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/2019/9/24/357 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/vhost/Kconfig | 9 + drivers/vhost/Makefile | 3 + drivers/vhost/mdev.c | 381 +++++++++++++++++++++++++++++++++++++ include/uapi/linux/vhost.h | 8 + 4 files changed, 401 insertions(+) create mode 100644 drivers/vhost/mdev.c diff --git a/drivers/vhost/Kconfig b/drivers/vhost/Kconfig index 3d03ccbd1adc..decf0be8efe9 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..1c12a25b86a2 --- /dev/null +++ b/drivers/vhost/mdev.c @@ -0,0 +1,381 @@ +// 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 "vhost.h" + +struct vhost_mdev { + /* The lock is to protect this structure. */ + struct mutex mutex; + struct vhost_dev dev; + struct vhost_virtqueue *vqs; + int nvqs; + u64 state; + u64 features; + u64 acked_features; + bool opened; + struct mdev_device *mdev; +}; + +static u8 mdev_get_status(struct mdev_device *mdev) +{ + const struct virtio_mdev_device_ops *ops = mdev_get_dev_ops(mdev); + + return ops->get_status(mdev); +} + +static void mdev_set_status(struct mdev_device *mdev, u8 status) +{ + const struct virtio_mdev_device_ops *ops = mdev_get_dev_ops(mdev); + + return ops->set_status(mdev, status); +} + +static void mdev_add_status(struct mdev_device *mdev, u8 status) +{ + status |= mdev_get_status(mdev); + mdev_set_status(mdev, status); +} + +static void mdev_reset(struct mdev_device *mdev) +{ + mdev_set_status(mdev, 0); +} + +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 long vhost_mdev_reset(struct vhost_mdev *m) +{ + struct mdev_device *mdev = m->mdev; + + mdev_reset(mdev); + mdev_add_status(mdev, VIRTIO_CONFIG_S_ACKNOWLEDGE); + mdev_add_status(mdev, VIRTIO_CONFIG_S_DRIVER); + return 0; +} + +static long vhost_mdev_start(struct vhost_mdev *m) +{ + struct mdev_device *mdev = m->mdev; + const struct virtio_mdev_device_ops *ops = mdev_get_dev_ops(mdev); + struct virtio_mdev_callback cb; + struct vhost_virtqueue *vq; + int idx; + + ops->set_features(mdev, m->acked_features); + + mdev_add_status(mdev, VIRTIO_CONFIG_S_FEATURES_OK); + if (!(mdev_get_status(mdev) & VIRTIO_CONFIG_S_FEATURES_OK)) + goto reset; + + for (idx = 0; idx < m->nvqs; idx++) { + vq = &m->vqs[idx]; + + if (!vq->desc || !vq->avail || !vq->used) + break; + + if (ops->set_vq_state(mdev, idx, vq->last_avail_idx)) + goto reset; + + /* + * In vhost-mdev, userspace should pass ring addresses + * in guest physical addresses when IOMMU is disabled or + * IOVAs when IOMMU is enabled. + */ + if (ops->set_vq_address(mdev, idx, (u64)vq->desc, + (u64)vq->avail, (u64)vq->used)) + goto reset; + + ops->set_vq_num(mdev, idx, vq->num); + + cb.callback = vhost_mdev_virtqueue_cb; + cb.private = vq; + ops->set_vq_cb(mdev, idx, &cb); + + ops->set_vq_ready(mdev, idx, 1); + } + + mdev_add_status(mdev, VIRTIO_CONFIG_S_DRIVER_OK); + if (mdev_get_status(mdev) & VIRTIO_CONFIG_S_NEEDS_RESET) + goto reset; + return 0; + +reset: + vhost_mdev_reset(m); + return -ENODEV; +} + +static long vhost_set_state(struct vhost_mdev *m, u64 __user *statep) +{ + u64 state; + long r; + + if (copy_from_user(&state, statep, sizeof(state))) + return -EFAULT; + + if (state >= VHOST_MDEV_S_MAX) + return -EINVAL; + + if (m->state == state) + return 0; + + m->state = state; + + switch (m->state) { + case VHOST_MDEV_S_RUNNING: + r = vhost_mdev_start(m); + break; + case VHOST_MDEV_S_STOPPED: + r = vhost_mdev_reset(m); + break; + default: + r = -EINVAL; + break; + } + + return r; +} + +static long vhost_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_set_features(struct vhost_mdev *m, u64 __user *featurep) +{ + u64 features; + + if (copy_from_user(&features, featurep, sizeof(features))) + return -EFAULT; + + if (features & ~m->features) + return -EINVAL; + + m->acked_features = features; + + return 0; +} + +static long vhost_get_vring_base(struct vhost_mdev *m, void __user *argp) +{ + const struct virtio_mdev_device_ops *ops = mdev_get_dev_ops(m->mdev); + struct vhost_virtqueue *vq; + u32 idx; + long r; + + r = get_user(idx, (u32 __user *)argp); + if (r < 0) + return r; + if (idx >= m->nvqs) + return -ENOBUFS; + + vq = &m->vqs[idx]; + vq->last_avail_idx = ops->get_vq_state(m->mdev, idx); + + return vhost_vring_ioctl(&m->dev, VHOST_GET_VRING_BASE, argp); +} + +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_SET_STATE: + r = vhost_set_state(m, argp); + break; + case VHOST_GET_FEATURES: + r = vhost_get_features(m, argp); + break; + case VHOST_SET_FEATURES: + r = vhost_set_features(m, argp); + break; + case VHOST_GET_VRING_BASE: + r = vhost_get_vring_base(m, argp); + break; + default: + r = vhost_dev_ioctl(&m->dev, cmd, argp); + if (r == -ENOIOCTLCMD) + r = vhost_vring_ioctl(&m->dev, 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; + + m = kzalloc(sizeof(*m), GFP_KERNEL | __GFP_RETRY_MAYFAIL); + if (!m) + return -ENOMEM; + + mutex_init(&m->mutex); + + nvqs = ops->get_queue_max(mdev); + m->nvqs = nvqs; + + m->vqs = kmalloc_array(nvqs, sizeof(struct vhost_virtqueue), + GFP_KERNEL); + if (!m->vqs) { + r = -ENOMEM; + goto err; + } + + r = vfio_add_group_dev(dev, &vfio_vhost_mdev_dev_ops, m); + if (r) + goto err; + + m->features = ops->get_features(mdev); + m->mdev = mdev; + return 0; + +err: + kfree(m->vqs); + kfree(m); + return r; +} + +static void vhost_mdev_remove(struct device *dev) +{ + struct vhost_mdev *m; + + m = vfio_del_group_dev(dev); + mutex_destroy(&m->mutex); + kfree(m->vqs); + kfree(m); +} + +static struct mdev_class_id id_table[] = { + { MDEV_ID_VHOST }, + { 0 }, +}; + +static struct mdev_driver vhost_mdev_driver = { + .name = "vhost_mdev", + .probe = vhost_mdev_probe, + .remove = vhost_mdev_remove, + .id_table = id_table, +}; + +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/uapi/linux/vhost.h b/include/uapi/linux/vhost.h index 40d028eed645..5afbc2f08fa3 100644 --- a/include/uapi/linux/vhost.h +++ b/include/uapi/linux/vhost.h @@ -116,4 +116,12 @@ #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 */ + +#define VHOST_MDEV_SET_STATE _IOW(VHOST_VIRTIO, 0x70, __u64) + +#define VHOST_MDEV_S_STOPPED 0 +#define VHOST_MDEV_S_RUNNING 1 +#define VHOST_MDEV_S_MAX 2 + #endif -- 2.17.1
