Re: [PATCH 5/5] vdpasim: vDPA device simulator

[Zhu Lingshan]

On 1/16/2020 8:42 PM, Jason Wang wrote:
> This patch implements a software vDPA networking device. The datapath
> is implemented through vringh and workqueue. The device has an on-chip
> IOMMU which translates IOVA to PA. For kernel virtio drivers, vDPA
> simulator driver provides dma_ops. For vhost driers, set_map() methods
> of vdpa_config_ops is implemented to accept mappings from vhost.
>
> A sysfs based management interface is implemented, devices are
> created and removed through:
>
> /sys/devices/virtual/vdpa_simulator/netdev/{create|remove}
>
> Netlink based lifecycle management could be implemented for vDPA
> simulator as well.
>
> Currently, vDPA device simulator will loopback TX traffic to RX. So
> the main use case for the device is vDPA feature testing, prototyping
> and development.
>
> Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
> ---
>   drivers/virtio/vdpa/Kconfig    |  17 +
>   drivers/virtio/vdpa/Makefile   |   1 +
>   drivers/virtio/vdpa/vdpa_sim.c | 796 +++++++++++++++++++++++++++++++++
>   3 files changed, 814 insertions(+)
>   create mode 100644 drivers/virtio/vdpa/vdpa_sim.c
>
> diff --git a/drivers/virtio/vdpa/Kconfig b/drivers/virtio/vdpa/Kconfig
> index 3032727b4d98..12ec25d48423 100644
> --- a/drivers/virtio/vdpa/Kconfig
> +++ b/drivers/virtio/vdpa/Kconfig
> @@ -7,3 +7,20 @@ config VDPA
>             datapath which complies with virtio specifications with
>             vendor specific control path.
>   
> +menuconfig VDPA_MENU
> +	bool "VDPA drivers"
> +	default n
> +
> +if VDPA_MENU
> +
> +config VDPA_SIM
> +	tristate "vDPA device simulator"
> +        select VDPA
> +        default n
> +        help
> +          vDPA networking device simulator which loop TX traffic back
> +          to RX. This device is used for testing, prototyping and
> +          development of vDPA.
> +
> +endif # VDPA_MENU
> +
> diff --git a/drivers/virtio/vdpa/Makefile b/drivers/virtio/vdpa/Makefile
> index ee6a35e8a4fb..5ec0e6ae3c57 100644
> --- a/drivers/virtio/vdpa/Makefile
> +++ b/drivers/virtio/vdpa/Makefile
> @@ -1,2 +1,3 @@
>   # SPDX-License-Identifier: GPL-2.0
>   obj-$(CONFIG_VDPA) += vdpa.o
> +obj-$(CONFIG_VDPA_SIM) += vdpa_sim.o
> diff --git a/drivers/virtio/vdpa/vdpa_sim.c b/drivers/virtio/vdpa/vdpa_sim.c
> new file mode 100644
> index 000000000000..85a235f99e3d
> --- /dev/null
> +++ b/drivers/virtio/vdpa/vdpa_sim.c
> @@ -0,0 +1,796 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * VDPA networking device simulator.
> + *
> + * Copyright (c) 2020, Red Hat Inc. All rights reserved.
