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Message-ID: <CACycT3tDkv9cUVDEctT6BZOELRzE9-VQpPOoSVOsm3XmzfFsxw@mail.gmail.com>
Date: Thu, 25 Mar 2021 15:47:56 +0800
From: Yongji Xie <xieyongji@...edance.com>
To: Jason Wang <jasowang@...hat.com>
Cc: "Michael S. Tsirkin" <mst@...hat.com>,
Stefan Hajnoczi <stefanha@...hat.com>,
Stefano Garzarella <sgarzare@...hat.com>,
Parav Pandit <parav@...dia.com>, Bob Liu <bob.liu@...cle.com>,
Christoph Hellwig <hch@...radead.org>,
Randy Dunlap <rdunlap@...radead.org>,
Matthew Wilcox <willy@...radead.org>, viro@...iv.linux.org.uk,
Jens Axboe <axboe@...nel.dk>, bcrl@...ck.org,
Jonathan Corbet <corbet@....net>,
Mika Penttilä <mika.penttila@...tfour.com>,
Dan Carpenter <dan.carpenter@...cle.com>,
virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org,
kvm@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: Re: Re: [PATCH v5 09/11] vduse: Introduce VDUSE - vDPA Device in Userspace
On Thu, Mar 25, 2021 at 2:31 PM Jason Wang <jasowang@...hat.com> wrote:
>
>
> 在 2021/3/24 下午4:55, Yongji Xie 写道:
> > On Wed, Mar 24, 2021 at 12:43 PM Jason Wang <jasowang@...hat.com> wrote:
> >>
> >> 在 2021/3/15 下午1:37, Xie Yongji 写道:
> >>> This VDUSE driver enables implementing vDPA devices in userspace.
> >>> Both control path and data path of vDPA devices will be able to
> >>> be handled in userspace.
> >>>
> >>> In the control path, the VDUSE driver will make use of message
> >>> mechnism to forward the config operation from vdpa bus driver
> >>> to userspace. Userspace can use read()/write() to receive/reply
> >>> those control messages.
> >>>
> >>> In the data path, userspace can use mmap() to access vDPA device's
> >>> iova regions obtained through VDUSE_IOTLB_GET_ENTRY ioctl. Besides,
> >>> userspace can use ioctl() to inject interrupt and use the eventfd
> >>> mechanism to receive virtqueue kicks.
> >>>
> >>> Signed-off-by: Xie Yongji <xieyongji@...edance.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 | 1281 ++++++++++++++++++++
> >>> include/uapi/linux/vduse.h | 153 +++
> >>> 6 files changed, 1451 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 a4c75a28c839..71722e6f8f23 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 a245809c99d0..77a1da522c21 100644
> >>> --- a/drivers/vdpa/Kconfig
> >>> +++ b/drivers/vdpa/Kconfig
> >>> @@ -25,6 +25,16 @@ config VDPA_SIM_NET
> >>> help
> >>> vDPA networking device simulator which loops TX traffic back to RX.
> >>>
> >>> +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..07d0ae92d470
> >>> --- /dev/null
> >>> +++ b/drivers/vdpa/vdpa_user/vduse_dev.c
> >>> @@ -0,0 +1,1281 @@
> >>> +// SPDX-License-Identifier: GPL-2.0-only
> >>> +/*
> >>> + * VDUSE: vDPA Device in Userspace
> >>> + *
> >>> + * Copyright (C) 2020 Bytedance Inc. and/or its affiliates. All rights reserved.
