Re: [PATCH V10 6/6] docs: sample driver to demonstrate how to implement virtio-mdev framework

Michael S. Tsirkin
2019-11-07T09:08:59Z

On Wed, Nov 06, 2019 at 09:35:31PM +0800, Jason Wang wrote:
> This sample driver creates mdev device that simulate virtio net device
> over virtio mdev transport. The device is implemented through vringh
> and workqueue. A device specific dma ops is to make sure HVA is used
> directly as the IOVA. This should be sufficient for kernel virtio
> driver to work.
>
> Only 'virtio' type is supported right now. I plan to add 'vhost' type
> on top which requires some virtual IOMMU implemented in this sample
> driver.
>
> Acked-by: Cornelia Huck <cohuck@redhat.com>
> Signed-off-by: Jason Wang <jasowang@redhat.com>

I'd prefer it that we call this something else, e.g.
mvnet-loopback. Just so people don't expect a fully
functional device somehow. Can be renamed when applying?

> ---
> MAINTAINERS | 1 +
> samples/Kconfig | 10 +
> samples/vfio-mdev/Makefile | 1 +
> samples/vfio-mdev/mvnet.c | 686 +++++++++++++++++++++++++++++++++++++
> 4 files changed, 698 insertions(+)
> create mode 100644 samples/vfio-mdev/mvnet.c
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 4997957443df..6e9ad105a28f 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -17249,6 +17249,7 @@ F: include/uapi/linux/virtio_*.h
> F: drivers/crypto/virtio/
> F: mm/balloon_compaction.c
> F: include/linux/mdev_virtio_ops.h
> +F: samples/vfio-mdev/mvnet.c
>
> VIRTIO BLOCK AND SCSI DRIVERS
> M: "Michael S. Tsirkin" <mst@redhat.com>
> diff --git a/samples/Kconfig b/samples/Kconfig
> index c8dacb4dda80..13a2443e18e0 100644
> --- a/samples/Kconfig
> +++ b/samples/Kconfig
> @@ -131,6 +131,16 @@ config SAMPLE_VFIO_MDEV_MDPY
> mediated device. It is a simple framebuffer and supports
> the region display interface (VFIO_GFX_PLANE_TYPE_REGION).
>
> +config SAMPLE_VIRTIO_MDEV_NET
> + tristate "Build VIRTIO net example mediated device sample code -- loadable modules only"
> + depends on VIRTIO_MDEV && VHOST_RING && m
> + help
> + Build a networking sample device for use as a virtio
> + mediated device. The device coopreates with virtio-mdev bus
> + driver to present an virtio ethernet driver for
> + kernel. It simply loopbacks all packets from its TX
> + virtqueue to its RX virtqueue.
> +
> config SAMPLE_VFIO_MDEV_MDPY_FB
> tristate "Build VFIO mdpy example guest fbdev driver -- loadable module only"
> depends on FB && m
> diff --git a/samples/vfio-mdev/Makefile b/samples/vfio-mdev/Makefile
> index 10d179c4fdeb..f34af90ed0a0 100644
> --- a/samples/vfio-mdev/Makefile
> +++ b/samples/vfio-mdev/Makefile
> @@ -3,3 +3,4 @@ obj-$(CONFIG_SAMPLE_VFIO_MDEV_MTTY) += mtty.o
> obj-$(CONFIG_SAMPLE_VFIO_MDEV_MDPY) += mdpy.o
> obj-$(CONFIG_SAMPLE_VFIO_MDEV_MDPY_FB) += mdpy-fb.o
> obj-$(CONFIG_SAMPLE_VFIO_MDEV_MBOCHS) += mbochs.o
> +obj-$(CONFIG_SAMPLE_VIRTIO_MDEV_NET) += mvnet.o
> diff --git a/samples/vfio-mdev/mvnet.c b/samples/vfio-mdev/mvnet.c
> new file mode 100644
> index 000000000000..a89aecfab68a
> --- /dev/null
> +++ b/samples/vfio-mdev/mvnet.c
> @@ -0,0 +1,686 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Mediated virtual virtio-net device driver.