> + *     Author: Jason Wang <jasowang@xxxxxxxxxx>
> + *
> + */
> +
> +#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/vringh.h>
> +#include <linux/vdpa.h>
> +#include <linux/vhost_iotlb.h>
> +#include <uapi/linux/virtio_config.h>
> +#include <uapi/linux/virtio_net.h>
> +
> +#define DRV_VERSION  "0.1"
> +#define DRV_AUTHOR   "Jason Wang <jasowang@xxxxxxxxxx>"
> +#define DRV_DESC     "vDPA Device Simulator"
> +#define DRV_LICENSE  "GPL v2"
> +
> +struct vdpasim_dev {
> +	struct class	*vd_class;
> +	struct idr	vd_idr;
> +	struct device	dev;
> +	struct kobject  *devices_kobj;
> +};
> +
> +struct vdpasim_dev *vdpasim_dev;
> +
> +struct vdpasim_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 VDPASIM_QUEUE_ALIGN PAGE_SIZE
> +#define VDPASIM_QUEUE_MAX 256
> +#define VDPASIM_DEVICE_ID 0x1
> +#define VDPASIM_VENDOR_ID 0
> +#define VDPASIM_VQ_NUM 0x2
> +#define VDPASIM_CLASS_NAME "vdpa_simulator"
> +#define VDPASIM_NAME "netdev"
> +
> +u64 vdpasim_features = (1ULL << VIRTIO_F_ANY_LAYOUT) |
> +		       (1ULL << VIRTIO_F_VERSION_1)  |
> +		       (1ULL << VIRTIO_F_IOMMU_PLATFORM);
> +
> +/* State of each vdpasim device */
> +struct vdpasim {
> +	struct vdpasim_virtqueue vqs[2];
> +	struct work_struct work;
> +	/* spinlock to synchronize virtqueue state */
> +	spinlock_t lock;
> +	struct vdpa_device vdpa;
> +	struct virtio_net_config config;
> +	struct vhost_iotlb *iommu;
> +	void *buffer;
> +	u32 status;
> +	u32 generation;
> +	u64 features;
> +	struct list_head next;
> +	guid_t uuid;
> +	char name[64];
> +};
> +
> +static struct mutex vsim_list_lock;
> +static struct list_head vsim_devices_list;
> +
> +static struct vdpasim *vdpa_to_sim(struct vdpa_device *vdpa)
> +{
> +	return container_of(vdpa, struct vdpasim, vdpa);
> +}
> +
> +static void vdpasim_queue_ready(struct vdpasim *vdpasim, unsigned int idx)
> +{
> +	struct vdpasim_virtqueue *vq = &vdpasim->vqs[idx];
> +	int ret;
> +
> +	ret = vringh_init_iotlb(&vq->vring, vdpasim_features, VDPASIM_QUEUE_MAX,
> +			        false, (struct vring_desc *)vq->desc_addr,
> +				(struct vring_avail *)vq->driver_addr,
> +				(struct vring_used *)vq->device_addr);
> +}
> +
> +static void vdpasim_vq_reset(struct vdpasim_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_iotlb(&vq->vring, vdpasim_features, VDPASIM_QUEUE_MAX,
> +			  false, 0, 0, 0);
> +}
> +
> +static void vdpasim_reset(struct vdpasim *vdpasim)
> +{
> +	int i;
> +
> +	for (i = 0; i < VDPASIM_VQ_NUM; i++)
> +		vdpasim_vq_reset(&vdpasim->vqs[i]);
> +
> +	vhost_iotlb_reset(vdpasim->iommu);
> +
> +	vdpasim->features = 0;
> +	vdpasim->status = 0;
> +	++vdpasim->generation;
> +}
> +
> +static void vdpasim_work(struct work_struct *work)
> +{
> +	struct vdpasim *vdpasim = container_of(work, struct
> +						 vdpasim, work);
> +	struct vdpasim_virtqueue *txq = &vdpasim->vqs[1];
> +	struct vdpasim_virtqueue *rxq = &vdpasim->vqs[0];
> +	size_t read, write, total_write;
> +	int err;
> +	int pkts = 0;
> +