> >>> + *
> >>> + * Author: Xie Yongji <xieyongji@...edance.com>
> >>> + *
> >>> + */
> >>> +
> >>> +#include <linux/init.h>
> >>> +#include <linux/module.h>
> >>> +#include <linux/miscdevice.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 <uapi/linux/vduse.h>
> >>> +#include <uapi/linux/vdpa.h>
> >>> +#include <uapi/linux/virtio_config.h>
> >>> +#include <linux/mod_devicetable.h>
> >>> +
> >>> +#include "iova_domain.h"
> >>> +
> >>> +#define DRV_VERSION "1.0"
> >>> +#define DRV_AUTHOR "Yongji Xie <xieyongji@...edance.com>"
> >>> +#define DRV_DESC "vDPA Device in Userspace"
> >>> +#define DRV_LICENSE "GPL v2"
> >>> +
> >>> +#define VDUSE_DEV_MAX (1U << MINORBITS)
> >>> +
> >>> +struct vduse_virtqueue {
> >>> + u16 index;
> >>> + bool ready;
> >>> + 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 cdev cdev;
> >>> + struct vduse_virtqueue *vqs;
> >>> + struct vduse_iova_domain *domain;
> >>> + spinlock_t msg_lock;
> >>> + atomic64_t msg_unique;
> >>> + wait_queue_head_t waitq;
> >>> + struct list_head send_list;
> >>> + struct list_head recv_list;
> >>> + struct list_head list;
> >>> + bool connected;
> >>> + int minor;
> >>> + u16 vq_size_max;
> >>> + u16 vq_num;
> >>> + u32 vq_align;
> >>> + u32 device_id;
> >>> + u32 vendor_id;
> >>> +};
> >>> +
> >>> +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;
> >>> +};
> >>> +
> >>> +static unsigned long max_bounce_size = (64 * 1024 * 1024);
> >>> +module_param(max_bounce_size, ulong, 0444);
> >>> +MODULE_PARM_DESC(max_bounce_size, "Maximum bounce buffer size. (default: 64M)");
> >>> +
> >>> +static unsigned long max_iova_size = (128 * 1024 * 1024);
> >>> +module_param(max_iova_size, ulong, 0444);
> >>> +MODULE_PARM_DESC(max_iova_size, "Maximum iova space size (default: 128M)");
> >>> +
> >>> +static DEFINE_MUTEX(vduse_lock);
> >>> +static LIST_HEAD(vduse_devs);
> >>> +static DEFINE_IDA(vduse_ida);
> >>> +
> >>> +static dev_t vduse_major;
> >>> +static struct class *vduse_class;
> >>> +static struct workqueue_struct *vduse_irq_wq;
> >>> +
> >>> +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 *tmp, *msg = NULL;
> >>> +
> >>> + list_for_each_entry(tmp, head, list) {
> >>> + if (tmp->req.request_id == request_id) {
> >>> + msg = tmp;
> >>> + list_del(&tmp->list);
> >>> + break;
> >>> + }
> >>> + }
> >>> +
> >>> + return msg;
> >>> +}
> >>> +
> >>> +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_sync(struct vduse_dev *dev,
> >>> + struct vduse_dev_msg *msg)
> >>> +{
> >>> + init_waitqueue_head(&msg->waitq);
> >>> + spin_lock(&dev->msg_lock);
> >>> + vduse_enqueue_msg(&dev->send_list, msg);
> >>> + wake_up(&dev->waitq);
> >>> + spin_unlock(&dev->msg_lock);
> >>> + wait_event_interruptible(msg->waitq, msg->completed);
> >>> + spin_lock(&dev->msg_lock);
> >>> + if (!msg->completed)
> >>> + list_del(&msg->list);
> >>> + spin_unlock(&dev->msg_lock);
> >>> +
> >>> + return (msg->resp.result == VDUSE_REQUEST_OK) ? 0 : -1;
> >>> +}
> >>> +
> >>> +static u64 vduse_dev_get_features(struct vduse_dev *dev)
> >>> +{
> >>> + struct vduse_dev_msg msg = { 0 };
> >>> +
> >>> + msg.req.type = VDUSE_GET_FEATURES;
> >>> + msg.req.request_id = atomic64_fetch_inc(&dev->msg_unique);
> >>
> >> Let's introduce a helper for the atomic64_fetch_inc() here.
> >>
> > Fine.
