On Thu, Sep 26, 2019 at 12:54:27PM +0800, 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. > > Signed-off-by: Tiwei Bie <tiwei.bie@xxxxxxxxx> > --- > 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 So assuming we have an underlying device that behaves like virtio: 1. Should we use SET_STATUS maybe? 2. Do we want a reset ioctl? 3. Do we want ability to enable rings individually? 4. Does device need to limit max ring size? 5. Does device need to limit max number of queues? -- MST _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