> + *
> + * Copyright (c) 2019, Red Hat Inc. All rights reserved.
> + * Author: Jason Wang <jasowang@redhat.com>
> + *
> + * Sample driver that creates mdev device that simulates ethernet loopback
> + * device.
> + *
> + * Usage:
> + *
> + * # modprobe virtio_mdev
> + * # modprobe mvnet
> + * # cd /sys/devices/virtual/mvnet/mvnet/mdev_supported_types/mvnet-virtio
> + * # echo "83b8f4f2-509f-382f-3c1e-e6bfe0fa1001" > ./create
> + * # cd devices/83b8f4f2-509f-382f-3c1e-e6bfe0fa1001
> + * # ls -d virtio0
> + * virtio0
> + */
> +
> +#include <linux/init.h>
> +#include <linux/module.h>
> +#include <linux/device.h>
> +#include <linux/kernel.h>
> +#include <linux/fs.h>
> +#include <linux/poll.h>
> +#include <linux/slab.h>
> +#include <linux/sched.h>
> +#include <linux/wait.h>
> +#include <linux/uuid.h>
> +#include <linux/iommu.h>
> +#include <linux/sysfs.h>
> +#include <linux/file.h>
> +#include <linux/etherdevice.h>
> +#include <linux/mdev.h>
> +#include <linux/vringh.h>
> +#include <linux/mdev_virtio_ops.h>
> +#include <uapi/linux/virtio_config.h>
> +#include <uapi/linux/virtio_net.h>
> +
> +#define VERSION_STRING "0.1"
> +#define DRIVER_AUTHOR "Red Hat Corporation"
> +
> +#define MVNET_CLASS_NAME "mvnet"
> +#define MVNET_NAME "mvnet"
> +
> +/*
> + * Global Structures
> + */
> +
> +static struct mvnet_dev {
> + struct class *vd_class;
> + struct idr vd_idr;
> + struct device dev;
> +} mvnet_dev;
> +
> +struct mvnet_virtqueue {
> + struct vringh vring;
> + struct vringh_kiov iov;
> + unsigned short head;
> + bool ready;
> + u64 desc_addr;
> + u64 device_addr;
> + u64 driver_addr;
> + u32 num;
> + void *private;
> + irqreturn_t (*cb)(void *data);
> +};
> +
> +#define MVNET_QUEUE_ALIGN PAGE_SIZE
> +#define MVNET_QUEUE_MAX 256
> +#define MVNET_DEVICE_ID 0x1
> +#define MVNET_VENDOR_ID 0
> +
> +u64 mvnet_features = (1ULL << VIRTIO_F_ANY_LAYOUT) |
> + (1ULL << VIRTIO_F_VERSION_1) |
> + (1ULL << VIRTIO_F_IOMMU_PLATFORM);
> +
> +/* State of each mdev device */
> +struct mvnet_state {
> + struct mvnet_virtqueue vqs[2];
> + struct work_struct work;
> + /* spinlock to synchronize virtqueue state */
> + spinlock_t lock;
> + struct mdev_device *mdev;
> + struct virtio_net_config config;
> + void *buffer;
> + u32 status;
> + u32 generation;
> + u64 features;
> + struct list_head next;
> +};
> +
> +static struct mutex mdev_list_lock;
> +static struct list_head mdev_devices_list;
> +
> +static void mvnet_queue_ready(struct mvnet_state *mvnet, unsigned int idx)
> +{
> + struct mvnet_virtqueue *vq = &mvnet->vqs[idx];
> + int ret;
> +
> + ret = vringh_init_kern(&vq->vring, mvnet_features, MVNET_QUEUE_MAX,
> + false, (struct vring_desc *)vq->desc_addr,
> + (struct vring_avail *)vq->driver_addr,
> + (struct vring_used *)vq->device_addr);
> +}
> +
> +static void mvnet_vq_reset(struct mvnet_virtqueue *vq)
> +{
> + vq->ready = 0;
> + vq->desc_addr = 0;
