Re: [PATCH v9 16/17] vduse: Introduce VDUSE - vDPA Device in Userspace
From: Yongji Xie
Date: Thu Jul 15 2021 - 00:04:11 EST
On Wed, Jul 14, 2021 at 5:12 PM Jason Wang <jasowang@xxxxxxxxxx> wrote:
>
>
> 在 2021/7/14 下午2:49, Yongji Xie 写道:
> > On Wed, Jul 14, 2021 at 1:45 PM Jason Wang <jasowang@xxxxxxxxxx> wrote:
> >>
> >> 在 2021/7/13 下午4:46, Xie Yongji 写道:
> >>> This VDUSE driver enables implementing software-emulated vDPA
> >>> devices in userspace. The vDPA device is created by
> >>> ioctl(VDUSE_CREATE_DEV) on /dev/vduse/control. Then a char device
> >>> interface (/dev/vduse/$NAME) is exported to userspace for device
> >>> emulation.
> >>>
> >>> In order to make the device emulation more secure, the device's
> >>> control path is handled in kernel. A message mechnism is introduced
> >>> to forward some dataplane related control messages to userspace.
> >>>
> >>> And in the data path, the DMA buffer will be mapped into userspace
> >>> address space through different ways depending on the vDPA bus to
> >>> which the vDPA device is attached. In virtio-vdpa case, the MMU-based
> >>> IOMMU driver is used to achieve that. And in vhost-vdpa case, the
> >>> DMA buffer is reside in a userspace memory region which can be shared
> >>> to the VDUSE userspace processs via transferring the shmfd.
> >>>
> >>> For more details on VDUSE design and usage, please see the follow-on
> >>> Documentation commit.
> >>>
> >>> Signed-off-by: Xie Yongji <xieyongji@xxxxxxxxxxxxx>
> >>> ---
> >>> Documentation/userspace-api/ioctl/ioctl-number.rst | 1 +
> >>> drivers/vdpa/Kconfig | 10 +
> >>> drivers/vdpa/Makefile | 1 +
> >>> drivers/vdpa/vdpa_user/Makefile | 5 +
> >>> drivers/vdpa/vdpa_user/vduse_dev.c | 1502 ++++++++++++++++++++
> >>> include/uapi/linux/vduse.h | 221 +++
> >>> 6 files changed, 1740 insertions(+)
> >>> create mode 100644 drivers/vdpa/vdpa_user/Makefile
> >>> create mode 100644 drivers/vdpa/vdpa_user/vduse_dev.c
> >>> create mode 100644 include/uapi/linux/vduse.h
> >>>
> >>> diff --git a/Documentation/userspace-api/ioctl/ioctl-number.rst b/Documentation/userspace-api/ioctl/ioctl-number.rst
> >>> index 1409e40e6345..293ca3aef358 100644
> >>> --- a/Documentation/userspace-api/ioctl/ioctl-number.rst
> >>> +++ b/Documentation/userspace-api/ioctl/ioctl-number.rst
> >>> @@ -300,6 +300,7 @@ Code Seq# Include File Comments
> >>> 'z' 10-4F drivers/s390/crypto/zcrypt_api.h conflict!
> >>> '|' 00-7F linux/media.h
> >>> 0x80 00-1F linux/fb.h
> >>> +0x81 00-1F linux/vduse.h
> >>> 0x89 00-06 arch/x86/include/asm/sockios.h
> >>> 0x89 0B-DF linux/sockios.h
> >>> 0x89 E0-EF linux/sockios.h SIOCPROTOPRIVATE range
> >>> diff --git a/drivers/vdpa/Kconfig b/drivers/vdpa/Kconfig
> >>> index a503c1b2bfd9..6e23bce6433a 100644
> >>> --- a/drivers/vdpa/Kconfig
> >>> +++ b/drivers/vdpa/Kconfig
> >>> @@ -33,6 +33,16 @@ config VDPA_SIM_BLOCK
> >>> vDPA block device simulator which terminates IO request in a
> >>> memory buffer.
