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Date: Wed, 27 Jan 2021 16:50:27 +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>, 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,
axboe@...nel.dk, bcrl@...ck.org, Jonathan Corbet <corbet@....net>,
virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org,
kvm@...r.kernel.org, linux-aio@...ck.org,
linux-fsdevel@...r.kernel.org
Subject: Re: Re: [RFC v3 08/11] vduse: Introduce VDUSE - vDPA Device in Userspace
On Tue, Jan 26, 2021 at 4:09 PM Jason Wang <jasowang@...hat.com> wrote:
>
>
> On 2021/1/19 下午1:07, Xie Yongji wrote:
> > 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, VDUSE_IOTLB_GET_FD ioctl will be used to get
> > the file descriptors referring to vDPA device's iova regions. Then
> > userspace can use mmap() to access those iova regions. Besides,
> > the eventfd mechanism is used to trigger interrupt callbacks and
> > receive virtqueue kicks in userspace.
> >
> > Signed-off-by: Xie Yongji <xieyongji@...edance.com>
> > ---
> > Documentation/driver-api/vduse.rst | 85 ++
> > Documentation/userspace-api/ioctl/ioctl-number.rst | 1 +
> > drivers/vdpa/Kconfig | 7 +
> > drivers/vdpa/Makefile | 1 +
> > drivers/vdpa/vdpa_user/Makefile | 5 +
> > drivers/vdpa/vdpa_user/eventfd.c | 221 ++++
> > drivers/vdpa/vdpa_user/eventfd.h | 48 +
> > drivers/vdpa/vdpa_user/iova_domain.c | 426 +++++++
> > drivers/vdpa/vdpa_user/iova_domain.h | 68 ++
> > drivers/vdpa/vdpa_user/vduse.h | 62 +
> > drivers/vdpa/vdpa_user/vduse_dev.c | 1217 ++++++++++++++++++++
> > include/uapi/linux/vdpa.h | 1 +
> > include/uapi/linux/vduse.h | 125 ++
> > 13 files changed, 2267 insertions(+)
> > create mode 100644 Documentation/driver-api/vduse.rst
> > create mode 100644 drivers/vdpa/vdpa_user/Makefile
> > create mode 100644 drivers/vdpa/vdpa_user/eventfd.c
> > create mode 100644 drivers/vdpa/vdpa_user/eventfd.h
> > create mode 100644 drivers/vdpa/vdpa_user/iova_domain.c
> > create mode 100644 drivers/vdpa/vdpa_user/iova_domain.h
> > create mode 100644 drivers/vdpa/vdpa_user/vduse.h
> > create mode 100644 drivers/vdpa/vdpa_user/vduse_dev.c
> > create mode 100644 include/uapi/linux/vduse.h
> >
> > diff --git a/Documentation/driver-api/vduse.rst b/Documentation/driver-api/vduse.rst
> > new file mode 100644
> > index 000000000000..9418a7f6646b
> > --- /dev/null
> > +++ b/Documentation/driver-api/vduse.rst
> > @@ -0,0 +1,85 @@
> > +==================================
> > +VDUSE - "vDPA Device in Userspace"
> > +==================================
> > +
> > +vDPA (virtio data path acceleration) device is a device that uses a
> > +datapath which complies with the virtio specifications with vendor
> > +specific control path. vDPA devices can be both physically located on
> > +the hardware or emulated by software. VDUSE is a framework that makes it
> > +possible to implement software-emulated vDPA devices in userspace.
> > +
> > +How VDUSE works
> > +------------
> > +Each userspace vDPA device is created by the VDUSE_CREATE_DEV ioctl on
> > +the VDUSE character device (/dev/vduse). Then a file descriptor pointing
> > +to the new resources will be returned, which can be used to implement the
> > +userspace vDPA device's control path and data path.
> > +
> > +To implement control path, the read/write operations to the file descriptor
> > +will be used to receive/reply the control messages from/to VDUSE driver.
>
>
> It's better to document the protocol here. E.g the identifier stuffs.
>
I have documented those stuffs in include/uapi/linux/vduse.h, is it
OK? Or add something like "Please see include/uapi/linux/vduse.h for
details."
>
> > +Those control messages are mostly based on the vdpa_config_ops which defines
> > +a unified interface to control different types of vDPA device.
> > +
> > +The following types of messages are provided by the VDUSE framework now:
> > +
> > +- VDUSE_SET_VQ_ADDR: Set the addresses of the different aspects of virtqueue.
>
>
> "Set the vring address of a virtqueue" might be better here.
>
OK.
>
> > +
> > +- VDUSE_SET_VQ_NUM: Set the size of virtqueue
> > +
> > +- VDUSE_SET_VQ_READY: Set ready status of virtqueue
> > +
> > +- VDUSE_GET_VQ_READY: Get ready status of virtqueue
> > +
> > +- VDUSE_SET_VQ_STATE: Set the state (last_avail_idx) for virtqueue
> > +
> > +- VDUSE_GET_VQ_STATE: Get the state (last_avail_idx) for virtqueue
>
>
> It's better not to mention layout specific stuffs here (last_avail_idx).
> Consider we should support packed virtqueue in the future.
>
I see.
>
> > +
> > +- VDUSE_SET_FEATURES: Set virtio features supported by the driver
> > +
> > +- VDUSE_GET_FEATURES: Get virtio features supported by the device
> > +
> > +- VDUSE_SET_STATUS: Set the device status
> > +
> > +- VDUSE_GET_STATUS: Get the device status
> > +
> > +- VDUSE_SET_CONFIG: Write to device specific configuration space
> > +
> > +- VDUSE_GET_CONFIG: Read from device specific configuration space
> > +
> > +- VDUSE_UPDATE_IOTLB: Notify userspace to update the memory mapping in device IOTLB
> > +
> > +Please see include/linux/vdpa.h for details.
> > +
> > +In the data path, vDPA device's iova regions will be mapped into userspace with
> > +the help of VDUSE_IOTLB_GET_FD ioctl on the userspace vDPA device fd:
> > +
> > +- VDUSE_IOTLB_GET_FD: get the file descriptor to iova region. Userspace can
> > + access this iova region by passing the fd to mmap(2).
> > +
> > +Besides, the eventfd mechanism is used to trigger interrupt callbacks and
> > +receive virtqueue kicks in userspace. The following ioctls on the userspace
> > +vDPA device fd are provided to support that:
> > +
> > +- VDUSE_VQ_SETUP_KICKFD: set the kickfd for virtqueue, this eventfd is used
> > + by VDUSE driver to notify userspace to consume the vring.
> > +
> > +- VDUSE_VQ_SETUP_IRQFD: set the irqfd for virtqueue, this eventfd is used
> > + by userspace to notify VDUSE driver to trigger interrupt callbacks.
> > +
> > +MMU-based IOMMU Driver
> > +----------------------
> > +In virtio-vdpa case, VDUSE framework implements a MMU-based on-chip IOMMU
> > +driver to support mapping the kernel dma buffer into the userspace iova
> > +region dynamically.
> > +
> > +The basic idea behind this driver is treating MMU (VA->PA) as IOMMU (IOVA->PA).
> > +The driver will set up MMU mapping instead of IOMMU mapping for the DMA transfer
> > +so that the userspace process is able to use its virtual address to access
> > +the dma buffer in kernel.
> > +
> > +And to avoid security issue, a bounce-buffering mechanism is introduced to
> > +prevent userspace accessing the original buffer directly which may contain other
> > +kernel data. During the mapping, unmapping, the driver will copy the data from
> > +the original buffer to the bounce buffer and back, depending on the direction of
> > +the transfer. And the bounce-buffer addresses will be mapped into the user address
> > +space instead of the original one.
> > 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 4be7be39be26..667354309bf4 100644
> > --- a/drivers/vdpa/Kconfig
> > +++ b/drivers/vdpa/Kconfig
> > @@ -21,6 +21,13 @@ config VDPA_SIM
> > to RX. This device is used for testing, prototyping and
> > development of vDPA.
> >
> > +config VDPA_USER
> > + tristate "VDUSE (vDPA Device in Userspace) support"
> > + depends on EVENTFD && MMU && HAS_DMA
>
>
> Need select VHOST_IOTLB.
>
OK.
>
> > + 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 d160e9b63a66..66e97778ad03 100644
> > --- a/drivers/vdpa/Makefile
> > +++ b/drivers/vdpa/Makefile
> > @@ -1,5 +1,6 @@
> > # 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-$(CONFIG_MLX5_VDPA) += mlx5/
> > diff --git a/drivers/vdpa/vdpa_user/Makefile b/drivers/vdpa/vdpa_user/Makefile
> > new file mode 100644
> > index 000000000000..b7645e36992b
> > --- /dev/null
> > +++ b/drivers/vdpa/vdpa_user/Makefile
> > @@ -0,0 +1,5 @@
> > +# SPDX-License-Identifier: GPL-2.0
> > +
> > +vduse-y := vduse_dev.o iova_domain.o eventfd.o
> > +
> > +obj-$(CONFIG_VDPA_USER) += vduse.o
> > diff --git a/drivers/vdpa/vdpa_user/eventfd.c b/drivers/vdpa/vdpa_user/eventfd.c
> > new file mode 100644
> > index 000000000000..dbffddb08908
> > --- /dev/null
> > +++ b/drivers/vdpa/vdpa_user/eventfd.c
> > @@ -0,0 +1,221 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/*
> > + * Eventfd support for VDUSE
> > + *
> > + * Copyright (C) 2020 Bytedance Inc. and/or its affiliates. All rights reserved.
