Re: [PATCH v3] vhost: introduce mdev based hardware backend
From: Jason Wang
Date: Wed Oct 30 2019 - 03:08:13 EST
On 2019/10/30 äå1:52, Tiwei Bie wrote:
> On Wed, Oct 30, 2019 at 09:55:57AM +0800, Jason Wang wrote:
>> On 2019/10/29 äå6:07, Tiwei Bie wrote:
>>> This patch introduces a mdev based hardware vhost backend.
>>> This backend is built on top of the same abstraction used
>>> in virtio-mdev and provides a generic vhost interface for
>>> userspace to accelerate the virtio devices in guest.
>>>
>>> This backend is implemented as a mdev device driver on top
>>> of the same mdev device ops used in virtio-mdev but using
>>> a different mdev class id, and it will register the device
>>> as a VFIO device for userspace to use. Userspace can setup
>>> the IOMMU with the existing VFIO container/group APIs and
>>> then get the device fd with the device name. After getting
>>> the device fd of this device, userspace can use vhost ioctls
>>> to setup the backend.
>>
>> Hi Tiwei:
>>
>> The patch looks good overall, just few comments & nits.
> Thanks for the review! I do appreciate it.
You're welcome :)
>
>>
>>> Signed-off-by: Tiwei Bie <tiwei.bie@xxxxxxxxx>
>>> ---
>>> This patch depends on below series:
>>> https://lkml.org/lkml/2019/10/23/614
>>>
>>> v2 -> v3:
>>> - Fix the return value (Jason);
>>> - Don't cache unnecessary information in vhost-mdev (Jason);
>>> - Get rid of the memset in open (Jason);
>>> - Add comments for VHOST_SET_MEM_TABLE, ... (Jason);
>>> - Filter out unsupported features in vhost-mdev (Jason);
>>> - Add _GET_DEVICE_ID ioctl (Jason);
>>> - Add _GET_CONFIG/_SET_CONFIG ioctls (Jason);
>>> - Drop _GET_QUEUE_NUM ioctl (Jason);
>>> - Fix the copy-paste errors in _IOW/_IOR usage;
>>> - Some minor fixes and improvements;
>>>
>>> v1 -> v2:
>>> - Replace _SET_STATE with _SET_STATUS (MST);
>>> - Check status bits at each step (MST);
>>> - Report the max ring size and max number of queues (MST);
>>> - Add missing MODULE_DEVICE_TABLE (Jason);
>>> - Only support the network backend w/o multiqueue for now;
>>> - Some minor fixes and improvements;
>>> - Rebase on top of virtio-mdev series v4;
>>>
>>> RFC v4 -> v1:
>>> - Implement vhost-mdev as a mdev device driver directly and
>>> connect it to VFIO container/group. (Jason);
>>> - Pass ring addresses as GPAs/IOVAs in vhost-mdev to avoid
>>> meaningless HVA->GPA translations (Jason);
>>>
>>> RFC v3 -> RFC v4:
>>> - Build vhost-mdev on top of the same abstraction used by
>>> virtio-mdev (Jason);
>>> - Introduce vhost fd and pass VFIO fd via SET_BACKEND ioctl (MST);
>>>
>>> RFC v2 -> RFC v3:
>>> - Reuse vhost's ioctls instead of inventing a VFIO regions/irqs
>>> based vhost protocol on top of vfio-mdev (Jason);
>>>
>>> RFC v1 -> RFC v2:
>>> - Introduce a new VFIO device type to build a vhost protocol
>>> on top of vfio-mdev;
>>>
>>> drivers/vfio/mdev/mdev_core.c | 20 ++
>>> drivers/vfio/mdev/mdev_private.h | 1 +
>>> drivers/vhost/Kconfig | 12 +
>>> drivers/vhost/Makefile | 3 +
>>> drivers/vhost/mdev.c | 554 +++++++++++++++++++++++++++++++
>>> include/linux/mdev.h | 5 +
>>> include/uapi/linux/vhost.h | 18 +
>>> include/uapi/linux/vhost_types.h | 8 +
>>> 8 files changed, 621 insertions(+)
>>> create mode 100644 drivers/vhost/mdev.c
>>>
>>> diff --git a/drivers/vfio/mdev/mdev_core.c b/drivers/vfio/mdev/mdev_core.c
>>> index 9b00c3513120..3cfd787d605c 100644
>>> --- a/drivers/vfio/mdev/mdev_core.c
>>> +++ b/drivers/vfio/mdev/mdev_core.c
>>> @@ -96,6 +96,26 @@ mdev_get_virtio_ops(struct mdev_device *mdev)
>>> }
>>> EXPORT_SYMBOL(mdev_get_virtio_ops);
>>>
>>> +/* Specify the vhost device ops for the mdev device, this
>>> + * must be called during create() callback for vhost mdev device.