> +	spin_lock(&vdpasim->lock);
> +
> +	if (!(vdpasim->status & VIRTIO_CONFIG_S_DRIVER_OK))
> +		goto out;
> +
> +	if (!txq->ready || !rxq->ready)
> +		goto out;
> +
> +	while (true) {
> +		total_write = 0;
> +		err = vringh_getdesc_iotlb(&txq->vring, &txq->iov, NULL,
> +					   &txq->head, GFP_ATOMIC);
> +		if (err <= 0)
> +			break;
> +
> +		err = vringh_getdesc_iotlb(&rxq->vring, NULL, &rxq->iov,
> +					   &rxq->head, GFP_ATOMIC);
> +		if (err <= 0) {
> +			vringh_complete_iotlb(&txq->vring, txq->head, 0);
> +			break;
> +		}
> +
> +		while (true) {
> +			read = vringh_iov_pull_iotlb(&txq->vring, &txq->iov,
> +						     vdpasim->buffer,
> +						     PAGE_SIZE);
> +			if (read <= 0)
> +				break;
> +
> +			write = vringh_iov_push_iotlb(&rxq->vring, &rxq->iov,
> +						      vdpasim->buffer, read);
> +			if (write <= 0)
> +				break;
> +
> +			total_write += write;
> +		}
> +
> +		/* Make sure data is wrote before advancing index */
> +		smp_wmb();
> +
> +		vringh_complete_iotlb(&txq->vring, txq->head, 0);
> +		vringh_complete_iotlb(&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(&vdpasim->work);
> +			goto out;
> +		}
> +	}
> +
> +out:
> +	spin_unlock(&vdpasim->lock);
> +}
> +
> +static int dir_to_perm(enum dma_data_direction dir)
> +{
> +	int perm = -EFAULT;
> +
> +	switch (dir) {
> +	case DMA_FROM_DEVICE:
> +		perm = VHOST_MAP_WO;
> +		break;
> +	case DMA_TO_DEVICE:
> +		perm = VHOST_MAP_RO;
> +		break;
> +	case DMA_BIDIRECTIONAL:
> +		perm = VHOST_MAP_RW;
> +		break;
> +	default:
> +		break;
> +	}
> +
> +	return perm;
> +}
> +
> +static dma_addr_t vdpasim_map_page(struct device *dev, struct page *page,
> +				   unsigned long offset, size_t size,
> +				   enum dma_data_direction dir,
> +				   unsigned long attrs)
> +{
> +	struct vdpa_device *vdpa = dev_to_vdpa(dev);
> +	struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
> +	struct vhost_iotlb *iommu = vdpasim->iommu;
> +	u64 pa = (page_to_pfn(page) << PAGE_SHIFT) + offset;
> +	int ret, perm = dir_to_perm(dir);
> +
> +	if (perm < 0)
> +		return DMA_MAPPING_ERROR;
> +
> +	/* For simplicity, use identical mapping to avoid e.g iova
> +	 * allocator.
> +	 */
> +	ret = vhost_iotlb_add_range(iommu, pa, pa + size - 1,
> +				    pa, dir_to_perm(dir));
> +	if (ret)
> +		return DMA_MAPPING_ERROR;
> +
> +	return (dma_addr_t)(pa);
> +}
> +
> +static void vdpasim_unmap_page(struct device *dev, dma_addr_t dma_addr,
> +			       size_t size, enum dma_data_direction dir,
> +			       unsigned long attrs)
> +{
> +	struct vdpa_device *vdpa = dev_to_vdpa(dev);
> +	struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
> +	struct vhost_iotlb *iommu = vdpasim->iommu;
> +
> +	vhost_iotlb_del_range(iommu, (u64)dma_addr,
> +			      (u64)dma_addr + size - 1);
> +}
> +
> +static void *vdpasim_alloc_coherent(struct device *dev, size_t size,
> +				    dma_addr_t *dma_addr, gfp_t flag,
> +				    unsigned long attrs)
> +{
> +	struct vdpa_device *vdpa = dev_to_vdpa(dev);
