_fd, VDUSE_IOTLB_GET_FD, &entry);
> +		if (fd < 0)
> +			return NULL;
> +
> +		size = entry.last - entry.start + 1;
> +		*len = entry.last - iova + 1;
> +		addr = mmap(0, size, perm_to_prot(entry.perm), MAP_SHARED,
> +			    fd, entry.offset);
> +		close(fd);
> +		if (addr == MAP_FAILED)
> +			return NULL;
> +
> +		/*
> +		 * Using some data structures such as linked list to store
> +		 * the iotlb mapping. The munmap(2) should be called for the
> +		 * cached mapping when the corresponding VDUSE_UPDATE_IOTLB
> +		 * message is received or the device is reset.
> +		 */
> +
> +		return addr + iova - entry.start;
> +	}
> +
> +3. Setup the kick eventfd for the specified virtqueues with the VDUSE_VQ_SETUP_KICKFD
> +   ioctl. The kick eventfd is used by VDUSE kernel module to notify userspace to
> +   consume the available ring. This is optional since userspace can choose to poll the
> +   available ring instead.
> +
> +4. Listen to the kick eventfd (optional) and consume the available ring. The buffer
> +   described by the descriptors in the descriptor table should be also mapped into
> +   userspace via the VDUSE_IOTLB_GET_FD ioctl before accessing.
> +
> +5. Inject an interrupt for specific virtqueue with the VDUSE_INJECT_VQ_IRQ ioctl
> +   after the used ring is filled.
> +
> +For more details on the uAPI, please see include/uapi/linux/vduse.h.

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Re: [PATCH v11 12/12] Documentation: Add documentation for VDUSE

[Jason Wang]

在 2021/8/18 下午8:06, Xie Yongji 写道:
> VDUSE (vDPA Device in Userspace) is a framework to support
> implementing software-emulated vDPA devices in userspace. This
> document is intended to clarify the VDUSE design and usage.
>
> Signed-off-by: Xie Yongji <xieyongji@bytedance.com>