> >
> >>> +
> >>> + return vduse_dev_msg_sync(dev, &msg) ? 0 : msg.resp.f.features;
> >>> +}
> >>> +
> >>> +static int vduse_dev_set_features(struct vduse_dev *dev, u64 features)
> >>> +{
> >>> + struct vduse_dev_msg msg = { 0 };
> >>> +
> >>> + msg.req.type = VDUSE_SET_FEATURES;
> >>> + msg.req.request_id = atomic64_fetch_inc(&dev->msg_unique);
> >>> + msg.req.f.features = features;
> >>> +
> >>> + return vduse_dev_msg_sync(dev, &msg);
> >>> +}
> >>> +
> >>> +static u8 vduse_dev_get_status(struct vduse_dev *dev)
> >>> +{
> >>> + struct vduse_dev_msg msg = { 0 };
> >>> +
> >>> + msg.req.type = VDUSE_GET_STATUS;
> >>> + msg.req.request_id = atomic64_fetch_inc(&dev->msg_unique);
> >>> +
> >>> + return vduse_dev_msg_sync(dev, &msg) ? 0 : msg.resp.s.status;
> >>> +}
> >>> +
> >>> +static void vduse_dev_set_status(struct vduse_dev *dev, u8 status)
> >>> +{
> >>> + struct vduse_dev_msg msg = { 0 };
> >>> +
> >>> + msg.req.type = VDUSE_SET_STATUS;
> >>> + msg.req.request_id = atomic64_fetch_inc(&dev->msg_unique);
> >>> + msg.req.s.status = status;
> >>> +
> >>> + vduse_dev_msg_sync(dev, &msg);
> >>> +}
> >>> +
> >>> +static void vduse_dev_get_config(struct vduse_dev *dev, unsigned int offset,
> >>> + void *buf, unsigned int len)
> >>> +{
> >>> + struct vduse_dev_msg msg = { 0 };
> >>> + unsigned int sz;
> >>> +
> >>> + while (len) {
> >>> + sz = min_t(unsigned int, len, sizeof(msg.req.config.data));
> >>> + msg.req.type = VDUSE_GET_CONFIG;
> >>> + msg.req.request_id = atomic64_fetch_inc(&dev->msg_unique);
> >>> + msg.req.config.offset = offset;
> >>> + msg.req.config.len = sz;
> >>> + vduse_dev_msg_sync(dev, &msg);
> >>> + memcpy(buf, msg.resp.config.data, sz);
> >>> + buf += sz;
> >>> + offset += sz;
> >>> + len -= sz;
> >>> + }
> >>> +}
> >>> +
> >>> +static void vduse_dev_set_config(struct vduse_dev *dev, unsigned int offset,
> >>> + const void *buf, unsigned int len)
> >>> +{
> >>> + struct vduse_dev_msg msg = { 0 };
> >>> + unsigned int sz;
> >>> +
> >>> + while (len) {
> >>> + sz = min_t(unsigned int, len, sizeof(msg.req.config.data));
> >>> + msg.req.type = VDUSE_SET_CONFIG;
> >>> + msg.req.request_id = atomic64_fetch_inc(&dev->msg_unique);
> >>> + msg.req.config.offset = offset;
> >>> + msg.req.config.len = sz;
> >>> + memcpy(msg.req.config.data, buf, sz);
> >>> + vduse_dev_msg_sync(dev, &msg);
> >>> + buf += sz;
> >>> + offset += sz;
> >>> + len -= sz;
> >>> + }
> >>> +}
> >>> +
> >>> +static void vduse_dev_set_vq_num(struct vduse_dev *dev,
> >>> + struct vduse_virtqueue *vq, u32 num)
> >>> +{
> >>> + struct vduse_dev_msg msg = { 0 };
> >>> +
> >>> + msg.req.type = VDUSE_SET_VQ_NUM;
> >>> + msg.req.request_id = atomic64_fetch_inc(&dev->msg_unique);
> >>> + msg.req.vq_num.index = vq->index;
> >>> + msg.req.vq_num.num = num;
> >>> +
> >>> + vduse_dev_msg_sync(dev, &msg);
> >>> +}
> >>> +
> >>> +static int vduse_dev_set_vq_addr(struct vduse_dev *dev,
> >>> + struct vduse_virtqueue *vq, u64 desc_addr,
> >>> + u64 driver_addr, u64 device_addr)
> >>> +{
> >>> + struct vduse_dev_msg msg = { 0 };
> >>> +
> >>> + msg.req.type = VDUSE_SET_VQ_ADDR;