> +	struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
> +	struct vhost_iotlb *iommu = vdpasim->iommu;
> +	void *addr = kmalloc(size, flag);
> +	int ret;
> +
> +	if (!addr)
> +		*dma_addr = DMA_MAPPING_ERROR;
> +	else {
> +		u64 pa = virt_to_phys(addr);
> +
> +		ret = vhost_iotlb_add_range(iommu, (u64)pa,
> +					    (u64)pa + size - 1,
> +					    pa, VHOST_MAP_RW);
> +		if (ret) {
> +			kfree(addr);
> +			*dma_addr = DMA_MAPPING_ERROR;
> +		} else
> +			*dma_addr = (dma_addr_t)pa;
> +	}
> +
> +	return addr;
> +}
> +
> +static void vdpasim_free_coherent(struct device *dev, size_t size,
> +				void *vaddr, dma_addr_t dma_addr,
> +				unsigned long attrs)
> +{
> +	struct vdpa_device *vdpa = dev_to_vdpa(dev);
> +	struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
> +	struct vhost_iotlb *iommu = vdpasim->iommu;
> +
> +	vhost_iotlb_del_range(iommu, (u64)dma_addr,
> +			       (u64)dma_addr + size - 1);
> +	kfree((void *)dma_addr);
> +}
> +
> +static const struct dma_map_ops vdpasim_dma_ops = {
> +	.map_page = vdpasim_map_page,
> +	.unmap_page = vdpasim_unmap_page,
> +	.alloc = vdpasim_alloc_coherent,
> +	.free = vdpasim_free_coherent,
> +};
> +

Hey Jason,

IMHO, it would be nice if dma_ops of the parent device could be re-used. 
vdpa_device is expecting to represent a physical device except this 
simulator, however, there are not enough information in vdpa_device.dev 
to indicating which kind physical device it attached to. Namely 
get_arch_dma_ops(struct bus type) can not work on vdpa_device.dev. Then 
it seems device drivers need to implement a wrap of dma_ops of parent 
devices. Can this work be done in the vdpa framework since it looks like 
a common task? Can "vd_dev->vdev.dev.parent = vdpa->dev->parent;" in 
virtio_vdpa_probe() do the work?

Thanks,
BR
Zhu Lingshan
> +static void vdpasim_release_dev(struct device *_d)
> +{
> +	struct vdpa_device *vdpa = dev_to_vdpa(_d);
> +	struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
> +
> +	sysfs_remove_link(vdpasim_dev->devices_kobj, vdpasim->name);
> +
> +	mutex_lock(&vsim_list_lock);
> +	list_del(&vdpasim->next);
> +	mutex_unlock(&vsim_list_lock);
> +
> +	kfree(vdpasim->buffer);
> +	kfree(vdpasim);
> +}
> +
> +static const struct vdpa_config_ops vdpasim_net_config_ops;
> +
> +static int vdpasim_create(const guid_t *uuid)
> +{
> +	struct vdpasim *vdpasim, *tmp;
> +	struct virtio_net_config *config;
> +	struct vdpa_device *vdpa;
> +	struct device *dev;
> +	int ret = -ENOMEM;
> +
> +	mutex_lock(&vsim_list_lock);
> +	list_for_each_entry(tmp, &vsim_devices_list, next) {
> +		if (guid_equal(&tmp->uuid, uuid)) {
> +			mutex_unlock(&vsim_list_lock);
> +			return -EEXIST;
> +		}
> +	}
> +
> +	vdpasim = kzalloc(sizeof(*vdpasim), GFP_KERNEL);
> +	if (!vdpasim)
> +		goto err_vdpa_alloc;
> +
> +	vdpasim->buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
> +	if (!vdpasim->buffer)
> +		goto err_buffer_alloc;
> +
> +	vdpasim->iommu = vhost_iotlb_alloc(2048, 0);
