Re: [PATCH v8 09/10] vduse: Introduce VDUSE - vDPA Device in Userspace

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在 2021/6/21 下午6:41, Yongji Xie 写道:
On Mon, Jun 21, 2021 at 5:14 PM Jason Wang <jasowang@xxxxxxxxxx> wrote:

在 2021/6/15 下午10:13, Xie Yongji 写道:
This VDUSE driver enables implementing vDPA devices in userspace.
The vDPA device's control path is handled in kernel and the data
path is handled in userspace.

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

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

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

diff --git a/Documentation/userspace-api/ioctl/ioctl-number.rst b/Documentation/userspace-api/ioctl/ioctl-number.rst
index 9bfc2b510c64..acd95e9dcfe7 100644
--- a/Documentation/userspace-api/ioctl/ioctl-number.rst
+++ b/Documentation/userspace-api/ioctl/ioctl-number.rst
@@ -300,6 +300,7 @@ Code  Seq#    Include File                                           Comments
   'z'   10-4F  drivers/s390/crypto/zcrypt_api.h                        conflict!
   '|'   00-7F  linux/media.h
   0x80  00-1F  linux/fb.h
+0x81  00-1F  linux/vduse.h
   0x89  00-06  arch/x86/include/asm/sockios.h
   0x89  0B-DF  linux/sockios.h
   0x89  E0-EF  linux/sockios.h                                         SIOCPROTOPRIVATE range
diff --git a/drivers/vdpa/Kconfig b/drivers/vdpa/Kconfig
index a503c1b2bfd9..6e23bce6433a 100644
--- a/drivers/vdpa/Kconfig
+++ b/drivers/vdpa/Kconfig
@@ -33,6 +33,16 @@ config VDPA_SIM_BLOCK
         vDPA block device simulator which terminates IO request in a
         memory buffer.

+config VDPA_USER
+     tristate "VDUSE (vDPA Device in Userspace) support"
+     depends on EVENTFD && MMU && HAS_DMA
+     select DMA_OPS
+     select VHOST_IOTLB
+     select IOMMU_IOVA
+     help
+       With VDUSE it is possible to emulate a vDPA Device
+       in a userspace program.
+
   config IFCVF
       tristate "Intel IFC VF vDPA driver"
       depends on PCI_MSI
diff --git a/drivers/vdpa/Makefile b/drivers/vdpa/Makefile
index 67fe7f3d6943..f02ebed33f19 100644
--- a/drivers/vdpa/Makefile
+++ b/drivers/vdpa/Makefile
@@ -1,6 +1,7 @@
   # SPDX-License-Identifier: GPL-2.0
   obj-$(CONFIG_VDPA) += vdpa.o
   obj-$(CONFIG_VDPA_SIM) += vdpa_sim/
+obj-$(CONFIG_VDPA_USER) += vdpa_user/
   obj-$(CONFIG_IFCVF)    += ifcvf/
   obj-$(CONFIG_MLX5_VDPA) += mlx5/
   obj-$(CONFIG_VP_VDPA)    += virtio_pci/
diff --git a/drivers/vdpa/vdpa_user/Makefile b/drivers/vdpa/vdpa_user/Makefile
new file mode 100644
index 000000000000..260e0b26af99
--- /dev/null
+++ b/drivers/vdpa/vdpa_user/Makefile
@@ -0,0 +1,5 @@
+# SPDX-License-Identifier: GPL-2.0
+
+vduse-y := vduse_dev.o iova_domain.o
+
+obj-$(CONFIG_VDPA_USER) += vduse.o
diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
new file mode 100644
index 000000000000..5271cbd15e28
--- /dev/null
+++ b/drivers/vdpa/vdpa_user/vduse_dev.c
@@ -0,0 +1,1453 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * VDUSE: vDPA Device in Userspace
+ *
+ * Copyright (C) 2020-2021 Bytedance Inc. and/or its affiliates. All rights reserved.
+ *
+ * Author: Xie Yongji <xieyongji@xxxxxxxxxxxxx>
+ *
+ */
+
+#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@xxxxxxxxxxxxx>"
+#define DRV_DESC     "vDPA Device in Userspace"
+#define DRV_LICENSE  "GPL v2"
+
+#define VDUSE_DEV_MAX (1U << MINORBITS)
+#define VDUSE_MAX_BOUNCE_SIZE (64 * 1024 * 1024)
+#define VDUSE_IOVA_SIZE (128 * 1024 * 1024)
+#define VDUSE_REQUEST_TIMEOUT 30
+
+struct vduse_virtqueue {
+     u16 index;
+     u32 num;
+     u32 avail_idx;
+     u64 desc_addr;
+     u64 driver_addr;
+     u64 device_addr;
+     bool ready;
+     bool kicked;
+     spinlock_t kick_lock;
+     spinlock_t irq_lock;
+     struct eventfd_ctx *kickfd;
+     struct vdpa_callback cb;
+     struct work_struct inject;
+};
+
+struct vduse_dev;
+
+struct vduse_vdpa {
+     struct vdpa_device vdpa;
+     struct vduse_dev *dev;
+};
+
+struct vduse_dev {
+     struct vduse_vdpa *vdev;
+     struct device *dev;
+     struct vduse_virtqueue *vqs;
+     struct vduse_iova_domain *domain;
+     char *name;
+     struct mutex lock;
+     spinlock_t msg_lock;
+     u64 msg_unique;
+     wait_queue_head_t waitq;
+     struct list_head send_list;
+     struct list_head recv_list;
+     struct vdpa_callback config_cb;
+     struct work_struct inject;
+     spinlock_t irq_lock;
+     int minor;
+     bool connected;
+     bool started;
+     u64 api_version;
+     u64 user_features;

Let's use device_features.

OK.

+     u64 features;

And driver features.

OK.