> >>>
> >>> +config VDPA_USER
> >>> + tristate "VDUSE (vDPA Device in Userspace) support"
> >>> + depends on EVENTFD && MMU && HAS_DMA
> >>> + select DMA_OPS
> >>> + select VHOST_IOTLB
> >>> + select IOMMU_IOVA
> >>> + help
> >>> + With VDUSE it is possible to emulate a vDPA Device
> >>> + in a userspace program.
> >>> +
> >>> config IFCVF
> >>> tristate "Intel IFC VF vDPA driver"
> >>> depends on PCI_MSI
> >>> diff --git a/drivers/vdpa/Makefile b/drivers/vdpa/Makefile
> >>> index 67fe7f3d6943..f02ebed33f19 100644
> >>> --- a/drivers/vdpa/Makefile
> >>> +++ b/drivers/vdpa/Makefile
> >>> @@ -1,6 +1,7 @@
> >>> # SPDX-License-Identifier: GPL-2.0
> >>> obj-$(CONFIG_VDPA) += vdpa.o
> >>> obj-$(CONFIG_VDPA_SIM) += vdpa_sim/
> >>> +obj-$(CONFIG_VDPA_USER) += vdpa_user/
> >>> obj-$(CONFIG_IFCVF) += ifcvf/
> >>> obj-$(CONFIG_MLX5_VDPA) += mlx5/
> >>> obj-$(CONFIG_VP_VDPA) += virtio_pci/
> >>> diff --git a/drivers/vdpa/vdpa_user/Makefile b/drivers/vdpa/vdpa_user/Makefile
> >>> new file mode 100644
> >>> index 000000000000..260e0b26af99
> >>> --- /dev/null
> >>> +++ b/drivers/vdpa/vdpa_user/Makefile
> >>> @@ -0,0 +1,5 @@
> >>> +# SPDX-License-Identifier: GPL-2.0
> >>> +
> >>> +vduse-y := vduse_dev.o iova_domain.o
> >>> +
> >>> +obj-$(CONFIG_VDPA_USER) += vduse.o
> >>> diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
> >>> new file mode 100644
> >>> index 000000000000..c994a4a4660c
> >>> --- /dev/null
> >>> +++ b/drivers/vdpa/vdpa_user/vduse_dev.c
> >>> @@ -0,0 +1,1502 @@
> >>> +// SPDX-License-Identifier: GPL-2.0-only
> >>> +/*
> >>> + * VDUSE: vDPA Device in Userspace
> >>> + *
> >>> + * Copyright (C) 2020-2021 Bytedance Inc. and/or its affiliates. All rights reserved.
> >>> + *
> >>> + * Author: Xie Yongji <xieyongji@xxxxxxxxxxxxx>
> >>> + *
> >>> + */
> >>> +
> >>> +#include <linux/init.h>
> >>> +#include <linux/module.h>
> >>> +#include <linux/cdev.h>
> >>> +#include <linux/device.h>
> >>> +#include <linux/eventfd.h>
> >>> +#include <linux/slab.h>
> >>> +#include <linux/wait.h>
> >>> +#include <linux/dma-map-ops.h>
> >>> +#include <linux/poll.h>
> >>> +#include <linux/file.h>
> >>> +#include <linux/uio.h>
> >>> +#include <linux/vdpa.h>
> >>> +#include <linux/nospec.h>
> >>> +#include <uapi/linux/vduse.h>
> >>> +#include <uapi/linux/vdpa.h>
> >>> +#include <uapi/linux/virtio_config.h>
> >>> +#include <uapi/linux/virtio_ids.h>
> >>> +#include <uapi/linux/virtio_blk.h>
> >>> +#include <linux/mod_devicetable.h>
> >>> +
> >>> +#include "iova_domain.h"
> >>> +
> >>> +#define DRV_AUTHOR "Yongji Xie <xieyongji@xxxxxxxxxxxxx>"
> >>> +#define DRV_DESC "vDPA Device in Userspace"
> >>> +#define DRV_LICENSE "GPL v2"
> >>> +
> >>> +#define VDUSE_DEV_MAX (1U << MINORBITS)
> >>> +#define VDUSE_MAX_BOUNCE_SIZE (64 * 1024 * 1024)
> >>> +#define VDUSE_IOVA_SIZE (128 * 1024 * 1024)
> >>> +#define VDUSE_REQUEST_TIMEOUT 30
> >>> +
> >>> +struct vduse_virtqueue {
> >>> + u16 index;
> >>> + u16 num_max;