> + vq->driver_addr = 0;
> + vq->device_addr = 0;
> + vq->cb = NULL;
> + vq->private = NULL;
> + vringh_init_kern(&vq->vring, mvnet_features, MVNET_QUEUE_MAX,
> + false, 0, 0, 0);
> +}
> +
> +static void mvnet_reset(struct mvnet_state *mvnet)
> +{
> + int i;
> +
> + for (i = 0; i < 2; i++)
> + mvnet_vq_reset(&mvnet->vqs[i]);
> +
> + mvnet->features = 0;
> + mvnet->status = 0;
> + ++mvnet->generation;
> +}
> +
> +static void mvnet_work(struct work_struct *work)
> +{
> + struct mvnet_state *mvnet = container_of(work, struct
> + mvnet_state, work);
> + struct mvnet_virtqueue *txq = &mvnet->vqs[1];
> + struct mvnet_virtqueue *rxq = &mvnet->vqs[0];
> + size_t read, write, total_write;
> + int err;
> + int pkts = 0;
> +
> + spin_lock(&mvnet->lock);
> +
> + if (!txq->ready || !rxq->ready)
> + goto out;
> +
> + while (true) {
> + total_write = 0;
> + err = vringh_getdesc_kern(&txq->vring, &txq->iov, NULL,
> + &txq->head, GFP_ATOMIC);
> + if (err <= 0)
> + break;
> +
> + err = vringh_getdesc_kern(&rxq->vring, NULL, &rxq->iov,
> + &rxq->head, GFP_ATOMIC);
> + if (err <= 0) {
> + vringh_complete_kern(&txq->vring, txq->head, 0);
> + break;
> + }
> +
> + while (true) {
> + read = vringh_iov_pull_kern(&txq->iov, mvnet->buffer,
> + PAGE_SIZE);
> + if (read <= 0)
> + break;
> +
> + write = vringh_iov_push_kern(&rxq->iov, mvnet->buffer,
> + read);
> + if (write <= 0)
> + break;
> +
> + total_write += write;
> + }
> +
> + /* Make sure data is wrote before advancing index */
> + smp_wmb();
> +
> + vringh_complete_kern(&txq->vring, txq->head, 0);
> + vringh_complete_kern(&rxq->vring, rxq->head, total_write);
> +
> + /* Make sure used is visible before rasing the interrupt. */
> + smp_wmb();
> +
> + local_bh_disable();
> + if (txq->cb)
> + txq->cb(txq->private);
> + if (rxq->cb)
> + rxq->cb(rxq->private);
> + local_bh_enable();
> +
> + if (++pkts > 4) {
> + schedule_work(&mvnet->work);
> + goto out;
> + }
> + }
> +
> +out:
> + spin_unlock(&mvnet->lock);
> +}
> +
> +static dma_addr_t mvnet_map_page(struct device *dev, struct page *page,
> + unsigned long offset, size_t size,
> + enum dma_data_direction dir,
> + unsigned long attrs)
> +{
> + /* Vringh can only use HVA */
> + return (dma_addr_t)(page_address(page) + offset);
> +}
> +
> +static void mvnet_unmap_page(struct device *dev, dma_addr_t dma_addr,
> + size_t size, enum dma_data_direction dir,
> + unsigned long attrs)
> +{
> +}
> +
> +static void *mvnet_alloc_coherent(struct device *dev, size_t size,
> + dma_addr_t *dma_addr, gfp_t flag,
> + unsigned long attrs)
> +{
> + void *addr = kmalloc(size, flag);
> +
> + if (!addr)
> + *dma_addr = DMA_MAPPING_ERROR;
> + else
> + *dma_addr = (dma_addr_t)addr;
> +
> + return addr;
> +}
> +
> +static void mvnet_free_coherent(struct device *dev, size_t size,
> + void *vaddr, dma_addr_t dma_addr,
> + unsigned long attrs)
> +{
> + kfree((void *)dma_addr);
> +}
> +