> > + *
> > + * Author: Xie Yongji <xieyongji@...edance.com>
> > + *
> > + */
> > +
> > +#include <linux/eventfd.h>
> > +#include <linux/poll.h>
> > +#include <linux/wait.h>
> > +#include <linux/slab.h>
> > +#include <linux/file.h>
> > +#include <uapi/linux/vduse.h>
> > +
> > +#include "eventfd.h"
> > +
> > +static struct workqueue_struct *vduse_irqfd_cleanup_wq;
> > +
> > +static void vduse_virqfd_shutdown(struct work_struct *work)
> > +{
> > + u64 cnt;
> > + struct vduse_virqfd *virqfd = container_of(work,
> > + struct vduse_virqfd, shutdown);
> > +
> > + eventfd_ctx_remove_wait_queue(virqfd->ctx, &virqfd->wait, &cnt);
> > + flush_work(&virqfd->inject);
> > + eventfd_ctx_put(virqfd->ctx);
> > + kfree(virqfd);
> > +}
> > +
> > +static void vduse_virqfd_inject(struct work_struct *work)
> > +{
> > + struct vduse_virqfd *virqfd = container_of(work,
> > + struct vduse_virqfd, inject);
> > + struct vduse_virtqueue *vq = virqfd->vq;
> > +
> > + spin_lock_irq(&vq->irq_lock);
> > + if (vq->ready && vq->cb)
> > + vq->cb(vq->private);
> > + spin_unlock_irq(&vq->irq_lock);
> > +}
> > +
> > +static void virqfd_deactivate(struct vduse_virqfd *virqfd)
> > +{
> > + queue_work(vduse_irqfd_cleanup_wq, &virqfd->shutdown);
> > +}
> > +
> > +static int vduse_virqfd_wakeup(wait_queue_entry_t *wait, unsigned int mode,
> > + int sync, void *key)
> > +{
> > + struct vduse_virqfd *virqfd = container_of(wait, struct vduse_virqfd, wait);
> > + struct vduse_virtqueue *vq = virqfd->vq;
> > +
> > + __poll_t flags = key_to_poll(key);
> > +
> > + if (flags & EPOLLIN)
> > + schedule_work(&virqfd->inject);
> > +
> > + if (flags & EPOLLHUP) {
> > + spin_lock(&vq->irq_lock);
> > + if (vq->virqfd == virqfd) {
> > + vq->virqfd = NULL;
> > + virqfd_deactivate(virqfd);
> > + }
> > + spin_unlock(&vq->irq_lock);
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +static void vduse_virqfd_ptable_queue_proc(struct file *file,
> > + wait_queue_head_t *wqh, poll_table *pt)
> > +{
> > + struct vduse_virqfd *virqfd = container_of(pt, struct vduse_virqfd, pt);
> > +
> > + add_wait_queue(wqh, &virqfd->wait);
> > +}
> > +
> > +int vduse_virqfd_setup(struct vduse_dev *dev,
> > + struct vduse_vq_eventfd *eventfd)
> > +{
> > + struct vduse_virqfd *virqfd;
> > + struct fd irqfd;
> > + struct eventfd_ctx *ctx;
> > + struct vduse_virtqueue *vq;
> > + __poll_t events;
> > + int ret;
> > +
> > + if (eventfd->index >= dev->vq_num)
> > + return -EINVAL;
> > +
> > + vq = &dev->vqs[eventfd->index];
> > + virqfd = kzalloc(sizeof(*virqfd), GFP_KERNEL);
> > + if (!virqfd)
> > + return -ENOMEM;
> > +
> > + INIT_WORK(&virqfd->shutdown, vduse_virqfd_shutdown);
> > + INIT_WORK(&virqfd->inject, vduse_virqfd_inject);
> > +
> > + ret = -EBADF;
> > + irqfd = fdget(eventfd->fd);
> > + if (!irqfd.file)
> > + goto err_fd;
> > +
> > + ctx = eventfd_ctx_fileget(irqfd.file);
> > + if (IS_ERR(ctx)) {
> > + ret = PTR_ERR(ctx);
> > + goto err_ctx;
> > + }
> > +
> > + virqfd->vq = vq;
> > + virqfd->ctx = ctx;
> > + spin_lock(&vq->irq_lock);
> > + if (vq->virqfd)
> > + virqfd_deactivate(virqfd);
> > + vq->virqfd = virqfd;
> > + spin_unlock(&vq->irq_lock);
> > +
> > + init_waitqueue_func_entry(&virqfd->wait, vduse_virqfd_wakeup);
> > + init_poll_funcptr(&virqfd->pt, vduse_virqfd_ptable_queue_proc);
> > +
> > + events = vfs_poll(irqfd.file, &virqfd->pt);
> > +
> > + /*
> > + * Check if there was an event already pending on the eventfd
> > + * before we registered and trigger it as if we didn't miss it.
> > + */
> > + if (events & EPOLLIN)
> > + schedule_work(&virqfd->inject);
> > +
> > + fdput(irqfd);
> > +
> > + return 0;
> > +err_ctx:
> > + fdput(irqfd);
> > +err_fd:
> > + kfree(virqfd);
> > + return ret;
> > +}
> > +
> > +void vduse_virqfd_release(struct vduse_dev *dev)
> > +{
> > + int i;
> > +
> > + for (i = 0; i < dev->vq_num; i++) {
> > + struct vduse_virtqueue *vq = &dev->vqs[i];
> > +
> > + spin_lock(&vq->irq_lock);
> > + if (vq->virqfd) {
> > + virqfd_deactivate(vq->virqfd);
> > + vq->virqfd = NULL;
> > + }
> > + spin_unlock(&vq->irq_lock);
> > + }
> > + flush_workqueue(vduse_irqfd_cleanup_wq);
> > +}
> > +
> > +int vduse_virqfd_init(void)
> > +{
> > + vduse_irqfd_cleanup_wq = alloc_workqueue("vduse-irqfd-cleanup",
> > + WQ_UNBOUND, 0);
> > + if (!vduse_irqfd_cleanup_wq)
> > + return -ENOMEM;
> > +
> > + return 0;
> > +}
> > +
> > +void vduse_virqfd_exit(void)
> > +{
> > + destroy_workqueue(vduse_irqfd_cleanup_wq);
> > +}
> > +
> > +void vduse_vq_kick(struct vduse_virtqueue *vq)
> > +{
> > + spin_lock(&vq->kick_lock);
> > + if (vq->ready && vq->kickfd)
> > + eventfd_signal(vq->kickfd, 1);
> > + spin_unlock(&vq->kick_lock);
> > +}
> > +
> > +int vduse_kickfd_setup(struct vduse_dev *dev,
> > + struct vduse_vq_eventfd *eventfd)
> > +{
> > + struct eventfd_ctx *ctx;
> > + struct vduse_virtqueue *vq;
> > +
> > + if (eventfd->index >= dev->vq_num)
> > + return -EINVAL;
> > +
> > + vq = &dev->vqs[eventfd->index];
> > + ctx = eventfd_ctx_fdget(eventfd->fd);
> > + if (IS_ERR(ctx))
> > + return PTR_ERR(ctx);
> > +
> > + spin_lock(&vq->kick_lock);
> > + if (vq->kickfd)
> > + eventfd_ctx_put(vq->kickfd);
> > + vq->kickfd = ctx;
> > + spin_unlock(&vq->kick_lock);
> > +
> > + return 0;
> > +}
> > +
> > +void vduse_kickfd_release(struct vduse_dev *dev)
> > +{
> > + 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);
> > + }
> > +}
> > diff --git a/drivers/vdpa/vdpa_user/eventfd.h b/drivers/vdpa/vdpa_user/eventfd.h
> > new file mode 100644
> > index 000000000000..14269ff27f47
> > --- /dev/null
> > +++ b/drivers/vdpa/vdpa_user/eventfd.h
> > @@ -0,0 +1,48 @@
> > +/* SPDX-License-Identifier: GPL-2.0-only */
> > +/*
> > + * Eventfd support for VDUSE
> > + *
> > + * Copyright (C) 2020 Bytedance Inc. and/or its affiliates. All rights reserved.
> > + *
> > + * Author: Xie Yongji <xieyongji@...edance.com>
> > + *
> > + */
> > +
> > +#ifndef _VDUSE_EVENTFD_H
> > +#define _VDUSE_EVENTFD_H
> > +
> > +#include <linux/eventfd.h>
> > +#include <linux/poll.h>
> > +#include <linux/wait.h>
> > +#include <uapi/linux/vduse.h>
> > +
> > +#include "vduse.h"
> > +
> > +struct vduse_dev;
> > +
> > +struct vduse_virqfd {
> > + struct eventfd_ctx *ctx;
> > + struct vduse_virtqueue *vq;
> > + struct work_struct inject;
> > + struct work_struct shutdown;
> > + wait_queue_entry_t wait;
> > + poll_table pt;
> > +};
> > +
> > +int vduse_virqfd_setup(struct vduse_dev *dev,
> > + struct vduse_vq_eventfd *eventfd);
> > +
> > +void vduse_virqfd_release(struct vduse_dev *dev);
> > +
> > +int vduse_virqfd_init(void);
> > +
> > +void vduse_virqfd_exit(void);
> > +
> > +void vduse_vq_kick(struct vduse_virtqueue *vq);
> > +
> > +int vduse_kickfd_setup(struct vduse_dev *dev,
> > + struct vduse_vq_eventfd *eventfd);
> > +
> > +void vduse_kickfd_release(struct vduse_dev *dev);
> > +
> > +#endif /* _VDUSE_EVENTFD_H */
> > diff --git a/drivers/vdpa/vdpa_user/iova_domain.c b/drivers/vdpa/vdpa_user/iova_domain.c
> > new file mode 100644
> > index 000000000000..cdfef8e9f9d6
> > --- /dev/null
> > +++ b/drivers/vdpa/vdpa_user/iova_domain.c
> > @@ -0,0 +1,426 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/*
> > + * MMU-based IOMMU implementation
> > + *
> > + * Copyright (C) 2020 Bytedance Inc. and/or its affiliates. All rights reserved.
