drivers/virtio/virtio_pci_modern.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * Virtio PCI driver - modern (virtio 1.0) device support
  *
  * This module allows virtio devices to be used over a virtual PCI device.
  * This can be used with QEMU based VMMs like KVM or Xen.
  *
  * Copyright IBM Corp. 2007
  * Copyright Red Hat, Inc. 2014
  *
  * Authors:
  *  Anthony Liguori  <aliguori@us.ibm.com>
  *  Rusty Russell <rusty@rustcorp.com.au>
  *  Michael S. Tsirkin <mst@redhat.com>
  */

 #include <linux/delay.h>
 #define VIRTIO_PCI_NO_LEGACY
 #define VIRTIO_RING_NO_LEGACY
 #include "virtio_pci_common.h"

 static u64 vp_get_features(struct virtio_device *vdev)
 {
 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);

 	return vp_modern_get_features(&vp_dev->mdev);
 }

 static void vp_transport_features(struct virtio_device *vdev, u64 features)
 {
 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
 	struct pci_dev *pci_dev = vp_dev->pci_dev;

 	if ((features & BIT_ULL(VIRTIO_F_SR_IOV)) &&
 			pci_find_ext_capability(pci_dev, PCI_EXT_CAP_ID_SRIOV))
 		__virtio_set_bit(vdev, VIRTIO_F_SR_IOV);
 }

 /* virtio config->finalize_features() implementation */
 static int vp_finalize_features(struct virtio_device *vdev)
 {
 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
 	u64 features = vdev->features;

 	/* Give virtio_ring a chance to accept features. */
 	vring_transport_features(vdev);

 	/* Give virtio_pci a chance to accept features. */
 	vp_transport_features(vdev, features);

 	if (!__virtio_test_bit(vdev, VIRTIO_F_VERSION_1)) {
 		dev_err(&vdev->dev, "virtio: device uses modern interface "
 			"but does not have VIRTIO_F_VERSION_1\n");
 		return -EINVAL;
 	}

 	vp_modern_set_features(&vp_dev->mdev, vdev->features);

 	return 0;
 }

 /* virtio config->get() implementation */
 static void vp_get(struct virtio_device *vdev, unsigned offset,
 		   void *buf, unsigned len)
 {
 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
 	struct virtio_pci_modern_device *mdev = &vp_dev->mdev;
 	void __iomem *device = mdev->device;
 	u8 b;
 	__le16 w;
 	__le32 l;

 	BUG_ON(offset + len > mdev->device_len);

 	switch (len) {
 	case 1:
 		b = ioread8(device + offset);
 		memcpy(buf, &b, sizeof b);
 		break;
 	case 2:
 		w = cpu_to_le16(ioread16(device + offset));
 		memcpy(buf, &w, sizeof w);
 		break;
 	case 4:
 		l = cpu_to_le32(ioread32(device + offset));
 		memcpy(buf, &l, sizeof l);
 		break;
 	case 8:
 		l = cpu_to_le32(ioread32(device + offset));
 		memcpy(buf, &l, sizeof l);
 		l = cpu_to_le32(ioread32(device + offset + sizeof l));
 		memcpy(buf + sizeof l, &l, sizeof l);
 		break;
 	default:
 		BUG();
 	}
 }

 /* the config->set() implementation.  it's symmetric to the config->get()
  * implementation */
 static void vp_set(struct virtio_device *vdev, unsigned offset,
 		   const void *buf, unsigned len)
 {
 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
 	struct virtio_pci_modern_device *mdev = &vp_dev->mdev;
 	void __iomem *device = mdev->device;
 	u8 b;
 	__le16 w;
 	__le32 l;

 	BUG_ON(offset + len > mdev->device_len);

 	switch (len) {
 	case 1:
 		memcpy(&b, buf, sizeof b);
 		iowrite8(b, device + offset);
 		break;
 	case 2:
 		memcpy(&w, buf, sizeof w);
 		iowrite16(le16_to_cpu(w), device + offset);
 		break;
 	case 4:
 		memcpy(&l, buf, sizeof l);
 		iowrite32(le32_to_cpu(l), device + offset);
 		break;
 	case 8:
 		memcpy(&l, buf, sizeof l);
 		iowrite32(le32_to_cpu(l), device + offset);
 		memcpy(&l, buf + sizeof l, sizeof l);
 		iowrite32(le32_to_cpu(l), device + offset + sizeof l);
 		break;
 	default:
 		BUG();
 	}
 }

 static u32 vp_generation(struct virtio_device *vdev)
 {
 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);

 	return vp_modern_generation(&vp_dev->mdev);
 }

 /* config->{get,set}_status() implementations */
 static u8 vp_get_status(struct virtio_device *vdev)
 {
 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);

 	return vp_modern_get_status(&vp_dev->mdev);
 }

 static void vp_set_status(struct virtio_device *vdev, u8 status)
 {
 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);