> +	if (!vdpasim->iommu)
> +		goto err_iotlb;
> +
> +	config = &vdpasim->config;
> +	config->mtu = 1500;
> +	config->status = VIRTIO_NET_S_LINK_UP;
> +	eth_random_addr(config->mac);
> +
> +	INIT_WORK(&vdpasim->work, vdpasim_work);
> +	spin_lock_init(&vdpasim->lock);
> +
> +	guid_copy(&vdpasim->uuid, uuid);
> +
> +	list_add(&vdpasim->next, &vsim_devices_list);
> +	vdpa = &vdpasim->vdpa;
> +
> +	mutex_unlock(&vsim_list_lock);
> +
> +	vdpa = &vdpasim->vdpa;
> +	vdpa->config = &vdpasim_net_config_ops;
> +	vdpa_set_parent(vdpa, &vdpasim_dev->dev);
> +	vdpa->dev.release = vdpasim_release_dev;
> +
> +	vringh_set_iotlb(&vdpasim->vqs[0].vring, vdpasim->iommu);
> +	vringh_set_iotlb(&vdpasim->vqs[1].vring, vdpasim->iommu);
> +
> +	dev = &vdpa->dev;
> +	dev->coherent_dma_mask = DMA_BIT_MASK(64);
> +	set_dma_ops(dev, &vdpasim_dma_ops);
> +
> +	ret = register_vdpa_device(vdpa);
> +	if (ret)
> +		goto err_register;
> +
> +	sprintf(vdpasim->name, "%pU", uuid);
> +
> +	ret = sysfs_create_link(vdpasim_dev->devices_kobj, &vdpa->dev.kobj,
> +				vdpasim->name);
> +	if (ret)
> +		goto err_link;
> +
> +	return 0;
> +
> +err_link:
> +err_register:
> +	vhost_iotlb_free(vdpasim->iommu);
> +	mutex_lock(&vsim_list_lock);
> +	list_del(&vdpasim->next);
> +	mutex_unlock(&vsim_list_lock);
> +err_iotlb:
> +	kfree(vdpasim->buffer);
> +err_buffer_alloc:
> +	kfree(vdpasim);
> +err_vdpa_alloc:
> +	return ret;
> +}
> +
> +static int vdpasim_remove(const guid_t *uuid)
> +{
> +	struct vdpasim *vds, *tmp;
> +	struct vdpa_device *vdpa = NULL;
> +	int ret = -EINVAL;
> +
> +	mutex_lock(&vsim_list_lock);
> +	list_for_each_entry_safe(vds, tmp, &vsim_devices_list, next) {
> +		if (guid_equal(&vds->uuid, uuid)) {
> +			vdpa = &vds->vdpa;
> +			ret = 0;
> +			break;
> +		}
> +	}
> +	mutex_unlock(&vsim_list_lock);
> +
> +	if (vdpa)
> +		unregister_vdpa_device(vdpa);
> +
> +	return ret;
> +}
> +
> +static int vdpasim_set_vq_address(struct vdpa_device *vdpa, u16 idx,
> +				  u64 desc_area, u64 driver_area,
> +				  u64 device_area)
> +{
> +	struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
> +	struct vdpasim_virtqueue *vq = &vdpasim->vqs[idx];
> +
> +	vq->desc_addr = desc_area;
> +	vq->driver_addr = driver_area;
> +	vq->device_addr = device_area;
> +
> +	return 0;
> +}
> +
> +static void vdpasim_set_vq_num(struct vdpa_device *vdpa, u16 idx, u32 num)
> +{
> +	struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
> +	struct vdpasim_virtqueue *vq = &vdpasim->vqs[idx];
> +
> +	vq->num = num;
> +}
> +
> +static void vdpasim_kick_vq(struct vdpa_device *vdpa, u16 idx)
> +{
> +	struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
> +	struct vdpasim_virtqueue *vq = &vdpasim->vqs[idx];
> +
> +	if (vq->ready)
> +		schedule_work(&vdpasim->work);
> +}
> +
> +static void vdpasim_set_vq_cb(struct vdpa_device *vdpa, u16 idx,
> +			      struct vdpa_callback *cb)
> +{
> +	struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