> +static const struct dma_map_ops mvnet_dma_ops = {
> + .map_page = mvnet_map_page,
> + .unmap_page = mvnet_unmap_page,
> + .alloc = mvnet_alloc_coherent,
> + .free = mvnet_free_coherent,
> +};
> +
> +static const struct mdev_virtio_device_ops mdev_virtio_ops;
> +
> +static int mvnet_create(struct kobject *kobj, struct mdev_device *mdev)
> +{
> + struct mvnet_state *mvnet;
> + struct virtio_net_config *config;
> + struct device *dev = mdev_dev(mdev);
> +
> + if (!mdev)
> + return -EINVAL;
> +
> + mvnet = kzalloc(sizeof(*mvnet), GFP_KERNEL);
> + if (!mvnet)
> + return -ENOMEM;
> +
> + mvnet->buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
> + if (!mvnet->buffer) {
> + kfree(mvnet);
> + return -ENOMEM;
> + }
> +
> + config = &mvnet->config;
> + config->mtu = 1500;
> + config->status = VIRTIO_NET_S_LINK_UP;
> + eth_random_addr(config->mac);
> +
> + INIT_WORK(&mvnet->work, mvnet_work);
> +
> + spin_lock_init(&mvnet->lock);
> + mvnet->mdev = mdev;
> + mdev_set_drvdata(mdev, mvnet);
> +
> + mutex_lock(&mdev_list_lock);
> + list_add(&mvnet->next, &mdev_devices_list);
> + mutex_unlock(&mdev_list_lock);
> +
> + dev->coherent_dma_mask = DMA_BIT_MASK(64);
> + set_dma_ops(dev, &mvnet_dma_ops);
> +
> + mdev_set_virtio_ops(mdev, &mdev_virtio_ops);
> +
> + return 0;
> +}
> +
> +static int mvnet_remove(struct mdev_device *mdev)
> +{
> + struct mvnet_state *mds, *tmp_mds;
> + struct mvnet_state *mvnet = mdev_get_drvdata(mdev);
> + int ret = -EINVAL;
> +
> + mutex_lock(&mdev_list_lock);
> + list_for_each_entry_safe(mds, tmp_mds, &mdev_devices_list, next) {
> + if (mvnet == mds) {
> + list_del(&mvnet->next);
> + mdev_set_drvdata(mdev, NULL);
> + kfree(mvnet->buffer);
> + kfree(mvnet);
> + ret = 0;
> + break;
> + }
> + }
> + mutex_unlock(&mdev_list_lock);
> +
> + return ret;
> +}
> +
> +static ssize_t
> +sample_mvnet_dev_show(struct device *dev, struct device_attribute *attr,
> + char *buf)
> +{
> + if (mdev_from_dev(dev))
> + return sprintf(buf, "This is MDEV %s\n", dev_name(dev));
> +
> + return sprintf(buf, "\n");
> +}
> +
> +static DEVICE_ATTR_RO(sample_mvnet_dev);
> +
> +static struct attribute *mvnet_dev_attrs[] = {
> + &dev_attr_sample_mvnet_dev.attr,
> + NULL,
> +};
> +
> +static const struct attribute_group mvnet_dev_group = {
> + .name = "mvnet_dev",
> + .attrs = mvnet_dev_attrs,
> +};
> +
> +static const struct attribute_group *mvnet_dev_groups[] = {
> + &mvnet_dev_group,
> + NULL,
> +};
> +
> +static ssize_t
> +sample_mdev_dev_show(struct device *dev, struct device_attribute *attr,
> + char *buf)
> +{
> + if (mdev_from_dev(dev))
> + return sprintf(buf, "This is MDEV %s\n", dev_name(dev));
> +
> + return sprintf(buf, "\n");
> +}
> +
> +static DEVICE_ATTR_RO(sample_mdev_dev);
> +
> +static struct attribute *mdev_dev_attrs[] = {
> + &dev_attr_sample_mdev_dev.attr,
> + NULL,
> +};
> +
> +static const struct attribute_group mdev_dev_group = {