> > + *
> > + * Author: Xie Yongji <xieyongji@...edance.com>
> > + *
> > + */
> > +
> > +#include <linux/slab.h>
> > +#include <linux/file.h>
> > +#include <linux/anon_inodes.h>
> > +
> > +#include "iova_domain.h"
> > +
> > +#define IOVA_START_PFN 1
> > +#define IOVA_ALLOC_ORDER 12
> > +#define IOVA_ALLOC_SIZE (1 << IOVA_ALLOC_ORDER)
>
>
> Can this work for all archs (e.g why not use PAGE_SIZE)?
>
It can work for all archs. Use IOVA_ALLOC_SIZE might save some space
in some cases/archs (e.g. PAGE_SIZE = 64K) when we have lots of
small-size I/Os.
>
> > +
> > +#define CONSISTENT_DMA_SIZE (1024 * 1024 * 1024)
> > +
> > +static inline struct page *
> > +vduse_domain_get_bounce_page(struct vduse_iova_domain *domain,
> > + unsigned long iova)
> > +{
> > + unsigned long index = iova >> PAGE_SHIFT;
> > +
> > + return domain->bounce_pages[index];
> > +}
> > +
> > +static inline void
> > +vduse_domain_set_bounce_page(struct vduse_iova_domain *domain,
> > + unsigned long iova, struct page *page)
> > +{
> > + unsigned long index = iova >> PAGE_SHIFT;
> > +
> > + domain->bounce_pages[index] = page;
> > +}
> > +
> > +static struct vduse_iova_map *
> > +vduse_domain_alloc_iova_map(struct vduse_iova_domain *domain,
> > + unsigned long iova, unsigned long orig,
> > + size_t size, enum dma_data_direction dir)
> > +{
> > + struct vduse_iova_map *map;
> > +
> > + map = kzalloc(sizeof(struct vduse_iova_map), GFP_ATOMIC);
> > + if (!map)
> > + return NULL;
> > +
> > + map->iova.start = iova;
> > + map->iova.last = iova + size - 1;
> > + map->orig = orig;
> > + map->size = size;
> > + map->dir = dir;
> > +
> > + return map;
> > +}
> > +
> > +static struct page *
> > +vduse_domain_get_mapping_page(struct vduse_iova_domain *domain,
> > + unsigned long iova)
> > +{
> > + unsigned long start = iova & PAGE_MASK;
> > + unsigned long last = start + PAGE_SIZE - 1;
> > + struct vduse_iova_map *map;
> > + struct interval_tree_node *node;
> > + struct page *page = NULL;
> > +
> > + spin_lock(&domain->map_lock);
> > + node = interval_tree_iter_first(&domain->mappings, start, last);
> > + if (!node)
> > + goto out;
> > +
> > + map = container_of(node, struct vduse_iova_map, iova);
> > + page = virt_to_page(map->orig + iova - map->iova.start);
> > + get_page(page);
> > +out:
> > + spin_unlock(&domain->map_lock);
> > +
> > + return page;
> > +}
> > +
> > +static struct page *
> > +vduse_domain_alloc_bounce_page(struct vduse_iova_domain *domain,
> > + unsigned long iova)
> > +{
> > + unsigned long start = iova & PAGE_MASK;
> > + unsigned long last = start + PAGE_SIZE - 1;
> > + struct vduse_iova_map *map;
> > + struct interval_tree_node *node;
> > + struct page *page = NULL, *new_page = alloc_page(GFP_KERNEL);
> > +
> > + if (!new_page)
> > + return NULL;
> > +
> > + spin_lock(&domain->map_lock);
> > + node = interval_tree_iter_first(&domain->mappings, start, last);
> > + if (!node) {
> > + __free_page(new_page);
> > + goto out;
> > + }
> > + page = vduse_domain_get_bounce_page(domain, iova);
> > + if (page) {
> > + get_page(page);
> > + __free_page(new_page);
>
>
> Let's delay the allocation of new_page until it is really required.
If so, we need to allocate the page in atomic context.
>
> > + goto out;
> > + }
> > + vduse_domain_set_bounce_page(domain, iova, new_page);
> > + get_page(new_page);
> > + page = new_page;
> > +
> > + while (node) {
>
>
> I may miss something but which case should we do the loop here?
>
When IOVA_ALLOC_SIZE != PAGE_SIZE
>
> > + unsigned int src_offset = 0, dst_offset = 0;
> > + void *src, *dst;
> > + size_t copy_len;
> > +
> > + map = container_of(node, struct vduse_iova_map, iova);
> > + node = interval_tree_iter_next(node, start, last);
> > + if (map->dir == DMA_FROM_DEVICE)
> > + continue;
> > +
> > + if (start > map->iova.start)
> > + src_offset = start - map->iova.start;
> > + else
> > + dst_offset = map->iova.start - start;
> > +
> > + src = (void *)(map->orig + src_offset);
> > + dst = page_address(page) + dst_offset;
> > + copy_len = min_t(size_t, map->size - src_offset,
> > + PAGE_SIZE - dst_offset);
> > + memcpy(dst, src, copy_len);
> > + }
> > +out:
> > + spin_unlock(&domain->map_lock);
> > +
> > + return page;
> > +}
> > +
> > +static void
> > +vduse_domain_free_bounce_pages(struct vduse_iova_domain *domain,
> > + unsigned long iova, size_t size)
> > +{
> > + struct page *page;
> > + struct interval_tree_node *node;
> > + unsigned long last = iova + size - 1;
> > +
> > + spin_lock(&domain->map_lock);
> > + node = interval_tree_iter_first(&domain->mappings, iova, last);
> > + if (WARN_ON(node))
> > + goto out;
> > +
> > + while (size > 0) {
> > + page = vduse_domain_get_bounce_page(domain, iova);
> > + if (page) {
> > + vduse_domain_set_bounce_page(domain, iova, NULL);
> > + __free_page(page);
> > + }
> > + size -= PAGE_SIZE;
> > + iova += PAGE_SIZE;
> > + }
> > +out:
> > + spin_unlock(&domain->map_lock);
> > +}
> > +
> > +static void vduse_domain_bounce(struct vduse_iova_domain *domain,
> > + unsigned long iova, unsigned long orig,
> > + size_t size, enum dma_data_direction dir)
> > +{
> > + unsigned int offset = offset_in_page(iova);
> > +
> > + while (size) {
> > + struct page *p = vduse_domain_get_bounce_page(domain, iova);
> > + size_t copy_len = min_t(size_t, PAGE_SIZE - offset, size);
> > + void *addr;
> > +
> > + WARN_ON(!p && dir == DMA_FROM_DEVICE);
> > +
> > + if (p) {
> > + addr = page_address(p) + offset;
> > + if (dir == DMA_TO_DEVICE)
> > + memcpy(addr, (void *)orig, copy_len);
> > + else if (dir == DMA_FROM_DEVICE)
> > + memcpy((void *)orig, addr, copy_len);
> > + }
> > +
> > + size -= copy_len;
> > + orig += copy_len;
> > + iova += copy_len;
> > + offset = 0;
> > + }
> > +}
> > +
> > +static unsigned long vduse_domain_alloc_iova(struct iova_domain *iovad,
> > + unsigned long size, unsigned long limit)
> > +{
> > + unsigned long shift = iova_shift(iovad);
> > + unsigned long iova_len = iova_align(iovad, size) >> shift;
> > + unsigned long iova_pfn;
> > +
> > + if (iova_len < (1 << (IOVA_RANGE_CACHE_MAX_SIZE - 1)))
> > + iova_len = roundup_pow_of_two(iova_len);
> > + iova_pfn = alloc_iova_fast(iovad, iova_len, limit >> shift, true);
> > +
> > + return iova_pfn << shift;
> > +}
> > +
> > +static void vduse_domain_free_iova(struct iova_domain *iovad,
> > + unsigned long iova, size_t size)
> > +{
> > + unsigned long shift = iova_shift(iovad);
> > + unsigned long iova_len = iova_align(iovad, size) >> shift;
> > +
> > + free_iova_fast(iovad, iova >> shift, iova_len);
> > +}
> > +
> > +dma_addr_t vduse_domain_map_page(struct vduse_iova_domain *domain,
> > + struct page *page, unsigned long offset,
> > + size_t size, enum dma_data_direction dir,
> > + unsigned long attrs)
> > +{
> > + struct iova_domain *iovad = &domain->stream_iovad;
> > + unsigned long limit = domain->bounce_size - 1;
> > + unsigned long iova = vduse_domain_alloc_iova(iovad, size, limit);
> > + unsigned long orig = (unsigned long)page_address(page) + offset;
> > + struct vduse_iova_map *map;
> > +
> > + if (!iova)
> > + return DMA_MAPPING_ERROR;
> > +
> > + map = vduse_domain_alloc_iova_map(domain, iova, orig, size, dir);
> > + if (!map) {
> > + vduse_domain_free_iova(iovad, iova, size);
> > + return DMA_MAPPING_ERROR;
> > + }
> > +
> > + spin_lock(&domain->map_lock);
> > + interval_tree_insert(&map->iova, &domain->mappings);