+     u32 device_id;
+     u32 vendor_id;
+     u32 generation;
+     u32 config_size;
+     void *config;
+     u8 status;
+     u16 vq_size_max;
+     u32 vq_num;
+     u32 vq_align;
+};
+
+struct vduse_dev_msg {
+     struct vduse_dev_request req;
+     struct vduse_dev_response resp;
+     struct list_head list;
+     wait_queue_head_t waitq;
+     bool completed;
+};
+
+struct vduse_control {
+     u64 api_version;
+};
+
+static DEFINE_MUTEX(vduse_lock);
+static DEFINE_IDR(vduse_idr);
+
+static dev_t vduse_major;
+static struct class *vduse_class;
+static struct cdev vduse_ctrl_cdev;
+static struct cdev vduse_cdev;
+static struct workqueue_struct *vduse_irq_wq;
+
+static u32 allowed_device_id[] = {
+     VIRTIO_ID_BLOCK,
+};
+
+static inline struct vduse_dev *vdpa_to_vduse(struct vdpa_device *vdpa)
+{
+     struct vduse_vdpa *vdev = container_of(vdpa, struct vduse_vdpa, vdpa);
+
+     return vdev->dev;
+}
+
+static inline struct vduse_dev *dev_to_vduse(struct device *dev)
+{
+     struct vdpa_device *vdpa = dev_to_vdpa(dev);
+
+     return vdpa_to_vduse(vdpa);
+}
+
+static struct vduse_dev_msg *vduse_find_msg(struct list_head *head,
+                                         uint32_t request_id)
+{
+     struct vduse_dev_msg *msg;
+
+     list_for_each_entry(msg, head, list) {
+             if (msg->req.request_id == request_id) {
+                     list_del(&msg->list);
+                     return msg;
+             }
+     }
+
+     return NULL;
+}
+
+static struct vduse_dev_msg *vduse_dequeue_msg(struct list_head *head)
+{
+     struct vduse_dev_msg *msg = NULL;
+
+     if (!list_empty(head)) {
+             msg = list_first_entry(head, struct vduse_dev_msg, list);
+             list_del(&msg->list);
+     }
+
+     return msg;
+}
+
+static void vduse_enqueue_msg(struct list_head *head,
+                           struct vduse_dev_msg *msg)
+{
+     list_add_tail(&msg->list, head);
+}
+
+static int vduse_dev_msg_send(struct vduse_dev *dev,
+                           struct vduse_dev_msg *msg, bool no_reply)
+{

It looks to me the only user for no_reply=true is the dataplane start. I
wonder no_reply is really needed consider we have switched to use
wait_event_killable_timeout().

Do we need to handle the error in this case if we remove the no_reply
flag. Print a warning message?


See below.



In another way, no_reply is false for vq state synchronization and IOTLB
updating. I wonder if we can simply use no_reply = true for them.

Looks like we can't, e.g. we need to get a reply from userspace for vq state.


Right.



+     init_waitqueue_head(&msg->waitq);
+     spin_lock(&dev->msg_lock);
+     msg->req.request_id = dev->msg_unique++;
+     vduse_enqueue_msg(&dev->send_list, msg);
+     wake_up(&dev->waitq);
+     spin_unlock(&dev->msg_lock);
+     if (no_reply)
+             return 0;
+
+     wait_event_killable_timeout(msg->waitq, msg->completed,
+                                 VDUSE_REQUEST_TIMEOUT * HZ);
+     spin_lock(&dev->msg_lock);
+     if (!msg->completed) {
+             list_del(&msg->list);
+             msg->resp.result = VDUSE_REQ_RESULT_FAILED;
+     }
+     spin_unlock(&dev->msg_lock);
+
+     return (msg->resp.result == VDUSE_REQ_RESULT_OK) ? 0 : -EIO;

Do we need to serialize the check by protecting it with the spinlock above?

Good point.

+}
+
+static void vduse_dev_msg_cleanup(struct vduse_dev *dev)
+{
+     struct vduse_dev_msg *msg;
+
+     spin_lock(&dev->msg_lock);
+     while ((msg = vduse_dequeue_msg(&dev->send_list))) {
+             if (msg->req.flags & VDUSE_REQ_FLAGS_NO_REPLY)
+                     kfree(msg);
+             else
+                     vduse_enqueue_msg(&dev->recv_list, msg);
+     }
+     while ((msg = vduse_dequeue_msg(&dev->recv_list))) {
+             msg->resp.result = VDUSE_REQ_RESULT_FAILED;
+             msg->completed = 1;
+             wake_up(&msg->waitq);
+     }
+     spin_unlock(&dev->msg_lock);
+}
+
+static void vduse_dev_start_dataplane(struct vduse_dev *dev)
+{
+     struct vduse_dev_msg *msg = kzalloc(sizeof(*msg),
+                                         GFP_KERNEL | __GFP_NOFAIL);
+
+     msg->req.type = VDUSE_START_DATAPLANE;
+     msg->req.flags |= VDUSE_REQ_FLAGS_NO_REPLY;
+     vduse_dev_msg_send(dev, msg, true);
+}
+
+static void vduse_dev_stop_dataplane(struct vduse_dev *dev)
+{
+     struct vduse_dev_msg *msg = kzalloc(sizeof(*msg),
+                                         GFP_KERNEL | __GFP_NOFAIL);
+
+     msg->req.type = VDUSE_STOP_DATAPLANE;
+     msg->req.flags |= VDUSE_REQ_FLAGS_NO_REPLY;

Can we simply use this flag instead of introducing a new parameter
(no_reply) in vduse_dev_msg_send()?

Looks good to me.

+     vduse_dev_msg_send(dev, msg, true);
+}
+
+static int vduse_dev_get_vq_state(struct vduse_dev *dev,
+                               struct vduse_virtqueue *vq,
+                               struct vdpa_vq_state *state)
+{
+     struct vduse_dev_msg msg = { 0 };
+     int ret;

Note that I post a series that implement the packed virtqueue support:

https://lists.linuxfoundation.org/pipermail/virtualization/2021-June/054501.html

So this patch needs to be updated as well.

Will do it.