> + .name = "vendor",
> + .attrs = mdev_dev_attrs,
> +};
> +
> +static const struct attribute_group *mdev_dev_groups[] = {
> + &mdev_dev_group,
> + NULL,
> +};
> +
> +#define MVNET_STRING_LEN 16
> +
> +static ssize_t
> +name_show(struct kobject *kobj, struct device *dev, char *buf)
> +{
> + char name[MVNET_STRING_LEN];
> + const char *name_str = "virtio-net";
> +
> + snprintf(name, MVNET_STRING_LEN, "%s", dev_driver_string(dev));
> + if (!strcmp(kobj->name, name))
> + return sprintf(buf, "%s\n", name_str);
> +
> + return -EINVAL;
> +}
> +
> +static MDEV_TYPE_ATTR_RO(name);
> +
> +static ssize_t
> +available_instances_show(struct kobject *kobj, struct device *dev, char *buf)
> +{
> + return sprintf(buf, "%d\n", INT_MAX);
> +}
> +
> +static MDEV_TYPE_ATTR_RO(available_instances);
> +
> +static ssize_t device_api_show(struct kobject *kobj, struct device *dev,
> + char *buf)
> +{
> + return sprintf(buf, "%s\n", VIRTIO_MDEV_DEVICE_API_STRING);
> +}
> +
> +static MDEV_TYPE_ATTR_RO(device_api);
> +
> +static struct attribute *mdev_types_attrs[] = {
> + &mdev_type_attr_name.attr,
> + &mdev_type_attr_device_api.attr,
> + &mdev_type_attr_available_instances.attr,
> + NULL,
> +};
> +
> +static struct attribute_group mdev_type_group = {
> + .name = "virtio",
> + .attrs = mdev_types_attrs,
> +};
> +
> +/* TBD: "vhost" type */
> +
> +static struct attribute_group *mdev_type_groups[] = {
> + &mdev_type_group,
> + NULL,
> +};
> +
> +static int mvnet_set_vq_address(struct mdev_device *mdev, u16 idx,
> + u64 desc_area, u64 driver_area, u64 device_area)
> +{
> + struct mvnet_state *mvnet = mdev_get_drvdata(mdev);
> + struct mvnet_virtqueue *vq = &mvnet->vqs[idx];
> +
> + vq->desc_addr = desc_area;
> + vq->driver_addr = driver_area;
> + vq->device_addr = device_area;
> +
> + return 0;
> +}
> +
> +static void mvnet_set_vq_num(struct mdev_device *mdev, u16 idx, u32 num)
> +{
> + struct mvnet_state *mvnet = mdev_get_drvdata(mdev);
> + struct mvnet_virtqueue *vq = &mvnet->vqs[idx];
> +
> + vq->num = num;
> +}
> +
> +static void mvnet_kick_vq(struct mdev_device *mdev, u16 idx)
> +{
> + struct mvnet_state *mvnet = mdev_get_drvdata(mdev);
> + struct mvnet_virtqueue *vq = &mvnet->vqs[idx];
> +
> + if (vq->ready)
> + schedule_work(&mvnet->work);
> +}
> +
> +static void mvnet_set_vq_cb(struct mdev_device *mdev, u16 idx,
> + struct virtio_mdev_callback *cb)
> +{
> + struct mvnet_state *mvnet = mdev_get_drvdata(mdev);
> + struct mvnet_virtqueue *vq = &mvnet->vqs[idx];
> +
> + vq->cb = cb->callback;
> + vq->private = cb->private;
> +}
> +
> +static void mvnet_set_vq_ready(struct mdev_device *mdev, u16 idx, bool ready)
> +{
> + struct mvnet_state *mvnet = mdev_get_drvdata(mdev);
> + struct mvnet_virtqueue *vq = &mvnet->vqs[idx];
> +
> + spin_lock(&mvnet->lock);
> + vq->ready = ready;
> + if (vq->ready)
> + mvnet_queue_ready(mvnet, idx);
> + spin_unlock(&mvnet->lock);