Acked-by: Jason Wang <jasowang@redhat.com>


> ---
>   Documentation/userspace-api/index.rst |   1 +
>   Documentation/userspace-api/vduse.rst | 233 ++++++++++++++++++++++++++++++++++
>   2 files changed, 234 insertions(+)
>   create mode 100644 Documentation/userspace-api/vduse.rst
>
> diff --git a/Documentation/userspace-api/index.rst b/Documentation/userspace-api/index.rst
> index 0b5eefed027e..c432be070f67 100644
> --- a/Documentation/userspace-api/index.rst
> +++ b/Documentation/userspace-api/index.rst
> @@ -27,6 +27,7 @@ place where this information is gathered.
>      iommu
>      media/index
>      sysfs-platform_profile
> +   vduse
>   
>   .. only::  subproject and html
>   
> diff --git a/Documentation/userspace-api/vduse.rst b/Documentation/userspace-api/vduse.rst
> new file mode 100644
> index 000000000000..42ef59ea5314
> --- /dev/null
> +++ b/Documentation/userspace-api/vduse.rst
> @@ -0,0 +1,233 @@
> +==================================
> +VDUSE - "vDPA Device in Userspace"
> +==================================
> +
> +vDPA (virtio data path acceleration) device is a device that uses a
> +datapath which complies with the virtio specifications with vendor
> +specific control path. vDPA devices can be both physically located on
> +the hardware or emulated by software. VDUSE is a framework that makes it
> +possible to implement software-emulated vDPA devices in userspace. And
> +to make the device emulation more secure, the emulated vDPA device's
> +control path is handled in the kernel and only the data path is
> +implemented in the userspace.
> +
> +Note that only virtio block device is supported by VDUSE framework now,
> +which can reduce security risks when the userspace process that implements
> +the data path is run by an unprivileged user. The support for other device
> +types can be added after the security issue of corresponding device driver
> +is clarified or fixed in the future.
> +
> +Create/Destroy VDUSE devices
> +------------------------
> +
> +VDUSE devices are created as follows:
> +
> +1. Create a new VDUSE instance with ioctl(VDUSE_CREATE_DEV) on
> +   /dev/vduse/control.
> +
> +2. Setup each virtqueue with ioctl(VDUSE_VQ_SETUP) on /dev/vduse/$NAME.
> +
> +3. Begin processing VDUSE messages from /dev/vduse/$NAME. The first
> +   messages will arrive while attaching the VDUSE instance to vDPA bus.
> +
> +4. Send the VDPA_CMD_DEV_NEW netlink message to attach the VDUSE
> +   instance to vDPA bus.
> +
> +VDUSE devices are destroyed as follows:
> +
> +1. Send the VDPA_CMD_DEV_DEL netlink message to detach the VDUSE
> +   instance from vDPA bus.
> +
> +2. Close the file descriptor referring to /dev/vduse/$NAME.
> +
> +3. Destroy the VDUSE instance with ioctl(VDUSE_DESTROY_DEV) on
> +   /dev/vduse/control.
> +
> +The netlink messages can be sent via vdpa tool in iproute2 or use the
> +below sample codes:
> +
> +.. code-block:: c
> +
> +	static int netlink_add_vduse(const char *name, enum vdpa_command cmd)
> +	{
> +		struct nl_sock *nlsock;
> +		struct nl_msg *msg;
> +		int famid;
> +
> +		nlsock = nl_socket_alloc();
> +		if (!nlsock)
> +			return -ENOMEM;
> +
> +		if (genl_connect(nlsock))
> +			goto free_sock;
> +
> +		famid = genl_ctrl_resolve(nlsock, VDPA_GENL_NAME);
> +		if (famid < 0)
> +			goto close_sock;
> +
> +		msg = nlmsg_alloc();
> +		if (!msg)
> +			goto close_sock;
> +
> +		if (!genlmsg_put(msg, NL_AUTO_PORT, NL_AUTO_SEQ, famid, 0, 0, cmd, 0))
> +			goto nla_put_failure;
> +
> +		NLA_PUT_STRING(msg, VDPA_ATTR_DEV_NAME, name);
> +		if (cmd == VDPA_CMD_DEV_NEW)
> +			NLA_PUT_STRING(msg, VDPA_ATTR_MGMTDEV_DEV_NAME, "vduse");
> +
> +		if (nl_send_sync(nlsock, msg))
> +			goto close_sock;
> +
> +		nl_close(nlsock);
> +		nl_socket_free(nlsock);
> +
> +		return 0;
> +	nla_put_failure:
> +		nlmsg_free(msg);
> +	close_sock:
> +		nl_close(nlsock);
> +	free_sock:
> +		nl_socket_free(nlsock);
> +		return -1;
> +	}
> +
> +How VDUSE works
> +---------------
> +
> +As mentioned above, a VDUSE device is created by ioctl(VDUSE_CREATE_DEV) on
> +/dev/vduse/control. With this ioctl, userspace can specify some basic configuration
> +such as device name (uniquely identify a VDUSE device), virtio features, virtio
> +configuration space, the number of virtqueues and so on for this emulated device.
> +Then a char device interface (/dev/vduse/$NAME) is exported to userspace for device
> +emulation. Userspace can use the VDUSE_VQ_SETUP ioctl on /dev/vduse/$NAME to