> > + spin_unlock(&domain->map_lock);
> > +
> > + if (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL)
> > + vduse_domain_bounce(domain, iova, orig, size, DMA_TO_DEVICE);
> > +
> > + return (dma_addr_t)iova;
> > +}
> > +
> > +void vduse_domain_unmap_page(struct vduse_iova_domain *domain,
> > + dma_addr_t dma_addr, size_t size,
> > + enum dma_data_direction dir, unsigned long attrs)
> > +{
> > + struct iova_domain *iovad = &domain->stream_iovad;
> > + unsigned long iova = (unsigned long)dma_addr;
> > + struct interval_tree_node *node;
> > + struct vduse_iova_map *map;
> > +
> > + spin_lock(&domain->map_lock);
> > + node = interval_tree_iter_first(&domain->mappings, iova, iova + 1);
> > + if (WARN_ON(!node)) {
> > + spin_unlock(&domain->map_lock);
> > + return;
> > + }
> > + interval_tree_remove(node, &domain->mappings);
> > + spin_unlock(&domain->map_lock);
> > +
> > + map = container_of(node, struct vduse_iova_map, iova);
> > + if (dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL)
> > + vduse_domain_bounce(domain, iova, map->orig,
> > + size, DMA_FROM_DEVICE);
> > + vduse_domain_free_iova(iovad, iova, size);
> > + kfree(map);
> > +}
> > +
> > +void *vduse_domain_alloc_coherent(struct vduse_iova_domain *domain,
> > + size_t size, dma_addr_t *dma_addr,
> > + gfp_t flag, unsigned long attrs)
> > +{
> > + struct iova_domain *iovad = &domain->consistent_iovad;
> > + unsigned long limit = domain->bounce_size + CONSISTENT_DMA_SIZE - 1;
> > + unsigned long iova = vduse_domain_alloc_iova(iovad, size, limit);
> > + void *orig = alloc_pages_exact(size, flag);
> > + struct vduse_iova_map *map;
> > +
> > + if (!iova || !orig)
> > + goto err;
> > +
> > + map = vduse_domain_alloc_iova_map(domain, iova, (unsigned long)orig,
> > + size, DMA_BIDIRECTIONAL);
> > + if (!map)
> > + goto err;
> > +
> > + spin_lock(&domain->map_lock);
> > + interval_tree_insert(&map->iova, &domain->mappings);
> > + spin_unlock(&domain->map_lock);
> > + *dma_addr = (dma_addr_t)iova;
> > +
> > + return orig;
> > +err:
> > + *dma_addr = DMA_MAPPING_ERROR;
> > + if (orig)
> > + free_pages_exact(orig, size);
> > + if (iova)
> > + vduse_domain_free_iova(iovad, iova, size);
> > +
> > + return NULL;
> > +}
> > +
> > +void vduse_domain_free_coherent(struct vduse_iova_domain *domain, size_t size,
> > + void *vaddr, dma_addr_t dma_addr,
> > + unsigned long attrs)
> > +{
> > + struct iova_domain *iovad = &domain->consistent_iovad;
> > + unsigned long iova = (unsigned long)dma_addr;
> > + struct interval_tree_node *node;
> > + struct vduse_iova_map *map;
> > +
> > + spin_lock(&domain->map_lock);
> > + node = interval_tree_iter_first(&domain->mappings, iova, iova + 1);
> > + if (WARN_ON(!node)) {
> > + spin_unlock(&domain->map_lock);
> > + return;
> > + }
> > + interval_tree_remove(node, &domain->mappings);
> > + spin_unlock(&domain->map_lock);
> > +
> > + map = container_of(node, struct vduse_iova_map, iova);
> > + vduse_domain_free_iova(iovad, iova, size);
> > + free_pages_exact(vaddr, size);
> > + kfree(map);
> > +}
> > +
> > +static vm_fault_t vduse_domain_mmap_fault(struct vm_fault *vmf)
> > +{
> > + struct vduse_iova_domain *domain = vmf->vma->vm_private_data;
> > + unsigned long iova = vmf->pgoff << PAGE_SHIFT;
> > + struct page *page;
> > +
> > + if (!domain)
> > + return VM_FAULT_SIGBUS;
> > +
> > + if (iova < domain->bounce_size)
> > + page = vduse_domain_alloc_bounce_page(domain, iova);
> > + else
> > + page = vduse_domain_get_mapping_page(domain, iova);
> > +
> > + if (!page)
> > + return VM_FAULT_SIGBUS;
> > +
> > + vmf->page = page;
> > +
> > + return 0;
> > +}
> > +
> > +static const struct vm_operations_struct vduse_domain_mmap_ops = {
> > + .fault = vduse_domain_mmap_fault,
> > +};
> > +
> > +static int vduse_domain_mmap(struct file *file, struct vm_area_struct *vma)
> > +{
> > + struct vduse_iova_domain *domain = file->private_data;
> > +
> > + vma->vm_flags |= VM_DONTCOPY | VM_DONTDUMP | VM_DONTEXPAND;
> > + vma->vm_private_data = domain;
> > + vma->vm_ops = &vduse_domain_mmap_ops;
> > +
> > + return 0;
> > +}
> > +
> > +static int vduse_domain_release(struct inode *inode, struct file *file)
> > +{
> > + struct vduse_iova_domain *domain = file->private_data;
> > +
> > + vduse_domain_free_bounce_pages(domain, 0, domain->bounce_size);
> > + put_iova_domain(&domain->stream_iovad);
> > + put_iova_domain(&domain->consistent_iovad);
> > + vfree(domain->bounce_pages);
> > + kfree(domain);
> > +
> > + return 0;
> > +}
> > +
> > +static const struct file_operations vduse_domain_fops = {
> > + .mmap = vduse_domain_mmap,
> > + .release = vduse_domain_release,
> > +};
>
>
> It's better to explain the reason for introducing a dedicated file for
> mmap() here.
>
To make the implementation of iova_domain independent with vduse_dev.
>
> > +
> > +void vduse_domain_destroy(struct vduse_iova_domain *domain)
> > +{
> > + fput(domain->file);
> > +}
> > +
> > +struct vduse_iova_domain *vduse_domain_create(size_t bounce_size)
> > +{
> > + struct vduse_iova_domain *domain;
> > + struct file *file;
> > + unsigned long bounce_pfns = PAGE_ALIGN(bounce_size) >> PAGE_SHIFT;
> > +
> > + domain = kzalloc(sizeof(*domain), GFP_KERNEL);
> > + if (!domain)
> > + return NULL;
> > +
> > + domain->bounce_size = PAGE_ALIGN(bounce_size);
> > + domain->bounce_pages = vzalloc(bounce_pfns * sizeof(struct page *));
> > + if (!domain->bounce_pages)
> > + goto err_page;
> > +
> > + file = anon_inode_getfile("[vduse-domain]", &vduse_domain_fops,
> > + domain, O_RDWR);
> > + if (IS_ERR(file))
> > + goto err_file;
> > +
> > + domain->file = file;
> > + spin_lock_init(&domain->map_lock);
> > + domain->mappings = RB_ROOT_CACHED;
> > + init_iova_domain(&domain->stream_iovad,
> > + IOVA_ALLOC_SIZE, IOVA_START_PFN);
> > + init_iova_domain(&domain->consistent_iovad,
> > + PAGE_SIZE, bounce_pfns);
> > +
> > + return domain;
> > +err_file:
> > + vfree(domain->bounce_pages);
> > +err_page:
> > + kfree(domain);
> > + return NULL;
> > +}
> > diff --git a/drivers/vdpa/vdpa_user/iova_domain.h b/drivers/vdpa/vdpa_user/iova_domain.h
> > new file mode 100644
> > index 000000000000..cc61866acb56
> > --- /dev/null
> > +++ b/drivers/vdpa/vdpa_user/iova_domain.h
> > @@ -0,0 +1,68 @@
> > +/* SPDX-License-Identifier: GPL-2.0-only */
> > +/*
> > + * MMU-based IOMMU implementation
> > + *
> > + * Copyright (C) 2020 Bytedance Inc. and/or its affiliates. All rights reserved.
> > + *
> > + * Author: Xie Yongji <xieyongji@...edance.com>
> > + *
> > + */
> > +
> > +#ifndef _VDUSE_IOVA_DOMAIN_H
> > +#define _VDUSE_IOVA_DOMAIN_H
> > +
> > +#include <linux/iova.h>
> > +#include <linux/interval_tree.h>
> > +#include <linux/dma-mapping.h>
> > +
> > +struct vduse_iova_map {
> > + struct interval_tree_node iova;
> > + unsigned long orig;
>
>
> Need a better name, probably "va"?
>
Fine.
>
> > + size_t size;
> > + enum dma_data_direction dir;
> > +};
> > +
> > +struct vduse_iova_domain {
> > + struct iova_domain stream_iovad;
> > + struct iova_domain consistent_iovad;
> > + struct page **bounce_pages;
> > + size_t bounce_size;
> > + struct rb_root_cached mappings;
>
>
> We had IOTLB, any reason for this extra mappings here?
>
It is used to store iova <-> vduse_iova_map (vaddr, size, dir)
mapping. We must use it to know how to do DMA bouncing during dma
unmapping.