> +	struct vdpasim_virtqueue *vq = &vdpasim->vqs[idx];
> +
> +	vq->cb = cb->callback;
> +	vq->private = cb->private;
> +}
> +
> +static void vdpasim_set_vq_ready(struct vdpa_device *vdpa, u16 idx, bool ready)
> +{
> +	struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
> +	struct vdpasim_virtqueue *vq = &vdpasim->vqs[idx];
> +
> +	spin_lock(&vdpasim->lock);
> +	vq->ready = ready;
> +	if (vq->ready)
> +		vdpasim_queue_ready(vdpasim, idx);
> +	spin_unlock(&vdpasim->lock);
> +}
> +
> +static bool vdpasim_get_vq_ready(struct vdpa_device *vdpa, u16 idx)
> +{
> +	struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
> +	struct vdpasim_virtqueue *vq = &vdpasim->vqs[idx];
> +
> +	return vq->ready;
> +}
> +
> +static int vdpasim_set_vq_state(struct vdpa_device *vdpa, u16 idx, u64 state)
> +{
> +	struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
> +	struct vdpasim_virtqueue *vq = &vdpasim->vqs[idx];
> +	struct vringh *vrh = &vq->vring;
> +
> +	spin_lock(&vdpasim->lock);
> +	vrh->last_avail_idx = state;
> +	spin_unlock(&vdpasim->lock);
> +
> +	return 0;
> +}
> +
> +static u64 vdpasim_get_vq_state(struct vdpa_device *vdpa, u16 idx)
> +{
> +	struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
> +	struct vdpasim_virtqueue *vq = &vdpasim->vqs[idx];
> +	struct vringh *vrh = &vq->vring;
> +
> +	return vrh->last_avail_idx;
> +}
> +
> +static u16 vdpasim_get_vq_align(struct vdpa_device *vdpa)
> +{
> +	return VDPASIM_QUEUE_ALIGN;
> +}
> +
> +static u64 vdpasim_get_features(struct vdpa_device *vdpa)
> +{
> +	return vdpasim_features;
> +}
> +
> +static int vdpasim_set_features(struct vdpa_device *vdpa, u64 features)
> +{
> +	struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
> +
> +	/* DMA mapping must be done by driver */
> +	if (!(features & (1ULL << VIRTIO_F_IOMMU_PLATFORM)))
> +		return -EINVAL;
> +
> +	vdpasim->features = features & vdpasim_features;
> +
> +	return 0;
> +}
> +
> +static void vdpasim_set_config_cb(struct vdpa_device *vdpa,
> +				  struct vdpa_callback *cb)
> +{
> +	/* We don't support config interrupt */
> +}
> +
> +static u16 vdpasim_get_vq_num_max(struct vdpa_device *vdpa)
> +{
> +	return VDPASIM_QUEUE_MAX;
> +}
> +
> +static u32 vdpasim_get_device_id(struct vdpa_device *vdpa)
> +{
> +	return VDPASIM_DEVICE_ID;
> +}
> +
> +static u32 vdpasim_get_vendor_id(struct vdpa_device *vdpa)
> +{
> +	return VDPASIM_VENDOR_ID;
> +}
> +
> +static u8 vdpasim_get_status(struct vdpa_device *vdpa)
> +{
> +	struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
> +	u8 status;
> +
> +	spin_lock(&vdpasim->lock);
> +	status = vdpasim->status;
> +	spin_unlock(&vdpasim->lock);
> +
> +	return vdpasim->status;
> +}
> +
> +static void vdpasim_set_status(struct vdpa_device *vdpa, u8 status)
> +{
> +	struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
> +
> +	spin_lock(&vdpasim->lock);
> +	vdpasim->status = status;
> +	if (status == 0)
> +		vdpasim_reset(vdpasim);
> +	spin_unlock(&vdpasim->lock);
> +}
> +