+
+     msg.req.type = VDUSE_GET_VQ_STATE;
+     msg.req.vq_state.index = vq->index;
+
+     ret = vduse_dev_msg_send(dev, &msg, false);
+     if (ret)
+             return ret;
+
+     state->avail_index = msg.resp.vq_state.avail_idx;
+     return 0;
+}
+
+static int vduse_dev_update_iotlb(struct vduse_dev *dev,
+                             u64 start, u64 last)
+{
+     struct vduse_dev_msg msg = { 0 };
+
+     if (last < start)
+             return -EINVAL;
+
+     msg.req.type = VDUSE_UPDATE_IOTLB;
+     msg.req.iova.start = start;
+     msg.req.iova.last = last;
+
+     return vduse_dev_msg_send(dev, &msg, false);
+}
+
+static ssize_t vduse_dev_read_iter(struct kiocb *iocb, struct iov_iter *to)
+{
+     struct file *file = iocb->ki_filp;
+     struct vduse_dev *dev = file->private_data;
+     struct vduse_dev_msg *msg;
+     int size = sizeof(struct vduse_dev_request);
+     ssize_t ret;
+
+     if (iov_iter_count(to) < size)
+             return -EINVAL;
+
+     spin_lock(&dev->msg_lock);
+     while (1) {
+             msg = vduse_dequeue_msg(&dev->send_list);
+             if (msg)
+                     break;
+
+             ret = -EAGAIN;
+             if (file->f_flags & O_NONBLOCK)
+                     goto unlock;
+
+             spin_unlock(&dev->msg_lock);
+             ret = wait_event_interruptible_exclusive(dev->waitq,
+                                     !list_empty(&dev->send_list));
+             if (ret)
+                     return ret;
+
+             spin_lock(&dev->msg_lock);
+     }
+     spin_unlock(&dev->msg_lock);
+     ret = copy_to_iter(&msg->req, size, to);
+     spin_lock(&dev->msg_lock);
+     if (ret != size) {
+             ret = -EFAULT;
+             vduse_enqueue_msg(&dev->send_list, msg);
+             goto unlock;
+     }
+     if (msg->req.flags & VDUSE_REQ_FLAGS_NO_REPLY)
+             kfree(msg);
+     else
+             vduse_enqueue_msg(&dev->recv_list, msg);
+unlock:
+     spin_unlock(&dev->msg_lock);
+
+     return ret;
+}
+
+static ssize_t vduse_dev_write_iter(struct kiocb *iocb, struct iov_iter *from)
+{
+     struct file *file = iocb->ki_filp;
+     struct vduse_dev *dev = file->private_data;
+     struct vduse_dev_response resp;
+     struct vduse_dev_msg *msg;
+     size_t ret;
+
+     ret = copy_from_iter(&resp, sizeof(resp), from);
+     if (ret != sizeof(resp))
+             return -EINVAL;
+
+     spin_lock(&dev->msg_lock);
+     msg = vduse_find_msg(&dev->recv_list, resp.request_id);
+     if (!msg) {
+             ret = -ENOENT;
+             goto unlock;
+     }
+
+     memcpy(&msg->resp, &resp, sizeof(resp));
+     msg->completed = 1;
+     wake_up(&msg->waitq);
+unlock:
+     spin_unlock(&dev->msg_lock);
+
+     return ret;
+}
+
+static __poll_t vduse_dev_poll(struct file *file, poll_table *wait)
+{
+     struct vduse_dev *dev = file->private_data;
+     __poll_t mask = 0;
+
+     poll_wait(file, &dev->waitq, wait);
+
+     if (!list_empty(&dev->send_list))
+             mask |= EPOLLIN | EPOLLRDNORM;
+     if (!list_empty(&dev->recv_list))
+             mask |= EPOLLOUT | EPOLLWRNORM;
+
+     return mask;
+}
+
+static void vduse_dev_reset(struct vduse_dev *dev)
+{
+     int i;
+     struct vduse_iova_domain *domain = dev->domain;
+
+     /* The coherent mappings are handled in vduse_dev_free_coherent() */
+     if (domain->bounce_map)
+             vduse_domain_reset_bounce_map(domain);
+
+     dev->features = 0;
+     dev->generation++;
+     spin_lock(&dev->irq_lock);
+     dev->config_cb.callback = NULL;
+     dev->config_cb.private = NULL;
+     spin_unlock(&dev->irq_lock);
+
+     for (i = 0; i < dev->vq_num; i++) {
+             struct vduse_virtqueue *vq = &dev->vqs[i];
+
+             vq->ready = false;
+             vq->desc_addr = 0;
+             vq->driver_addr = 0;
+             vq->device_addr = 0;
+             vq->avail_idx = 0;
+             vq->num = 0;
+
+             spin_lock(&vq->kick_lock);
+             vq->kicked = false;
+             if (vq->kickfd)
+                     eventfd_ctx_put(vq->kickfd);
+             vq->kickfd = NULL;
+             spin_unlock(&vq->kick_lock);
+
+             spin_lock(&vq->irq_lock);
+             vq->cb.callback = NULL;
+             vq->cb.private = NULL;
+             spin_unlock(&vq->irq_lock);
+     }
+}
+
+static int vduse_vdpa_set_vq_address(struct vdpa_device *vdpa, u16 idx,
+                             u64 desc_area, u64 driver_area,
+                             u64 device_area)
+{
+     struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+     struct vduse_virtqueue *vq = &dev->vqs[idx];
+
+     vq->desc_addr = desc_area;
+     vq->driver_addr = driver_area;
+     vq->device_addr = device_area;
+
+     return 0;
+}
+
+static void vduse_vdpa_kick_vq(struct vdpa_device *vdpa, u16 idx)
+{
+     struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+     struct vduse_virtqueue *vq = &dev->vqs[idx];
+
+     spin_lock(&vq->kick_lock);
+     if (!vq->ready)
+             goto unlock;
+
+     if (vq->kickfd)
+             eventfd_signal(vq->kickfd, 1);
+     else
+             vq->kicked = true;
+unlock:
+     spin_unlock(&vq->kick_lock);
+}
+
+static void vduse_vdpa_set_vq_cb(struct vdpa_device *vdpa, u16 idx,
+                           struct vdpa_callback *cb)
+{
+     struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+     struct vduse_virtqueue *vq = &dev->vqs[idx];
+
+     spin_lock(&vq->irq_lock);
+     vq->cb.callback = cb->callback;
+     vq->cb.private = cb->private;
+     spin_unlock(&vq->irq_lock);
+}
+
+static void vduse_vdpa_set_vq_num(struct vdpa_device *vdpa, u16 idx, u32 num)
+{
+     struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+     struct vduse_virtqueue *vq = &dev->vqs[idx];
+
+     vq->num = num;
+}
+
+static void vduse_vdpa_set_vq_ready(struct vdpa_device *vdpa,
+                                     u16 idx, bool ready)
+{
+     struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+     struct vduse_virtqueue *vq = &dev->vqs[idx];
+
+     vq->ready = ready;
+}
+
+static bool vduse_vdpa_get_vq_ready(struct vdpa_device *vdpa, u16 idx)
+{
+     struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+     struct vduse_virtqueue *vq = &dev->vqs[idx];
+
+     return vq->ready;
+}
+
+static int vduse_vdpa_set_vq_state(struct vdpa_device *vdpa, u16 idx,
+                             const struct vdpa_vq_state *state)
+{
+     struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+     struct vduse_virtqueue *vq = &dev->vqs[idx];
+
+     vq->avail_idx = state->avail_index;
+     return 0;
+}
+
+static int vduse_vdpa_get_vq_state(struct vdpa_device *vdpa, u16 idx,
+                             struct vdpa_vq_state *state)
+{
+     struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+     struct vduse_virtqueue *vq = &dev->vqs[idx];
+
+     return vduse_dev_get_vq_state(dev, vq, state);
+}
+
+static u32 vduse_vdpa_get_vq_align(struct vdpa_device *vdpa)
+{
+     struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+
+     return dev->vq_align;
+}
+
+static u64 vduse_vdpa_get_features(struct vdpa_device *vdpa)
+{
+     struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+
+     return dev->user_features;
+}
+
+static int vduse_vdpa_set_features(struct vdpa_device *vdpa, u64 features)
+{
+     struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+
+     dev->features = features;
+     return 0;
+}
+
+static void vduse_vdpa_set_config_cb(struct vdpa_device *vdpa,
+                               struct vdpa_callback *cb)
+{
+     struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+
+     spin_lock(&dev->irq_lock);
+     dev->config_cb.callback = cb->callback;
+     dev->config_cb.private = cb->private;
+     spin_unlock(&dev->irq_lock);
+}
+
+static u16 vduse_vdpa_get_vq_num_max(struct vdpa_device *vdpa)
+{
+     struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+
+     return dev->vq_size_max;
+}
+
+static u32 vduse_vdpa_get_device_id(struct vdpa_device *vdpa)
+{
+     struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+
+     return dev->device_id;
+}
+
+static u32 vduse_vdpa_get_vendor_id(struct vdpa_device *vdpa)
+{
+     struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+
+     return dev->vendor_id;
+}
+
+static u8 vduse_vdpa_get_status(struct vdpa_device *vdpa)
+{
+     struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+
+     return dev->status;
+}
+
+static void vduse_vdpa_set_status(struct vdpa_device *vdpa, u8 status)
+{
+     struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+     bool started = !!(status & VIRTIO_CONFIG_S_DRIVER_OK);
+
+     dev->status = status;
+
+     if (dev->started == started)
+             return;