> +add per-virtqueue configuration such as the max size of virtqueue to the device.
> +
> +After the initialization, the VDUSE device can be attached to vDPA bus via
> +the VDPA_CMD_DEV_NEW netlink message. Userspace needs to read()/write() on
> +/dev/vduse/$NAME to receive/reply some control messages from/to VDUSE kernel
> +module as follows:
> +
> +.. code-block:: c
> +
> +	static int vduse_message_handler(int dev_fd)
> +	{
> +		int len;
> +		struct vduse_dev_request req;
> +		struct vduse_dev_response resp;
> +
> +		len = read(dev_fd, &req, sizeof(req));
> +		if (len != sizeof(req))
> +			return -1;
> +
> +		resp.request_id = req.request_id;
> +
> +		switch (req.type) {
> +
> +		/* handle different types of messages */
> +
> +		}
> +
> +		len = write(dev_fd, &resp, sizeof(resp));
> +		if (len != sizeof(resp))
> +			return -1;
> +
> +		return 0;
> +	}
> +
> +There are now three types of messages introduced by VDUSE framework:
> +
> +- VDUSE_GET_VQ_STATE: Get the state for virtqueue, userspace should return
> +  avail index for split virtqueue or the device/driver ring wrap counters and
> +  the avail and used index for packed virtqueue.
> +
> +- VDUSE_SET_STATUS: Set the device status, userspace should follow
> +  the virtio spec: https://docs.oasis-open.org/virtio/virtio/v1.1/virtio-v1.1.html
> +  to process this message. For example, fail to set the FEATURES_OK device
> +  status bit if the device can not accept the negotiated virtio features
> +  get from the VDUSE_DEV_GET_FEATURES ioctl.
> +
> +- VDUSE_UPDATE_IOTLB: Notify userspace to update the memory mapping for specified
> +  IOVA range, userspace should firstly remove the old mapping, then setup the new
> +  mapping via the VDUSE_IOTLB_GET_FD ioctl.
> +
> +After DRIVER_OK status bit is set via the VDUSE_SET_STATUS message, userspace is
> +able to start the dataplane processing as follows:
> +
> +1. Get the specified virtqueue's information with the VDUSE_VQ_GET_INFO ioctl,
> +   including the size, the IOVAs of descriptor table, available ring and used ring,
> +   the state and the ready status.
> +
> +2. Pass the above IOVAs to the VDUSE_IOTLB_GET_FD ioctl so that those IOVA regions
> +   can be mapped into userspace. Some sample codes is shown below:
> +
> +.. code-block:: c
> +
> +	static int perm_to_prot(uint8_t perm)
> +	{
> +		int prot = 0;
> +
> +		switch (perm) {
> +		case VDUSE_ACCESS_WO:
> +			prot |= PROT_WRITE;
> +			break;
> +		case VDUSE_ACCESS_RO:
> +			prot |= PROT_READ;
> +			break;
> +		case VDUSE_ACCESS_RW:
> +			prot |= PROT_READ | PROT_WRITE;
> +			break;
> +		}
> +
> +		return prot;
> +	}
> +
> +	static void *iova_to_va(int dev_fd, uint64_t iova, uint64_t *len)
> +	{
> +		int fd;
> +		void *addr;
> +		size_t size;
> +		struct vduse_iotlb_entry entry;
> +
> +		entry.start = iova;
> +		entry.last = iova;
> +
> +		/*
> +		 * Find the first IOVA region that overlaps with the specified
> +		 * range [start, last] and return the corresponding file descriptor.
> +		 */
> +		fd = ioctl(dev_fd, VDUSE_IOTLB_GET_FD, &entry);
> +		if (fd < 0)
> +			return NULL;
> +
> +		size = entry.last - entry.start + 1;
> +		*len = entry.last - iova + 1;
> +		addr = mmap(0, size, perm_to_prot(entry.perm), MAP_SHARED,
> +			    fd, entry.offset);
> +		close(fd);
> +		if (addr == MAP_FAILED)
> +			return NULL;
> +
> +		/*
> +		 * Using some data structures such as linked list to store
> +		 * the iotlb mapping. The munmap(2) should be called for the
> +		 * cached mapping when the corresponding VDUSE_UPDATE_IOTLB
> +		 * message is received or the device is reset.
> +		 */
> +
> +		return addr + iova - entry.start;
> +	}
> +
> +3. Setup the kick eventfd for the specified virtqueues with the VDUSE_VQ_SETUP_KICKFD
> +   ioctl. The kick eventfd is used by VDUSE kernel module to notify userspace to
> +   consume the available ring. This is optional since userspace can choose to poll the
> +   available ring instead.
> +
> +4. Listen to the kick eventfd (optional) and consume the available ring. The buffer
> +   described by the descriptors in the descriptor table should be also mapped into
> +   userspace via the VDUSE_IOTLB_GET_FD ioctl before accessing.
> +
> +5. Inject an interrupt for specific virtqueue with the VDUSE_INJECT_VQ_IRQ ioctl
> +   after the used ring is filled.
> +
> +For more details on the uAPI, please see include/uapi/linux/vduse.h.