> +static void vdpasim_get_config(struct vdpa_device *vdpa, unsigned int offset,
> +			     void *buf, unsigned int len)
> +{
> +	struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
> +
> +	if (offset + len < sizeof(struct virtio_net_config))
> +		memcpy(buf, &vdpasim->config + offset, len);
> +}
> +
> +static void vdpasim_set_config(struct vdpa_device *vdpa, unsigned int offset,
> +			     const void *buf, unsigned int len)
> +{
> +	/* No writable config supportted by vdpasim */
> +}
> +
> +static u32 vdpasim_get_generation(struct vdpa_device *vdpa)
> +{
> +	struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
> +
> +	return vdpasim->generation;
> +}
> +
> +static int vdpasim_set_map(struct vdpa_device *vdpa,
> +			   struct vhost_iotlb *iotlb)
> +{
> +	struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
> +	struct vhost_iotlb_map *map;
> +	u64 start = 0ULL, last = 0ULL - 1;
> +	int ret;
> +
> +	vhost_iotlb_reset(vdpasim->iommu);
> +
> +	for (map = vhost_iotlb_itree_first(iotlb, start, last); map;
> +	     map = vhost_iotlb_itree_next(map, start, last)) {
> +		ret = vhost_iotlb_add_range(vdpasim->iommu, map->start,
> +					    map->last, map->addr, map->perm);
> +		if (ret)
> +			goto err;
> +	}
> +	return 0;
> +
> +err:
> +	vhost_iotlb_reset(vdpasim->iommu);
> +	return ret;
> +}
> +
> +static const struct vdpa_config_ops vdpasim_net_config_ops = {
> +	.set_vq_address         = vdpasim_set_vq_address,
> +	.set_vq_num             = vdpasim_set_vq_num,
> +	.kick_vq                = vdpasim_kick_vq,
> +	.set_vq_cb              = vdpasim_set_vq_cb,
> +	.set_vq_ready           = vdpasim_set_vq_ready,
> +	.get_vq_ready           = vdpasim_get_vq_ready,
> +	.set_vq_state           = vdpasim_set_vq_state,
> +	.get_vq_state           = vdpasim_get_vq_state,
> +	.get_vq_align           = vdpasim_get_vq_align,
> +	.get_features           = vdpasim_get_features,
> +	.set_features           = vdpasim_set_features,
> +	.set_config_cb          = vdpasim_set_config_cb,
> +	.get_vq_num_max         = vdpasim_get_vq_num_max,
> +	.get_device_id          = vdpasim_get_device_id,
> +	.get_vendor_id          = vdpasim_get_vendor_id,
> +	.get_status             = vdpasim_get_status,
> +	.set_status             = vdpasim_set_status,
> +	.get_config             = vdpasim_get_config,
> +	.set_config             = vdpasim_set_config,
> +	.get_generation         = vdpasim_get_generation,
> +	.set_map                = vdpasim_set_map,
> +};
> +
> +static void vdpasim_device_release(struct device *dev)
> +{
> +	struct vdpasim_dev *vdpasim_dev =
> +	       container_of(dev, struct vdpasim_dev, dev);
> +
> +	vdpasim_dev->dev.bus = NULL;
> +	idr_destroy(&vdpasim_dev->vd_idr);
> +	class_destroy(vdpasim_dev->vd_class);
> +	vdpasim_dev->vd_class = NULL;
> +	kfree(vdpasim_dev);
> +}
> +
> +static ssize_t create_store(struct kobject *kobj, struct kobj_attribute *attr,
> +			    const char *buf, size_t count)
> +{
> +	char *str;