> >>> + msg.req.request_id = atomic64_fetch_inc(&dev->msg_unique);
> >>> + msg.req.vq_addr.index = vq->index;
> >>> + msg.req.vq_addr.desc_addr = desc_addr;
> >>> + msg.req.vq_addr.driver_addr = driver_addr;
> >>> + msg.req.vq_addr.device_addr = device_addr;
> >>> +
> >>> + return vduse_dev_msg_sync(dev, &msg);
> >>> +}
> >>> +
> >>> +static void vduse_dev_set_vq_ready(struct vduse_dev *dev,
> >>> + struct vduse_virtqueue *vq, bool ready)
> >>> +{
> >>> + struct vduse_dev_msg msg = { 0 };
> >>> +
> >>> + msg.req.type = VDUSE_SET_VQ_READY;
> >>> + msg.req.request_id = atomic64_fetch_inc(&dev->msg_unique);
> >>> + msg.req.vq_ready.index = vq->index;
> >>> + msg.req.vq_ready.ready = ready;
> >>> +
> >>> + vduse_dev_msg_sync(dev, &msg);
> >>> +}
> >>> +
> >>> +static bool vduse_dev_get_vq_ready(struct vduse_dev *dev,
> >>> + struct vduse_virtqueue *vq)
> >>> +{
> >>> + struct vduse_dev_msg msg = { 0 };
> >>> +
> >>> + msg.req.type = VDUSE_GET_VQ_READY;
> >>> + msg.req.request_id = atomic64_fetch_inc(&dev->msg_unique);
> >>> + msg.req.vq_ready.index = vq->index;
> >>> +
> >>> + return vduse_dev_msg_sync(dev, &msg) ? false : msg.resp.vq_ready.ready;
> >>> +}
> >>> +
> >>> +static int vduse_dev_get_vq_state(struct vduse_dev *dev,
> >>> + struct vduse_virtqueue *vq,
> >>> + struct vdpa_vq_state *state)
> >>> +{
> >>> + struct vduse_dev_msg msg = { 0 };
> >>> + int ret;
> >>> +
> >>> + msg.req.type = VDUSE_GET_VQ_STATE;
> >>> + msg.req.request_id = atomic64_fetch_inc(&dev->msg_unique);
> >>> + msg.req.vq_state.index = vq->index;
> >>> +
> >>> + ret = vduse_dev_msg_sync(dev, &msg);
> >>> + if (!ret)
> >>> + state->avail_index = msg.resp.vq_state.avail_idx;
> >>> +
> >>> + return ret;
> >>> +}
> >>> +
> >>> +static int vduse_dev_set_vq_state(struct vduse_dev *dev,
> >>> + struct vduse_virtqueue *vq,
> >>> + const struct vdpa_vq_state *state)
> >>> +{
> >>> + struct vduse_dev_msg msg = { 0 };
> >>> +
> >>> + msg.req.type = VDUSE_SET_VQ_STATE;
> >>> + msg.req.request_id = atomic64_fetch_inc(&dev->msg_unique);
> >>> + msg.req.vq_state.index = vq->index;
> >>> + msg.req.vq_state.avail_idx = state->avail_index;
> >>> +
> >>> + return vduse_dev_msg_sync(dev, &msg);
> >>> +}
> >>> +
> >>> +static int vduse_dev_update_iotlb(struct vduse_dev *dev,
> >>> + u64 start, u64 last)
> >>> +{
> >>> + struct vduse_dev_msg *msg;
> >>> +
> >>> + if (last < start)
> >>> + return -EINVAL;
> >>> +
> >>> + msg = kzalloc(sizeof(*msg), GFP_ATOMIC);
> >>
> >> The return value is not checked.
> >>
> > Will fix it.
> >
> >>> + msg->req.type = VDUSE_UPDATE_IOTLB;
> >>
> >> What would usespace do after receiving VDUSE_UPDATE_IOTLB? If it still
> >> needs to issue VDUSE_GET_ENTRY with probably -EINVAL, it's kind of
> >> overkill. So it looks to me that the VDUSE_UPDATE_IOTLB is acutally kind
> >> of flush or unmap here. If this is true, should we introduce a new type
> >> or just rename it as VDUSE_IOTLB_UNMAP?
> >>
> > VDUSE_UPDATE_IOTLB is used to notify userspace of refreshing (include
> > mapping and unmapping) the iotlb mapping. The reason why we can't use
> > flush/unmap is explained below.