If we check dev->status == status, (or only check the DRIVER_OK bit)
then there's no need to introduce an extra dev->started.

Will do it.

+
+     dev->started = started;
+     if (dev->started) {
+             vduse_dev_start_dataplane(dev);
+     } else {
+             vduse_dev_reset(dev);
+             vduse_dev_stop_dataplane(dev);

I wonder if no_reply work for the case of vhost-vdpa. For virtio-vDPA,
we have bouncing buffers so it's harmless if usersapce dataplane keeps
performing read/write. For vhost-vDPA we don't have such stuffs.

OK. So it still needs to be synchronized here. If so, how to handle
the error? Looks like printing a warning message should be enough.


We need fix a way to propagate the error to the userspace.

E.g if we want to stop the deivce, we will delay the status reset until we get respose from the userspace?



+     }
+}
+
+static size_t vduse_vdpa_get_config_size(struct vdpa_device *vdpa)
+{
+     struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+
+     return dev->config_size;
+}
+
+static void vduse_vdpa_get_config(struct vdpa_device *vdpa, unsigned int offset,
+                               void *buf, unsigned int len)
+{
+     struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+
+     memcpy(buf, dev->config + offset, len);
+}
+
+static void vduse_vdpa_set_config(struct vdpa_device *vdpa, unsigned int offset,
+                     const void *buf, unsigned int len)
+{
+     /* Now we only support read-only configuration space */
+}
+
+static u32 vduse_vdpa_get_generation(struct vdpa_device *vdpa)
+{
+     struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+
+     return dev->generation;
+}
+
+static int vduse_vdpa_set_map(struct vdpa_device *vdpa,
+                             struct vhost_iotlb *iotlb)
+{
+     struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+     int ret;
+
+     ret = vduse_domain_set_map(dev->domain, iotlb);
+     if (ret)
+             return ret;
+
+     ret = vduse_dev_update_iotlb(dev, 0ULL, ULLONG_MAX);
+     if (ret) {
+             vduse_domain_clear_map(dev->domain, iotlb);
+             return ret;
+     }
+
+     return 0;
+}
+
+static void vduse_vdpa_free(struct vdpa_device *vdpa)
+{
+     struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+
+     dev->vdev = NULL;
+}
+
+static const struct vdpa_config_ops vduse_vdpa_config_ops = {
+     .set_vq_address         = vduse_vdpa_set_vq_address,
+     .kick_vq                = vduse_vdpa_kick_vq,
+     .set_vq_cb              = vduse_vdpa_set_vq_cb,
+     .set_vq_num             = vduse_vdpa_set_vq_num,
+     .set_vq_ready           = vduse_vdpa_set_vq_ready,
+     .get_vq_ready           = vduse_vdpa_get_vq_ready,
+     .set_vq_state           = vduse_vdpa_set_vq_state,
+     .get_vq_state           = vduse_vdpa_get_vq_state,
+     .get_vq_align           = vduse_vdpa_get_vq_align,
+     .get_features           = vduse_vdpa_get_features,
+     .set_features           = vduse_vdpa_set_features,
+     .set_config_cb          = vduse_vdpa_set_config_cb,
+     .get_vq_num_max         = vduse_vdpa_get_vq_num_max,
+     .get_device_id          = vduse_vdpa_get_device_id,
+     .get_vendor_id          = vduse_vdpa_get_vendor_id,
+     .get_status             = vduse_vdpa_get_status,
+     .set_status             = vduse_vdpa_set_status,
+     .get_config_size        = vduse_vdpa_get_config_size,
+     .get_config             = vduse_vdpa_get_config,
+     .set_config             = vduse_vdpa_set_config,
+     .get_generation         = vduse_vdpa_get_generation,
+     .set_map                = vduse_vdpa_set_map,
+     .free                   = vduse_vdpa_free,
+};
+
+static dma_addr_t vduse_dev_map_page(struct device *dev, struct page *page,
+                                  unsigned long offset, size_t size,
+                                  enum dma_data_direction dir,
+                                  unsigned long attrs)
+{
+     struct vduse_dev *vdev = dev_to_vduse(dev);
+     struct vduse_iova_domain *domain = vdev->domain;
+
+     return vduse_domain_map_page(domain, page, offset, size, dir, attrs);
+}
+
+static void vduse_dev_unmap_page(struct device *dev, dma_addr_t dma_addr,
+                             size_t size, enum dma_data_direction dir,
+                             unsigned long attrs)
+{
+     struct vduse_dev *vdev = dev_to_vduse(dev);
+     struct vduse_iova_domain *domain = vdev->domain;
+
+     return vduse_domain_unmap_page(domain, dma_addr, size, dir, attrs);
+}
+
+static void *vduse_dev_alloc_coherent(struct device *dev, size_t size,
+                                     dma_addr_t *dma_addr, gfp_t flag,
+                                     unsigned long attrs)
+{
+     struct vduse_dev *vdev = dev_to_vduse(dev);
+     struct vduse_iova_domain *domain = vdev->domain;
+     unsigned long iova;
+     void *addr;
+
+     *dma_addr = DMA_MAPPING_ERROR;
+     addr = vduse_domain_alloc_coherent(domain, size,
+                             (dma_addr_t *)&iova, flag, attrs);
+     if (!addr)
+             return NULL;
+
+     *dma_addr = (dma_addr_t)iova;
+
+     return addr;
+}
+
+static void vduse_dev_free_coherent(struct device *dev, size_t size,
+                                     void *vaddr, dma_addr_t dma_addr,
+                                     unsigned long attrs)
+{
+     struct vduse_dev *vdev = dev_to_vduse(dev);
+     struct vduse_iova_domain *domain = vdev->domain;
+
+     vduse_domain_free_coherent(domain, size, vaddr, dma_addr, attrs);
+}
+
+static size_t vduse_dev_max_mapping_size(struct device *dev)
+{
+     struct vduse_dev *vdev = dev_to_vduse(dev);
+     struct vduse_iova_domain *domain = vdev->domain;