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Re: [PATCH v11 03/12] vdpa: Fix some coding style issues

[Stefano Garzarella]

On Wed, Aug 18, 2021 at 08:06:33PM +0800, Xie Yongji wrote:
>Fix some code indent issues and following checkpatch warning:
>
>WARNING: Prefer 'unsigned int' to bare use of 'unsigned'
>371: FILE: include/linux/vdpa.h:371:
>+static inline void vdpa_get_config(struct vdpa_device *vdev, unsigned offset,
>
>Signed-off-by: Xie Yongji <xieyongji@bytedance.com>
>---
> include/linux/vdpa.h | 34 +++++++++++++++++-----------------
> 1 file changed, 17 insertions(+), 17 deletions(-)

Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>

>
>diff --git a/include/linux/vdpa.h b/include/linux/vdpa.h
>index 954b340f6c2f..8a645f8f4476 100644
>--- a/include/linux/vdpa.h
>+++ b/include/linux/vdpa.h
>@@ -43,17 +43,17 @@ struct vdpa_vq_state_split {
>  * @last_used_idx: used index
>  */
> struct vdpa_vq_state_packed {
>-        u16	last_avail_counter:1;
>-        u16	last_avail_idx:15;
>-        u16	last_used_counter:1;
>-        u16	last_used_idx:15;
>+	u16	last_avail_counter:1;
>+	u16	last_avail_idx:15;
>+	u16	last_used_counter:1;
>+	u16	last_used_idx:15;
> };
>
> struct vdpa_vq_state {
>-     union {
>-          struct vdpa_vq_state_split split;
>-          struct vdpa_vq_state_packed packed;
>-     };
>+	union {
>+		struct vdpa_vq_state_split split;
>+		struct vdpa_vq_state_packed packed;
>+	};
> };
>
> struct vdpa_mgmt_dev;
>@@ -131,7 +131,7 @@ struct vdpa_iova_range {
>  *				@vdev: vdpa device
>  *				@idx: virtqueue index
>  *				@state: pointer to returned state (last_avail_idx)
>- * @get_vq_notification: 	Get the notification area for a virtqueue
>+ * @get_vq_notification:	Get the notification area for a virtqueue
>  *				@vdev: vdpa device
>  *				@idx: virtqueue index
>  *				Returns the notifcation area
>@@ -353,25 +353,25 @@ static inline struct device *vdpa_get_dma_dev(struct vdpa_device *vdev)
>
> static inline void vdpa_reset(struct vdpa_device *vdev)
> {
>-        const struct vdpa_config_ops *ops = vdev->config;
>+	const struct vdpa_config_ops *ops = vdev->config;
>
> 	vdev->features_valid = false;
>-        ops->set_status(vdev, 0);
>+	ops->set_status(vdev, 0);
> }
>
> static inline int vdpa_set_features(struct vdpa_device *vdev, u64 features)
> {
>-        const struct vdpa_config_ops *ops = vdev->config;
>+	const struct vdpa_config_ops *ops = vdev->config;
>
> 	vdev->features_valid = true;
>-        return ops->set_features(vdev, features);
>+	return ops->set_features(vdev, features);
> }
>
>-
>-static inline void vdpa_get_config(struct vdpa_device *vdev, unsigned offset,
>-				   void *buf, unsigned int len)
>+static inline void vdpa_get_config(struct vdpa_device *vdev,
>+				   unsigned int offset, void *buf,
>+				   unsigned int len)
> {
>-        const struct vdpa_config_ops *ops = vdev->config;
>+	const struct vdpa_config_ops *ops = vdev->config;
>
> 	/*
> 	 * Config accesses aren't supposed to trigger before features are set.
>-- 
>2.11.0
>

