[V10,6/6] docs: sample driver to demonstrate how to implement virtio-mdev framework
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Message ID 20191106133531.693-7-jasowang@redhat.com
State New
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Series
  • mdev based hardware virtio offloading support
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Commit Message

Jason Wang Nov. 6, 2019, 1:35 p.m. UTC
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>
---
 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

Comments

Michael S. Tsirkin Nov. 7, 2019, 9:08 a.m. UTC | #1
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
Jason Wang Nov. 7, 2019, 10:18 a.m. UTC | #2
On 2019/11/7 下午5:08, Michael S. Tsirkin wrote:
> 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?


Actually, I plan to extend it as another standard network interface for 
kernel. It could be either a standalone pseudo device or a stack device. 
Does this sounds good to you?

Thanks


>
>
Michael S. Tsirkin Nov. 7, 2019, 11:21 a.m. UTC | #3
On Thu, Nov 07, 2019 at 06:18:45PM +0800, Jason Wang wrote:
> 
> On 2019/11/7 下午5:08, Michael S. Tsirkin wrote:
> > 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?
> 
> 
> Actually, I plan to extend it as another standard network interface for
> kernel. It could be either a standalone pseudo device or a stack device.
> Does this sounds good to you?
> 
> Thanks

That's a big change in an interface so it's a good reason
to rename the driver at that point right?
Oherwise users of an old kernel would expect a stacked driver
and get a loopback instead.

Or did I miss something?

> 
> > 
> >
Jason Wang Nov. 7, 2019, 12:43 p.m. UTC | #4
On 2019/11/7 下午7:21, Michael S. Tsirkin wrote:
> On Thu, Nov 07, 2019 at 06:18:45PM +0800, Jason Wang wrote:
>> On 2019/11/7 下午5:08, Michael S. Tsirkin wrote:
>>> 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?
>> Actually, I plan to extend it as another standard network interface for
>> kernel. It could be either a standalone pseudo device or a stack device.
>> Does this sounds good to you?
>>
>> Thanks
> That's a big change in an interface so it's a good reason
> to rename the driver at that point right?
> Oherwise users of an old kernel would expect a stacked driver
> and get a loopback instead.
>
> Or did I miss something?


My understanding is that it was a sample driver in /doc. It should not 
be used in production environment. Otherwise we need to move it to 
driver/virtio.

But if you insist, I can post a V11.

Thanks
Jason Wang Nov. 7, 2019, 12:47 p.m. UTC | #5
On 2019/11/7 下午8:43, Jason Wang wrote:
>
> On 2019/11/7 下午7:21, Michael S. Tsirkin wrote:
>> On Thu, Nov 07, 2019 at 06:18:45PM +0800, Jason Wang wrote:
>>> On 2019/11/7 下午5:08, Michael S. Tsirkin wrote:
>>>> 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?
>>> Actually, I plan to extend it as another standard network interface for
>>> kernel. It could be either a standalone pseudo device or a stack 
>>> device.
>>> Does this sounds good to you?
>>>
>>> Thanks
>> That's a big change in an interface so it's a good reason
>> to rename the driver at that point right?
>> Oherwise users of an old kernel would expect a stacked driver
>> and get a loopback instead.
>>
>> Or did I miss something?
>
>
> My understanding is that it was a sample driver in /doc. It should not 
> be used in production environment. Otherwise we need to move it to 
> driver/virtio.
>
> But if you insist, I can post a V11.
>
> Thanks 


Or maybe it's better to rename the type of current mdev from 'virtio' to 
'virtio-loopback'. Then we can add more types in the future.

Thanks
Michael S. Tsirkin Nov. 7, 2019, 1:08 p.m. UTC | #6
On Thu, Nov 07, 2019 at 08:47:06PM +0800, Jason Wang wrote:
> 
> On 2019/11/7 下午8:43, Jason Wang wrote:
> > 
> > On 2019/11/7 下午7:21, Michael S. Tsirkin wrote:
> > > On Thu, Nov 07, 2019 at 06:18:45PM +0800, Jason Wang wrote:
> > > > On 2019/11/7 下午5:08, Michael S. Tsirkin wrote:
> > > > > 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?
> > > > Actually, I plan to extend it as another standard network interface for
> > > > kernel. It could be either a standalone pseudo device or a stack
> > > > device.
> > > > Does this sounds good to you?
> > > > 
> > > > Thanks
> > > That's a big change in an interface so it's a good reason
> > > to rename the driver at that point right?
> > > Oherwise users of an old kernel would expect a stacked driver
> > > and get a loopback instead.
> > > 
> > > Or did I miss something?
> > 
> > 
> > My understanding is that it was a sample driver in /doc. It should not
> > be used in production environment. Otherwise we need to move it to
> > driver/virtio.
> > 
> > But if you insist, I can post a V11.
> > 
> > Thanks
> 
> 
> Or maybe it's better to rename the type of current mdev from 'virtio' to
> 'virtio-loopback'. Then we can add more types in the future.
> 
> Thanks
> 