>>> + */
>>> +void mdev_set_vhost_ops(struct mdev_device *mdev,
>>> + const struct virtio_mdev_device_ops *vhost_ops)
>>> +{
>>> + mdev_set_class(mdev, MDEV_CLASS_ID_VHOST);
>>> + mdev->vhost_ops = vhost_ops;
>>> +}
>>> +EXPORT_SYMBOL(mdev_set_vhost_ops);
>>> +
>>> +/* Get the vhost device ops for the mdev device. */
>>> +const struct virtio_mdev_device_ops *
>>> +mdev_get_vhost_ops(struct mdev_device *mdev)
>>> +{
>>> + WARN_ON(mdev->class_id != MDEV_CLASS_ID_VHOST);
>>> + return mdev->vhost_ops;
>>> +}
>>> +EXPORT_SYMBOL(mdev_get_vhost_ops);
>>> +
>>> struct device *mdev_dev(struct mdev_device *mdev)
>>> {
>>> return &mdev->dev;
>>> diff --git a/drivers/vfio/mdev/mdev_private.h b/drivers/vfio/mdev/mdev_private.h
>>> index 7b47890c34e7..5597c846e52f 100644
>>> --- a/drivers/vfio/mdev/mdev_private.h
>>> +++ b/drivers/vfio/mdev/mdev_private.h
>>> @@ -40,6 +40,7 @@ struct mdev_device {
>>> union {
>>> const struct vfio_mdev_device_ops *vfio_ops;
>>> const struct virtio_mdev_device_ops *virtio_ops;
>>> + const struct virtio_mdev_device_ops *vhost_ops;
>>> };
>>> };
>>>
>>> diff --git a/drivers/vhost/Kconfig b/drivers/vhost/Kconfig
>>> index 3d03ccbd1adc..062cada28f89 100644
>>> --- a/drivers/vhost/Kconfig
>>> +++ b/drivers/vhost/Kconfig
>>> @@ -34,6 +34,18 @@ config VHOST_VSOCK
>>> To compile this driver as a module, choose M here: the module will be called
>>> vhost_vsock.
>>>
>>> +config VHOST_MDEV
>>> + tristate "Vhost driver for Mediated devices"
>>> + depends on EVENTFD && VFIO && VFIO_MDEV
>>> + select VHOST
>>> + default n
>>> + ---help---
>>> + This kernel module can be loaded in host kernel to accelerate
>>> + guest virtio devices with the mediated device based backends.
>>> +
>>> + To compile this driver as a module, choose M here: the module will
>>> + be called vhost_mdev.
>>> +
>>> config VHOST
>>> tristate
>>> ---help---
>>> diff --git a/drivers/vhost/Makefile b/drivers/vhost/Makefile
>>> index 6c6df24f770c..ad9c0f8c6d8c 100644
>>> --- a/drivers/vhost/Makefile
>>> +++ b/drivers/vhost/Makefile
>>> @@ -10,4 +10,7 @@ vhost_vsock-y := vsock.o
>>>
>>> obj-$(CONFIG_VHOST_RING) += vringh.o
>>>
>>> +obj-$(CONFIG_VHOST_MDEV) += vhost_mdev.o
>>> +vhost_mdev-y := mdev.o
>>> +
>>> obj-$(CONFIG_VHOST) += vhost.o
>>> diff --git a/drivers/vhost/mdev.c b/drivers/vhost/mdev.c
>>> new file mode 100644
>>> index 000000000000..35b2fb33e686
>>> --- /dev/null
>>> +++ b/drivers/vhost/mdev.c
>>> @@ -0,0 +1,554 @@
>>> +// SPDX-License-Identifier: GPL-2.0
>>> +/*
>>> + * Vhost driver for mediated device based backends.
>>> + *
>>> + * Copyright (C) 2018-2019 Intel Corporation.
>>> + *
>>> + * Author: Tiwei Bie <tiwei.bie@xxxxxxxxx>
>>> + *
>>> + * Thanks to Jason Wang and Michael S. Tsirkin for the valuable
>>> + * comments and suggestions. And thanks to Cunming Liang and
>>> + * Zhihong Wang for all their supports.