>
> > + spinlock_t map_lock;
> > + struct file *file;
> > +};
> > +
> > +static inline struct file *
> > +vduse_domain_file(struct vduse_iova_domain *domain)
> > +{
> > + return domain->file;
> > +}
> > +
> > +static inline unsigned long
> > +vduse_domain_get_offset(struct vduse_iova_domain *domain, unsigned long iova)
> > +{
> > + return iova;
> > +}
> > +
> > +dma_addr_t vduse_domain_map_page(struct vduse_iova_domain *domain,
> > + struct page *page, unsigned long offset,
> > + size_t size, enum dma_data_direction dir,
> > + unsigned long attrs);
> > +
> > +void vduse_domain_unmap_page(struct vduse_iova_domain *domain,
> > + dma_addr_t dma_addr, size_t size,
> > + enum dma_data_direction dir, unsigned long attrs);
> > +
> > +void *vduse_domain_alloc_coherent(struct vduse_iova_domain *domain,
> > + size_t size, dma_addr_t *dma_addr,
> > + gfp_t flag, unsigned long attrs);
> > +
> > +void vduse_domain_free_coherent(struct vduse_iova_domain *domain, size_t size,
> > + void *vaddr, dma_addr_t dma_addr,
> > + unsigned long attrs);
> > +
> > +void vduse_domain_destroy(struct vduse_iova_domain *domain);
> > +
> > +struct vduse_iova_domain *vduse_domain_create(size_t bounce_size);
> > +
> > +#endif /* _VDUSE_IOVA_DOMAIN_H */
> > diff --git a/drivers/vdpa/vdpa_user/vduse.h b/drivers/vdpa/vdpa_user/vduse.h
> > new file mode 100644
> > index 000000000000..3566d229382e
> > --- /dev/null
> > +++ b/drivers/vdpa/vdpa_user/vduse.h
> > @@ -0,0 +1,62 @@
> > +/* 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>
> > + *
> > + */
> > +
> > +#ifndef _VDUSE_H
> > +#define _VDUSE_H
> > +
> > +#include <linux/eventfd.h>
> > +#include <linux/wait.h>
> > +#include <linux/vdpa.h>
> > +
> > +#include "iova_domain.h"
> > +#include "eventfd.h"
> > +
> > +struct vduse_virtqueue {
> > + u16 index;
> > + bool ready;
> > + spinlock_t kick_lock;
> > + spinlock_t irq_lock;
> > + struct eventfd_ctx *kickfd;
> > + struct vduse_virqfd *virqfd;
> > + void *private;
> > + irqreturn_t (*cb)(void *data);
> > +};
> > +
> > +struct vduse_dev;
> > +
> > +struct vduse_vdpa {
> > + struct vdpa_device vdpa;
> > + struct vduse_dev *dev;
> > +};
> > +
> > +struct vduse_dev {
> > + struct vduse_vdpa *vdev;
> > + struct mutex lock;
> > + struct vduse_virtqueue *vqs;
> > + struct vduse_iova_domain *domain;
> > + struct vhost_iotlb *iommu;
> > + spinlock_t iommu_lock;
> > + atomic_t bounce_map;
> > + 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;
> > + u32 id;
> > + u16 vq_size_max;
> > + u16 vq_num;
> > + u32 vq_align;
> > + u32 device_id;
> > + u32 vendor_id;
> > +};
> > +
> > +#endif /* _VDUSE_H_ */
> > diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
> > new file mode 100644
> > index 000000000000..1cf759bc5914
> > --- /dev/null
> > +++ b/drivers/vdpa/vdpa_user/vduse_dev.c
> > @@ -0,0 +1,1217 @@
> > +// 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/device.h>
> > +#include <linux/eventfd.h>
> > +#include <linux/slab.h>
> > +#include <linux/wait.h>
> > +#include <linux/dma-map-ops.h>
> > +#include <linux/anon_inodes.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 "vduse.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"
> > +
> > +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;
> > + refcount_t refcnt;
>
>
> The reference count here will bring extra complexity. I think we can
> sync through msg_lock.
>
Do you mean using wait_event_interruptible_locked() and
wake_up_locked()? I think it works.
>
>
> > +};
> > +
> > +static struct workqueue_struct *vduse_vdpa_wq;
> > +static DEFINE_MUTEX(vduse_lock);
> > +static LIST_HEAD(vduse_devs);
> > +
> > +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_dev_new_msg(struct vduse_dev *dev, int type)
> > +{
> > + struct vduse_dev_msg *msg = kzalloc(sizeof(*msg),
> > + GFP_KERNEL | __GFP_NOFAIL);
> > +
> > + msg->req.type = type;
> > + msg->req.unique = atomic64_fetch_inc(&dev->msg_unique);
>
>
> This looks not safe, let's use idr here.
>
Could you give more details? Looks like idr should not used in this
case which can not tolerate failure. And using a list to store the msg
is better than using idr when the msg needs to be re-inserted in some
cases.
>
> > + init_waitqueue_head(&msg->waitq);
> > + refcount_set(&msg->refcnt, 1);
> > +
> > + return msg;
> > +}
> > +
> > +static void vduse_dev_msg_get(struct vduse_dev_msg *msg)
> > +{
> > + refcount_inc(&msg->refcnt);
> > +}
> > +
> > +static void vduse_dev_msg_put(struct vduse_dev_msg *msg)
> > +{
> > + if (refcount_dec_and_test(&msg->refcnt))
> > + kfree(msg);
> > +}
> > +
> > +static struct vduse_dev_msg *vduse_dev_find_msg(struct vduse_dev *dev,
> > + struct list_head *head,
> > + uint32_t unique)
> > +{
> > + struct vduse_dev_msg *tmp, *msg = NULL;
> > +
> > + spin_lock(&dev->msg_lock);
> > + list_for_each_entry(tmp, head, list) {
> > + if (tmp->req.unique == unique) {
> > + msg = tmp;
> > + list_del(&tmp->list);
> > + break;
> > + }
> > + }
> > + spin_unlock(&dev->msg_lock);
> > +
> > + return msg;
> > +}
> > +
> > +static struct vduse_dev_msg *vduse_dev_dequeue_msg(struct vduse_dev *dev,
> > + struct list_head *head)
> > +{
> > + struct vduse_dev_msg *msg = NULL;
> > +
> > + spin_lock(&dev->msg_lock);
> > + if (!list_empty(head)) {
> > + msg = list_first_entry(head, struct vduse_dev_msg, list);
> > + list_del(&msg->list);
> > + }
> > + spin_unlock(&dev->msg_lock);
> > +
> > + return msg;
> > +}
> > +
> > +static void vduse_dev_enqueue_msg(struct vduse_dev *dev,
> > + struct vduse_dev_msg *msg, struct list_head *head)
> > +{
> > + spin_lock(&dev->msg_lock);
> > + list_add_tail(&msg->list, head);
> > + spin_unlock(&dev->msg_lock);
> > +}
> > +
> > +static int vduse_dev_msg_sync(struct vduse_dev *dev, struct vduse_dev_msg *msg)
> > +{
> > + int ret;
> > +
> > + vduse_dev_enqueue_msg(dev, msg, &dev->send_list);
> > + wake_up(&dev->waitq);
> > + wait_event(msg->waitq, msg->completed);
>
>
> This is uninterruptible wait, it means if the userspace forget to
> process the command, we will stuck here forever.
>
Yes, wait_event_interruptible() should be better here.
>
> > + /* coupled with smp_wmb() in vduse_dev_msg_complete() */
> > + smp_rmb();
>
>
> Instead of using barriers, I wonder why not simply use msg lock here?
>
As mentioned above, using
wait_event_interruptible_locked()/wake_up_locked() is OK to me.
>
> > + ret = msg->resp.result;
> > +
> > + return ret;
> > +}
> > +
> > +static void vduse_dev_msg_complete(struct vduse_dev_msg *msg,
> > + struct vduse_dev_response *resp)
> > +{
> > + vduse_dev_msg_get(msg);
> > + memcpy(&msg->resp, resp, sizeof(*resp));
> > + /* coupled with smp_rmb() in vduse_dev_msg_sync() */
> > + smp_wmb();
> > + msg->completed = 1;
> > + wake_up(&msg->waitq);
> > + vduse_dev_msg_put(msg);
> > +}
> > +
> > +static u64 vduse_dev_get_features(struct vduse_dev *dev)
> > +{
> > + struct vduse_dev_msg *msg = vduse_dev_new_msg(dev, VDUSE_GET_FEATURES);
> > + u64 features;
> > +
> > + vduse_dev_msg_sync(dev, msg);
> > + features = msg->resp.features;
> > + vduse_dev_msg_put(msg);
> > +
> > + return features;
> > +}
> > +
> > +static int vduse_dev_set_features(struct vduse_dev *dev, u64 features)
> > +{
> > + struct vduse_dev_msg *msg = vduse_dev_new_msg(dev, VDUSE_SET_FEATURES);
> > + int ret;
> > +
> > + msg->req.size = sizeof(features);
> > + msg->req.features = features;
> > +
> > + ret = vduse_dev_msg_sync(dev, msg);
> > + vduse_dev_msg_put(msg);
> > +
> > + return ret;
> > +}
> > +
> > +static u8 vduse_dev_get_status(struct vduse_dev *dev)
> > +{
> > + struct vduse_dev_msg *msg = vduse_dev_new_msg(dev, VDUSE_GET_STATUS);
> > + u8 status;
> > +
> > + vduse_dev_msg_sync(dev, msg);
> > + status = msg->resp.status;
> > + vduse_dev_msg_put(msg);
> > +
> > + return status;
> > +}
> > +
> > +static void vduse_dev_set_status(struct vduse_dev *dev, u8 status)
> > +{
> > + struct vduse_dev_msg *msg = vduse_dev_new_msg(dev, VDUSE_SET_STATUS);
> > +
> > + msg->req.size = sizeof(status);
> > + msg->req.status = status;
> > +
> > + vduse_dev_msg_sync(dev, msg);
> > + vduse_dev_msg_put(msg);
> > +}
> > +
> > +static void vduse_dev_get_config(struct vduse_dev *dev, unsigned int offset,
> > + void *buf, unsigned int len)
> > +{
> > + struct vduse_dev_msg *msg = vduse_dev_new_msg(dev, VDUSE_GET_CONFIG);
> > +
> > + WARN_ON(len > sizeof(msg->req.config.data));
> > +
> > + msg->req.size = sizeof(struct vduse_dev_config_data);
> > + msg->req.config.offset = offset;
> > + msg->req.config.len = len;
> > + vduse_dev_msg_sync(dev, msg);
> > + memcpy(buf, msg->resp.config.data, len);
> > + vduse_dev_msg_put(msg);
> > +}
> > +
> > +static void vduse_dev_set_config(struct vduse_dev *dev, unsigned int offset,