Maybe but is virtio actually a loopback somehow? I thought we
can bind a regular virtio device there, no?
Michael S. Tsirkin Nov. 7, 2019, 1:08 p.m. UTC | #7
On Thu, Nov 07, 2019 at 08:43:29PM +0800, Jason Wang wrote:
> 
> On 2019/11/7 下午7:21, Michael S. Tsirkin wrote:
> > On Thu, Nov 07, 2019 at 06:18:45PM +0800, Jason Wang wrote:
> > > On 2019/11/7 下午5:08, Michael S. Tsirkin wrote:
> > > > 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?
> > > Actually, I plan to extend it as another standard network interface for
> > > kernel. It could be either a standalone pseudo device or a stack device.
> > > Does this sounds good to you?
> > > 
> > > Thanks
> > That's a big change in an interface so it's a good reason
> > to rename the driver at that point right?
> > Oherwise users of an old kernel would expect a stacked driver
> > and get a loopback instead.
> > 
> > Or did I miss something?
> 
> 
> My understanding is that it was a sample driver in /doc. It should not be
> used in production environment. Otherwise we need to move it to
> driver/virtio.
> 
> But if you insist, I can post a V11.
> 
> Thanks

this can be a patch on top.
Jason Wang Nov. 7, 2019, 1:32 p.m. UTC | #8
On 2019/11/7 下午9:08, Michael S. Tsirkin wrote:
> On Thu, Nov 07, 2019 at 08:43:29PM +0800, Jason Wang wrote:
>> On 2019/11/7 下午7:21, Michael S. Tsirkin wrote:
>>> On Thu, Nov 07, 2019 at 06:18:45PM +0800, Jason Wang wrote:
>>>> On 2019/11/7 下午5:08, Michael S. Tsirkin wrote:
>>>>> 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?
>>>> Actually, I plan to extend it as another standard network interface for
>>>> kernel. It could be either a standalone pseudo device or a stack device.
>>>> Does this sounds good to you?
>>>>
>>>> Thanks
>>> That's a big change in an interface so it's a good reason
>>> to rename the driver at that point right?
>>> Oherwise users of an old kernel would expect a stacked driver
>>> and get a loopback instead.
>>>
>>> Or did I miss something?
>>
>> My understanding is that it was a sample driver in /doc. It should not be
>> used in production environment. Otherwise we need to move it to
>> driver/virtio.
>>
>> But if you insist, I can post a V11.
>>
>> Thanks
> this can be a patch on top.


Then maybe it's better just extend it to work as a normal networking 
device on top?

Thanks
Jason Wang Nov. 7, 2019, 1:40 p.m. UTC | #9
On 2019/11/7 下午9:08, Michael S. Tsirkin wrote:
> On Thu, Nov 07, 2019 at 08:47:06PM +0800, Jason Wang wrote:
>> On 2019/11/7 下午8:43, Jason Wang wrote:
>>> On 2019/11/7 下午7:21, Michael S. Tsirkin wrote:
>>>> On Thu, Nov 07, 2019 at 06:18:45PM +0800, Jason Wang wrote:
>>>>> On 2019/11/7 下午5:08, Michael S. Tsirkin wrote:
>>>>>> 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?
>>>>> Actually, I plan to extend it as another standard network interface for
>>>>> kernel. It could be either a standalone pseudo device or a stack
>>>>> device.
>>>>> Does this sounds good to you?
>>>>>
>>>>> Thanks
>>>> That's a big change in an interface so it's a good reason
>>>> to rename the driver at that point right?
>>>> Oherwise users of an old kernel would expect a stacked driver
>>>> and get a loopback instead.
>>>>
>>>> Or did I miss something?
>>>
>>> My understanding is that it was a sample driver in /doc. It should not
>>> be used in production environment. Otherwise we need to move it to
>>> driver/virtio.
>>>
>>> But if you insist, I can post a V11.
>>>
>>> Thanks
>>
>> Or maybe it's better to rename the type of current mdev from 'virtio' to
>> 'virtio-loopback'. Then we can add more types in the future.
>>
>> Thanks
>>
> Maybe but is virtio actually a loopback somehow? I thought we
> can bind a regular virtio device there, no?


It has a prefix, so user will see "mvnet-virtio-loopback".