> +}
> +
> +static bool mvnet_get_vq_ready(struct mdev_device *mdev, u16 idx)
> +{
> + struct mvnet_state *mvnet = mdev_get_drvdata(mdev);
> + struct mvnet_virtqueue *vq = &mvnet->vqs[idx];
> +
> + return vq->ready;
> +}
> +
> +static int mvnet_set_vq_state(struct mdev_device *mdev, u16 idx, u64 state)
> +{
> + struct mvnet_state *mvnet = mdev_get_drvdata(mdev);
> + struct mvnet_virtqueue *vq = &mvnet->vqs[idx];
> + struct vringh *vrh = &vq->vring;
> +
> + spin_lock(&mvnet->lock);
> + vrh->last_avail_idx = state;
> + spin_unlock(&mvnet->lock);
> +
> + return 0;
> +}
> +
> +static u64 mvnet_get_vq_state(struct mdev_device *mdev, u16 idx)
> +{
> + struct mvnet_state *mvnet = mdev_get_drvdata(mdev);
> + struct mvnet_virtqueue *vq = &mvnet->vqs[idx];
> + struct vringh *vrh = &vq->vring;
> +
> + return vrh->last_avail_idx;
> +}
> +
> +static u16 mvnet_get_vq_align(struct mdev_device *mdev)
> +{
> + return MVNET_QUEUE_ALIGN;
> +}
> +
> +static u64 mvnet_get_features(struct mdev_device *mdev)
> +{
> + return mvnet_features;
> +}
> +
> +static int mvnet_set_features(struct mdev_device *mdev, u64 features)
> +{
> + struct mvnet_state *mvnet = mdev_get_drvdata(mdev);
> +
> + /* DMA mapping must be done by driver */
> + if (!(features & (1ULL << VIRTIO_F_IOMMU_PLATFORM)))
> + return -EINVAL;
> +
> + mvnet->features = features & mvnet_features;
> +
> + return 0;
> +}
> +
> +static void mvnet_set_config_cb(struct mdev_device *mdev,
> + struct virtio_mdev_callback *cb)
> +{
> + /* We don't support config interrupt */
> +}
> +
> +static u16 mvnet_get_vq_num_max(struct mdev_device *mdev)
> +{
> + return MVNET_QUEUE_MAX;
> +}
> +
> +static u32 mvnet_get_device_id(struct mdev_device *mdev)
> +{
> + return MVNET_DEVICE_ID;
> +}
> +
> +static u32 mvnet_get_vendor_id(struct mdev_device *mdev)
> +{
> + return MVNET_VENDOR_ID;
> +}
> +
> +static u8 mvnet_get_status(struct mdev_device *mdev)
> +{
> + struct mvnet_state *mvnet = mdev_get_drvdata(mdev);
> +
> + return mvnet->status;
> +}
> +
> +static void mvnet_set_status(struct mdev_device *mdev, u8 status)
> +{
> + struct mvnet_state *mvnet = mdev_get_drvdata(mdev);
> +
> + mvnet->status = status;
> +
> + if (status == 0) {
> + spin_lock(&mvnet->lock);
> + mvnet_reset(mvnet);
> + spin_unlock(&mvnet->lock);
> + }
> +}
> +
> +static void mvnet_get_config(struct mdev_device *mdev, unsigned int offset,
> + void *buf, unsigned int len)
> +{
> + struct mvnet_state *mvnet = mdev_get_drvdata(mdev);
> +
> + if (offset + len < sizeof(struct virtio_net_config))
> + memcpy(buf, &mvnet->config + offset, len);
> +}
> +
> +static void mvnet_set_config(struct mdev_device *mdev, unsigned int offset,
> + const void *buf, unsigned int len)
> +{
> + /* No writable config supportted by mvnet */
> +}
> +
> +static u32 mvnet_get_generation(struct mdev_device *mdev)
> +{
> + struct mvnet_state *mvnet = mdev_get_drvdata(mdev);