+
+     return domain->bounce_size;
+}
+
+static const struct dma_map_ops vduse_dev_dma_ops = {
+     .map_page = vduse_dev_map_page,
+     .unmap_page = vduse_dev_unmap_page,
+     .alloc = vduse_dev_alloc_coherent,
+     .free = vduse_dev_free_coherent,
+     .max_mapping_size = vduse_dev_max_mapping_size,
+};
+
+static unsigned int perm_to_file_flags(u8 perm)
+{
+     unsigned int flags = 0;
+
+     switch (perm) {
+     case VDUSE_ACCESS_WO:
+             flags |= O_WRONLY;
+             break;
+     case VDUSE_ACCESS_RO:
+             flags |= O_RDONLY;
+             break;
+     case VDUSE_ACCESS_RW:
+             flags |= O_RDWR;
+             break;
+     default:
+             WARN(1, "invalidate vhost IOTLB permission\n");
+             break;
+     }
+
+     return flags;
+}
+
+static int vduse_kickfd_setup(struct vduse_dev *dev,
+                     struct vduse_vq_eventfd *eventfd)
+{
+     struct eventfd_ctx *ctx = NULL;
+     struct vduse_virtqueue *vq;
+     u32 index;
+
+     if (eventfd->index >= dev->vq_num)
+             return -EINVAL;
+
+     index = array_index_nospec(eventfd->index, dev->vq_num);
+     vq = &dev->vqs[index];
+     if (eventfd->fd >= 0) {
+             ctx = eventfd_ctx_fdget(eventfd->fd);
+             if (IS_ERR(ctx))
+                     return PTR_ERR(ctx);
+     } else if (eventfd->fd != VDUSE_EVENTFD_DEASSIGN)
+             return 0;
+
+     spin_lock(&vq->kick_lock);
+     if (vq->kickfd)
+             eventfd_ctx_put(vq->kickfd);
+     vq->kickfd = ctx;
+     if (vq->ready && vq->kicked && vq->kickfd) {
+             eventfd_signal(vq->kickfd, 1);
+             vq->kicked = false;
+     }
+     spin_unlock(&vq->kick_lock);
+
+     return 0;
+}
+
+static void vduse_dev_irq_inject(struct work_struct *work)
+{
+     struct vduse_dev *dev = container_of(work, struct vduse_dev, inject);
+
+     spin_lock_irq(&dev->irq_lock);
+     if (dev->config_cb.callback)
+             dev->config_cb.callback(dev->config_cb.private);
+     spin_unlock_irq(&dev->irq_lock);
+}
+
+static void vduse_vq_irq_inject(struct work_struct *work)
+{
+     struct vduse_virtqueue *vq = container_of(work,
+                                     struct vduse_virtqueue, inject);
+
+     spin_lock_irq(&vq->irq_lock);
+     if (vq->ready && vq->cb.callback)
+             vq->cb.callback(vq->cb.private);
+     spin_unlock_irq(&vq->irq_lock);
+}
+
+static long vduse_dev_ioctl(struct file *file, unsigned int cmd,
+                         unsigned long arg)
+{
+     struct vduse_dev *dev = file->private_data;
+     void __user *argp = (void __user *)arg;
+     int ret;
+
+     switch (cmd) {
+     case VDUSE_IOTLB_GET_FD: {
+             struct vduse_iotlb_entry entry;
+             struct vhost_iotlb_map *map;
+             struct vdpa_map_file *map_file;
+             struct vduse_iova_domain *domain = dev->domain;
+             struct file *f = NULL;
+
+             ret = -EFAULT;
+             if (copy_from_user(&entry, argp, sizeof(entry)))
+                     break;
+
+             ret = -EINVAL;
+             if (entry.start > entry.last)
+                     break;
+
+             spin_lock(&domain->iotlb_lock);
+             map = vhost_iotlb_itree_first(domain->iotlb,
+                                           entry.start, entry.last);
+             if (map) {
+                     map_file = (struct vdpa_map_file *)map->opaque;
+                     f = get_file(map_file->file);
+                     entry.offset = map_file->offset;
+                     entry.start = map->start;
+                     entry.last = map->last;
+                     entry.perm = map->perm;
+             }
+             spin_unlock(&domain->iotlb_lock);
+             ret = -EINVAL;
+             if (!f)
+                     break;
+
+             ret = -EFAULT;
+             if (copy_to_user(argp, &entry, sizeof(entry))) {
+                     fput(f);
+                     break;
+             }
+             ret = receive_fd(f, perm_to_file_flags(entry.perm));
+             fput(f);
+             break;
+     }
+     case VDUSE_DEV_GET_FEATURES:
+             ret = put_user(dev->features, (u64 __user *)argp);
+             break;
+     case VDUSE_DEV_UPDATE_CONFIG: {
+             struct vduse_config_update config;
+             unsigned long size = offsetof(struct vduse_config_update,
+                                           buffer);
+
+             ret = -EFAULT;
+             if (copy_from_user(&config, argp, size))
+                     break;
+
+             ret = -EINVAL;
+             if (config.length == 0 ||
+                 config.length > dev->config_size - config.offset)
+                     break;
+
+             ret = -EFAULT;
+             if (copy_from_user(dev->config + config.offset, argp + size,
+                                config.length))
+                     break;
+
+             ret = 0;
+             queue_work(vduse_irq_wq, &dev->inject);

I wonder if it's better to separate config interrupt out of config
update or we need document this.

I have documented it in the docs. Looks like a config update should be
always followed by a config interrupt. I didn't find a case that uses
them separately.


The uAPI doesn't prevent us from the following scenario:

update_config(mac[0], ..);
update_config(max[1], ..);

So it looks to me it's better to separate the config interrupt from the config updating.



+             break;
+     }
+     case VDUSE_VQ_GET_INFO: {

Do we need to limit this only when DRIVER_OK is set?

Any reason to add this limitation?


Otherwise the vq is not fully initialized, e.g the desc_addr might not be correct.