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Re: [PATCH v11 05/12] vhost-vdpa: Handle the failure of vdpa_reset()

[Stefano Garzarella]

On Wed, Aug 18, 2021 at 08:06:35PM +0800, Xie Yongji wrote:
>The vdpa_reset() may fail now. This adds check to its return
>value and fail the vhost_vdpa_open().
>
>Signed-off-by: Xie Yongji <xieyongji@bytedance.com>
>---
> drivers/vhost/vdpa.c | 9 ++++++---
> 1 file changed, 6 insertions(+), 3 deletions(-)

Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>

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Re: [PATCH v11 01/12] iova: Export alloc_iova_fast() and free_iova_fast()

[Michael S. Tsirkin]

On Wed, Aug 18, 2021 at 08:06:31PM +0800, Xie Yongji wrote:
> Export alloc_iova_fast() and free_iova_fast() so that
> some modules can make use of the per-CPU cache to get
> rid of rbtree spinlock in alloc_iova() and free_iova()
> during IOVA allocation.
> 
> Signed-off-by: Xie Yongji <xieyongji@bytedance.com>


This needs ack from iommu maintainers. Guys?

> ---
>  drivers/iommu/iova.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c
> index b6cf5f16123b..3941ed6bb99b 100644
> --- a/drivers/iommu/iova.c
> +++ b/drivers/iommu/iova.c
> @@ -521,6 +521,7 @@ alloc_iova_fast(struct iova_domain *iovad, unsigned long size,
>  
>  	return new_iova->pfn_lo;
>  }
> +EXPORT_SYMBOL_GPL(alloc_iova_fast);
>  
>  /**
>   * free_iova_fast - free iova pfn range into rcache
> @@ -538,6 +539,7 @@ free_iova_fast(struct iova_domain *iovad, unsigned long pfn, unsigned long size)
>  
>  	free_iova(iovad, pfn);
>  }
> +EXPORT_SYMBOL_GPL(free_iova_fast);
>  
>  #define fq_ring_for_each(i, fq) \
>  	for ((i) = (fq)->head; (i) != (fq)->tail; (i) = ((i) + 1) % IOVA_FQ_SIZE)
> -- 
> 2.11.0

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Re: [PATCH v11 11/12] vduse: Introduce VDUSE - vDPA Device in Userspace

[Michael S. Tsirkin]

On Wed, Aug 18, 2021 at 08:06:41PM +0800, Xie Yongji wrote:
> 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.
> 
> Signed-off-by: Xie Yongji <xieyongji@bytedance.com>

Build bot seems unhappy with this patch.