 	/* We should never be setting status to 0. */
 	BUG_ON(status == 0);
 	vp_modern_set_status(&vp_dev->mdev, status);
 }

 static void vp_reset(struct virtio_device *vdev)
 {
 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
 	struct virtio_pci_modern_device *mdev = &vp_dev->mdev;

 	/* 0 status means a reset. */
 	vp_modern_set_status(mdev, 0);
 	/* After writing 0 to device_status, the driver MUST wait for a read of
 	 * device_status to return 0 before reinitializing the device.
 	 * This will flush out the status write, and flush in device writes,
 	 * including MSI-X interrupts, if any.
 	 */
 	while (vp_modern_get_status(mdev))
 		msleep(1);
 	/* Flush pending VQ/configuration callbacks. */
 	vp_synchronize_vectors(vdev);
 }

 static u16 vp_config_vector(struct virtio_pci_device *vp_dev, u16 vector)
 {
 	return vp_modern_config_vector(&vp_dev->mdev, vector);
 }

 static struct virtqueue *setup_vq(struct virtio_pci_device *vp_dev,
 				  struct virtio_pci_vq_info *info,
 				  unsigned index,
 				  void (*callback)(struct virtqueue *vq),
 				  const char *name,
 				  bool ctx,
 				  u16 msix_vec)
 {

 	struct virtio_pci_modern_device *mdev = &vp_dev->mdev;
 	struct virtqueue *vq;
 	u16 num;
 	int err;

 	if (index >= vp_modern_get_num_queues(mdev))
 		return ERR_PTR(-ENOENT);

 	/* Check if queue is either not available or already active. */
 	num = vp_modern_get_queue_size(mdev, index);
 	if (!num || vp_modern_get_queue_enable(mdev, index))
 		return ERR_PTR(-ENOENT);

 	if (num & (num - 1)) {
 		dev_warn(&vp_dev->pci_dev->dev, "bad queue size %u", num);
 		return ERR_PTR(-EINVAL);
 	}

 	info->msix_vector = msix_vec;

 	/* create the vring */
 	vq = vring_create_virtqueue(index, num,
 				    SMP_CACHE_BYTES, &vp_dev->vdev,
 				    true, true, ctx,
 				    vp_notify, callback, name);
 	if (!vq)
 		return ERR_PTR(-ENOMEM);

 	/* activate the queue */
 	vp_modern_set_queue_size(mdev, index, virtqueue_get_vring_size(vq));
 	vp_modern_queue_address(mdev, index, virtqueue_get_desc_addr(vq),
 				virtqueue_get_avail_addr(vq),
 				virtqueue_get_used_addr(vq));

 	vq->priv = (void __force *)vp_modern_map_vq_notify(mdev, index, NULL);
 	if (!vq->priv) {
 		err = -ENOMEM;
 		goto err_map_notify;
 	}

 	if (msix_vec != VIRTIO_MSI_NO_VECTOR) {
 		msix_vec = vp_modern_queue_vector(mdev, index, msix_vec);
 		if (msix_vec == VIRTIO_MSI_NO_VECTOR) {
 			err = -EBUSY;
 			goto err_assign_vector;
 		}
 	}

 	return vq;

 err_assign_vector:
 	if (!mdev->notify_base)
 		pci_iounmap(mdev->pci_dev, (void __iomem __force *)vq->priv);
 err_map_notify:
 	vring_del_virtqueue(vq);
 	return ERR_PTR(err);
 }

 static int vp_modern_find_vqs(struct virtio_device *vdev, unsigned nvqs,
 			      struct virtqueue *vqs[],
 			      vq_callback_t *callbacks[],
 			      const char * const names[], const bool *ctx,
 			      struct irq_affinity *desc)
 {
 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
 	struct virtqueue *vq;
 	int rc = vp_find_vqs(vdev, nvqs, vqs, callbacks, names, ctx, desc);

 	if (rc)
 		return rc;