>>> + */
>>> +
>>> +#include <linux/kernel.h>
>>> +#include <linux/module.h>
>>> +#include <linux/mdev.h>
>>> +#include <linux/vfio.h>
>>> +#include <linux/vhost.h>
>>> +#include <linux/virtio_net.h>
>>> +#include <linux/virtio_mdev_ops.h>
>>> +
>>> +#include "vhost.h"
>>> +
>>> +enum {
>>> + VHOST_MDEV_FEATURES =
>>> + (1ULL << VIRTIO_F_NOTIFY_ON_EMPTY) |
>>> + (1ULL << VIRTIO_F_ANY_LAYOUT) |
>>> + (1ULL << VIRTIO_F_VERSION_1) |
>>> + (1ULL << VIRTIO_F_IOMMU_PLATFORM) |
>>> + (1ULL << VIRTIO_F_RING_PACKED) |
>>> + (1ULL << VIRTIO_F_ORDER_PLATFORM) |
>>> + (1ULL << VIRTIO_RING_F_INDIRECT_DESC) |
>>> + (1ULL << VIRTIO_RING_F_EVENT_IDX),
>>> +
>>> + VHOST_MDEV_NET_FEATURES = VHOST_MDEV_FEATURES |
>>> + (1ULL << VIRTIO_NET_F_CSUM) |
>>> + (1ULL << VIRTIO_NET_F_GUEST_CSUM) |
>>> + (1ULL << VIRTIO_NET_F_MTU) |
>>> + (1ULL << VIRTIO_NET_F_MAC) |
>>> + (1ULL << VIRTIO_NET_F_GUEST_TSO4) |
>>> + (1ULL << VIRTIO_NET_F_GUEST_TSO6) |
>>> + (1ULL << VIRTIO_NET_F_GUEST_ECN) |
>>> + (1ULL << VIRTIO_NET_F_GUEST_UFO) |
>>> + (1ULL << VIRTIO_NET_F_HOST_TSO4) |
>>> + (1ULL << VIRTIO_NET_F_HOST_TSO6) |
>>> + (1ULL << VIRTIO_NET_F_HOST_ECN) |
>>> + (1ULL << VIRTIO_NET_F_HOST_UFO) |
>>> + (1ULL << VIRTIO_NET_F_MRG_RXBUF) |
>>> + (1ULL << VIRTIO_NET_F_STATUS) |
>>> + (1ULL << VIRTIO_NET_F_SPEED_DUPLEX),
>>> +};
>>> +
>>> +/* Currently, only network backend w/o multiqueue is supported. */
>>> +#define VHOST_MDEV_VQ_MAX 2
>>> +
>>> +struct vhost_mdev {
>>> + /* The lock is to protect this structure. */
>>> + struct mutex mutex;
>>> + struct vhost_dev dev;
>>> + struct vhost_virtqueue *vqs;
>>> + int nvqs;
>>> + int virtio_id;
>>> + bool opened;
>>> + struct mdev_device *mdev;
>>> +};
>>> +
>>> +static const u64 vhost_mdev_features[] = {
>>> + [VIRTIO_ID_NET] = VHOST_MDEV_NET_FEATURES,
>>> +};
>>> +
>>> +static void handle_vq_kick(struct vhost_work *work)
>>> +{
>>> + struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
>>> + poll.work);
>>> + struct vhost_mdev *m = container_of(vq->dev, struct vhost_mdev, dev);
>>> + const struct virtio_mdev_device_ops *ops = mdev_get_vhost_ops(m->mdev);
>>> +
>>> + ops->kick_vq(m->mdev, vq - m->vqs);
>>> +}
>>> +
>>> +static irqreturn_t vhost_mdev_virtqueue_cb(void *private)
>>> +{
>>> + struct vhost_virtqueue *vq = private;
>>> + struct eventfd_ctx *call_ctx = vq->call_ctx;
>>> +
>>> + if (call_ctx)
>>> + eventfd_signal(call_ctx, 1);
>>> +
>>> + return IRQ_HANDLED;
>>> +}
>>> +
>>> +static void vhost_mdev_reset(struct vhost_mdev *m)
>>> +{
>>> + struct mdev_device *mdev = m->mdev;
>>> + const struct virtio_mdev_device_ops *ops = mdev_get_vhost_ops(mdev);
>>> +
>>> + ops->set_status(mdev, 0);
>>> +}
>>> +
>>> +static long vhost_mdev_get_device_id(struct vhost_mdev *m, u8 __user *argp)
>>> +{
>>> + struct mdev_device *mdev = m->mdev;
>>> + const struct virtio_mdev_device_ops *ops = mdev_get_vhost_ops(mdev);
>>> + u32 device_id;
>>> +
>>> + device_id = ops->get_device_id(mdev);
>>> +
>>> + if (copy_to_user(argp, &device_id, sizeof(device_id)))
>>> + return -EFAULT;
>>> +
>>> + return 0;
>>> +}
>>
>> I believe we need get_vendor_id() as well?