> >>> + u32 num;
> >>> + u64 desc_addr;
> >>> + u64 driver_addr;
> >>> + u64 device_addr;
> >>> + struct vdpa_vq_state state;
> >>> + bool ready;
> >>> + bool kicked;
> >>> + spinlock_t kick_lock;
> >>> + spinlock_t irq_lock;
> >>> + struct eventfd_ctx *kickfd;
> >>> + struct vdpa_callback cb;
> >>> + struct work_struct inject;
> >>> +};
> >>> +
> >>> +struct vduse_dev;
> >>> +
> >>> +struct vduse_vdpa {
> >>> + struct vdpa_device vdpa;
> >>> + struct vduse_dev *dev;
> >>> +};
> >>> +
> >>> +struct vduse_dev {
> >>> + struct vduse_vdpa *vdev;
> >>> + struct device *dev;
> >>> + struct vduse_virtqueue *vqs;
> >>> + struct vduse_iova_domain *domain;
> >>> + char *name;
> >>> + struct mutex lock;
> >>> + spinlock_t msg_lock;
> >>> + u64 msg_unique;
> >>> + 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;
> >>> + u64 api_version;
> >>> + u64 device_features;
> >>> + u64 driver_features;
> >>> + u32 device_id;
> >>> + u32 vendor_id;
> >>> + u32 generation;
> >>> + u32 config_size;
> >>> + void *config;
> >>> + u8 status;
> >>> + u32 vq_num;
> >>> + u32 vq_align;
> >>> +};
> >>> +
> >>> +struct vduse_dev_msg {
> >>> + struct vduse_dev_request req;
> >>> + struct vduse_dev_response resp;
> >>> + struct list_head list;
> >>> + wait_queue_head_t waitq;
> >>> + bool completed;
> >>> +};
> >>> +
> >>> +struct vduse_control {
> >>> + u64 api_version;
> >>> +};
> >>> +
> >>> +static DEFINE_MUTEX(vduse_lock);
> >>> +static DEFINE_IDR(vduse_idr);
> >>> +
> >>> +static dev_t vduse_major;
> >>> +static struct class *vduse_class;
> >>> +static struct cdev vduse_ctrl_cdev;
> >>> +static struct cdev vduse_cdev;
> >>> +static struct workqueue_struct *vduse_irq_wq;
> >>> +
> >>> +static u32 allowed_device_id[] = {
> >>> + VIRTIO_ID_BLOCK,
> >>> +};
> >>> +
> >>> +static inline struct vduse_dev *vdpa_to_vduse(struct vdpa_device *vdpa)
> >>> +{
> >>> + struct vduse_vdpa *vdev = container_of(vdpa, struct vduse_vdpa, vdpa);
> >>> +
> >>> + return vdev->dev;
> >>> +}
> >>> +
> >>> +static inline struct vduse_dev *dev_to_vduse(struct device *dev)
> >>> +{
> >>> + struct vdpa_device *vdpa = dev_to_vdpa(dev);
> >>> +
> >>> + return vdpa_to_vduse(vdpa);
> >>> +}
> >>> +
> >>> +static struct vduse_dev_msg *vduse_find_msg(struct list_head *head,
> >>> + uint32_t request_id)
> >>> +{
> >>> + struct vduse_dev_msg *msg;
> >>> +
> >>> + list_for_each_entry(msg, head, list) {
> >>> + if (msg->req.request_id == request_id) {
> >>> + list_del(&msg->list);
> >>> + return msg;
> >>> + }
> >>> + }
> >>> +
> >>> + return NULL;
> >>> +}
> >>> +
> >>> +static struct vduse_dev_msg *vduse_dequeue_msg(struct list_head *head)
> >>> +{
> >>> + struct vduse_dev_msg *msg = NULL;
> >>> +
> >>> + if (!list_empty(head)) {
> >>> + msg = list_first_entry(head, struct vduse_dev_msg, list);
> >>> + list_del(&msg->list);
> >>> + }
> >>> +
> >>> + return msg;
> >>> +}
> >>> +
> >>> +static void vduse_enqueue_msg(struct list_head *head,