 	/* Select and activate all queues. Has to be done last: once we do
 	 * this, there's no way to go back except reset.
 	 */
 	list_for_each_entry(vq, &vdev->vqs, list)
 		vp_modern_set_queue_enable(&vp_dev->mdev, vq->index, true);

 	return 0;
 }

 static void del_vq(struct virtio_pci_vq_info *info)
 {
 	struct virtqueue *vq = info->vq;
 	struct virtio_pci_device *vp_dev = to_vp_device(vq->vdev);
 	struct virtio_pci_modern_device *mdev = &vp_dev->mdev;

 	if (vp_dev->msix_enabled)
 		vp_modern_queue_vector(mdev, vq->index,
 				       VIRTIO_MSI_NO_VECTOR);

 	if (!mdev->notify_base)
 		pci_iounmap(mdev->pci_dev, (void __force __iomem *)vq->priv);

 	vring_del_virtqueue(vq);
 }

 static int virtio_pci_find_shm_cap(struct pci_dev *dev, u8 required_id,
 				   u8 *bar, u64 *offset, u64 *len)
 {
 	int pos;

 	for (pos = pci_find_capability(dev, PCI_CAP_ID_VNDR); pos > 0;
 	     pos = pci_find_next_capability(dev, pos, PCI_CAP_ID_VNDR)) {
 		u8 type, cap_len, id, res_bar;
 		u32 tmp32;
 		u64 res_offset, res_length;

 		pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_cap,
 							 cfg_type), &type);
 		if (type != VIRTIO_PCI_CAP_SHARED_MEMORY_CFG)
 			continue;

 		pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_cap,
 							 cap_len), &cap_len);
 		if (cap_len != sizeof(struct virtio_pci_cap64)) {
 			dev_err(&dev->dev, "%s: shm cap with bad size offset:"
 				" %d size: %d\n", __func__, pos, cap_len);
 			continue;
 		}

 		pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_cap,
 							 id), &id);
 		if (id != required_id)
 			continue;

 		pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_cap,
 							 bar), &res_bar);
 		if (res_bar >= PCI_STD_NUM_BARS)
 			continue;

 		/* Type and ID match, and the BAR value isn't reserved.
 		 * Looks good.
 		 */

 		/* Read the lower 32bit of length and offset */
 		pci_read_config_dword(dev, pos + offsetof(struct virtio_pci_cap,
 							  offset), &tmp32);
 		res_offset = tmp32;
 		pci_read_config_dword(dev, pos + offsetof(struct virtio_pci_cap,
 							  length), &tmp32);
 		res_length = tmp32;

 		/* and now the top half */
 		pci_read_config_dword(dev,
 				      pos + offsetof(struct virtio_pci_cap64,
 						     offset_hi), &tmp32);
 		res_offset |= ((u64)tmp32) << 32;
 		pci_read_config_dword(dev,
 				      pos + offsetof(struct virtio_pci_cap64,
 						     length_hi), &tmp32);
 		res_length |= ((u64)tmp32) << 32;

 		*bar = res_bar;
 		*offset = res_offset;
 		*len = res_length;

 		return pos;
 	}
 	return 0;
 }

 static bool vp_get_shm_region(struct virtio_device *vdev,
 			      struct virtio_shm_region *region, u8 id)
 {
 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
 	struct pci_dev *pci_dev = vp_dev->pci_dev;
 	u8 bar;
 	u64 offset, len;
 	phys_addr_t phys_addr;
 	size_t bar_len;

 	if (!virtio_pci_find_shm_cap(pci_dev, id, &bar, &offset, &len))
 		return false;

 	phys_addr = pci_resource_start(pci_dev, bar);
 	bar_len = pci_resource_len(pci_dev, bar);

 	if ((offset + len) < offset) {
 		dev_err(&pci_dev->dev, "%s: cap offset+len overflow detected\n",
 			__func__);
 		return false;
 	}

 	if (offset + len > bar_len) {
 		dev_err(&pci_dev->dev, "%s: bar shorter than cap offset+len\n",
 			__func__);
 		return false;
 	}

 	region->len = len;
 	region->addr = (u64) phys_addr + offset;