> ---
>  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                 | 1611 ++++++++++++++++++++
>  include/uapi/linux/vduse.h                         |  304 ++++
>  6 files changed, 1932 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 1409e40e6345..293ca3aef358 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..ce081b7895d5
> --- /dev/null
> +++ b/drivers/vdpa/vdpa_user/vduse_dev.c
> @@ -0,0 +1,1611 @@
> +// 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 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);
> +	}
> +}
> +
> +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];
> +
> +	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, u16 idx)
> +{
> +	struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> +
> +	return dev->vqs[idx].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;
> +
> +		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);
> +		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);
> diff --git a/include/uapi/linux/vduse.h b/include/uapi/linux/vduse.h
> new file mode 100644
> index 000000000000..2e885824fd49
> --- /dev/null
> +++ b/include/uapi/linux/vduse.h
> @@ -0,0 +1,304 @@
> +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
> +#ifndef _UAPI_VDUSE_H_
> +#define _UAPI_VDUSE_H_
> +
> +#include <linux/types.h>
> +
> +#define VDUSE_BASE	0x81
> +
> +/* The ioctls for control device (/dev/vduse/control) */
> +
> +#define VDUSE_API_VERSION	0
> +
> +/*
> + * Get the version of VDUSE API that kernel supported (VDUSE_API_VERSION).
> + * This is used for future extension.
> + */
> +#define VDUSE_GET_API_VERSION	_IOR(VDUSE_BASE, 0x00, __u64)
> +
> +/* Set the version of VDUSE API that userspace supported. */
> +#define VDUSE_SET_API_VERSION	_IOW(VDUSE_BASE, 0x01, __u64)
> +
> +/**
> + * struct vduse_dev_config - basic configuration of a VDUSE device
> + * @name: VDUSE device name, needs to be NUL terminated
> + * @vendor_id: virtio vendor id
> + * @device_id: virtio device id
> + * @features: virtio features
> + * @vq_num: the number of virtqueues
> + * @vq_align: the allocation alignment of virtqueue's metadata
> + * @reserved: for future use, needs to be initialized to zero
> + * @config_size: the size of the configuration space
> + * @config: the buffer of the configuration space
> + *
> + * Structure used by VDUSE_CREATE_DEV ioctl to create VDUSE device.
> + */
> +struct vduse_dev_config {
> +#define VDUSE_NAME_MAX	256
> +	char name[VDUSE_NAME_MAX];
> +	__u32 vendor_id;
> +	__u32 device_id;
> +	__u64 features;
> +	__u32 vq_num;
> +	__u32 vq_align;
> +	__u32 reserved[13];
> +	__u32 config_size;
> +	__u8 config[];
> +};
> +
> +/* Create a VDUSE device which is represented by a char device (/dev/vduse/$NAME) */
> +#define VDUSE_CREATE_DEV	_IOW(VDUSE_BASE, 0x02, struct vduse_dev_config)
> +
> +/*
> + * Destroy a VDUSE device. Make sure there are no more references
> + * to the char device (/dev/vduse/$NAME).
> + */
> +#define VDUSE_DESTROY_DEV	_IOW(VDUSE_BASE, 0x03, char[VDUSE_NAME_MAX])
> +
> +/* The ioctls for VDUSE device (/dev/vduse/$NAME) */
> +
> +/**
> + * struct vduse_iotlb_entry - entry of IOTLB to describe one IOVA region [start, last]
> + * @offset: the mmap offset on returned file descriptor
> + * @start: start of the IOVA region
> + * @last: last of the IOVA region
> + * @perm: access permission of the IOVA region
> + *
> + * Structure used by VDUSE_IOTLB_GET_FD ioctl to find an overlapped IOVA region.
> + */
> +struct vduse_iotlb_entry {
> +	__u64 offset;
> +	__u64 start;
> +	__u64 last;
> +#define VDUSE_ACCESS_RO 0x1
> +#define VDUSE_ACCESS_WO 0x2
> +#define VDUSE_ACCESS_RW 0x3
> +	__u8 perm;
> +};
> +
> +/*