> >>> + struct vduse_dev_msg *msg)
> >>> +{
> >>> + list_add_tail(&msg->list, head);
> >>> +}
> >>> +
> >>> +static int vduse_dev_msg_sync(struct vduse_dev *dev,
> >>> + struct vduse_dev_msg *msg)
> >>> +{
> >>> + int ret;
> >>> +
> >>> + 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);
> >>> +
> >>> + 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;
> >>> + }
> >>> + ret = (msg->resp.result == VDUSE_REQ_RESULT_OK) ? 0 : -EIO;
> >>
> >> I think we should mark the device as malfunction when there is a timeout
> >> and forbid any userspace operations except for the destroy aftwards for
> >> safety.
> >>
> > Is it necessary? Actually we can't stop the dataplane processing in
> > userspace.
>
>
> That's fine since for virtio-vdpa, we use bounce buffer, for vhost, it
> works like the device can be reset.
>
>
> > It doesn’t seem to help much if we only forbid ioctl and
> > read/write. And there might be some messages that can tolerate
> > failure.
>
>
> I think at least we should figure out fatal failures and forbid any
> future userspace operations.
>
OK. It is indeed necessary to figure out fatal failures so that userspace knows.
> > Even userspace can do something like NEEDS_RESET to do
> > recovery.
>
>
> Yes, but that's not someting we can depend.
>
>
> >
> >>> + spin_unlock(&dev->msg_lock);
> >>> +
> >>> + return ret;
> >>> +}
> >>> +
> >>> +static int vduse_dev_get_vq_state_packed(struct vduse_dev *dev,
> >>> + struct vduse_virtqueue *vq,
> >>> + struct vdpa_vq_state_packed *packed)
> >>> +{
> >>> + struct vduse_dev_msg msg = { 0 };
> >>> + int ret;
> >>> +
> >>> + msg.req.type = VDUSE_GET_VQ_STATE;
> >>> + msg.req.vq_state.index = vq->index;
> >>> +
> >>> + ret = vduse_dev_msg_sync(dev, &msg);
> >>> + if (ret)
> >>> + return ret;
> >>> +
> >>> + packed->last_avail_counter =
> >>> + msg.resp.vq_state.packed.last_avail_counter;
> >>> + packed->last_avail_idx = msg.resp.vq_state.packed.last_avail_idx;
> >>> + packed->last_used_counter = msg.resp.vq_state.packed.last_used_counter;
> >>> + packed->last_used_idx = msg.resp.vq_state.packed.last_used_idx;
> >>> +
> >>> + return 0;
> >>> +}
> >>> +
> >>> +static int vduse_dev_get_vq_state_split(struct vduse_dev *dev,
> >>> + struct vduse_virtqueue *vq,
> >>> + struct vdpa_vq_state_split *split)
> >>> +{
> >>> + struct vduse_dev_msg msg = { 0 };
> >>> + int ret;
> >>> +
> >>> + msg.req.type = VDUSE_GET_VQ_STATE;
> >>> + msg.req.vq_state.index = vq->index;
> >>> +
> >>> + ret = vduse_dev_msg_sync(dev, &msg);
> >>> + if (ret)
> >>> + return ret;
> >>> +
> >>> + split->avail_index = msg.resp.vq_state.split.avail_index;
> >>> +
> >>> + return 0;
> >>> +}
> >>> +
> >>> +static int vduse_dev_set_status(struct vduse_dev *dev, u8 status)
> >>> +{
> >>> + struct vduse_dev_msg msg = { 0 };
> >>> +
> >>> + msg.req.type = VDUSE_SET_STATUS;
> >>> + msg.req.s.status = status;
> >>> +
> >>> + return vduse_dev_msg_sync(dev, &msg);
> >>> +}