 	return true;
 }

 static const struct virtio_config_ops virtio_pci_config_nodev_ops = {
 	.get		= NULL,
 	.set		= NULL,
 	.generation	= vp_generation,
 	.get_status	= vp_get_status,
 	.set_status	= vp_set_status,
 	.reset		= vp_reset,
 	.find_vqs	= vp_modern_find_vqs,
 	.del_vqs	= vp_del_vqs,
 	.get_features	= vp_get_features,
 	.finalize_features = vp_finalize_features,
 	.bus_name	= vp_bus_name,
 	.set_vq_affinity = vp_set_vq_affinity,
 	.get_vq_affinity = vp_get_vq_affinity,
 	.get_shm_region  = vp_get_shm_region,
 };

 static const struct virtio_config_ops virtio_pci_config_ops = {
 	.get		= vp_get,
 	.set		= vp_set,
 	.generation	= vp_generation,
 	.get_status	= vp_get_status,
 	.set_status	= vp_set_status,
 	.reset		= vp_reset,
 	.find_vqs	= vp_modern_find_vqs,
 	.del_vqs	= vp_del_vqs,
 	.get_features	= vp_get_features,
 	.finalize_features = vp_finalize_features,
 	.bus_name	= vp_bus_name,
 	.set_vq_affinity = vp_set_vq_affinity,
 	.get_vq_affinity = vp_get_vq_affinity,
 	.get_shm_region  = vp_get_shm_region,
 };

 /* the PCI probing function */
 int virtio_pci_modern_probe(struct virtio_pci_device *vp_dev)
 {
 	struct virtio_pci_modern_device *mdev = &vp_dev->mdev;
 	struct pci_dev *pci_dev = vp_dev->pci_dev;
 	int err;

 	mdev->pci_dev = pci_dev;

 	err = vp_modern_probe(mdev);
 	if (err)
 		return err;

 	if (mdev->device)
 		vp_dev->vdev.config = &virtio_pci_config_ops;
 	else
 		vp_dev->vdev.config = &virtio_pci_config_nodev_ops;

 	vp_dev->config_vector = vp_config_vector;
 	vp_dev->setup_vq = setup_vq;
 	vp_dev->del_vq = del_vq;
 	vp_dev->isr = mdev->isr;
 	vp_dev->vdev.id = mdev->id;

 	return 0;
 }

 void virtio_pci_modern_remove(struct virtio_pci_device *vp_dev)
 {
 	struct virtio_pci_modern_device *mdev = &vp_dev->mdev;

 	vp_modern_remove(mdev);
 }
	// SPDX-License-Identifier: GPL-2.0-or-later
	/*
	* Virtio PCI driver - modern (virtio 1.0) device support
	*
	* This module allows virtio devices to be used over a virtual PCI device.
	* This can be used with QEMU based VMMs like KVM or Xen.
	*
	* Copyright IBM Corp. 2007
	* Copyright Red Hat, Inc. 2014
	*
	* Authors:
	* Anthony Liguori <aliguori@us.ibm.com>
	* Rusty Russell <rusty@rustcorp.com.au>
	* Michael S. Tsirkin <mst@redhat.com>
	*/

	#include <linux/delay.h>
	#define VIRTIO_PCI_NO_LEGACY
	#define VIRTIO_RING_NO_LEGACY
	#include "virtio_pci_common.h"

	static u64 vp_get_features(struct virtio_device *vdev)
	{
	struct virtio_pci_device *vp_dev = to_vp_device(vdev);

	return vp_modern_get_features(&vp_dev->mdev);
	}

	static void vp_transport_features(struct virtio_device *vdev, u64 features)
	{
	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
	struct pci_dev *pci_dev = vp_dev->pci_dev;

	if ((features & BIT_ULL(VIRTIO_F_SR_IOV)) &&
	pci_find_ext_capability(pci_dev, PCI_EXT_CAP_ID_SRIOV))
	__virtio_set_bit(vdev, VIRTIO_F_SR_IOV);
	}

	/* virtio config->finalize_features() implementation */
	static int vp_finalize_features(struct virtio_device *vdev)
	{
	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
	u64 features = vdev->features;

	/* Give virtio_ring a chance to accept features. */
	vring_transport_features(vdev);