> Currently, there is no official way for vendors to do vendor
> specific extensions in vhost-mdev yet. It might be better to
> add this ioctl when we support this.
Good point.
>
>>
>>> +
>>> +static long vhost_mdev_get_status(struct vhost_mdev *m, u8 __user *statusp)
>>> +{
>>> + struct mdev_device *mdev = m->mdev;
>>> + const struct virtio_mdev_device_ops *ops = mdev_get_vhost_ops(mdev);
>>> + u8 status;
>>> +
>>> + status = ops->get_status(mdev);
>>> +
>>> + if (copy_to_user(statusp, &status, sizeof(status)))
>>> + return -EFAULT;
>>> +
>>> + return 0;
>>> +}
>>> +
>>> +static long vhost_mdev_set_status(struct vhost_mdev *m, u8 __user *statusp)
>>> +{
>>> + struct mdev_device *mdev = m->mdev;
>>> + const struct virtio_mdev_device_ops *ops = mdev_get_vhost_ops(mdev);
>>> + u8 status;
>>> +
>>> + if (copy_from_user(&status, statusp, sizeof(status)))
>>> + return -EFAULT;
>>> +
>>> + /*
>>> + * Userspace shouldn't remove status bits unless reset the
>>> + * status to 0.
>>> + */
>>> + if (status != 0 && (ops->get_status(mdev) & ~status) != 0)
>>> + return -EINVAL;
>>> +
>>> + ops->set_status(mdev, status);
>>> +
>>> + return 0;
>>> +}
>>> +
>>> +static int vhost_mdev_config_validate(struct vhost_mdev *m,
>>> + struct vhost_mdev_config *c)
>>> +{
>>> + long size = 0;
>>> +
>>> + switch (m->virtio_id) {
>>> + case VIRTIO_ID_NET:
>>> + size = sizeof(struct virtio_net_config);
>>> + break;
>>> + }
>>> +
>>> + if (c->len == 0)
>>> + return -EINVAL;
>>> +
>>> + if (c->off >= size || c->len > size || c->off + c->len > size)
>>> + return -E2BIG;
>>> +
>>> + return 0;
>>> +}
>>> +
>>> +static long vhost_mdev_get_config(struct vhost_mdev *m,
>>> + struct vhost_mdev_config __user *c)
>>> +{
>>> + struct mdev_device *mdev = m->mdev;
>>> + const struct virtio_mdev_device_ops *ops = mdev_get_vhost_ops(mdev);
>>> + struct vhost_mdev_config config;
>>> + unsigned long size = offsetof(struct vhost_mdev_config, buf);
>>> + u8 *buf;
>>> +
>>> + if (copy_from_user(&config, c, size))
>>> + return -EFAULT;
>>> + if (vhost_mdev_config_validate(m, &config))
>>> + return -EINVAL;
>>
>> I think it's better to let the parent to do such validation. Especially
>> consider that the size of config may depend on feature (e.g MQ).
> Above check is just a basic sanity check to make sure
> that e.g. we won't alloc a huge amount of memory.
I see.