> >
> >>> + msg->req.request_id = atomic64_fetch_inc(&dev->msg_unique);
> >>> + msg->req.iova.start = start;
> >>> + msg->req.iova.last = last;
> >>> +
> >>> + return vduse_dev_msg_sync(dev, msg);
> >>> +}
> >>> +
> >>> +static ssize_t vduse_dev_read_iter(struct kiocb *iocb, struct iov_iter *to)
> >>> +{
> >>> + struct file *file = iocb->ki_filp;
> >>> + struct vduse_dev *dev = file->private_data;
> >>> + struct vduse_dev_msg *msg;
> >>> + int size = sizeof(struct vduse_dev_request);
> >>> + ssize_t ret = 0;
> >>> +
> >>> + if (iov_iter_count(to) < size)
> >>> + return 0;
> >>> +
> >>> + spin_lock(&dev->msg_lock);
> >>> + while (1) {
> >>> + msg = vduse_dequeue_msg(&dev->send_list);
> >>> + if (msg)
> >>> + break;
> >>> +
> >>> + ret = -EAGAIN;
> >>> + if (file->f_flags & O_NONBLOCK)
> >>> + goto unlock;
> >>> +
> >>> + spin_unlock(&dev->msg_lock);
> >>> + ret = wait_event_interruptible_exclusive(dev->waitq,
> >>> + !list_empty(&dev->send_list));
> >>> + if (ret)
> >>> + return ret;
> >>> +
> >>> + spin_lock(&dev->msg_lock);
> >>> + }
> >>> + spin_unlock(&dev->msg_lock);
> >>> + ret = copy_to_iter(&msg->req, size, to);
> >>> + spin_lock(&dev->msg_lock);
> >>> + if (ret != size) {
> >>> + ret = -EFAULT;
> >>> + vduse_enqueue_msg(&dev->send_list, msg);
> >>> + goto unlock;
> >>> + }
> >>> + vduse_enqueue_msg(&dev->recv_list, msg);
> >>> +unlock:
> >>> + spin_unlock(&dev->msg_lock);
> >>> +
> >>> + return ret;
> >>> +}
> >>> +
> >>> +static 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 = -EINVAL;
> >>> + 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;
> >>
> >> EPOLLOUT is missed here?
> >>
> > Why do we need EPOLLOUT here?
>
>
> It means the fd is ready to be wrote?
>
OK, I got it.
>
> >
> >>> +
> >>> + return mask;
> >>> +}
> >>> +
> >>> +static void vduse_dev_reset(struct vduse_dev *dev)
> >>> +{
> >>> + int i;
> >>> +
> >>> + vduse_domain_reset_bounce_map(dev->domain);
> >>> + vduse_dev_update_iotlb(dev, 0ULL, ULLONG_MAX);
> >>
> >> Simialrly, IOTLB update should be done before the resetting?
> >>
> > The problem is userspace can still get valid bounce mapping through
> > VDUSE_IOTLB_GET_ENTRY between receiving IOTLB_UNMAP and bounce mapping
> > reset. Then userspace has no way to know when to invalidate these
> > mappings.
>
>
> Right, I think it might be helpful to add a comment here to explain the
> order.
>
Fine with me.
>
> >
> >> And it would be helpful to add comment to explain how coherent mappings
> >> is handled.
> >>
> > OK. It would be handled in vduse_dev_free_coherent().