> >>> +
> >>> +static int vduse_dev_update_iotlb(struct vduse_dev *dev,
> >>> + u64 start, u64 last)
> >>> +{
> >>> + struct vduse_dev_msg msg = { 0 };
> >>> +
> >>> + if (last < start)
> >>> + return -EINVAL;
> >>> +
> >>> + msg.req.type = VDUSE_UPDATE_IOTLB;
> >>> + msg.req.iova.start = start;
> >>> + msg.req.iova.last = last;
> >>> +
> >>> + return vduse_dev_msg_sync(dev, &msg);
> >>> +}
> >>> +
> >>> +static ssize_t vduse_dev_read_iter(struct kiocb *iocb, struct iov_iter *to)
> >>> +{
> >>> + struct file *file = iocb->ki_filp;
> >>> + struct vduse_dev *dev = file->private_data;
> >>> + struct vduse_dev_msg *msg;
> >>> + int size = sizeof(struct vduse_dev_request);
> >>> + ssize_t ret;
> >>> +
> >>> + if (iov_iter_count(to) < size)
> >>> + return -EINVAL;
> >>> +
> >>> + spin_lock(&dev->msg_lock);
> >>> + while (1) {
> >>> + msg = vduse_dequeue_msg(&dev->send_list);
> >>> + if (msg)
> >>> + break;
> >>> +
> >>> + ret = -EAGAIN;
> >>> + if (file->f_flags & O_NONBLOCK)
> >>> + goto unlock;
> >>> +
> >>> + spin_unlock(&dev->msg_lock);
> >>> + ret = wait_event_interruptible_exclusive(dev->waitq,
> >>> + !list_empty(&dev->send_list));
> >>> + if (ret)
> >>> + return ret;
> >>> +
> >>> + spin_lock(&dev->msg_lock);
> >>> + }
> >>> + spin_unlock(&dev->msg_lock);
> >>> + ret = copy_to_iter(&msg->req, size, to);
> >>> + spin_lock(&dev->msg_lock);
> >>> + if (ret != size) {
> >>> + ret = -EFAULT;
> >>> + vduse_enqueue_msg(&dev->send_list, msg);
> >>> + goto unlock;
> >>> + }
> >>> + vduse_enqueue_msg(&dev->recv_list, msg);
> >>> +unlock:
> >>> + spin_unlock(&dev->msg_lock);
> >>> +
> >>> + return ret;
> >>> +}
> >>> +
> >>> +static 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->driver_features = 0;
> >>> + dev->generation++;
> >>> + spin_lock(&dev->irq_lock);
> >>> + dev->config_cb.callback = NULL;
> >>> + dev->config_cb.private = NULL;
> >>> + spin_unlock(&dev->irq_lock);
> >>> + flush_work(&dev->inject);
> >>> +
> >>> + for (i = 0; i < dev->vq_num; i++) {
> >>> + struct vduse_virtqueue *vq = &dev->vqs[i];
> >>> +
> >>> + vq->ready = false;
> >>> + vq->desc_addr = 0;
> >>> + vq->driver_addr = 0;
> >>> + vq->device_addr = 0;
> >>> + vq->num = 0;
> >>> + memset(&vq->state, 0, sizeof(vq->state));
> >>> +
> >>> + spin_lock(&vq->kick_lock);
> >>> + vq->kicked = false;
> >>> + if (vq->kickfd)
> >>> + eventfd_ctx_put(vq->kickfd);
> >>> + vq->kickfd = NULL;
> >>> + spin_unlock(&vq->kick_lock);
> >>> +
> >>> + spin_lock(&vq->irq_lock);
> >>> + vq->cb.callback = NULL;
> >>> + vq->cb.private = NULL;
> >>> + spin_unlock(&vq->irq_lock);
> >>> + flush_work(&vq->inject);
> >>> + }
> >>> +}
> >>> +
> >>> +static int vduse_vdpa_set_vq_address(struct vdpa_device *vdpa, u16 idx,
> >>> + u64 desc_area, u64 driver_area,
> >>> + u64 device_area)
> >>> +{
> >>> + struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> >>> + struct vduse_virtqueue *vq = &dev->vqs[idx];
> >>> +
> >>> + vq->desc_addr = desc_area;