>
>>
>>> + buf = kvzalloc(config.len, GFP_KERNEL);
>>> + if (!buf)
>>> + return -ENOMEM;
>>> +
>>> + ops->get_config(mdev, config.off, buf, config.len);
>>> +
>>> + if (copy_to_user(c->buf, buf, config.len)) {
>>> + kvfree(buf);
>>> + return -EFAULT;
>>> + }
>>> +
>>> + kvfree(buf);
>>> + return 0;
>>> +}
>>> +
>>> +static long vhost_mdev_set_config(struct vhost_mdev *m,
>>> + struct vhost_mdev_config __user *c)
>>> +{
>>> + struct mdev_device *mdev = m->mdev;
>>> + const struct virtio_mdev_device_ops *ops = mdev_get_vhost_ops(mdev);
>>> + struct vhost_mdev_config config;
>>> + unsigned long size = offsetof(struct vhost_mdev_config, buf);
>>> + u8 *buf;
>>> +
>>> + if (copy_from_user(&config, c, size))
>>> + return -EFAULT;
>>> + if (vhost_mdev_config_validate(m, &config))
>>> + return -EINVAL;
>>> + buf = kvzalloc(config.len, GFP_KERNEL);
>>> + if (!buf)
>>> + return -ENOMEM;
>>> +
>>> + if (copy_from_user(buf, c->buf, config.len)) {
>>> + kvfree(buf);
>>> + return -EFAULT;
>>> + }
>>> +
>>> + ops->set_config(mdev, config.off, buf, config.len);
>>> +
>>> + kvfree(buf);
>>> + return 0;
>>> +}
>>> +
>>> +static long vhost_mdev_get_features(struct vhost_mdev *m, u64 __user *featurep)
>>> +{
>>> + struct mdev_device *mdev = m->mdev;
>>> + const struct virtio_mdev_device_ops *ops = mdev_get_vhost_ops(mdev);
>>> + u64 features;
>>> +
>>> + features = ops->get_features(mdev);
>>> + features &= vhost_mdev_features[m->virtio_id];
>>> +
>>> + if (copy_to_user(featurep, &features, sizeof(features)))
>>> + return -EFAULT;
>>> +
>>> + return 0;
>>> +}
>>> +
>>> +static long vhost_mdev_set_features(struct vhost_mdev *m, u64 __user *featurep)
>>> +{
>>> + struct mdev_device *mdev = m->mdev;
>>> + const struct virtio_mdev_device_ops *ops = mdev_get_vhost_ops(mdev);
>>> + u64 features;
>>> +
>>> + /*
>>> + * It's not allowed to change the features after they have
>>> + * been negotiated.
>>> + */
>>> + if (ops->get_status(mdev) & VIRTIO_CONFIG_S_FEATURES_OK)
>>> + return -EBUSY;
>>> +
>>> + if (copy_from_user(&features, featurep, sizeof(features)))
>>> + return -EFAULT;
>>> +
>>> + if (features & ~vhost_mdev_features[m->virtio_id])
>>> + return -EINVAL;
>>> +
>>> + if (ops->set_features(mdev, features))
>>> + return -EINVAL;
>>> +
>>> + return 0;
>>> +}
>>> +
>>> +static long vhost_mdev_get_vring_num(struct vhost_mdev *m, u16 __user *argp)
>>> +{
>>> + struct mdev_device *mdev = m->mdev;
>>> + const struct virtio_mdev_device_ops *ops = mdev_get_vhost_ops(mdev);
>>> + u16 num;
>>> +
>>> + num = ops->get_vq_num_max(mdev);
>>> +
>>> + if (copy_to_user(argp, &num, sizeof(num)))
>>> + return -EFAULT;
>>> +
>>> + return 0;
>>> +}
>>> +
>>> +static long vhost_mdev_vring_ioctl(struct vhost_mdev *m, unsigned int cmd,
>>> + void __user *argp)
>>> +{
>>> + struct mdev_device *mdev = m->mdev;
>>> + const struct virtio_mdev_device_ops *ops = mdev_get_vhost_ops(mdev);
>>> + struct virtio_mdev_callback cb;
>>> + struct vhost_virtqueue *vq;
>>> + struct vhost_vring_state s;
>>> + u8 status;
>>> + u32 idx;
>>> + long r;
>>> +
>>> + r = get_user(idx, (u32 __user *)argp);
>>> + if (r < 0)
>>> + return r;
>>> + if (idx >= m->nvqs)
>>> + return -ENOBUFS;
>>> +
>>> + status = ops->get_status(mdev);
>>> +
>>> + /*
>>> + * It's not allowed to detect and program vqs before
>>> + * features negotiation or after enabling driver.
>>> + */
>>> + if (!(status & VIRTIO_CONFIG_S_FEATURES_OK) ||
>>> + (status & VIRTIO_CONFIG_S_DRIVER_OK))
>>> + return -EBUSY;
>>> +
>>> + vq = &m->vqs[idx];
>>> +
>>> + if (cmd == VHOST_MDEV_SET_VRING_ENABLE) {
>>> + if (copy_from_user(&s, argp, sizeof(s)))
>>> + return -EFAULT;
>>> + ops->set_vq_ready(mdev, idx, s.num);
>>> + return 0;
>>> + }
>>> +
>>> + /*
>>> + * It's not allowed to detect and program vqs with
>>> + * vqs enabled.