+             struct vduse_vq_info vq_info;
+             u32 vq_index;
+
+             ret = -EFAULT;
+             if (copy_from_user(&vq_info, argp, sizeof(vq_info)))
+                     break;
+
+             ret = -EINVAL;
+             if (vq_info.index >= dev->vq_num)
+                     break;
+
+             vq_index = array_index_nospec(vq_info.index, dev->vq_num);
+             vq_info.desc_addr = dev->vqs[vq_index].desc_addr;
+             vq_info.driver_addr = dev->vqs[vq_index].driver_addr;
+             vq_info.device_addr = dev->vqs[vq_index].device_addr;
+             vq_info.num = dev->vqs[vq_index].num;
+             vq_info.avail_idx = dev->vqs[vq_index].avail_idx;
+             vq_info.ready = dev->vqs[vq_index].ready;
+
+             ret = -EFAULT;
+             if (copy_to_user(argp, &vq_info, sizeof(vq_info)))
+                     break;
+
+             ret = 0;
+             break;
+     }
+     case VDUSE_VQ_SETUP_KICKFD: {
+             struct vduse_vq_eventfd eventfd;
+
+             ret = -EFAULT;
+             if (copy_from_user(&eventfd, argp, sizeof(eventfd)))
+                     break;
+
+             ret = vduse_kickfd_setup(dev, &eventfd);
+             break;
+     }
+     case VDUSE_VQ_INJECT_IRQ: {
+             u32 vq_index;
+
+             ret = -EFAULT;
+             if (get_user(vq_index, (u32 __user *)argp))
+                     break;
+
+             ret = -EINVAL;
+             if (vq_index >= dev->vq_num)
+                     break;
+
+             ret = 0;
+             vq_index = array_index_nospec(vq_index, dev->vq_num);
+             queue_work(vduse_irq_wq, &dev->vqs[vq_index].inject);
+             break;
+     }
+     default:
+             ret = -ENOIOCTLCMD;
+             break;
+     }
+
+     return ret;
+}
+
+static int vduse_dev_release(struct inode *inode, struct file *file)
+{
+     struct vduse_dev *dev = file->private_data;
+
+     spin_lock(&dev->msg_lock);
+     /* Make sure the inflight messages can processed after reconncection */
+     list_splice_init(&dev->recv_list, &dev->send_list);
+     spin_unlock(&dev->msg_lock);
+     dev->connected = false;
+
+     return 0;
+}
+
+static struct vduse_dev *vduse_dev_get_from_minor(int minor)
+{
+     struct vduse_dev *dev;
+
+     mutex_lock(&vduse_lock);
+     dev = idr_find(&vduse_idr, minor);
+     mutex_unlock(&vduse_lock);
+
+     return dev;
+}
+
+static int vduse_dev_open(struct inode *inode, struct file *file)
+{
+     int ret;
+     struct vduse_dev *dev = vduse_dev_get_from_minor(iminor(inode));
+
+     if (!dev)
+             return -ENODEV;
+
+     ret = -EBUSY;
+     mutex_lock(&dev->lock);
+     if (dev->connected)
+             goto unlock;
+
+     ret = 0;
+     dev->connected = true;
+     file->private_data = dev;
+unlock:
+     mutex_unlock(&dev->lock);
+
+     return ret;
+}
+
+static const struct file_operations vduse_dev_fops = {
+     .owner          = THIS_MODULE,
+     .open           = vduse_dev_open,
+     .release        = vduse_dev_release,
+     .read_iter      = vduse_dev_read_iter,
+     .write_iter     = vduse_dev_write_iter,
+     .poll           = vduse_dev_poll,
+     .unlocked_ioctl = vduse_dev_ioctl,
+     .compat_ioctl   = compat_ptr_ioctl,
+     .llseek         = noop_llseek,
+};
+
+static struct vduse_dev *vduse_dev_create(void)
+{
+     struct vduse_dev *dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+
+     if (!dev)
+             return NULL;
+
+     mutex_init(&dev->lock);
+     spin_lock_init(&dev->msg_lock);
+     INIT_LIST_HEAD(&dev->send_list);
+     INIT_LIST_HEAD(&dev->recv_list);
+     spin_lock_init(&dev->irq_lock);
+
+     INIT_WORK(&dev->inject, vduse_dev_irq_inject);
+     init_waitqueue_head(&dev->waitq);
+
+     return dev;
+}
+
+static void vduse_dev_destroy(struct vduse_dev *dev)
+{
+     kfree(dev);
+}
+
+static struct vduse_dev *vduse_find_dev(const char *name)
+{
+     struct vduse_dev *dev;
+     int id;
+
+     idr_for_each_entry(&vduse_idr, dev, id)
+             if (!strcmp(dev->name, name))
+                     return dev;
+
+     return NULL;
+}
+
+static int vduse_destroy_dev(char *name)
+{
+     struct vduse_dev *dev = vduse_find_dev(name);
+
+     if (!dev)
+             return -EINVAL;
+
+     mutex_lock(&dev->lock);
+     if (dev->vdev || dev->connected) {
+             mutex_unlock(&dev->lock);
+             return -EBUSY;
+     }
+     dev->connected = true;
+     mutex_unlock(&dev->lock);
+
+     vduse_dev_msg_cleanup(dev);
+     device_destroy(vduse_class, MKDEV(MAJOR(vduse_major), dev->minor));
+     idr_remove(&vduse_idr, dev->minor);
+     kvfree(dev->config);
+     kfree(dev->vqs);
+     vduse_domain_destroy(dev->domain);
+     kfree(dev->name);
+     vduse_dev_destroy(dev);
+     module_put(THIS_MODULE);
+
+     return 0;
+}
+
+static bool device_is_allowed(u32 device_id)
+{
+     int i;
+
+     for (i = 0; i < ARRAY_SIZE(allowed_device_id); i++)
+             if (allowed_device_id[i] == device_id)
+                     return true;
+
+     return false;
+}
+
+static bool features_is_valid(u64 features)
+{
+     if (!(features & (1ULL << VIRTIO_F_ACCESS_PLATFORM)))
+             return false;
+
+     /* Now we only support read-only configuration space */
+     if (features & (1ULL << VIRTIO_BLK_F_CONFIG_WCE))
+             return false;
+
+     return true;
+}
+
+static bool vduse_validate_config(struct vduse_dev_config *config)
+{
+     if (config->bounce_size > VDUSE_MAX_BOUNCE_SIZE)
+             return false;
+
+     if (config->vq_align > PAGE_SIZE)
+             return false;
+
+     if (config->config_size > PAGE_SIZE)
+             return false;
+
+     if (!device_is_allowed(config->device_id))
+             return false;
+
+     if (!features_is_valid(config->features))
+             return false;

Do we need to validate whether or not config_size is too small otherwise
we may have OOB access in get_config()?

How about adding validation in get_config()? It seems to be hard to
define the lower bound.