> >>> + vq->driver_addr = driver_area;
> >>> + vq->device_addr = device_area;
> >>> +
> >>> + return 0;
> >>> +}
> >>> +
> >>> +static void vduse_vdpa_kick_vq(struct vdpa_device *vdpa, u16 idx)
> >>> +{
> >>> + struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> >>> + struct vduse_virtqueue *vq = &dev->vqs[idx];
> >>> +
> >>> + spin_lock(&vq->kick_lock);
> >>> + if (!vq->ready)
> >>> + goto unlock;
> >>> +
> >>> + if (vq->kickfd)
> >>> + eventfd_signal(vq->kickfd, 1);
> >>> + else
> >>> + vq->kicked = true;
> >>> +unlock:
> >>> + spin_unlock(&vq->kick_lock);
> >>> +}
> >>> +
> >>> +static void vduse_vdpa_set_vq_cb(struct vdpa_device *vdpa, u16 idx,
> >>> + struct vdpa_callback *cb)
> >>> +{
> >>> + struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> >>> + struct vduse_virtqueue *vq = &dev->vqs[idx];
> >>> +
> >>> + spin_lock(&vq->irq_lock);
> >>> + vq->cb.callback = cb->callback;
> >>> + vq->cb.private = cb->private;
> >>> + spin_unlock(&vq->irq_lock);
> >>> +}
> >>> +
> >>> +static void vduse_vdpa_set_vq_num(struct vdpa_device *vdpa, u16 idx, u32 num)
> >>> +{
> >>> + struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> >>> + struct vduse_virtqueue *vq = &dev->vqs[idx];
> >>> +
> >>> + vq->num = num;
> >>> +}
> >>> +
> >>> +static void vduse_vdpa_set_vq_ready(struct vdpa_device *vdpa,
> >>> + u16 idx, bool ready)
> >>> +{
> >>> + struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> >>> + struct vduse_virtqueue *vq = &dev->vqs[idx];
> >>> +
> >>> + vq->ready = ready;
> >>> +}
> >>> +
> >>> +static bool vduse_vdpa_get_vq_ready(struct vdpa_device *vdpa, u16 idx)
> >>> +{
> >>> + struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> >>> + struct vduse_virtqueue *vq = &dev->vqs[idx];
> >>> +
> >>> + return vq->ready;
> >>> +}
> >>> +
> >>> +static int vduse_vdpa_set_vq_state(struct vdpa_device *vdpa, u16 idx,
> >>> + const struct vdpa_vq_state *state)
> >>> +{
> >>> + struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> >>> + struct vduse_virtqueue *vq = &dev->vqs[idx];
> >>> +
> >>> + if (dev->driver_features & BIT_ULL(VIRTIO_F_RING_PACKED)) {
> >>> + vq->state.packed.last_avail_counter =
> >>> + state->packed.last_avail_counter;
> >>> + vq->state.packed.last_avail_idx = state->packed.last_avail_idx;
> >>> + vq->state.packed.last_used_counter =
> >>> + state->packed.last_used_counter;
> >>> + vq->state.packed.last_used_idx = state->packed.last_used_idx;
> >>> + } else
> >>> + vq->state.split.avail_index = state->split.avail_index;
> >>> +
> >>> + return 0;
> >>> +}
> >>> +
> >>> +static int vduse_vdpa_get_vq_state(struct vdpa_device *vdpa, u16 idx,
> >>> + struct vdpa_vq_state *state)
> >>> +{
> >>> + struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> >>> + struct vduse_virtqueue *vq = &dev->vqs[idx];
> >>> +
> >>> + if (dev->driver_features & BIT_ULL(VIRTIO_F_RING_PACKED))
> >>> + return vduse_dev_get_vq_state_packed(dev, vq, &state->packed);