> > + const void *buf, unsigned int len)
> > +{
> > + struct vduse_dev_msg *msg = vduse_dev_new_msg(dev, VDUSE_SET_CONFIG);
> > +
> > + WARN_ON(len > sizeof(msg->req.config.data));
> > +
> > + msg->req.size = sizeof(struct vduse_dev_config_data);
> > + msg->req.config.offset = offset;
> > + msg->req.config.len = len;
> > + memcpy(msg->req.config.data, buf, len);
> > + vduse_dev_msg_sync(dev, msg);
> > + vduse_dev_msg_put(msg);
> > +}
> > +
> > +static void vduse_dev_set_vq_num(struct vduse_dev *dev,
> > + struct vduse_virtqueue *vq, u32 num)
> > +{
> > + struct vduse_dev_msg *msg = vduse_dev_new_msg(dev, VDUSE_SET_VQ_NUM);
> > +
> > + msg->req.size = sizeof(struct vduse_vq_num);
> > + msg->req.vq_num.index = vq->index;
> > + msg->req.vq_num.num = num;
> > +
> > + vduse_dev_msg_sync(dev, msg);
> > + vduse_dev_msg_put(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 = vduse_dev_new_msg(dev, VDUSE_SET_VQ_ADDR);
> > + int ret;
> > +
> > + msg->req.size = sizeof(struct vduse_vq_addr);
> > + 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;
> > +
> > + ret = vduse_dev_msg_sync(dev, msg);
> > + vduse_dev_msg_put(msg);
> > +
> > + return ret;
> > +}
> > +
> > +static void vduse_dev_set_vq_ready(struct vduse_dev *dev,
> > + struct vduse_virtqueue *vq, bool ready)
> > +{
> > + struct vduse_dev_msg *msg = vduse_dev_new_msg(dev, VDUSE_SET_VQ_READY);
> > +
> > + msg->req.size = sizeof(struct vduse_vq_ready);
> > + msg->req.vq_ready.index = vq->index;
> > + msg->req.vq_ready.ready = ready;
> > +
> > + vduse_dev_msg_sync(dev, msg);
> > + vduse_dev_msg_put(msg);
> > +}
> > +
> > +static bool vduse_dev_get_vq_ready(struct vduse_dev *dev,
> > + struct vduse_virtqueue *vq)
> > +{
> > + struct vduse_dev_msg *msg = vduse_dev_new_msg(dev, VDUSE_GET_VQ_READY);
> > + bool ready;
> > +
> > + msg->req.size = sizeof(struct vduse_vq_ready);
> > + msg->req.vq_ready.index = vq->index;
> > +
> > + vduse_dev_msg_sync(dev, msg);
> > + ready = msg->resp.vq_ready.ready;
> > + vduse_dev_msg_put(msg);
> > +
> > + return 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 = vduse_dev_new_msg(dev, VDUSE_GET_VQ_STATE);
> > + int ret;
> > +
> > + msg->req.size = sizeof(struct vduse_vq_state);
> > + msg->req.vq_state.index = vq->index;
> > +
> > + ret = vduse_dev_msg_sync(dev, msg);
> > + state->avail_index = msg->resp.vq_state.avail_idx;
> > + vduse_dev_msg_put(msg);
> > +
> > + 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 = vduse_dev_new_msg(dev, VDUSE_SET_VQ_STATE);
> > + int ret;
> > +
> > + msg->req.size = sizeof(struct vduse_vq_state);
> > + msg->req.vq_state.index = vq->index;
> > + msg->req.vq_state.avail_idx = state->avail_index;
> > +
> > + ret = vduse_dev_msg_sync(dev, msg);
> > + vduse_dev_msg_put(msg);
> > +
> > + return ret;
> > +}
> > +
> > +static int vduse_dev_update_iotlb(struct vduse_dev *dev,
> > + u64 start, u64 last)
> > +{
> > + struct vduse_dev_msg *msg;
> > + int ret;
> > +
> > + if (last < start)
> > + return -EINVAL;
> > +
> > + msg = vduse_dev_new_msg(dev, VDUSE_UPDATE_IOTLB);
>
>
> This is actually a IOTLB invalidation. So let's rename the function and
> message type.
>
Actually VDUSE_UPDATE_IOTLB now is used to notify userspace that IOTLB
is changed rather than IOTLB needs to be invalidated. Then userspace
can use GET_IOTLB ioctl to get the change. It seems to be more
friendly to userspace.
>
> > + msg->req.size = sizeof(struct vduse_iova_range);
> > + msg->req.iova.start = start;
> > + msg->req.iova.last = last;
> > +
> > + ret = vduse_dev_msg_sync(dev, msg);
> > + vduse_dev_msg_put(msg);
> > +
> > + return ret;
> > +}
> > +
> > +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;
> > +
> > + while (1) {
> > + msg = vduse_dev_dequeue_msg(dev, &dev->send_list);
> > + if (msg)
> > + break;
> > +
> > + if (file->f_flags & O_NONBLOCK)
> > + return -EAGAIN;
> > +
> > + ret = wait_event_interruptible_exclusive(dev->waitq,
> > + !list_empty(&dev->send_list));
> > + if (ret)
> > + return ret;
> > + }
> > + ret = copy_to_iter(&msg->req, size, to);
> > + if (ret != size) {
> > + vduse_dev_enqueue_msg(dev, msg, &dev->send_list);
> > + return -EFAULT;
> > + }
> > + vduse_dev_enqueue_msg(dev, msg, &dev->recv_list);
> > +
> > + 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;
> > +
> > + msg = vduse_dev_find_msg(dev, &dev->recv_list, resp.unique);
> > + if (!msg)
> > + return -EINVAL;
> > +
> > + vduse_dev_msg_complete(msg, &resp);
>
>
> So we had multiple types of requests/responses, is this better to
> introduce a queue based admin interface other than ioctl?
>
Sorry, I didn't get your point. What do you mean by queue-based admin
interface? Virtqueue-based?
>
> > +
> > + 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;
> > +
> > + return mask;
> > +}
> > +
> > +static int vduse_iotlb_add_range(struct vduse_dev *dev,
> > + u64 start, u64 last,
> > + u64 addr, unsigned int perm,
> > + struct file *file, u64 offset)
> > +{
> > + struct vhost_iotlb_file *iotlb_file;
> > + int ret;
> > +
> > + iotlb_file = kmalloc(sizeof(*iotlb_file), GFP_ATOMIC);
> > + if (!iotlb_file)
> > + return -ENOMEM;
> > +
> > + iotlb_file->file = get_file(file);
> > + iotlb_file->offset = offset;
> > +
> > + spin_lock(&dev->iommu_lock);
> > + ret = vhost_iotlb_add_range(dev->iommu, start, last,
> > + addr, perm, iotlb_file);
> > + spin_unlock(&dev->iommu_lock);
> > + if (ret) {
> > + fput(iotlb_file->file);
> > + kfree(iotlb_file);
> > + return ret;
> > + }
> > + return 0;
> > +}
> > +
> > +static void vduse_iotlb_del_range(struct vduse_dev *dev, u64 start, u64 last)
> > +{
> > + struct vhost_iotlb_file *iotlb_file;
> > + struct vhost_iotlb_map *map;
> > +
> > + spin_lock(&dev->iommu_lock);
> > + while ((map = vhost_iotlb_itree_first(dev->iommu, start, last))) {
> > + iotlb_file = (struct vhost_iotlb_file *)map->opaque;
> > + fput(iotlb_file->file);
> > + kfree(iotlb_file);
> > + vhost_iotlb_map_free(dev->iommu, map);
> > + }
> > + spin_unlock(&dev->iommu_lock);
> > +}
> > +
> > +static void vduse_dev_reset(struct vduse_dev *dev)
> > +{
> > + int i;
> > +
> > + atomic_set(&dev->bounce_map, 0);
> > + vduse_iotlb_del_range(dev, 0ULL, 0ULL - 1);
> > + vduse_dev_update_iotlb(dev, 0ULL, 0ULL - 1);
>
>
> ULLONG_MAX please.
>
OK.
>
> > +
> > + 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 = NULL;
> > + vq->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];
> > +
> > + vduse_vq_kick(vq);
> > +}
> > +
> > +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];
> > +
> > + vq->cb = cb->callback;
> > + vq->private = cb->private;
> > +}
> > +
> > +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);
> > + u64 fixed = (1ULL << VIRTIO_F_ACCESS_PLATFORM);
> > +
> > + return (vduse_dev_get_features(dev) | fixed);
> > +}
> > +
> > +static int vduse_vdpa_set_features(struct vdpa_device *vdpa, u64 features)
> > +{
> > + struct vduse_dev *dev = vdpa_to_vduse(vdpa);
> > +
> > + 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 */
>
>
> If it's not hard, let's add this. Otherwise we need a per device feature
> blacklist to filter out all features that depends on config interrupt.
>
Will do it.
>
> > +}
> > +
> > +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);
> > + else
> > + vduse_dev_update_iotlb(dev, 0ULL, 0ULL - 1);
>
>
> Any reason for such IOTLB invalidation here?
>
As I mentioned before, this is used to notify userspace to update the
IOTLB. Mainly for virtio-vdpa case.
>
> > +
> > + 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);
> > + struct vhost_iotlb_map *map;
> > + struct vhost_iotlb_file *iotlb_file;
> > + u64 start = 0ULL, last = 0ULL - 1;
> > + int ret = 0;
> > +
> > + vduse_iotlb_del_range(dev, start, last);
> > +
> > + for (map = vhost_iotlb_itree_first(iotlb, start, last); map;
> > + map = vhost_iotlb_itree_next(map, start, last)) {
> > + if (!map->opaque)
> > + continue;
>
>
> What will happen if we simply accept NULL opaque here?
>
No file to mmap in userspace. So it's useless.
>
> > +
> > + iotlb_file = (struct vhost_iotlb_file *)map->opaque;
> > + ret = vduse_iotlb_add_range(dev, map->start, map->last,
> > + map->addr, map->perm,
> > + iotlb_file->file,
> > + iotlb_file->offset);
> > + if (ret)
> > + break;
> > + }
> > + vduse_dev_update_iotlb(dev, start, last);
> > +
> > + 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;
> > +
> > + if (atomic_xchg(&vdev->bounce_map, 1) == 0 &&
> > + vduse_iotlb_add_range(vdev, 0, domain->bounce_size - 1,
> > + 0, VDUSE_ACCESS_RW,
>
>
> Is this safe to use VDUSE_ACCESS_RW here, consider we might have device
> readonly mappings.
>
This mapping is for the whole bounce buffer. Maybe userspace needs to
tell us if it only support readonly mappings.