> +	guid_t uuid;
> +	int ret;
> +
> +	if ((count < UUID_STRING_LEN) || (count > UUID_STRING_LEN + 1))
> +		return -EINVAL;
> +
> +	str = kstrndup(buf, count, GFP_KERNEL);
> +	if (!str)
> +		return -ENOMEM;
> +
> +	ret = guid_parse(str, &uuid);
> +	kfree(str);
> +	if (ret)
> +		return ret;
> +
> +	ret = vdpasim_create(&uuid);
> +	if (ret)
> +		return ret;
> +
> +	return count;
> +}
> +
> +static ssize_t remove_store(struct kobject *kobj, struct kobj_attribute *attr,
> +			    const char *buf, size_t count)
> +{
> +	char *str;
> +	guid_t uuid;
> +	int ret;
> +
> +	if ((count < UUID_STRING_LEN) || (count > UUID_STRING_LEN + 1))
> +		return -EINVAL;
> +
> +	str = kstrndup(buf, count, GFP_KERNEL);
> +	if (!str)
> +		return -ENOMEM;
> +
> +	ret = guid_parse(str, &uuid);
> +	kfree(str);
> +	if (ret)
> +		return ret;
> +
> +	ret = vdpasim_remove(&uuid);
> +	if (ret)
> +		return ret;
> +
> +	return count;
> +}
> +
> +static struct kobj_attribute create_attribute = __ATTR_WO(create);
> +static struct kobj_attribute remove_attribute = __ATTR_WO(remove);
> +
> +static struct attribute *attrs[] = {
> +	&create_attribute.attr,
> +	&remove_attribute.attr,
> +	NULL,
> +};
> +
> +static struct attribute_group attr_group = {
> +	.attrs = attrs,
> +};
> +
> +static int __init vdpasim_dev_init(void)
> +{
> +	struct device *dev;
> +	int ret = 0;
> +
> +	vdpasim_dev = kzalloc(sizeof(*vdpasim_dev), GFP_KERNEL);
> +	if (!vdpasim_dev)
> +		return -ENOMEM;
> +
> +	idr_init(&vdpasim_dev->vd_idr);
> +
> +	vdpasim_dev->vd_class = class_create(THIS_MODULE, VDPASIM_CLASS_NAME);
> +
> +	if (IS_ERR(vdpasim_dev->vd_class)) {
> +		pr_err("Error: failed to register vdpasim_dev class\n");
> +		ret = PTR_ERR(vdpasim_dev->vd_class);
> +		goto err_class;
> +	}
> +
> +	dev = &vdpasim_dev->dev;
> +	dev->class = vdpasim_dev->vd_class;
> +	dev->release = vdpasim_device_release;
> +	dev_set_name(dev, "%s", VDPASIM_NAME);
> +
> +	ret = device_register(&vdpasim_dev->dev);
> +	if (ret)
> +		goto err_register;
> +
> +	ret = sysfs_create_group(&vdpasim_dev->dev.kobj, &attr_group);
> +	if (ret)
> +		goto err_create;
> +
> +	vdpasim_dev->devices_kobj = kobject_create_and_add("devices",
> +							   &dev->kobj);
> +	if (!vdpasim_dev->devices_kobj) {
> +		ret = -ENOMEM;
> +		goto err_devices;
> +	}
> +
> +	mutex_init(&vsim_list_lock);
> +	INIT_LIST_HEAD(&vsim_devices_list);
> +
> +	return 0;
> +
> +err_devices:
> +	sysfs_remove_group(&vdpasim_dev->dev.kobj, &attr_group);
> +err_create:
> +	device_unregister(&vdpasim_dev->dev);
> +err_register:
> +	class_destroy(vdpasim_dev->vd_class);
> +err_class:
> +	kfree(vdpasim_dev);
> +	vdpasim_dev = NULL;
> +	return ret;
> +}
> +
> +static void __exit vdpasim_dev_exit(void)
> +{
> +	device_unregister(&vdpasim_dev->dev);
> +}
> +
> +module_init(vdpasim_dev_init)
> +module_exit(vdpasim_dev_exit)
> +
> +MODULE_VERSION(DRV_VERSION);
> +MODULE_LICENSE(DRV_LICENSE);
> +MODULE_AUTHOR(DRV_AUTHOR);
> +MODULE_DESCRIPTION(DRV_DESC);