> >
> >>> +
> >>> + for (i = 0; i < dev->vq_num; i++) {
> >>> + struct vduse_virtqueue *vq = &dev->vqs[i];
> >>> +
> >>> + spin_lock(&vq->irq_lock);
> >>> + vq->ready = false;
> >>> + 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];
> >>> +
> >>> + return vduse_dev_set_vq_addr(dev, vq, desc_area,
> >>> + driver_area, device_area);
> >>> +}
> >>> +
> >>> +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 && vq->kickfd)
> >>> + eventfd_signal(vq->kickfd, 1);
> >>> + 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];
> >>> +
> >>> + vduse_dev_set_vq_num(dev, vq, 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];
> >>> +
> >>> + vduse_dev_set_vq_ready(dev, vq, ready);
> >>> + 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];
> >>> +
> >>> + vq->ready = vduse_dev_get_vq_ready(dev, vq);
> >>> +
> >>> + 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];
> >>> +
> >>> + return vduse_dev_set_vq_state(dev, vq, state);
> >>> +}
> >>> +
> >>> +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 vduse_dev_get_features(dev);
> >>> +}
> >>> +
> >>> +static int vduse_vdpa_set_features(struct vdpa_device *vdpa, u64 features)
> >>> +{
> >>> + struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> >>> +
> >>> + if (!(features & (1ULL << VIRTIO_F_ACCESS_PLATFORM)))
> >>> + return -EINVAL;
> >>> +
> >>> + return vduse_dev_set_features(dev, features);
> >>> +}
> >>> +
> >>> +static void vduse_vdpa_set_config_cb(struct vdpa_device *vdpa,
> >>> + struct vdpa_callback *cb)
> >>> +{
> >>> + /* We don't support config interrupt */
> >>> +}
> >>> +
> >>> +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 vduse_dev_get_status(dev);
> >>> +}
> >>> +
> >>> +static void vduse_vdpa_set_status(struct vdpa_device *vdpa, u8 status)
> >>> +{
> >>> + struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> >>> +
> >>> + if (status == 0)
> >>> + vduse_dev_reset(dev);
> >>> +
> >>> + vduse_dev_set_status(dev, status);
> >>> +}
> >>> +
> >>> +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);
> >>> +
> >>> + vduse_dev_get_config(dev, offset, buf, len);
> >>> +}
> >>> +
> >>> +static void vduse_vdpa_set_config(struct vdpa_device *vdpa, unsigned int offset,
> >>> + const void *buf, unsigned int len)
> >>> +{
> >>> + struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> >>> +
> >>> + vduse_dev_set_config(dev, offset, buf, len);
> >>> +}
> >>> +
> >>> +static int vduse_vdpa_set_map(struct vdpa_device *vdpa,
> >>> + struct vhost_iotlb *iotlb)
> >>> +{
> >>> + struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> >>> + int ret;
> >>> +
> >>
> >> So I wonder we need to do the vhost_dev_update_iotlb() before
> >> vduse_domain_set_map().
> >>
> >> That is, we need to make sure the userspace's IOTLB is cleared after
> >> setting up the new map?
> >>
> > The same problem I described above. So we use UPDATE_IOTLB messages to
> > notify userspace of refreshing the IOTLB after we change the iotlb
> > itree.
>
>
> Yes.
>
>
> >
> >>> + ret = vduse_domain_set_map(dev->domain, iotlb);
> >>> + vduse_dev_update_iotlb(dev, 0ULL, ULLONG_MAX);
> >>> +
> >>> + return ret;
> >>> +}
> >>> +
> >>> +static void vduse_vdpa_free(struct vdpa_device *vdpa)
> >>> +{
> >>> + struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> >>> +
> >>> + WARN_ON(!list_empty(&dev->send_list));
> >>> + WARN_ON(!list_empty(&dev->recv_list));
> >>> + 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 = vduse_vdpa_get_config,
> >>> + .set_config = vduse_vdpa_set_config,
> >>> + .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;
> >>> + vduse_dev_update_iotlb(vdev, iova, iova + size - 1);
> >>> +
> >>> + 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;
> >>> + unsigned long start = (unsigned long)dma_addr;
> >>> + unsigned long last = start + size - 1;
> >>> +
> >>> + vduse_domain_free_coherent(domain, size, vaddr, dma_addr, attrs);
> >>> + vduse_dev_update_iotlb(vdev, start, last);
> >>> +}
> >>> +
> >>> +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,
> >>> +};
> >>> +
> >>> +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;
> >>> +
> >>> + if (eventfd->index >= dev->vq_num)
> >>> + return -EINVAL;
> >>> +
> >>> + vq = &dev->vqs[eventfd->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;
> >>> + spin_unlock(&vq->kick_lock);
> >>> +
> >>> + return 0;
> >>> +}
> >>> +
> >>> +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_ENTRY: {
> >>> + 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;
> >>> +
> >>> + spin_lock(&domain->iotlb_lock);
> >>> + map = vhost_iotlb_itree_first(domain->iotlb,
> >>> + entry.start, entry.start + 1);
> >>> + 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;
> >>
> >> So we need document this in the uAPI doc. I think when userspace see
> >> -EINVAL it means the map doesn't exist.
> >>
> > Fine with me.
> >
> >> Or should we make it more explicitly by e.g introduing new flags.
