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Subject: Re: [PATCH v8 09/10] vduse: Introduce VDUSE - vDPA Device in
 Userspace
To:     Yongji Xie <xieyongji@bytedance.com>
Cc:     "Michael S. Tsirkin" <mst@redhat.com>,
        Stefan Hajnoczi <stefanha@redhat.com>,
        Stefano Garzarella <sgarzare@redhat.com>,
        Parav Pandit <parav@nvidia.com>,
        Christoph Hellwig <hch@infradead.org>,
        Christian Brauner <christian.brauner@canonical.com>,
        Randy Dunlap <rdunlap@infradead.org>,
        Matthew Wilcox <willy@infradead.org>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Jens Axboe <axboe@kernel.dk>, bcrl@kvack.org,
        Jonathan Corbet <corbet@lwn.net>,
        =?UTF-8?Q?Mika_Penttil=c3=a4?= <mika.penttila@nextfour.com>,
        Dan Carpenter <dan.carpenter@oracle.com>, joro@8bytes.org,
        Greg KH <gregkh@linuxfoundation.org>, songmuchun@bytedance.com,
        virtualization <virtualization@lists.linux-foundation.org>,
        netdev@vger.kernel.org, kvm <kvm@vger.kernel.org>,
        linux-fsdevel@vger.kernel.org, iommu@lists.linux-foundation.org,
        linux-kernel <linux-kernel@vger.kernel.org>
References: <20210615141331.407-1-xieyongji@bytedance.com>
 <20210615141331.407-10-xieyongji@bytedance.com>
 <adfb2be9-9ed9-ca37-ac37-4cd00bdff349@redhat.com>
 <CACycT3tAON+-qZev+9EqyL2XbgH5HDspOqNt3ohQLQ8GqVK=EA@mail.gmail.com>
From:   Jason Wang <jasowang@redhat.com>
Message-ID: <1bba439f-ffc8-c20e-e8a4-ac73e890c592@redhat.com>
Date:   Tue, 22 Jun 2021 13:06:42 +0800
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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@redhat.com> 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@bytedance.com>
>>> ---
>>>    Documentation/userspace-api/ioctl/ioctl-number.rst |    1 +
>>>    drivers/vdpa/Kconfig                               |   10 +
>>>    drivers/vdpa/Makefile                              |    1 +
>>>    drivers/vdpa/vdpa_user/Makefile                    |    5 +
>>>    drivers/vdpa/vdpa_user/vduse_dev.c                 | 1453 ++++++++++++++++++++
>>>    include/uapi/linux/vduse.h                         |  143 ++
>>>    6 files changed, 1613 insertions(+)
>>>    create mode 100644 drivers/vdpa/vdpa_user/Makefile
>>>    create mode 100644 drivers/vdpa/vdpa_user/vduse_dev.c
>>>    create mode 100644 include/uapi/linux/vduse.h
>>>
>>> diff --git a/Documentation/userspace-api/ioctl/ioctl-number.rst b/Documentation/userspace-api/ioctl/ioctl-number.rst
>>> index 9bfc2b510c64..acd95e9dcfe7 100644
>>> --- a/Documentation/userspace-api/ioctl/ioctl-number.rst
>>> +++ b/Documentation/userspace-api/ioctl/ioctl-number.rst
>>> @@ -300,6 +300,7 @@ Code  Seq#    Include File                                           Comments
>>>    'z'   10-4F  drivers/s390/crypto/zcrypt_api.h                        conflict!
>>>    '|'   00-7F  linux/media.h
>>>    0x80  00-1F  linux/fb.h
>>> +0x81  00-1F  linux/vduse.h
>>>    0x89  00-06  arch/x86/include/asm/sockios.h
>>>    0x89  0B-DF  linux/sockios.h
>>>    0x89  E0-EF  linux/sockios.h                                         SIOCPROTOPRIVATE range
>>> diff --git a/drivers/vdpa/Kconfig b/drivers/vdpa/Kconfig
>>> index a503c1b2bfd9..6e23bce6433a 100644
>>> --- a/drivers/vdpa/Kconfig
>>> +++ b/drivers/vdpa/Kconfig
>>> @@ -33,6 +33,16 @@ config VDPA_SIM_BLOCK
>>>          vDPA block device simulator which terminates IO request in a
>>>          memory buffer.
>>>
>>> +config VDPA_USER
>>> +     tristate "VDUSE (vDPA Device in Userspace) support"
>>> +     depends on EVENTFD && MMU && HAS_DMA
>>> +     select DMA_OPS
>>> +     select VHOST_IOTLB
>>> +     select IOMMU_IOVA
>>> +     help
>>> +       With VDUSE it is possible to emulate a vDPA Device
>>> +       in a userspace program.
>>> +
>>>    config IFCVF
>>>        tristate "Intel IFC VF vDPA driver"
>>>        depends on PCI_MSI
>>> diff --git a/drivers/vdpa/Makefile b/drivers/vdpa/Makefile
>>> index 67fe7f3d6943..f02ebed33f19 100644
>>> --- a/drivers/vdpa/Makefile
>>> +++ b/drivers/vdpa/Makefile
>>> @@ -1,6 +1,7 @@
>>>    # SPDX-License-Identifier: GPL-2.0
>>>    obj-$(CONFIG_VDPA) += vdpa.o
>>>    obj-$(CONFIG_VDPA_SIM) += vdpa_sim/
>>> +obj-$(CONFIG_VDPA_USER) += vdpa_user/
>>>    obj-$(CONFIG_IFCVF)    += ifcvf/
>>>    obj-$(CONFIG_MLX5_VDPA) += mlx5/
>>>    obj-$(CONFIG_VP_VDPA)    += virtio_pci/
>>> diff --git a/drivers/vdpa/vdpa_user/Makefile b/drivers/vdpa/vdpa_user/Makefile
>>> new file mode 100644
>>> index 000000000000..260e0b26af99
>>> --- /dev/null
>>> +++ b/drivers/vdpa/vdpa_user/Makefile
>>> @@ -0,0 +1,5 @@
>>> +# SPDX-License-Identifier: GPL-2.0
>>> +
>>> +vduse-y := vduse_dev.o iova_domain.o
>>> +
>>> +obj-$(CONFIG_VDPA_USER) += vduse.o
>>> diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
>>> new file mode 100644
>>> index 000000000000..5271cbd15e28
>>> --- /dev/null
>>> +++ b/drivers/vdpa/vdpa_user/vduse_dev.c
>>> @@ -0,0 +1,1453 @@
>>> +// SPDX-License-Identifier: GPL-2.0-only
>>> +/*
>>> + * VDUSE: vDPA Device in Userspace
>>> + *
>>> + * Copyright (C) 2020-2021 Bytedance Inc. and/or its affiliates. All rights reserved.
>>> + *
>>> + * Author: Xie Yongji <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_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
>