> + * Find the first IOVA region that overlaps with the range [start, last]
> + * and return the corresponding file descriptor. Return -EINVAL means the
> + * IOVA region doesn't exist. Caller should set start and last fields.
> + */
> +#define VDUSE_IOTLB_GET_FD	_IOWR(VDUSE_BASE, 0x10, struct vduse_iotlb_entry)
> +
> +/*
> + * Get the negotiated virtio features. It's a subset of the features in
> + * struct vduse_dev_config which can be accepted by virtio driver. It's
> + * only valid after FEATURES_OK status bit is set.
> + */
> +#define VDUSE_DEV_GET_FEATURES	_IOR(VDUSE_BASE, 0x11, __u64)
> +
> +/**
> + * struct vduse_config_data - data used to update configuration space
> + * @offset: the offset from the beginning of configuration space
> + * @length: the length to write to configuration space
> + * @buffer: the buffer used to write from
> + *
> + * Structure used by VDUSE_DEV_SET_CONFIG ioctl to update device
> + * configuration space.
> + */
> +struct vduse_config_data {
> +	__u32 offset;
> +	__u32 length;
> +	__u8 buffer[];
> +};
> +
> +/* Set device configuration space */
> +#define VDUSE_DEV_SET_CONFIG	_IOW(VDUSE_BASE, 0x12, struct vduse_config_data)
> +
> +/*
> + * Inject a config interrupt. It's usually used to notify virtio driver
> + * that device configuration space has changed.
> + */
> +#define VDUSE_DEV_INJECT_CONFIG_IRQ	_IO(VDUSE_BASE, 0x13)
> +
> +/**
> + * struct vduse_vq_config - basic configuration of a virtqueue
> + * @index: virtqueue index
> + * @max_size: the max size of virtqueue
> + *
> + * Structure used by VDUSE_VQ_SETUP ioctl to setup a virtqueue.
> + */
> +struct vduse_vq_config {
> +	__u32 index;
> +	__u16 max_size;
> +};
> +
> +/*
> + * Setup the specified virtqueue. Make sure all virtqueues have been
> + * configured before the device is attached to vDPA bus.
> + */
> +#define VDUSE_VQ_SETUP		_IOW(VDUSE_BASE, 0x14, struct vduse_vq_config)
> +
> +/**
> + * struct vduse_vq_state_split - split virtqueue state
> + * @avail_index: available index
> + */
> +struct vduse_vq_state_split {
> +	__u16 avail_index;
> +};
> +
> +/**
> + * struct vduse_vq_state_packed - packed virtqueue state
> + * @last_avail_counter: last driver ring wrap counter observed by device
> + * @last_avail_idx: device available index
> + * @last_used_counter: device ring wrap counter
> + * @last_used_idx: used index
> + */
> +struct vduse_vq_state_packed {
> +	__u16 last_avail_counter;
> +	__u16 last_avail_idx;
> +	__u16 last_used_counter;
> +	__u16 last_used_idx;
> +};
> +
> +/**
> + * struct vduse_vq_info - information of a virtqueue
> + * @index: virtqueue index
> + * @num: the size of virtqueue
> + * @desc_addr: address of desc area
> + * @driver_addr: address of driver area
> + * @device_addr: address of device area
> + * @split: split virtqueue state
> + * @packed: packed virtqueue state
> + * @ready: ready status of virtqueue
> + *
> + * Structure used by VDUSE_VQ_GET_INFO ioctl to get virtqueue's information.
> + */
> +struct vduse_vq_info {
> +	__u32 index;
> +	__u32 num;
> +	__u64 desc_addr;
> +	__u64 driver_addr;
> +	__u64 device_addr;
> +	union {
> +		struct vduse_vq_state_split split;
> +		struct vduse_vq_state_packed packed;
> +	};
> +	__u8 ready;
> +};
> +
> +/* Get the specified virtqueue's information. Caller should set index field. */
> +#define VDUSE_VQ_GET_INFO	_IOWR(VDUSE_BASE, 0x15, struct vduse_vq_info)
> +
> +/**
> + * struct vduse_vq_eventfd - eventfd configuration for a virtqueue
> + * @index: virtqueue index
> + * @fd: eventfd, -1 means de-assigning the eventfd
> + *
> + * Structure used by VDUSE_VQ_SETUP_KICKFD ioctl to setup kick eventfd.
> + */
> +struct vduse_vq_eventfd {
> +	__u32 index;