> >>
> >>
> >>> + if (!f)
> >>> + break;
> >>> +
> >>> + ret = -EFAULT;
> >>> + if (copy_to_user(argp, &entry, sizeof(entry))) {
> >>> + fput(f);
> >>> + break;
> >>> + }
> >>> + ret = receive_fd_user(f, argp, perm_to_file_flags(entry.perm));
> >>> + fput(f);
> >>> + 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_INJECT_VQ_IRQ:
> >>> + ret = -EINVAL;
> >>> + if (arg >= dev->vq_num)
> >>> + break;
> >>> +
> >>> + ret = 0;
> >>> + queue_work(vduse_irq_wq, &dev->vqs[arg].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;
> >>> + struct vduse_dev_msg *msg;
> >>> + int i;
> >>> +
> >>> + for (i = 0; i < dev->vq_num; i++) {
> >>> + struct vduse_virtqueue *vq = &dev->vqs[i];
> >>> +
> >>> + spin_lock(&vq->kick_lock);
> >>> + if (vq->kickfd)
> >>> + eventfd_ctx_put(vq->kickfd);
> >>> + vq->kickfd = NULL;
> >>> + spin_unlock(&vq->kick_lock);
> >>> + }
> >>> +
> >>> + spin_lock(&dev->msg_lock);
> >>> + while ((msg = vduse_dequeue_msg(&dev->recv_list)))
> >>> + vduse_enqueue_msg(&dev->send_list, msg);
> >>
> >> What's the goal of this?
> >>
> > Support reconnecting. Make sure userspace daemon can get the inflight
> > messages after reboot.
>
>
> I see, plase add a comment for this.
>
OK.
>
> >
> >> In addition to free the messages, we need wake up the processes that is
> >> in the waitq in this case.
> >>
> >>
> >>> + spin_unlock(&dev->msg_lock);
> >>> +
> >>> + dev->connected = false;
> >>
> >> Do we need to hold vduse mutex here?
> >>
> > Looks like I didn't find any situation that requires the mutex.
>
>
> Ok, I guess the reason is because there will be no external reference
> for the device?
>
Yes, only one process can open this device now.
>
> >
> >>> +
> >>> + return 0;
> >>> +}
> >>> +
> >>> +static int vduse_dev_open(struct inode *inode, struct file *file)
> >>> +{
> >>> + struct vduse_dev *dev = container_of(inode->i_cdev,
> >>> + struct vduse_dev, cdev);
> >>> + int ret = -EBUSY;
> >>> +
> >>> + mutex_lock(&vduse_lock);
> >>> + if (dev->connected)
> >>> + goto unlock;
> >>> +
> >>> + ret = 0;
> >>> + dev->connected = true;
> >>> + file->private_data = dev;
> >>> +unlock:
> >>> + mutex_unlock(&vduse_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;
> >>> +
> >>> + spin_lock_init(&dev->msg_lock);
> >>> + INIT_LIST_HEAD(&dev->send_list);
> >>> + INIT_LIST_HEAD(&dev->recv_list);
> >>> + atomic64_set(&dev->msg_unique, 0);
> >>> +
> >>> + 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 *tmp, *dev = NULL;
> >>> +
> >>> + list_for_each_entry(tmp, &vduse_devs, list) {
> >>> + if (!strcmp(dev_name(&tmp->dev), name)) {
> >>> + dev = tmp;
> >>> + break;
> >>> + }
> >>> + }
> >>> + return dev;
> >>> +}
> >>> +
> >>> +static int vduse_destroy_dev(char *name)
> >>> +{
> >>> + struct vduse_dev *dev = vduse_find_dev(name);
> >>> +
> >>> + if (!dev)
> >>> + return -EINVAL;
> >>> +
> >>> + if (dev->vdev || dev->connected)
> >>> + return -EBUSY;
> >>> +
> >>> + dev->connected = true;
> >>
> >> Need mutex here?
> >>
> > vduse_destroy_dev() is protected by the vduse_mutex.
>
>
> I see.