> >>> +
> >>> + return vduse_dev_get_vq_state_split(dev, vq, &state->split);
> >>> +}
> >>> +
> >>> +static u32 vduse_vdpa_get_vq_align(struct vdpa_device *vdpa)
> >>> +{
> >>> + struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> >>> +
> >>> + return dev->vq_align;
> >>> +}
> >>> +
> >>> +static u64 vduse_vdpa_get_features(struct vdpa_device *vdpa)
> >>> +{
> >>> + struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> >>> +
> >>> + return dev->device_features;
> >>> +}
> >>> +
> >>> +static int vduse_vdpa_set_features(struct vdpa_device *vdpa, u64 features)
> >>> +{
> >>> + struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> >>> +
> >>> + dev->driver_features = features;
> >>> + return 0;
> >>> +}
> >>> +
> >>> +static void vduse_vdpa_set_config_cb(struct vdpa_device *vdpa,
> >>> + struct vdpa_callback *cb)
> >>> +{
> >>> + struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> >>> +
> >>> + spin_lock(&dev->irq_lock);
> >>> + dev->config_cb.callback = cb->callback;
> >>> + dev->config_cb.private = cb->private;
> >>> + spin_unlock(&dev->irq_lock);
> >>> +}
> >>> +
> >>> +static u16 vduse_vdpa_get_vq_num_max(struct vdpa_device *vdpa, u16 idx)
> >>> +{
> >>> + struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> >>> +
> >>> + return dev->vqs[idx].num_max;
> >>> +}
> >>> +
> >>> +static u32 vduse_vdpa_get_device_id(struct vdpa_device *vdpa)
> >>> +{
> >>> + struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> >>> +
> >>> + return dev->device_id;
> >>> +}
> >>> +
> >>> +static u32 vduse_vdpa_get_vendor_id(struct vdpa_device *vdpa)
> >>> +{
> >>> + struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> >>> +
> >>> + return dev->vendor_id;
> >>> +}
> >>> +
> >>> +static u8 vduse_vdpa_get_status(struct vdpa_device *vdpa)
> >>> +{
> >>> + struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> >>> +
> >>> + return dev->status;
> >>> +}
> >>> +
> >>> +static void vduse_vdpa_set_status(struct vdpa_device *vdpa, u8 status)
> >>> +{
> >>> + struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> >>> +
> >>> + if (vduse_dev_set_status(dev, status))
> >>> + return;
> >>> +
> >>> + dev->status = status;
> >>
> >> It looks to me such design exclude the possibility of letting userspace
> >> device to set bit like (NEEDS_RESET) in the future.
> >>
> > Looks like we can achieve that via the ioctl.
>
>
> Which ioctl can be used for this?
>
I mean we can introduce a new ioctl for that in the future.
>
> >
> >> I wonder if it's better to do something similar to ccw:
> >>
> >> 1) requires the userspace to update the status bit in the response
> >> 2) update the dev->status to the status in the response if no timeout
> >>
> >> Then userspace could then set NEEDS_RESET if necessary.
> >>
> > But NEEDS_RESET does not only happen in this case.
>
>
> Yes, so you need an ioctl for userspace to update the device status
> (NEEDS_RESET) probably.