It should work.

Thanks



+
+     return true;
+}
+
+static int vduse_create_dev(struct vduse_dev_config *config,
+                         void *config_buf, u64 api_version)
+{
+     int i, ret;
+     struct vduse_dev *dev;
+
+     ret = -EEXIST;
+     if (vduse_find_dev(config->name))
+             goto err;
+
+     ret = -ENOMEM;
+     dev = vduse_dev_create();
+     if (!dev)
+             goto err;
+
+     dev->api_version = api_version;
+     dev->user_features = config->features;
+     dev->device_id = config->device_id;
+     dev->vendor_id = config->vendor_id;
+     dev->name = kstrdup(config->name, GFP_KERNEL);
+     if (!dev->name)
+             goto err_str;
+
+     dev->domain = vduse_domain_create(VDUSE_IOVA_SIZE - 1,
+                                       config->bounce_size);
+     if (!dev->domain)
+             goto err_domain;
+
+     dev->config = config_buf;
+     dev->config_size = config->config_size;
+     dev->vq_align = config->vq_align;
+     dev->vq_size_max = config->vq_size_max;
+     dev->vq_num = config->vq_num;
+     dev->vqs = kcalloc(dev->vq_num, sizeof(*dev->vqs), GFP_KERNEL);
+     if (!dev->vqs)
+             goto err_vqs;
+
+     for (i = 0; i < dev->vq_num; i++) {
+             dev->vqs[i].index = i;
+             INIT_WORK(&dev->vqs[i].inject, vduse_vq_irq_inject);
+             spin_lock_init(&dev->vqs[i].kick_lock);
+             spin_lock_init(&dev->vqs[i].irq_lock);
+     }
+
+     ret = idr_alloc(&vduse_idr, dev, 1, VDUSE_DEV_MAX, GFP_KERNEL);
+     if (ret < 0)
+             goto err_idr;
+
+     dev->minor = ret;
+     dev->dev = device_create(vduse_class, NULL,
+                              MKDEV(MAJOR(vduse_major), dev->minor),
+                              NULL, "%s", config->name);
+     if (IS_ERR(dev->dev)) {
+             ret = PTR_ERR(dev->dev);
+             goto err_dev;
+     }
+     __module_get(THIS_MODULE);
+
+     return 0;
+err_dev:
+     idr_remove(&vduse_idr, dev->minor);
+err_idr:
+     kfree(dev->vqs);
+err_vqs:
+     vduse_domain_destroy(dev->domain);
+err_domain:
+     kfree(dev->name);
+err_str:
+     vduse_dev_destroy(dev);
+err:
+     kvfree(config_buf);
+     return ret;
+}
+
+static long vduse_ioctl(struct file *file, unsigned int cmd,
+                     unsigned long arg)
+{
+     int ret;
+     void __user *argp = (void __user *)arg;
+     struct vduse_control *control = file->private_data;
+
+     mutex_lock(&vduse_lock);
+     switch (cmd) {
+     case VDUSE_GET_API_VERSION:
+             ret = put_user(control->api_version, (u64 __user *)argp);
+             break;
+     case VDUSE_SET_API_VERSION: {
+             u64 api_version;
+
+             ret = -EFAULT;
+             if (get_user(api_version, (u64 __user *)argp))
+                     break;
+
+             ret = -EINVAL;
+             if (api_version > VDUSE_API_VERSION)
+                     break;
+
+             ret = 0;
+             control->api_version = api_version;
+             break;
+     }
+     case VDUSE_CREATE_DEV: {
+             struct vduse_dev_config config;
+             unsigned long size = offsetof(struct vduse_dev_config, config);
+             void *buf;
+
+             ret = -EFAULT;
+             if (copy_from_user(&config, argp, size))
+                     break;
+
+             ret = -EINVAL;
+             if (vduse_validate_config(&config) == false)
+                     break;
+
+             buf = vmemdup_user(argp + size, config.config_size);
+             if (IS_ERR(buf)) {
+                     ret = PTR_ERR(buf);
+                     break;
+             }
+             ret = vduse_create_dev(&config, buf, control->api_version);
+             break;
+     }
+     case VDUSE_DESTROY_DEV: {
+             char name[VDUSE_NAME_MAX];
+
+             ret = -EFAULT;
+             if (copy_from_user(name, argp, VDUSE_NAME_MAX))
+                     break;
+
+             ret = vduse_destroy_dev(name);
+             break;
+     }
+     default:
+             ret = -EINVAL;
+             break;
+     }
+     mutex_unlock(&vduse_lock);
+
+     return ret;
+}
+
+static int vduse_release(struct inode *inode, struct file *file)
+{
+     struct vduse_control *control = file->private_data;
+
+     kfree(control);
+     return 0;
+}
+
+static int vduse_open(struct inode *inode, struct file *file)
+{
+     struct vduse_control *control;
+
+     control = kmalloc(sizeof(struct vduse_control), GFP_KERNEL);
+     if (!control)
+             return -ENOMEM;
+
+     control->api_version = VDUSE_API_VERSION;
+     file->private_data = control;
+
+     return 0;
+}
+
+static const struct file_operations vduse_ctrl_fops = {
+     .owner          = THIS_MODULE,
+     .open           = vduse_open,
+     .release        = vduse_release,
+     .unlocked_ioctl = vduse_ioctl,
+     .compat_ioctl   = compat_ptr_ioctl,
+     .llseek         = noop_llseek,
+};
+
+static char *vduse_devnode(struct device *dev, umode_t *mode)
+{
+     return kasprintf(GFP_KERNEL, "vduse/%s", dev_name(dev));
+}
+
+static void vduse_mgmtdev_release(struct device *dev)
+{
+}
+
+static struct device vduse_mgmtdev = {
+     .init_name = "vduse",
+     .release = vduse_mgmtdev_release,
+};
+
+static struct vdpa_mgmt_dev mgmt_dev;
+
+static int vduse_dev_init_vdpa(struct vduse_dev *dev, const char *name)
+{
+     struct vduse_vdpa *vdev;
+     int ret;
+
+     if (dev->vdev)
+             return -EEXIST;
+
+     vdev = vdpa_alloc_device(struct vduse_vdpa, vdpa, dev->dev,