	/* Give virtio_pci a chance to accept features. */
	vp_transport_features(vdev, features);

	if (!__virtio_test_bit(vdev, VIRTIO_F_VERSION_1)) {
	dev_err(&vdev->dev, "virtio: device uses modern interface "
	"but does not have VIRTIO_F_VERSION_1\n");
	return -EINVAL;
	}

	vp_modern_set_features(&vp_dev->mdev, vdev->features);

	return 0;
	}

	/* virtio config->get() implementation */
	static void vp_get(struct virtio_device *vdev, unsigned offset,
	void *buf, unsigned len)
	{
	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
	struct virtio_pci_modern_device *mdev = &vp_dev->mdev;
	void __iomem *device = mdev->device;
	u8 b;
	__le16 w;
	__le32 l;

	BUG_ON(offset + len > mdev->device_len);

	switch (len) {
	case 1:
	b = ioread8(device + offset);
	memcpy(buf, &b, sizeof b);
	break;
	case 2:
	w = cpu_to_le16(ioread16(device + offset));
	memcpy(buf, &w, sizeof w);
	break;
	case 4:
	l = cpu_to_le32(ioread32(device + offset));
	memcpy(buf, &l, sizeof l);
	break;
	case 8:
	l = cpu_to_le32(ioread32(device + offset));
	memcpy(buf, &l, sizeof l);
	l = cpu_to_le32(ioread32(device + offset + sizeof l));
	memcpy(buf + sizeof l, &l, sizeof l);
	break;
	default:
	BUG();
	}
	}

	/* the config->set() implementation. it's symmetric to the config->get()
	* implementation */
	static void vp_set(struct virtio_device *vdev, unsigned offset,
	const void *buf, unsigned len)
	{
	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
	struct virtio_pci_modern_device *mdev = &vp_dev->mdev;
	void __iomem *device = mdev->device;
	u8 b;
	__le16 w;
	__le32 l;

	BUG_ON(offset + len > mdev->device_len);

	switch (len) {
	case 1:
	memcpy(&b, buf, sizeof b);
	iowrite8(b, device + offset);
	break;
	case 2:
	memcpy(&w, buf, sizeof w);
	iowrite16(le16_to_cpu(w), device + offset);
	break;
	case 4:
	memcpy(&l, buf, sizeof l);
	iowrite32(le32_to_cpu(l), device + offset);
	break;
	case 8:
	memcpy(&l, buf, sizeof l);
	iowrite32(le32_to_cpu(l), device + offset);
	memcpy(&l, buf + sizeof l, sizeof l);
	iowrite32(le32_to_cpu(l), device + offset + sizeof l);
	break;
	default:
	BUG();
	}
	}

	static u32 vp_generation(struct virtio_device *vdev)
	{
	struct virtio_pci_device *vp_dev = to_vp_device(vdev);

	return vp_modern_generation(&vp_dev->mdev);
	}

	/* config->{get,set}_status() implementations */
	static u8 vp_get_status(struct virtio_device *vdev)
	{
	struct virtio_pci_device *vp_dev = to_vp_device(vdev);

	return vp_modern_get_status(&vp_dev->mdev);
	}

	static void vp_set_status(struct virtio_device *vdev, u8 status)
	{
	struct virtio_pci_device *vp_dev = to_vp_device(vdev);

	/* We should never be setting status to 0. */
	BUG_ON(status == 0);
	vp_modern_set_status(&vp_dev->mdev, status);
	}

	static void vp_reset(struct virtio_device *vdev)
	{
	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
	struct virtio_pci_modern_device *mdev = &vp_dev->mdev;

	/* 0 status means a reset. */
	vp_modern_set_status(mdev, 0);
	/* After writing 0 to device_status, the driver MUST wait for a read of
	* device_status to return 0 before reinitializing the device.
	* This will flush out the status write, and flush in device writes,
	* including MSI-X interrupts, if any.
	*/
	while (vp_modern_get_status(mdev))
	msleep(1);
	/* Flush pending VQ/configuration callbacks. */
	vp_synchronize_vectors(vdev);
	}

	static u16 vp_config_vector(struct virtio_pci_device *vp_dev, u16 vector)
	{
	return vp_modern_config_vector(&vp_dev->mdev, vector);
	}

	static struct virtqueue setup_vq(struct virtio_pci_device vp_dev,
	struct virtio_pci_vq_info *info,
	unsigned index,
	void (callback)(struct virtqueue vq),
	const char *name,
	bool ctx,
	u16 msix_vec)
	{

	struct virtio_pci_modern_device *mdev = &vp_dev->mdev;
	struct virtqueue *vq;
	u16 num;
	int err;

	if (index >= vp_modern_get_num_queues(mdev))
	return ERR_PTR(-ENOENT);