> +
> + return mvnet->generation;
> +}
> +
> +static const struct mdev_virtio_device_ops mdev_virtio_ops = {
> + .set_vq_address = mvnet_set_vq_address,
> + .set_vq_num = mvnet_set_vq_num,
> + .kick_vq = mvnet_kick_vq,
> + .set_vq_cb = mvnet_set_vq_cb,
> + .set_vq_ready = mvnet_set_vq_ready,
> + .get_vq_ready = mvnet_get_vq_ready,
> + .set_vq_state = mvnet_set_vq_state,
> + .get_vq_state = mvnet_get_vq_state,
> + .get_vq_align = mvnet_get_vq_align,
> + .get_features = mvnet_get_features,
> + .set_features = mvnet_set_features,
> + .set_config_cb = mvnet_set_config_cb,
> + .get_vq_num_max = mvnet_get_vq_num_max,
> + .get_device_id = mvnet_get_device_id,
> + .get_vendor_id = mvnet_get_vendor_id,
> + .get_status = mvnet_get_status,
> + .set_status = mvnet_set_status,
> + .get_config = mvnet_get_config,
> + .set_config = mvnet_set_config,
> + .get_generation = mvnet_get_generation,
> +};
> +
> +static const struct mdev_parent_ops mdev_fops = {
> + .owner = THIS_MODULE,
> + .dev_attr_groups = mvnet_dev_groups,
> + .mdev_attr_groups = mdev_dev_groups,
> + .supported_type_groups = mdev_type_groups,
> + .create = mvnet_create,
> + .remove = mvnet_remove,
> +};
> +
> +static void mvnet_device_release(struct device *dev)
> +{
> + dev_dbg(dev, "mvnet: released\n");
> +}
> +
> +static int __init mvnet_dev_init(void)
> +{
> + int ret = 0;
> +
> + pr_info("mvnet_dev: %s\n", __func__);
> +
> + memset(&mvnet_dev, 0, sizeof(mvnet_dev));
> +
> + idr_init(&mvnet_dev.vd_idr);
> +
> + mvnet_dev.vd_class = class_create(THIS_MODULE, MVNET_CLASS_NAME);
> +
> + if (IS_ERR(mvnet_dev.vd_class)) {
> + pr_err("Error: failed to register mvnet_dev class\n");
> + ret = PTR_ERR(mvnet_dev.vd_class);
> + goto failed1;
> + }
> +
> + mvnet_dev.dev.class = mvnet_dev.vd_class;
> + mvnet_dev.dev.release = mvnet_device_release;
> + dev_set_name(&mvnet_dev.dev, "%s", MVNET_NAME);
> +
> + ret = device_register(&mvnet_dev.dev);
> + if (ret)
> + goto failed2;
> +
> + ret = mdev_register_device(&mvnet_dev.dev, &mdev_fops);
> + if (ret)
> + goto failed3;
> +
> + mutex_init(&mdev_list_lock);
> + INIT_LIST_HEAD(&mdev_devices_list);
> +
> + goto all_done;
> +
> +failed3:
> +
> + device_unregister(&mvnet_dev.dev);
> +failed2:
> + class_destroy(mvnet_dev.vd_class);
> +
> +failed1:
> +all_done:
> + return ret;
> +}
> +
> +static void __exit mvnet_dev_exit(void)
> +{
> + mvnet_dev.dev.bus = NULL;
> + mdev_unregister_device(&mvnet_dev.dev);
> +
> + device_unregister(&mvnet_dev.dev);
> + idr_destroy(&mvnet_dev.vd_idr);
> + class_destroy(mvnet_dev.vd_class);
> + mvnet_dev.vd_class = NULL;
> + pr_info("mvnet_dev: Unloaded!\n");
> +}
> +
> +module_init(mvnet_dev_init)
> +module_exit(mvnet_dev_exit)
> +
> +MODULE_LICENSE("GPL v2");
> +MODULE_INFO(supported, "Simulate loopback ethernet device over mdev");
> +MODULE_VERSION(VERSION_STRING);
> +MODULE_AUTHOR(DRIVER_AUTHOR);
> --
> 2.19.1