>>> + */
>>> + if (ops->get_vq_ready(mdev, idx))
>>> + return -EBUSY;
>>> +
>>> + if (cmd == VHOST_GET_VRING_BASE)
>>> + vq->last_avail_idx = ops->get_vq_state(m->mdev, idx);
>>> +
>>> + r = vhost_vring_ioctl(&m->dev, cmd, argp);
>>> + if (r)
>>> + return r;
>>> +
>>> + switch (cmd) {
>>> + case VHOST_SET_VRING_ADDR:
>>> + /*
>>> + * In vhost-mdev, the ring addresses set by userspace should
>>> + * be the DMA addresses within the VFIO container/group.
>>> + */
>>> + if (ops->set_vq_address(mdev, idx, (u64)vq->desc,
>>> + (u64)vq->avail, (u64)vq->used))
>>> + r = -ENODEV;
>>
>> Nit: It looks to me that we need expose alignment of vq to userspace
>> (get_vq_align()).
> Guest drivers are using (maybe hardcoded) alignments based
> on the alignment requirements defined in the spec. It might
> be better to let backends follow the same standard for the
> compatibility.
Ok.
Thanks
>
>> Thanks
>>
>>
>>> + break;
>>> +
>>> + case VHOST_SET_VRING_BASE:
>>> + if (ops->set_vq_state(mdev, idx, vq->last_avail_idx))
>>> + r = -ENODEV;
>>> + break;
>>> +
>>> + case VHOST_SET_VRING_CALL:
>>> + if (vq->call_ctx) {
>>> + cb.callback = vhost_mdev_virtqueue_cb;
>>> + cb.private = vq;
>>> + } else {
>>> + cb.callback = NULL;
>>> + cb.private = NULL;
>>> + }
>>> + ops->set_vq_cb(mdev, idx, &cb);
>>> + break;
>>> +
>>> + case VHOST_SET_VRING_NUM:
>>> + ops->set_vq_num(mdev, idx, vq->num);
>>> + break;
>>> + }
>>> +
>>> + return r;
>>> +}
>>> +
>>> +static int vhost_mdev_open(void *device_data)
>>> +{
>>> + struct vhost_mdev *m = device_data;
>>> + struct vhost_dev *dev;
>>> + struct vhost_virtqueue **vqs;
>>> + int nvqs, i, r;
>>> +
>>> + if (!try_module_get(THIS_MODULE))
>>> + return -ENODEV;
>>> +
>>> + mutex_lock(&m->mutex);
>>> +
>>> + if (m->opened) {
>>> + r = -EBUSY;
>>> + goto err;
>>> + }
>>> +
>>> + nvqs = m->nvqs;
>>> + vhost_mdev_reset(m);
>>> +
>>> + vqs = kmalloc_array(nvqs, sizeof(*vqs), GFP_KERNEL);
>>> + if (!vqs) {
>>> + r = -ENOMEM;
>>> + goto err;
>>> + }
>>> +
>>> + dev = &m->dev;
>>> + for (i = 0; i < nvqs; i++) {
>>> + vqs[i] = &m->vqs[i];
>>> + vqs[i]->handle_kick = handle_vq_kick;
>>> + }
>>> + vhost_dev_init(dev, vqs, nvqs, 0, 0, 0);
>>> + m->opened = true;
>>> + mutex_unlock(&m->mutex);
>>> +
>>> + return 0;
>>> +
>>> +err:
>>> + mutex_unlock(&m->mutex);
>>> + module_put(THIS_MODULE);
>>> + return r;
>>> +}
>>> +
>>> +static void vhost_mdev_release(void *device_data)
>>> +{
>>> + struct vhost_mdev *m = device_data;
>>> +
>>> + mutex_lock(&m->mutex);
>>> + vhost_mdev_reset(m);
>>> + vhost_dev_stop(&m->dev);
>>> + vhost_dev_cleanup(&m->dev);
>>> +
>>> + kfree(m->dev.vqs);
>>> + m->opened = false;
>>> + mutex_unlock(&m->mutex);
>>> + module_put(THIS_MODULE);
>>> +}
>>> +
>>> +static long vhost_mdev_unlocked_ioctl(void *device_data,
>>> + unsigned int cmd, unsigned long arg)
>>> +{
>>> + struct vhost_mdev *m = device_data;
>>> + void __user *argp = (void __user *)arg;
>>> + long r;
>>> +
>>> + mutex_lock(&m->mutex);
>>> +
>>> + switch (cmd) {
>>> + case VHOST_MDEV_GET_DEVICE_ID:
>>> + r = vhost_mdev_get_device_id(m, argp);
>>> + break;
>>> + case VHOST_MDEV_GET_STATUS:
>>> + r = vhost_mdev_get_status(m, argp);
>>> + break;
>>> + case VHOST_MDEV_SET_STATUS:
>>> + r = vhost_mdev_set_status(m, argp);
>>> + break;
>>> + case VHOST_MDEV_GET_CONFIG:
>>> + r = vhost_mdev_get_config(m, argp);
>>> + break;
>>> + case VHOST_MDEV_SET_CONFIG:
>>> + r = vhost_mdev_set_config(m, argp);
>>> + break;
>>> + case VHOST_GET_FEATURES:
>>> + r = vhost_mdev_get_features(m, argp);
>>> + break;
>>> + case VHOST_SET_FEATURES:
>>> + r = vhost_mdev_set_features(m, argp);
>>> + break;
>>> + case VHOST_MDEV_GET_VRING_NUM:
>>> + r = vhost_mdev_get_vring_num(m, argp);
>>> + break;
>>> + default:
>>> + /*
>>> + * VHOST_SET_MEM_TABLE, VHOST_SET_LOG_BASE, and
>>> + * VHOST_SET_LOG_FD are not used yet.