Thanks

>
Michael S. Tsirkin Nov. 7, 2019, 1:50 p.m. UTC | #10
On Thu, Nov 07, 2019 at 09:32:29PM +0800, Jason Wang wrote:
> 
> On 2019/11/7 下午9:08, Michael S. Tsirkin wrote:
> > On Thu, Nov 07, 2019 at 08:43:29PM +0800, Jason Wang wrote:
> > > On 2019/11/7 下午7:21, Michael S. Tsirkin wrote:
> > > > On Thu, Nov 07, 2019 at 06:18:45PM +0800, Jason Wang wrote:
> > > > > On 2019/11/7 下午5:08, Michael S. Tsirkin wrote:
> > > > > > 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?
> > > > > Actually, I plan to extend it as another standard network interface for
> > > > > kernel. It could be either a standalone pseudo device or a stack device.
> > > > > Does this sounds good to you?
> > > > > 
> > > > > Thanks
> > > > That's a big change in an interface so it's a good reason
> > > > to rename the driver at that point right?
> > > > Oherwise users of an old kernel would expect a stacked driver
> > > > and get a loopback instead.
> > > > 
> > > > Or did I miss something?
> > > 
> > > My understanding is that it was a sample driver in /doc. It should not be
> > > used in production environment. Otherwise we need to move it to
> > > driver/virtio.
> > > 
> > > But if you insist, I can post a V11.
> > > 
> > > Thanks
> > this can be a patch on top.
> 
> 
> Then maybe it's better just extend it to work as a normal networking device
> on top?
> 
> Thanks

That would be a substantial change. Maybe drop 6/6 for now until
we have a better handle on this?
Michael S. Tsirkin Nov. 7, 2019, 1:51 p.m. UTC | #11
On Thu, Nov 07, 2019 at 09:40:09PM +0800, Jason Wang wrote:
> 
> On 2019/11/7 下午9:08, Michael S. Tsirkin wrote:
> > On Thu, Nov 07, 2019 at 08:47:06PM +0800, Jason Wang wrote:
> > > On 2019/11/7 下午8:43, Jason Wang wrote:
> > > > On 2019/11/7 下午7:21, Michael S. Tsirkin wrote:
> > > > > On Thu, Nov 07, 2019 at 06:18:45PM +0800, Jason Wang wrote:
> > > > > > On 2019/11/7 下午5:08, Michael S. Tsirkin wrote:
> > > > > > > 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?
> > > > > > Actually, I plan to extend it as another standard network interface for
> > > > > > kernel. It could be either a standalone pseudo device or a stack
> > > > > > device.
> > > > > > Does this sounds good to you?
> > > > > > 
> > > > > > Thanks
> > > > > That's a big change in an interface so it's a good reason
> > > > > to rename the driver at that point right?
> > > > > Oherwise users of an old kernel would expect a stacked driver
> > > > > and get a loopback instead.
> > > > > 
> > > > > Or did I miss something?
> > > > 
> > > > My understanding is that it was a sample driver in /doc. It should not
> > > > be used in production environment. Otherwise we need to move it to
> > > > driver/virtio.
> > > > 
> > > > But if you insist, I can post a V11.
> > > > 
> > > > Thanks
> > > 
> > > Or maybe it's better to rename the type of current mdev from 'virtio' to
> > > 'virtio-loopback'. Then we can add more types in the future.
> > > 
> > > Thanks
> > > 
> > Maybe but is virtio actually a loopback somehow? I thought we
> > can bind a regular virtio device there, no?
> 
> 
> It has a prefix, so user will see "mvnet-virtio-loopback".
> 
> Thanks
> 


yes but it's mvnet that is doing the loopback, not virtio
Jason Wang Nov. 7, 2019, 2:20 p.m. UTC | #12
On 2019/11/7 下午9:50, Michael S. Tsirkin wrote:
> On Thu, Nov 07, 2019 at 09:32:29PM +0800, Jason Wang wrote:
>> On 2019/11/7 下午9:08, Michael S. Tsirkin wrote:
>>> On Thu, Nov 07, 2019 at 08:43:29PM +0800, Jason Wang wrote:
>>>> On 2019/11/7 下午7:21, Michael S. Tsirkin wrote:
>>>>> On Thu, Nov 07, 2019 at 06:18:45PM +0800, Jason Wang wrote:
>>>>>> On 2019/11/7 下午5:08, Michael S. Tsirkin wrote:
>>>>>>> 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?
>>>>>> Actually, I plan to extend it as another standard network interface for
>>>>>> kernel. It could be either a standalone pseudo device or a stack device.
>>>>>> Does this sounds good to you?
>>>>>>
>>>>>> Thanks
>>>>> That's a big change in an interface so it's a good reason
>>>>> to rename the driver at that point right?
>>>>> Oherwise users of an old kernel would expect a stacked driver
>>>>> and get a loopback instead.
>>>>>
>>>>> Or did I miss something?
>>>> My understanding is that it was a sample driver in /doc. It should not be
>>>> used in production environment. Otherwise we need to move it to
>>>> driver/virtio.
>>>>
>>>> But if you insist, I can post a V11.
>>>>
>>>> Thanks
>>> this can be a patch on top.
>> Then maybe it's better just extend it to work as a normal networking device
>> on top?
>>
>> Thanks
> That would be a substantial change. Maybe drop 6/6 for now until
> we have a better handle on this?
>

Ok, consider the change should be small, I will post V11 where I can fix 
the typos spotted.

Thanks

Patch
diff mbox series

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);