+                              &vduse_vdpa_config_ops, name, true);
+     if (!vdev)
+             return -ENOMEM;
+
+     dev->vdev = vdev;
+     vdev->dev = dev;
+     vdev->vdpa.dev.dma_mask = &vdev->vdpa.dev.coherent_dma_mask;
+     ret = dma_set_mask_and_coherent(&vdev->vdpa.dev, DMA_BIT_MASK(64));
+     if (ret) {
+             put_device(&vdev->vdpa.dev);
+             return ret;
+     }
+     set_dma_ops(&vdev->vdpa.dev, &vduse_dev_dma_ops);
+     vdev->vdpa.dma_dev = &vdev->vdpa.dev;
+     vdev->vdpa.mdev = &mgmt_dev;
+
+     return 0;
+}
+
+static int vdpa_dev_add(struct vdpa_mgmt_dev *mdev, const char *name)
+{
+     struct vduse_dev *dev;
+     int ret;
+
+     mutex_lock(&vduse_lock);
+     dev = vduse_find_dev(name);
+     if (!dev) {
+             mutex_unlock(&vduse_lock);
+             return -EINVAL;
+     }
+     ret = vduse_dev_init_vdpa(dev, name);
+     mutex_unlock(&vduse_lock);
+     if (ret)
+             return ret;
+
+     ret = _vdpa_register_device(&dev->vdev->vdpa, dev->vq_num);
+     if (ret) {
+             put_device(&dev->vdev->vdpa.dev);
+             return ret;
+     }
+
+     return 0;
+}
+
+static void vdpa_dev_del(struct vdpa_mgmt_dev *mdev, struct vdpa_device *dev)
+{
+     _vdpa_unregister_device(dev);
+}
+
+static const struct vdpa_mgmtdev_ops vdpa_dev_mgmtdev_ops = {
+     .dev_add = vdpa_dev_add,
+     .dev_del = vdpa_dev_del,
+};
+
+static struct virtio_device_id id_table[] = {
+     { VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID },
+     { 0 },
+};
+
+static struct vdpa_mgmt_dev mgmt_dev = {
+     .device = &vduse_mgmtdev,
+     .id_table = id_table,
+     .ops = &vdpa_dev_mgmtdev_ops,
+};
+
+static int vduse_mgmtdev_init(void)
+{
+     int ret;
+
+     ret = device_register(&vduse_mgmtdev);
+     if (ret)
+             return ret;
+
+     ret = vdpa_mgmtdev_register(&mgmt_dev);
+     if (ret)
+             goto err;
+
+     return 0;
+err:
+     device_unregister(&vduse_mgmtdev);
+     return ret;
+}
+
+static void vduse_mgmtdev_exit(void)
+{
+     vdpa_mgmtdev_unregister(&mgmt_dev);
+     device_unregister(&vduse_mgmtdev);
+}
+
+static int vduse_init(void)
+{
+     int ret;
+     struct device *dev;
+
+     vduse_class = class_create(THIS_MODULE, "vduse");
+     if (IS_ERR(vduse_class))
+             return PTR_ERR(vduse_class);
+
+     vduse_class->devnode = vduse_devnode;
+
+     ret = alloc_chrdev_region(&vduse_major, 0, VDUSE_DEV_MAX, "vduse");
+     if (ret)
+             goto err_chardev_region;
+
+     /* /dev/vduse/control */
+     cdev_init(&vduse_ctrl_cdev, &vduse_ctrl_fops);
+     vduse_ctrl_cdev.owner = THIS_MODULE;
+     ret = cdev_add(&vduse_ctrl_cdev, vduse_major, 1);
+     if (ret)
+             goto err_ctrl_cdev;
+
+     dev = device_create(vduse_class, NULL, vduse_major, NULL, "control");
+     if (IS_ERR(dev)) {
+             ret = PTR_ERR(dev);
+             goto err_device;
+     }
+
+     /* /dev/vduse/$DEVICE */
+     cdev_init(&vduse_cdev, &vduse_dev_fops);
+     vduse_cdev.owner = THIS_MODULE;
+     ret = cdev_add(&vduse_cdev, MKDEV(MAJOR(vduse_major), 1),
+                    VDUSE_DEV_MAX - 1);
+     if (ret)
+             goto err_cdev;
+
+     vduse_irq_wq = alloc_workqueue("vduse-irq",
+                             WQ_HIGHPRI | WQ_SYSFS | WQ_UNBOUND, 0);
+     if (!vduse_irq_wq)
+             goto err_wq;
+
+     ret = vduse_domain_init();
+     if (ret)
+             goto err_domain;
+
+     ret = vduse_mgmtdev_init();
+     if (ret)
+             goto err_mgmtdev;
+
+     return 0;
+err_mgmtdev:
+     vduse_domain_exit();
+err_domain:
+     destroy_workqueue(vduse_irq_wq);
+err_wq:
+     cdev_del(&vduse_cdev);
+err_cdev:
+     device_destroy(vduse_class, vduse_major);
+err_device:
+     cdev_del(&vduse_ctrl_cdev);
+err_ctrl_cdev:
+     unregister_chrdev_region(vduse_major, VDUSE_DEV_MAX);
+err_chardev_region:
+     class_destroy(vduse_class);
+     return ret;
+}
+module_init(vduse_init);
+
+static void vduse_exit(void)
+{
+     vduse_mgmtdev_exit();
+     vduse_domain_exit();
+     destroy_workqueue(vduse_irq_wq);
+     cdev_del(&vduse_cdev);
+     device_destroy(vduse_class, vduse_major);
+     cdev_del(&vduse_ctrl_cdev);
+     unregister_chrdev_region(vduse_major, VDUSE_DEV_MAX);
+     class_destroy(vduse_class);
+}
+module_exit(vduse_exit);
+
+MODULE_LICENSE(DRV_LICENSE);
+MODULE_AUTHOR(DRV_AUTHOR);
+MODULE_DESCRIPTION(DRV_DESC);
diff --git a/include/uapi/linux/vduse.h b/include/uapi/linux/vduse.h
new file mode 100644
index 000000000000..f21b2e51b5c8
--- /dev/null
+++ b/include/uapi/linux/vduse.h
@@ -0,0 +1,143 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+#ifndef _UAPI_VDUSE_H_
+#define _UAPI_VDUSE_H_
+
+#include <linux/types.h>
+
+#define VDUSE_API_VERSION    0
+
+#define VDUSE_NAME_MAX       256
+
+/* the control messages definition for read/write */
+
+enum vduse_req_type {
+     /* Get the state for virtqueue from userspace */
+     VDUSE_GET_VQ_STATE,
+     /* Notify userspace to start the dataplane, no reply */
+     VDUSE_START_DATAPLANE,
+     /* Notify userspace to stop the dataplane, no reply */
+     VDUSE_STOP_DATAPLANE,
+     /* Notify userspace to update the memory mapping in device IOTLB */
+     VDUSE_UPDATE_IOTLB,
+};
+
+struct vduse_vq_state {
+     __u32 index; /* virtqueue index */
+     __u32 avail_idx; /* virtqueue state (last_avail_idx) */
+};

This needs some tweaks to support packed virtqueue.

OK.

Thanks,
Yongji


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