> +#define VDUSE_EVENTFD_DEASSIGN -1
> +	int fd;
> +};
> +
> +/*
> + * Setup kick eventfd for specified virtqueue. The kick eventfd is used
> + * by VDUSE kernel module to notify userspace to consume the avail vring.
> + */
> +#define VDUSE_VQ_SETUP_KICKFD	_IOW(VDUSE_BASE, 0x16, struct vduse_vq_eventfd)
> +
> +/*
> + * Inject an interrupt for specific virtqueue. It's used to notify virtio driver
> + * to consume the used vring.
> + */
> +#define VDUSE_VQ_INJECT_IRQ	_IOW(VDUSE_BASE, 0x17, __u32)
> +
> +/* The control messages definition for read(2)/write(2) on /dev/vduse/$NAME */
> +
> +/**
> + * enum vduse_req_type - request type
> + * @VDUSE_GET_VQ_STATE: get the state for specified virtqueue from userspace
> + * @VDUSE_SET_STATUS: set the device status
> + * @VDUSE_UPDATE_IOTLB: Notify userspace to update the memory mapping for
> + *                      specified IOVA range via VDUSE_IOTLB_GET_FD ioctl
> + */
> +enum vduse_req_type {
> +	VDUSE_GET_VQ_STATE,
> +	VDUSE_SET_STATUS,
> +	VDUSE_UPDATE_IOTLB,
> +};
> +
> +/**
> + * struct vduse_vq_state - virtqueue state
> + * @index: virtqueue index
> + * @split: split virtqueue state
> + * @packed: packed virtqueue state
> + */
> +struct vduse_vq_state {
> +	__u32 index;
> +	union {
> +		struct vduse_vq_state_split split;
> +		struct vduse_vq_state_packed packed;
> +	};
> +};
> +
> +/**
> + * struct vduse_dev_status - device status
> + * @status: device status
> + */
> +struct vduse_dev_status {
> +	__u8 status;
> +};
> +
> +/**
> + * struct vduse_iova_range - IOVA range [start, last]
> + * @start: start of the IOVA range
> + * @last: last of the IOVA range
> + */
> +struct vduse_iova_range {
> +	__u64 start;
> +	__u64 last;
> +};
> +
> +/**
> + * struct vduse_dev_request - control request
> + * @type: request type
> + * @request_id: request id
> + * @reserved: for future use
> + * @vq_state: virtqueue state, only index field is available
> + * @s: device status
> + * @iova: IOVA range for updating
> + * @padding: padding
> + *
> + * Structure used by read(2) on /dev/vduse/$NAME.
> + */
> +struct vduse_dev_request {
> +	__u32 type;
> +	__u32 request_id;
> +	__u32 reserved[4];
> +	union {
> +		struct vduse_vq_state vq_state;
> +		struct vduse_dev_status s;
> +		struct vduse_iova_range iova;
> +		__u32 padding[32];
> +	};
> +};
> +
> +/**
> + * struct vduse_dev_response - response to control request
> + * @request_id: corresponding request id
> + * @result: the result of request
> + * @reserved: for future use, needs to be initialized to zero
> + * @vq_state: virtqueue state
> + * @padding: padding
> + *
> + * Structure used by write(2) on /dev/vduse/$NAME.
> + */
> +struct vduse_dev_response {
> +	__u32 request_id;
> +#define VDUSE_REQ_RESULT_OK	0x00
> +#define VDUSE_REQ_RESULT_FAILED	0x01
> +	__u32 result;
> +	__u32 reserved[4];
> +	union {
> +		struct vduse_vq_state vq_state;
> +		__u32 padding[32];
> +	};
> +};
> +
> +#endif /* _UAPI_VDUSE_H_ */
> -- 
> 2.11.0

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Re: [PATCH v11 01/12] iova: Export alloc_iova_fast() and free_iova_fast()

[Will Deacon]

On Tue, Aug 24, 2021 at 02:08:33PM -0400, Michael S. Tsirkin wrote:
> On Wed, Aug 18, 2021 at 08:06:31PM +0800, Xie Yongji wrote:
> > Export alloc_iova_fast() and free_iova_fast() so that
> > some modules can make use of the per-CPU cache to get
> > rid of rbtree spinlock in alloc_iova() and free_iova()
> > during IOVA allocation.
> > 
> > Signed-off-by: Xie Yongji <xieyongji@bytedance.com>
> 
> 
> This needs ack from iommu maintainers. Guys?

Looks fine to me:

Acked-by: Will Deacon <will@kernel.org>

Will
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