	/* Check if queue is either not available or already active. */
	num = vp_modern_get_queue_size(mdev, index);
	if (!num \|\| vp_modern_get_queue_enable(mdev, index))
	return ERR_PTR(-ENOENT);

	if (num & (num - 1)) {
	dev_warn(&vp_dev->pci_dev->dev, "bad queue size %u", num);
	return ERR_PTR(-EINVAL);
	}

	info->msix_vector = msix_vec;

	/* create the vring */
	vq = vring_create_virtqueue(index, num,
	SMP_CACHE_BYTES, &vp_dev->vdev,
	true, true, ctx,
	vp_notify, callback, name);
	if (!vq)
	return ERR_PTR(-ENOMEM);

	/* activate the queue */
	vp_modern_set_queue_size(mdev, index, virtqueue_get_vring_size(vq));
	vp_modern_queue_address(mdev, index, virtqueue_get_desc_addr(vq),
	virtqueue_get_avail_addr(vq),
	virtqueue_get_used_addr(vq));

	vq->priv = (void __force *)vp_modern_map_vq_notify(mdev, index, NULL);
	if (!vq->priv) {
	err = -ENOMEM;
	goto err_map_notify;
	}

	if (msix_vec != VIRTIO_MSI_NO_VECTOR) {
	msix_vec = vp_modern_queue_vector(mdev, index, msix_vec);
	if (msix_vec == VIRTIO_MSI_NO_VECTOR) {
	err = -EBUSY;
	goto err_assign_vector;
	}
	}

	return vq;

	err_assign_vector:
	if (!mdev->notify_base)
	pci_iounmap(mdev->pci_dev, (void __iomem __force *)vq->priv);
	err_map_notify:
	vring_del_virtqueue(vq);
	return ERR_PTR(err);
	}

	static int vp_modern_find_vqs(struct virtio_device *vdev, unsigned nvqs,
	struct virtqueue *vqs[],
	vq_callback_t *callbacks[],
	const char * const names[], const bool *ctx,
	struct irq_affinity *desc)
	{
	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
	struct virtqueue *vq;
	int rc = vp_find_vqs(vdev, nvqs, vqs, callbacks, names, ctx, desc);

	if (rc)
	return rc;

	/* Select and activate all queues. Has to be done last: once we do
	* this, there's no way to go back except reset.
	*/
	list_for_each_entry(vq, &vdev->vqs, list)
	vp_modern_set_queue_enable(&vp_dev->mdev, vq->index, true);

	return 0;
	}

	static void del_vq(struct virtio_pci_vq_info *info)
	{
	struct virtqueue *vq = info->vq;
	struct virtio_pci_device *vp_dev = to_vp_device(vq->vdev);
	struct virtio_pci_modern_device *mdev = &vp_dev->mdev;

	if (vp_dev->msix_enabled)
	vp_modern_queue_vector(mdev, vq->index,
	VIRTIO_MSI_NO_VECTOR);

	if (!mdev->notify_base)
	pci_iounmap(mdev->pci_dev, (void __force __iomem *)vq->priv);

	vring_del_virtqueue(vq);
	}

	static int virtio_pci_find_shm_cap(struct pci_dev *dev, u8 required_id,
	u8 bar, u64 offset, u64 *len)
	{
	int pos;

	for (pos = pci_find_capability(dev, PCI_CAP_ID_VNDR); pos > 0;
	pos = pci_find_next_capability(dev, pos, PCI_CAP_ID_VNDR)) {
	u8 type, cap_len, id, res_bar;
	u32 tmp32;
	u64 res_offset, res_length;

	pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_cap,
	cfg_type), &type);
	if (type != VIRTIO_PCI_CAP_SHARED_MEMORY_CFG)
	continue;

	pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_cap,
	cap_len), &cap_len);
	if (cap_len != sizeof(struct virtio_pci_cap64)) {
	dev_err(&dev->dev, "%s: shm cap with bad size offset:"
	" %d size: %d\n", __func__, pos, cap_len);
	continue;
	}

	pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_cap,
	id), &id);
	if (id != required_id)
	continue;

	pci_read_config_byte(dev, pos + offsetof(struct virtio_pci_cap,
	bar), &res_bar);
	if (res_bar >= PCI_STD_NUM_BARS)
	continue;