>
>
> >
> >>> + list_del(&dev->list);
> >>> + cdev_device_del(&dev->cdev, &dev->dev);
> >>> + put_device(&dev->dev);
> >>> +
> >>> + return 0;
> >>> +}
> >>> +
> >>> +static void vduse_release_dev(struct device *device)
> >>> +{
> >>> + struct vduse_dev *dev =
> >>> + container_of(device, struct vduse_dev, dev);
> >>> +
> >>> + ida_simple_remove(&vduse_ida, dev->minor);
> >>> + kfree(dev->vqs);
> >>> + vduse_domain_destroy(dev->domain);
> >>> + vduse_dev_destroy(dev);
> >>> + module_put(THIS_MODULE);
> >>> +}
> >>> +
> >>> +static int vduse_create_dev(struct vduse_dev_config *config)
> >>> +{
> >>> + int i, ret = -ENOMEM;
> >>> + struct vduse_dev *dev;
> >>> +
> >>> + if (config->bounce_size > max_bounce_size)
> >>> + return -EINVAL;
> >>> +
> >>> + if (config->bounce_size > max_iova_size)
> >>> + return -EINVAL;
> >>> +
> >>> + if (vduse_find_dev(config->name))
> >>> + return -EEXIST;
> >>> +
> >>> + dev = vduse_dev_create();
> >>> + if (!dev)
> >>> + return -ENOMEM;
> >>> +
> >>> + dev->device_id = config->device_id;
> >>> + dev->vendor_id = config->vendor_id;
> >>> + dev->domain = vduse_domain_create(max_iova_size - 1,
> >>> + config->bounce_size);
> >>> + if (!dev->domain)
> >>> + goto err_domain;
> >>> +
> >>> + 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 = ida_simple_get(&vduse_ida, 0, VDUSE_DEV_MAX, GFP_KERNEL);
> >>> + if (ret < 0)
> >>> + goto err_ida;
> >>> +
> >>> + dev->minor = ret;
> >>> + device_initialize(&dev->dev);
> >>> + dev->dev.release = vduse_release_dev;
> >>> + dev->dev.class = vduse_class;
> >>> + dev->dev.devt = MKDEV(MAJOR(vduse_major), dev->minor);
> >>> + ret = dev_set_name(&dev->dev, "%s", config->name);
> >>> + if (ret)
> >>> + goto err_name;
> >>> +
> >>> + cdev_init(&dev->cdev, &vduse_dev_fops);
> >>> + dev->cdev.owner = THIS_MODULE;
> >>> +
> >>> + ret = cdev_device_add(&dev->cdev, &dev->dev);
> >>> + if (ret) {
> >>> + put_device(&dev->dev);
> >>> + return ret;
> >>> + }
> >>> + list_add(&dev->list, &vduse_devs);
> >>> + __module_get(THIS_MODULE);
> >>> +
> >>> + return 0;
> >>> +err_name:
> >>> + ida_simple_remove(&vduse_ida, dev->minor);
> >>> +err_ida:
> >>> + kfree(dev->vqs);
> >>> +err_vqs:
> >>> + vduse_domain_destroy(dev->domain);
> >>> +err_domain:
> >>
> >> So the rewind after device_initialize() looks wrong, we should use
> >> put_device() which will use dev.relase().
> >>
> > Oh, yes. We should also call put_device() in err_name case.
> >
> >> See the comment of device_initialize():
> >>
> >> * NOTE: Use put_device() to give up your reference instead of freeing
> >> * @dev directly once you have called this function.
> >> */
> >>
> >>> + vduse_dev_destroy(dev);
> >>> + return ret;
> >>> +}
> >>> +
> >>> +static long vduse_ioctl(struct file *file, unsigned int cmd,
> >>> + unsigned long arg)
> >>> +{
> >>> + int ret;
> >>> + void __user *argp = (void __user *)arg;
> >>> +
> >>> + mutex_lock(&vduse_lock);
> >>> + switch (cmd) {
> >>> + case VDUSE_GET_API_VERSION:
> >>> + ret = VDUSE_API_VERSION;
> >>
> >> To preseve the uAPI compatibility, besides GET_API_VERSION, we need
> >> SET_API_VERSION to support older userspace.
> >>
> > Shouldn't the userspace keep compatibility to support older kernel? If
> > so, we only need GET_API_VERSION here.
>
>
> Actually the reverse. The new kernel need to make sure the old userspace
> can work. That is to say the kenrel should support version 0 forever
> even if it supports e.g version 1.
>
OK, I see.
Thanks,
Yongji
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