>>> + */
>>> + r = vhost_dev_ioctl(&m->dev, cmd, argp);
>>> + if (r == -ENOIOCTLCMD)
>>> + r = vhost_mdev_vring_ioctl(m, cmd, argp);
>>> + }
>>> +
>>> + mutex_unlock(&m->mutex);
>>> + return r;
>>> +}
>>> +
>>> +static const struct vfio_device_ops vfio_vhost_mdev_dev_ops = {
>>> + .name = "vfio-vhost-mdev",
>>> + .open = vhost_mdev_open,
>>> + .release = vhost_mdev_release,
>>> + .ioctl = vhost_mdev_unlocked_ioctl,
>>> +};
>>> +
>>> +static int vhost_mdev_probe(struct device *dev)
>>> +{
>>> + struct mdev_device *mdev = mdev_from_dev(dev);
>>> + const struct virtio_mdev_device_ops *ops = mdev_get_vhost_ops(mdev);
>>> + struct vhost_mdev *m;
>>> + int nvqs, r;
>>> +
>>> + /* Currently, we only accept the network devices. */
>>> + if (ops->get_device_id(mdev) != VIRTIO_ID_NET)
>>> + return -ENOTSUPP;
>>> +
>>> + if (ops->get_mdev_features(mdev) != VIRTIO_MDEV_F_VERSION_1)
>>> + return -ENOTSUPP;
>>> +
>>> + m = devm_kzalloc(dev, sizeof(*m), GFP_KERNEL | __GFP_RETRY_MAYFAIL);
>>> + if (!m)
>>> + return -ENOMEM;
>>> +
>>> + nvqs = VHOST_MDEV_VQ_MAX;
>>> +
>>> + m->vqs = devm_kmalloc_array(dev, nvqs, sizeof(struct vhost_virtqueue),
>>> + GFP_KERNEL);
>>> + if (!m->vqs)
>>> + return -ENOMEM;
>>> +
>>> + mutex_init(&m->mutex);
>>> +
>>> + m->mdev = mdev;
>>> + m->nvqs = nvqs;
>>> + m->virtio_id = ops->get_device_id(mdev);
>>> +
>>> + r = vfio_add_group_dev(dev, &vfio_vhost_mdev_dev_ops, m);
>>> + if (r) {
>>> + mutex_destroy(&m->mutex);
>>> + return r;
>>> + }
>>> +
>>> + return 0;
>>> +}
>>> +
>>> +static void vhost_mdev_remove(struct device *dev)
>>> +{
>>> + struct vhost_mdev *m;
>>> +
>>> + m = vfio_del_group_dev(dev);
>>> + mutex_destroy(&m->mutex);
>>> +}
>>> +
>>> +static const struct mdev_class_id vhost_mdev_match[] = {
>>> + { MDEV_CLASS_ID_VHOST },
>>> + { 0 },
>>> +};
>>> +MODULE_DEVICE_TABLE(mdev, vhost_mdev_match);
>>> +
>>> +static struct mdev_driver vhost_mdev_driver = {
>>> + .name = "vhost_mdev",
>>> + .probe = vhost_mdev_probe,
>>> + .remove = vhost_mdev_remove,
>>> + .id_table = vhost_mdev_match,
>>> +};
>>> +
>>> +static int __init vhost_mdev_init(void)
>>> +{
>>> + return mdev_register_driver(&vhost_mdev_driver, THIS_MODULE);
>>> +}
>>> +module_init(vhost_mdev_init);
>>> +
>>> +static void __exit vhost_mdev_exit(void)
>>> +{
>>> + mdev_unregister_driver(&vhost_mdev_driver);
>>> +}
>>> +module_exit(vhost_mdev_exit);
>>> +
>>> +MODULE_VERSION("0.0.1");
>>> +MODULE_LICENSE("GPL v2");
>>> +MODULE_AUTHOR("Intel Corporation");
>>> +MODULE_DESCRIPTION("Mediated device based accelerator for virtio");
>>> diff --git a/include/linux/mdev.h b/include/linux/mdev.h
>>> index 9b69b0bbebfd..3e1e03926355 100644
>>> --- a/include/linux/mdev.h
>>> +++ b/include/linux/mdev.h