	/* Type and ID match, and the BAR value isn't reserved.
	* Looks good.
	*/

	/* Read the lower 32bit of length and offset */
	pci_read_config_dword(dev, pos + offsetof(struct virtio_pci_cap,
	offset), &tmp32);
	res_offset = tmp32;
	pci_read_config_dword(dev, pos + offsetof(struct virtio_pci_cap,
	length), &tmp32);
	res_length = tmp32;

	/* and now the top half */
	pci_read_config_dword(dev,
	pos + offsetof(struct virtio_pci_cap64,
	offset_hi), &tmp32);
	res_offset \|= ((u64)tmp32) << 32;
	pci_read_config_dword(dev,
	pos + offsetof(struct virtio_pci_cap64,
	length_hi), &tmp32);
	res_length \|= ((u64)tmp32) << 32;

	*bar = res_bar;
	*offset = res_offset;
	*len = res_length;

	return pos;
	}
	return 0;
	}

	static bool vp_get_shm_region(struct virtio_device *vdev,
	struct virtio_shm_region *region, u8 id)
	{
	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
	struct pci_dev *pci_dev = vp_dev->pci_dev;
	u8 bar;
	u64 offset, len;
	phys_addr_t phys_addr;
	size_t bar_len;

	if (!virtio_pci_find_shm_cap(pci_dev, id, &bar, &offset, &len))
	return false;

	phys_addr = pci_resource_start(pci_dev, bar);
	bar_len = pci_resource_len(pci_dev, bar);

	if ((offset + len) < offset) {
	dev_err(&pci_dev->dev, "%s: cap offset+len overflow detected\n",
	__func__);
	return false;
	}

	if (offset + len > bar_len) {
	dev_err(&pci_dev->dev, "%s: bar shorter than cap offset+len\n",
	__func__);
	return false;
	}

	region->len = len;
	region->addr = (u64) phys_addr + offset;

	return true;
	}

	static const struct virtio_config_ops virtio_pci_config_nodev_ops = {
	.get = NULL,
	.set = NULL,
	.generation = vp_generation,
	.get_status = vp_get_status,
	.set_status = vp_set_status,
	.reset = vp_reset,
	.find_vqs = vp_modern_find_vqs,
	.del_vqs = vp_del_vqs,
	.get_features = vp_get_features,
	.finalize_features = vp_finalize_features,
	.bus_name = vp_bus_name,
	.set_vq_affinity = vp_set_vq_affinity,
	.get_vq_affinity = vp_get_vq_affinity,
	.get_shm_region = vp_get_shm_region,
	};

	static const struct virtio_config_ops virtio_pci_config_ops = {
	.get = vp_get,
	.set = vp_set,
	.generation = vp_generation,
	.get_status = vp_get_status,
	.set_status = vp_set_status,
	.reset = vp_reset,
	.find_vqs = vp_modern_find_vqs,
	.del_vqs = vp_del_vqs,
	.get_features = vp_get_features,
	.finalize_features = vp_finalize_features,
	.bus_name = vp_bus_name,
	.set_vq_affinity = vp_set_vq_affinity,
	.get_vq_affinity = vp_get_vq_affinity,
	.get_shm_region = vp_get_shm_region,
	};

	/* the PCI probing function */
	int virtio_pci_modern_probe(struct virtio_pci_device *vp_dev)
	{
	struct virtio_pci_modern_device *mdev = &vp_dev->mdev;
	struct pci_dev *pci_dev = vp_dev->pci_dev;
	int err;

	mdev->pci_dev = pci_dev;

	err = vp_modern_probe(mdev);
	if (err)
	return err;

	if (mdev->device)
	vp_dev->vdev.config = &virtio_pci_config_ops;
	else
	vp_dev->vdev.config = &virtio_pci_config_nodev_ops;

	vp_dev->config_vector = vp_config_vector;
	vp_dev->setup_vq = setup_vq;
	vp_dev->del_vq = del_vq;
	vp_dev->isr = mdev->isr;
	vp_dev->vdev.id = mdev->id;

	return 0;
	}

	void virtio_pci_modern_remove(struct virtio_pci_device *vp_dev)
	{
	struct virtio_pci_modern_device *mdev = &vp_dev->mdev;

	vp_modern_remove(mdev);
	}