>
> > + vduse_domain_file(domain),
> > + vduse_domain_get_offset(domain, 0))) {
> > + atomic_set(&vdev->bounce_map, 0);
> > + return DMA_MAPPING_ERROR;
> > + }
> > +
> > + 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;
> > +
> > + if (vduse_iotlb_add_range(vdev, iova, iova + size - 1,
> > + iova, VDUSE_ACCESS_RW,
> > + vduse_domain_file(domain),
> > + vduse_domain_get_offset(domain, iova))) {
> > + vduse_domain_free_coherent(domain, size, addr, iova, attrs);
> > + 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;
> > + unsigned long start = (unsigned long)dma_addr;
> > + unsigned long last = start + size - 1;
> > +
> > + vduse_iotlb_del_range(vdev, start, last);
> > + vduse_dev_update_iotlb(vdev, start, last);
> > + vduse_domain_free_coherent(domain, size, vaddr, dma_addr, attrs);
> > +}
> > +
> > +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 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;
> > +
> > + mutex_lock(&dev->lock);
> > + switch (cmd) {
> > + case VDUSE_IOTLB_GET_FD: {
> > + struct vduse_iotlb_entry entry;
> > + struct vhost_iotlb_map *map;
> > + struct vhost_iotlb_file *iotlb_file;
> > + struct file *f = NULL;
> > +
> > + ret = -EFAULT;
> > + if (copy_from_user(&entry, argp, sizeof(entry)))
> > + break;
> > +
> > + spin_lock(&dev->iommu_lock);
> > + map = vhost_iotlb_itree_first(dev->iommu, entry.start,
> > + entry.last);
> > + if (map) {
> > + iotlb_file = (struct vhost_iotlb_file *)map->opaque;
> > + f = get_file(iotlb_file->file);
> > + entry.offset = iotlb_file->offset;
> > + entry.start = map->start;
> > + entry.last = map->last;
> > + entry.perm = map->perm;
> > + }
> > + spin_unlock(&dev->iommu_lock);
> > + if (!f) {
> > + ret = -EINVAL;
> > + break;
> > + }
> > + if (copy_to_user(argp, &entry, sizeof(entry))) {
> > + fput(f);
> > + ret = -EFAULT;
> > + break;
> > + }
> > + ret = get_unused_fd_flags(perm_to_file_flags(entry.perm));
> > + if (ret < 0) {
> > + fput(f);
> > + break;
> > + }
> > + fd_install(ret, 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_VQ_SETUP_IRQFD: {
> > + struct vduse_vq_eventfd eventfd;
> > +
> > + ret = -EFAULT;
> > + if (copy_from_user(&eventfd, argp, sizeof(eventfd)))
> > + break;
> > +
> > + ret = vduse_virqfd_setup(dev, &eventfd);
> > + break;
> > + }
> > + }
> > + mutex_unlock(&dev->lock);
> > +
> > + return ret;
> > +}
> > +
> > +static int vduse_dev_release(struct inode *inode, struct file *file)
> > +{
> > + struct vduse_dev *dev = file->private_data;
> > +
> > + vduse_kickfd_release(dev);
> > + vduse_virqfd_release(dev);
> > + dev->connected = false;
> > +
> > + return 0;
> > +}
> > +
> > +static const struct file_operations vduse_dev_fops = {
> > + .owner = THIS_MODULE,
> > + .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;
> > +
> > + dev->iommu = vhost_iotlb_alloc(2048, 0);
>
>
> Is 2048 sufficient here?
>
How about letting userspace to define it?
>
> > + if (!dev->iommu) {
> > + kfree(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);
> > + atomic64_set(&dev->msg_unique, 0);
> > + spin_lock_init(&dev->iommu_lock);
> > + atomic_set(&dev->bounce_map, 0);
> > +
> > + init_waitqueue_head(&dev->waitq);
> > +
> > + return dev;
> > +}
> > +
> > +static void vduse_dev_destroy(struct vduse_dev *dev)
> > +{
> > + vhost_iotlb_free(dev->iommu);
> > + mutex_destroy(&dev->lock);
> > + kfree(dev);
> > +}
> > +
> > +static struct vduse_dev *vduse_find_dev(u32 id)
> > +{
> > + struct vduse_dev *tmp, *dev = NULL;
> > +
> > + list_for_each_entry(tmp, &vduse_devs, list) {
> > + if (tmp->id == id) {
> > + dev = tmp;
> > + break;
> > + }
> > + }
> > + return dev;
> > +}
> > +
> > +static int vduse_destroy_dev(u32 id)
> > +{
> > + struct vduse_dev *dev = vduse_find_dev(id);
> > +
> > + if (!dev)
> > + return -EINVAL;
> > +
> > + if (dev->vdev || dev->connected)
> > + return -EBUSY;
> > +
> > + list_del(&dev->list);
> > + kfree(dev->vqs);
> > + vduse_domain_destroy(dev->domain);
> > + vduse_dev_destroy(dev);
> > +
> > + return 0;
> > +}
> > +
> > +static int vduse_create_dev(struct vduse_dev_config *config)
> > +{
> > + int i, fd;
> > + struct vduse_dev *dev;
> > + char name[64];
> > +
> > + if (vduse_find_dev(config->id))
> > + return -EEXIST;
> > +
> > + dev = vduse_dev_create();
> > + if (!dev)
> > + return -ENOMEM;
> > +
> > + dev->id = config->id;
> > + dev->device_id = config->device_id;
> > + dev->vendor_id = config->vendor_id;
> > + dev->domain = vduse_domain_create(config->bounce_size);
>
>
> Do we need a upper limit of bounce_size?
>
I agree. Any comment for the value?
>
> > + 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;
> > + spin_lock_init(&dev->vqs[i].kick_lock);
> > + spin_lock_init(&dev->vqs[i].irq_lock);
> > + }
> > +
> > + snprintf(name, sizeof(name), "[vduse-dev:%u]", config->id);
> > + fd = anon_inode_getfd(name, &vduse_dev_fops, dev, O_RDWR | O_CLOEXEC);
>
>
> Any reason for closing on exec here?
>
Looks like we can remove this flag.
>
> > + if (fd < 0)
> > + goto err_fd;
> > +
> > + dev->connected = true;
> > + list_add(&dev->list, &vduse_devs);
> > +
> > + return fd;
> > +err_fd:
> > + kfree(dev->vqs);
> > +err_vqs:
> > + vduse_domain_destroy(dev->domain);
> > +err_domain:
> > + vduse_dev_destroy(dev);
> > + return fd;
> > +}
> > +
> > +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_CREATE_DEV: {
> > + struct vduse_dev_config config;
> > +
> > + ret = -EFAULT;
> > + if (copy_from_user(&config, argp, sizeof(config)))
> > + break;
> > +
> > + ret = vduse_create_dev(&config);
> > + break;
> > + }
> > + case VDUSE_DESTROY_DEV:
> > + ret = vduse_destroy_dev(arg);
> > + break;
> > + default:
> > + ret = -EINVAL;
> > + break;
> > + }
> > + mutex_unlock(&vduse_lock);
> > +
> > + return ret;
> > +}
> > +
> > +static const struct file_operations vduse_fops = {
> > + .owner = THIS_MODULE,
> > + .unlocked_ioctl = vduse_ioctl,
> > + .compat_ioctl = compat_ptr_ioctl,
> > + .llseek = noop_llseek,
> > +};
> > +
> > +static struct miscdevice vduse_misc = {
> > + .fops = &vduse_fops,
> > + .minor = MISC_DYNAMIC_MINOR,
> > + .name = "vduse",
> > +};
> > +
> > +static void vduse_parent_release(struct device *dev)
> > +{
> > +}
> > +
> > +static struct device vduse_parent = {
> > + .init_name = "vduse",
> > + .release = vduse_parent_release,
> > +};
> > +
> > +static struct vdpa_parent_dev parent_dev;
> > +
> > +static int vduse_dev_add_vdpa(struct vduse_dev *dev, const char *name)
> > +{
> > + struct vduse_vdpa *vdev = dev->vdev;
> > + int ret;
> > +
> > + if (vdev)
> > + return -EEXIST;
> > +
> > + vdev = vdpa_alloc_device(struct vduse_vdpa, vdpa, NULL,
> > + &vduse_vdpa_config_ops,
> > + dev->vq_num, name, true);
> > + if (!vdev)
> > + return -ENOMEM;
> > +
> > + 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)
> > + goto err;
> > +
> > + set_dma_ops(&vdev->vdpa.dev, &vduse_dev_dma_ops);
> > + vdev->vdpa.dma_dev = &vdev->vdpa.dev;
> > + vdev->vdpa.pdev = &parent_dev;
> > +
> > + ret = _vdpa_register_device(&vdev->vdpa);
> > + if (ret)
> > + goto err;
> > +
> > + dev->vdev = vdev;
> > +
> > + return 0;
> > +err:
> > + put_device(&vdev->vdpa.dev);
> > + return ret;
> > +}
> > +
> > +static struct vdpa_device *vdpa_dev_add(struct vdpa_parent_dev *pdev,
> > + const char *name, u32 device_id,
> > + struct nlattr **attrs)
> > +{
> > + u32 vduse_id;
> > + struct vduse_dev *dev;
> > + int ret = -EINVAL;
> > +
> > + if (!attrs[VDPA_ATTR_BACKEND_ID])
> > + return ERR_PTR(-EINVAL);
> > +
> > + mutex_lock(&vduse_lock);
> > + vduse_id = nla_get_u32(attrs[VDPA_ATTR_BACKEND_ID]);
>
>
> I wonder why not using name here?
>
Do you mean use the same name for both backend and frontend? If so, we
need to add a name for vduse device or replace id with name to
identify a vduse device. Which way do you prefer?
> And it looks to me it would be easier if we create a char device per
> vduse. This makes the device addressing more robust than passing id
> silently among processes.
>
It's OK to me.