>>> @@ -117,6 +117,10 @@ void mdev_set_virtio_ops(struct mdev_device *mdev,
>>> const struct virtio_mdev_device_ops *virtio_ops);
>>> const struct virtio_mdev_device_ops *
>>> mdev_get_virtio_ops(struct mdev_device *mdev);
>>> +void mdev_set_vhost_ops(struct mdev_device *mdev,
>>> + const struct virtio_mdev_device_ops *vhost_ops);
>>> +const struct virtio_mdev_device_ops *
>>> +mdev_get_vhost_ops(struct mdev_device *mdev);
>>>
>>> extern struct bus_type mdev_bus_type;
>>>
>>> @@ -133,6 +137,7 @@ struct mdev_device *mdev_from_dev(struct device *dev);
>>> enum {
>>> MDEV_CLASS_ID_VFIO = 1,
>>> MDEV_CLASS_ID_VIRTIO = 2,
>>> + MDEV_CLASS_ID_VHOST = 3,
>>> /* New entries must be added here */
>>> };
>>>
>>> diff --git a/include/uapi/linux/vhost.h b/include/uapi/linux/vhost.h
>>> index 40d028eed645..061a2824a1b3 100644
>>> --- a/include/uapi/linux/vhost.h
>>> +++ b/include/uapi/linux/vhost.h
>>> @@ -116,4 +116,22 @@
>>> #define VHOST_VSOCK_SET_GUEST_CID _IOW(VHOST_VIRTIO, 0x60, __u64)
>>> #define VHOST_VSOCK_SET_RUNNING _IOW(VHOST_VIRTIO, 0x61, int)
>>>
>>> +/* VHOST_MDEV specific defines */
>>> +
>>> +/* Get the device id. The device ids follow the same definition of
>>> + * the device id defined in virtio-spec. */
>>> +#define VHOST_MDEV_GET_DEVICE_ID _IOR(VHOST_VIRTIO, 0x70, __u32)
>>> +/* Get and set the status. The status bits follow the same definition
>>> + * of the device status defined in virtio-spec. */
>>> +#define VHOST_MDEV_GET_STATUS _IOR(VHOST_VIRTIO, 0x71, __u8)
>>> +#define VHOST_MDEV_SET_STATUS _IOW(VHOST_VIRTIO, 0x72, __u8)
>>> +/* Get and set the device config. The device config follows the same
>>> + * definition of the device config defined in virtio-spec. */
>>> +#define VHOST_MDEV_GET_CONFIG _IOR(VHOST_VIRTIO, 0x73, struct vhost_mdev_config)
>>> +#define VHOST_MDEV_SET_CONFIG _IOW(VHOST_VIRTIO, 0x74, struct vhost_mdev_config)
>>> +/* Enable/disable the ring. */
>>> +#define VHOST_MDEV_SET_VRING_ENABLE _IOW(VHOST_VIRTIO, 0x75, struct vhost_vring_state)
>>> +/* Get the max ring size. */
>>> +#define VHOST_MDEV_GET_VRING_NUM _IOR(VHOST_VIRTIO, 0x76, __u16)
>>> +
>>> #endif
>>> diff --git a/include/uapi/linux/vhost_types.h b/include/uapi/linux/vhost_types.h
>>> index c907290ff065..7b105d0b2fb9 100644
>>> --- a/include/uapi/linux/vhost_types.h
>>> +++ b/include/uapi/linux/vhost_types.h
>>> @@ -119,6 +119,14 @@ struct vhost_scsi_target {
>>> unsigned short reserved;
>>> };
>>>
>>> +/* VHOST_MDEV specific definitions */
>>> +
>>> +struct vhost_mdev_config {
>>> + __u32 off;
>>> + __u32 len;
>>> + __u8 buf[0];
>>> +};
>>> +
>>> /* Feature bits */
>>> /* Log all write descriptors. Can be changed while device is active. */
>>> #define VHOST_F_LOG_ALL 26