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. Signed-off-by: Tiwei Bie <tiwei....@intel.com> --- This patch depends on below series: https://lkml.org/lkml/2019/10/17/286 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 | 12 + drivers/vhost/Kconfig | 9 + drivers/vhost/Makefile | 3 + drivers/vhost/mdev.c | 415 ++++++++++++++++++++++++++++++++++ include/linux/mdev.h | 3 + include/uapi/linux/vhost.h | 13 ++ 6 files changed, 455 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 5834f6b7c7a5..2963f65e6648 100644 --- a/drivers/vfio/mdev/mdev_core.c +++ b/drivers/vfio/mdev/mdev_core.c @@ -69,6 +69,18 @@ void mdev_set_virtio_ops(struct mdev_device *mdev, } EXPORT_SYMBOL(mdev_set_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) +{ + WARN_ON(mdev->class_id); + mdev->class_id = MDEV_CLASS_ID_VHOST; + mdev->device_ops = vhost_ops; +} +EXPORT_SYMBOL(mdev_set_vhost_ops); + const void *mdev_get_dev_ops(struct mdev_device *mdev) { return mdev->device_ops; diff --git a/drivers/vhost/Kconfig b/drivers/vhost/Kconfig index 3d03ccbd1adc..7b5c2f655af7 100644 --- a/drivers/vhost/Kconfig +++ b/drivers/vhost/Kconfig @@ -34,6 +34,15 @@ 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--- + Say M here to enable the vhost_mdev module for use with + the mediated device based hardware vhost accelerators. + 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..5f9cae61018c --- /dev/null +++ b/drivers/vhost/mdev.c @@ -0,0 +1,415 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2018-2019 Intel Corporation. + */ + +#include <linux/compat.h> +#include <linux/kernel.h> +#include <linux/miscdevice.h> +#include <linux/mdev.h> +#include <linux/module.h> +#include <linux/vfio.h> +#include <linux/vhost.h> +#include <linux/virtio_mdev.h> +#include <linux/virtio_ids.h> + +#include "vhost.h" + +/* 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; + u64 status; + u64 features; + u64 acked_features; + bool opened; + struct mdev_device *mdev; +}; + +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_dev_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_dev_ops(mdev); + + m->status = 0; + return ops->set_status(mdev, m->status); +} + +static long vhost_mdev_get_status(struct vhost_mdev *m, u8 __user *statusp) +{ + const struct virtio_mdev_device_ops *ops = mdev_get_dev_ops(m->mdev); + struct mdev_device *mdev = m->mdev; + u8 status; + + status = ops->get_status(mdev); + m->status = status; + + 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) +{ + const struct virtio_mdev_device_ops *ops = mdev_get_dev_ops(m->mdev); + struct mdev_device *mdev = m->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 && (m->status & ~status) != 0) + return -EINVAL; + + ops->set_status(mdev, status); + m->status = ops->get_status(mdev); + + return 0; +} + +static long vhost_mdev_get_features(struct vhost_mdev *m, u64 __user *featurep) +{ + if (copy_to_user(featurep, &m->features, sizeof(m->features))) + return -EFAULT; + return 0; +} + +static long vhost_mdev_set_features(struct vhost_mdev *m, u64 __user *featurep) +{ + const struct virtio_mdev_device_ops *ops = mdev_get_dev_ops(m->mdev); + struct mdev_device *mdev = m->mdev; + u64 features; + + /* + * It's not allowed to change the features after they have + * been negotiated. + */ + if (m->status & VIRTIO_CONFIG_S_FEATURES_OK) + return -EPERM; + + if (copy_from_user(&features, featurep, sizeof(features))) + return -EFAULT; + + if (features & ~m->features) + return -EINVAL; + + m->acked_features = features; + if (ops->set_features(mdev, m->acked_features)) + return -ENODEV; + + return 0; +} + +static long vhost_mdev_get_vring_num(struct vhost_mdev *m, u16 __user *argp) +{ + const struct virtio_mdev_device_ops *ops = mdev_get_dev_ops(m->mdev); + struct mdev_device *mdev = m->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_get_queue_num(struct vhost_mdev *m, u32 __user *argp) +{ + u32 nvqs = m->nvqs; + + if (copy_to_user(argp, &nvqs, sizeof(nvqs))) + return -EFAULT; + return 0; +} + +static long vhost_mdev_vring_ioctl(struct vhost_mdev *m, unsigned int cmd, + void __user *argp) +{ + const struct virtio_mdev_device_ops *ops = mdev_get_dev_ops(m->mdev); + struct mdev_device *mdev = m->mdev; + struct virtio_mdev_callback cb; + struct vhost_virtqueue *vq; + struct vhost_vring_state s; + u32 idx; + long r; + + r = get_user(idx, (u32 __user *)argp); + if (r < 0) + return r; + if (idx >= m->nvqs) + return -ENOBUFS; + + /* + * It's not allowed to detect and program vqs before + * features negotiation or after enabling driver. + */ + if (!(m->status & VIRTIO_CONFIG_S_FEATURES_OK) || + (m->status & VIRTIO_CONFIG_S_DRIVER_OK)) + return -EPERM; + + 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 -EPERM; + + 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; + 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); + + memset(&m->dev, 0, sizeof(m->dev)); + memset(m->vqs, 0, nvqs * sizeof(struct vhost_virtqueue)); + + 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_STATUS: + r = vhost_mdev_get_status(m, argp); + break; + case VHOST_MDEV_SET_STATUS: + r = vhost_mdev_set_status(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; + case VHOST_MDEV_GET_QUEUE_NUM: + r = vhost_mdev_get_queue_num(m, argp); + break; + default: + 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_dev_ops(mdev); + struct vhost_mdev *m; + int nvqs, r; + + /* Currently, only network backend is supported. */ + 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->nvqs = nvqs; + + m->vqs = devm_kmalloc_array(dev, nvqs, sizeof(struct vhost_virtqueue), + GFP_KERNEL); + if (!m->vqs) + return -ENOMEM; + + r = vfio_add_group_dev(dev, &vfio_vhost_mdev_dev_ops, m); + if (r) + return r; + + mutex_init(&m->mutex); + m->features = ops->get_features(mdev); + m->mdev = mdev; + 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_DESCRIPTION("Mediated device based accelerator for virtio"); diff --git a/include/linux/mdev.h b/include/linux/mdev.h index 13e045e09d3b..6060cdbe6d3e 100644 --- a/include/linux/mdev.h +++ b/include/linux/mdev.h @@ -114,6 +114,8 @@ void mdev_set_vfio_ops(struct mdev_device *mdev, const struct vfio_mdev_device_ops *vfio_ops); void mdev_set_virtio_ops(struct mdev_device *mdev, const struct virtio_mdev_device_ops *virtio_ops); +void mdev_set_vhost_ops(struct mdev_device *mdev, + const struct virtio_mdev_device_ops *vhost_ops); const void *mdev_get_dev_ops(struct mdev_device *mdev); extern struct bus_type mdev_bus_type; @@ -131,6 +133,7 @@ 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..dad3c62bd91b 100644 --- a/include/uapi/linux/vhost.h +++ b/include/uapi/linux/vhost.h @@ -116,4 +116,17 @@ #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 and set the status of the backend. The status bits follow the + * same definition of the device status defined in virtio-spec. */ +#define VHOST_MDEV_GET_STATUS _IOW(VHOST_VIRTIO, 0x70, __u8) +#define VHOST_MDEV_SET_STATUS _IOW(VHOST_VIRTIO, 0x71, __u8) +/* Enable/disable the ring. */ +#define VHOST_MDEV_SET_VRING_ENABLE _IOW(VHOST_VIRTIO, 0x72, struct vhost_vring_state) +/* Get the max ring size. */ +#define VHOST_MDEV_GET_VRING_NUM _IOW(VHOST_VIRTIO, 0x73, __u16) +/* Get the max number of queues. */ +#define VHOST_MDEV_GET_QUEUE_NUM _IOW(VHOST_VIRTIO, 0x74, __u32) + #endif -- 2.23.0