>
> > + dev = vduse_find_dev(vduse_id);
> > + if (!dev)
> > + goto unlock;
> > +
> > + if (dev->device_id != device_id)
> > + goto unlock;
> > +
> > + ret = vduse_dev_add_vdpa(dev, name);
> > +unlock:
> > + mutex_unlock(&vduse_lock);
> > + if (ret)
> > + return ERR_PTR(ret);
> > +
> > + return &dev->vdev->vdpa;
> > +}
> > +
> > +static void vdpa_dev_del(struct vdpa_parent_dev *pdev, struct vdpa_device *dev)
> > +{
> > + _vdpa_unregister_device(dev);
> > +}
> > +
> > +static const struct vdpa_dev_ops vdpa_dev_parent_ops = {
> > + .dev_add = vdpa_dev_add,
> > + .dev_del = vdpa_dev_del
> > +};
> > +
> > +static struct virtio_device_id id_table[] = {
> > + { VIRTIO_DEV_ANY_ID, VIRTIO_DEV_ANY_ID },
> > + { 0 },
> > +};
> > +
> > +static struct vdpa_parent_dev parent_dev = {
> > + .device = &vduse_parent,
> > + .id_table = id_table,
> > + .ops = &vdpa_dev_parent_ops,
> > +};
> > +
> > +static int vduse_parentdev_init(void)
> > +{
> > + int ret;
> > +
> > + ret = device_register(&vduse_parent);
> > + if (ret)
> > + return ret;
> > +
> > + ret = vdpa_parentdev_register(&parent_dev);
> > + if (ret)
> > + goto err;
> > +
> > + return 0;
> > +err:
> > + device_unregister(&vduse_parent);
> > + return ret;
> > +}
> > +
> > +static void vduse_parentdev_exit(void)
> > +{
> > + vdpa_parentdev_unregister(&parent_dev);
> > + device_unregister(&vduse_parent);
> > +}
> > +
> > +static int vduse_init(void)
> > +{
> > + int ret;
> > +
> > + ret = misc_register(&vduse_misc);
> > + if (ret)
> > + return ret;
> > +
> > + ret = -ENOMEM;
> > + vduse_vdpa_wq = alloc_workqueue("vduse-vdpa", WQ_UNBOUND, 1);
> > + if (!vduse_vdpa_wq)
> > + goto err_vdpa_wq;
> > +
> > + ret = vduse_virqfd_init();
> > + if (ret)
> > + goto err_irqfd;
> > +
> > + ret = vduse_parentdev_init();
> > + if (ret)
> > + goto err_parentdev;
> > +
> > + return 0;
> > +err_parentdev:
> > + vduse_virqfd_exit();
> > +err_irqfd:
> > + destroy_workqueue(vduse_vdpa_wq);
> > +err_vdpa_wq:
> > + misc_deregister(&vduse_misc);
> > + return ret;
> > +}
> > +module_init(vduse_init);
> > +
> > +static void vduse_exit(void)
> > +{
> > + misc_deregister(&vduse_misc);
> > + destroy_workqueue(vduse_vdpa_wq);
> > + vduse_virqfd_exit();
> > + vduse_parentdev_exit();
> > +}
> > +module_exit(vduse_exit);
> > +
> > +MODULE_VERSION(DRV_VERSION);
> > +MODULE_LICENSE(DRV_LICENSE);
> > +MODULE_AUTHOR(DRV_AUTHOR);
> > +MODULE_DESCRIPTION(DRV_DESC);
> > diff --git a/include/uapi/linux/vdpa.h b/include/uapi/linux/vdpa.h
> > index bba8b83a94b5..a7a841e5ffc7 100644
> > --- a/include/uapi/linux/vdpa.h
> > +++ b/include/uapi/linux/vdpa.h
> > @@ -33,6 +33,7 @@ enum vdpa_attr {
> > VDPA_ATTR_DEV_VENDOR_ID, /* u32 */
> > VDPA_ATTR_DEV_MAX_VQS, /* u32 */
> > VDPA_ATTR_DEV_MAX_VQ_SIZE, /* u16 */
> > + VDPA_ATTR_BACKEND_ID, /* u32 */
>
>
> As discussed, this needs more thought. But if necessary, we need a
> separate patch for this.
>
OK.
>
> >
> > /* new attributes must be added above here */
> > VDPA_ATTR_MAX,
> > diff --git a/include/uapi/linux/vduse.h b/include/uapi/linux/vduse.h
> > new file mode 100644
> > index 000000000000..9fb555ddcfbd
> > --- /dev/null
> > +++ b/include/uapi/linux/vduse.h
> > @@ -0,0 +1,125 @@
> > +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
> > +#ifndef _UAPI_VDUSE_H_
> > +#define _UAPI_VDUSE_H_
> > +
> > +#include <linux/types.h>
> > +
> > +/* the control messages definition for read/write */
> > +
> > +#define VDUSE_CONFIG_DATA_LEN 256
> > +
> > +enum vduse_req_type {
> > + VDUSE_SET_VQ_NUM,
> > + VDUSE_SET_VQ_ADDR,
> > + VDUSE_SET_VQ_READY,
> > + VDUSE_GET_VQ_READY,
> > + VDUSE_SET_VQ_STATE,
> > + VDUSE_GET_VQ_STATE,
> > + VDUSE_SET_FEATURES,
> > + VDUSE_GET_FEATURES,
> > + VDUSE_SET_STATUS,
> > + VDUSE_GET_STATUS,
> > + VDUSE_SET_CONFIG,
> > + VDUSE_GET_CONFIG,
> > + VDUSE_UPDATE_IOTLB,
> > +};
> > +
> > +struct vduse_vq_num {
> > + __u32 index;
> > + __u32 num;
> > +};
> > +
> > +struct vduse_vq_addr {
> > + __u32 index;
> > + __u64 desc_addr;
> > + __u64 driver_addr;
> > + __u64 device_addr;
> > +};
> > +
> > +struct vduse_vq_ready {
> > + __u32 index;
> > + __u8 ready;
> > +};
> > +
> > +struct vduse_vq_state {
> > + __u32 index;
> > + __u16 avail_idx;
> > +};
> > +
> > +struct vduse_dev_config_data {
> > + __u32 offset;
> > + __u32 len;
> > + __u8 data[VDUSE_CONFIG_DATA_LEN];
>
>
> This no guarantee that 256 is sufficient here.
>
If the size is larger than 256, we can try to split the original request.
>
> > +};
> > +
> > +struct vduse_iova_range {
> > + __u64 start;
> > + __u64 last;
> > +};
> > +
> > +struct vduse_dev_request {
> > + __u32 type; /* request type */
> > + __u32 unique; /* request id */
> > + __u32 flags; /* request flags */
>
>
> Seems unused in this series.
>
This is for future use.
>
> > + __u32 size; /* the payload size */
>
>
> Unused.
>
Will remove it.
>
> > + union {
> > + struct vduse_vq_num vq_num; /* virtqueue num */
> > + struct vduse_vq_addr vq_addr; /* virtqueue address */
> > + struct vduse_vq_ready vq_ready; /* virtqueue ready status */
> > + struct vduse_vq_state vq_state; /* virtqueue state */
> > + struct vduse_dev_config_data config; /* virtio device config space */
> > + struct vduse_iova_range iova; /* iova range for updating */
> > + __u64 features; /* virtio features */
> > + __u8 status; /* device status */
>
>
> Let's add some padding for future extensions.
>
Is sizeof(vduse_dev_config_data) ok? Or char[1024]?
>
> > + };
> > +};
> > +
> > +struct vduse_dev_response {
> > + __u32 unique; /* corresponding request id */
>
>
> Let's use request id.
>
Fine.
>
> > + __s32 result; /* the result of request */
>
>
> Let's use macro or enum to define the success and failure value.
>
Will do it.
>
> > + union {
> > + struct vduse_vq_ready vq_ready; /* virtqueue ready status */
> > + struct vduse_vq_state vq_state; /* virtqueue state */
> > + struct vduse_dev_config_data config; /* virtio device config space */
> > + __u64 features; /* virtio features */
> > + __u8 status; /* device status */
> > + };
> > +};
> > +
> > +/* ioctls */
> > +
> > +struct vduse_dev_config {
> > + __u32 id; /* vduse device id */
> > + __u32 vendor_id; /* virtio vendor id */
> > + __u32 device_id; /* virtio device id */
> > + __u64 bounce_size; /* bounce buffer size for iommu */
> > + __u16 vq_num; /* the number of virtqueues */
> > + __u16 vq_size_max; /* the max size of virtqueue */
> > + __u32 vq_align; /* the allocation alignment of virtqueue's metadata */
> > +};
> > +
> > +struct vduse_iotlb_entry {
> > + __u64 offset; /* the mmap offset on fd */
> > + __u64 start; /* start of the IOVA range */
> > + __u64 last; /* last of the IOVA range */
> > +#define VDUSE_ACCESS_RO 0x1
> > +#define VDUSE_ACCESS_WO 0x2
> > +#define VDUSE_ACCESS_RW 0x3
> > + __u8 perm; /* access permission of this range */
> > +};
> > +
> > +struct vduse_vq_eventfd {
> > + __u32 index; /* virtqueue index */
> > + __u32 fd; /* eventfd */
>
>
> Any reason for not using int here?
>
Will use __s32 instead.
>
> > +};
> > +
> > +#define VDUSE_BASE 0x81
> > +
> > +#define VDUSE_CREATE_DEV _IOW(VDUSE_BASE, 0x01, struct vduse_dev_config)
> > +#define VDUSE_DESTROY_DEV _IO(VDUSE_BASE, 0x02)
> > +
> > +#define VDUSE_IOTLB_GET_FD _IOWR(VDUSE_BASE, 0x04, struct vduse_iotlb_entry)
> > +#define VDUSE_VQ_SETUP_KICKFD _IOW(VDUSE_BASE, 0x05, struct vduse_vq_eventfd)
> > +#define VDUSE_VQ_SETUP_IRQFD _IOW(VDUSE_BASE, 0x06, struct vduse_vq_eventfd)
>
>
> Better with documentation to explain those ioctls.
>
Will do it.
Thanks,
Yongji
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