>
Yes, but I'd like to do that after the initial version is merged since
NEEDS_RESET is not supported now.
>
> >
> >>> + if (status == 0)
> >>> + vduse_dev_reset(dev);
> >>> +}
> >>> +
> >>> +static size_t vduse_vdpa_get_config_size(struct vdpa_device *vdpa)
> >>> +{
> >>> + struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> >>> +
> >>> + return dev->config_size;
> >>> +}
> >>> +
> >>> +static void vduse_vdpa_get_config(struct vdpa_device *vdpa, unsigned int offset,
> >>> + void *buf, unsigned int len)
> >>> +{
> >>> + struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> >>> +
> >>> + if (len > dev->config_size - offset)
> >>> + return;
> >>> +
> >>> + memcpy(buf, dev->config + offset, len);
> >>> +}
> >>> +
> >>> +static void vduse_vdpa_set_config(struct vdpa_device *vdpa, unsigned int offset,
> >>> + const void *buf, unsigned int len)
> >>> +{
> >>> + /* Now we only support read-only configuration space */
> >>> +}
> >>> +
> >>> +static 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 bool vduse_dev_is_ready(struct vduse_dev *dev)
> >>> +{
> >>> + int i;
> >>> +
> >>> + for (i = 0; i < dev->vq_num; i++)
> >>> + if (!dev->vqs[i].num_max)
> >>> + return false;
> >>> +
> >>> + return true;
> >>> +}
> >>> +
> >>> +static void vduse_dev_irq_inject(struct work_struct *work)
> >>> +{
> >>> + struct vduse_dev *dev = container_of(work, struct vduse_dev, inject);
> >>> +
> >>> + spin_lock_irq(&dev->irq_lock);
> >>> + if (dev->config_cb.callback)
> >>> + dev->config_cb.callback(dev->config_cb.private);
> >>> + spin_unlock_irq(&dev->irq_lock);
> >>> +}
> >>> +
> >>> +static void vduse_vq_irq_inject(struct work_struct *work)
> >>> +{
> >>> + struct vduse_virtqueue *vq = container_of(work,
> >>> + struct vduse_virtqueue, inject);
> >>> +
> >>> + spin_lock_irq(&vq->irq_lock);
> >>> + if (vq->ready && vq->cb.callback)
> >>> + vq->cb.callback(vq->cb.private);
> >>> + spin_unlock_irq(&vq->irq_lock);
> >>> +}
> >>> +
> >>> +static long vduse_dev_ioctl(struct file *file, unsigned int cmd,
> >>> + unsigned long arg)
> >>> +{
> >>> + struct vduse_dev *dev = file->private_data;
> >>> + void __user *argp = (void __user *)arg;
> >>> + int ret;
> >>> +
> >>> + 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:
> >>
> >> Let's add a comment to explain here. E.g we just mirror what driver
> >> wrote and the drier is expected to check FEATURE_OK.
> >>
> > I already document some details in include/uapi/linux/vduse.h and
> > Documentation/userspace-api/vduse.rst
>
>
> The point is the behavior of "mirroring" is one of the choice:
>
> "
>
> The device MUST present any valid feature bits the driver has written
> indriver_feature, starting at bitdriver_feature_select∗32 for
> anydriver_feature_selectwritten by the driver. Valid feature bits are
> those which are subset of the correspondingdevice_featurebits. The
> device MAY present invalid bits written by the driver.Note:This means
> that a device can ignore writes for feature bits it never offers, and
> simply present 0 on reads. Or it can just mirror what the driver wrote
> (but it will still have to check them when the driver sets
> FEATURES_OK).Note:A driver shouldn’t write invalid bits anyway, as
> per3.1.1
> <https://docs.oasis-open.org/virtio/virtio/v1.1/csprd01/virtio-v1.1-csprd01.html#x1-930001>,
> but this attempts to handle it.
>
> "
>
> It would be helpful to add a comment here or people may check whether it
> follows the spec.
>
OK, I see.
Thanks,
Yongji