drivers/pci/iov.c - arm/linux-arm64-legacy - Git at Google

 /*
  * drivers/pci/iov.c
  *
  * Copyright (C) 2009 Intel Corporation, Yu Zhao <yu.zhao@intel.com>
  *
  * PCI Express I/O Virtualization (IOV) support.
  *   Single Root IOV 1.0
  *   Address Translation Service 1.0
  */

 #include <linux/pci.h>
 #include <linux/slab.h>
 #include <linux/mutex.h>
 #include <linux/export.h>
 #include <linux/string.h>
 #include <linux/delay.h>
 #include <linux/pci-ats.h>
 #include "pci.h"

 #define VIRTFN_ID_LEN	16

 static inline u8 virtfn_bus(struct pci_dev *dev, int id)
 {
 	return dev->bus->number + ((dev->devfn + dev->sriov->offset +
 				    dev->sriov->stride * id) >> 8);
 }

 static inline u8 virtfn_devfn(struct pci_dev *dev, int id)
 {
 	return (dev->devfn + dev->sriov->offset +
 		dev->sriov->stride * id) & 0xff;
 }

 static struct pci_bus *virtfn_add_bus(struct pci_bus *bus, int busnr)
 {
 	struct pci_bus *child;

 	if (bus->number == busnr)
 		return bus;

 	child = pci_find_bus(pci_domain_nr(bus), busnr);
 	if (child)
 		return child;

 	child = pci_add_new_bus(bus, NULL, busnr);
 	if (!child)
 		return NULL;

 	pci_bus_insert_busn_res(child, busnr, busnr);

 	return child;
 }

 static void virtfn_remove_bus(struct pci_bus *physbus, struct pci_bus *virtbus)
 {
 	if (physbus != virtbus && list_empty(&virtbus->devices))
 		pci_remove_bus(virtbus);
 }

 static int virtfn_add(struct pci_dev *dev, int id, int reset)
 {
 	int i;
 	int rc = -ENOMEM;
 	u64 size;
 	char buf[VIRTFN_ID_LEN];
 	struct pci_dev *virtfn;
 	struct resource *res;
 	struct pci_sriov *iov = dev->sriov;
 	struct pci_bus *bus;

 	mutex_lock(&iov->dev->sriov->lock);
 	bus = virtfn_add_bus(dev->bus, virtfn_bus(dev, id));
 	if (!bus)
 		goto failed;

 	virtfn = pci_alloc_dev(bus);
 	if (!virtfn)
 		goto failed0;

 	virtfn->devfn = virtfn_devfn(dev, id);
 	virtfn->vendor = dev->vendor;
 	pci_read_config_word(dev, iov->pos + PCI_SRIOV_VF_DID, &virtfn->device);
 	pci_setup_device(virtfn);
 	virtfn->dev.parent = dev->dev.parent;
 	virtfn->physfn = pci_dev_get(dev);
 	virtfn->is_virtfn = 1;
 	virtfn->multifunction = 0;

 	for (i = 0; i < PCI_SRIOV_NUM_BARS; i++) {
 		res = dev->resource + PCI_IOV_RESOURCES + i;
 		if (!res->parent)
 			continue;
 		virtfn->resource[i].name = pci_name(virtfn);
 		virtfn->resource[i].flags = res->flags;
 		size = resource_size(res);
 		do_div(size, iov->total_VFs);
 		virtfn->resource[i].start = res->start + size * id;
 		virtfn->resource[i].end = virtfn->resource[i].start + size - 1;
 		rc = request_resource(res, &virtfn->resource[i]);
 		BUG_ON(rc);
 	}

 	if (reset)
 		__pci_reset_function(virtfn);

 	pci_device_add(virtfn, virtfn->bus);
 	mutex_unlock(&iov->dev->sriov->lock);

 	pci_bus_add_device(virtfn);
 	sprintf(buf, "virtfn%u", id);
 	rc = sysfs_create_link(&dev->dev.kobj, &virtfn->dev.kobj, buf);
 	if (rc)
 		goto failed1;
 	rc = sysfs_create_link(&virtfn->dev.kobj, &dev->dev.kobj, "physfn");
 	if (rc)
 		goto failed2;

 	kobject_uevent(&virtfn->dev.kobj, KOBJ_CHANGE);

 	return 0;

 failed2:
 	sysfs_remove_link(&dev->dev.kobj, buf);
 failed1:
 	pci_dev_put(dev);
 	mutex_lock(&iov->dev->sriov->lock);
 	pci_stop_and_remove_bus_device(virtfn);
 failed0:
 	virtfn_remove_bus(dev->bus, bus);
 failed:
 	mutex_unlock(&iov->dev->sriov->lock);

 	return rc;
 }

 static void virtfn_remove(struct pci_dev *dev, int id, int reset)
 {
 	char buf[VIRTFN_ID_LEN];
 	struct pci_dev *virtfn;
 	struct pci_sriov *iov = dev->sriov;

 	virtfn = pci_get_domain_bus_and_slot(pci_domain_nr(dev->bus),
 					     virtfn_bus(dev, id),
 					     virtfn_devfn(dev, id));
 	if (!virtfn)
 		return;

 	if (reset) {
 		device_release_driver(&virtfn->dev);
 		__pci_reset_function(virtfn);
 	}

 	sprintf(buf, "virtfn%u", id);
 	sysfs_remove_link(&dev->dev.kobj, buf);
 	/*
 	 * pci_stop_dev() could have been called for this virtfn already,
 	 * so the directory for the virtfn may have been removed before.
 	 * Double check to avoid spurious sysfs warnings.
 	 */
 	if (virtfn->dev.kobj.sd)
 		sysfs_remove_link(&virtfn->dev.kobj, "physfn");

 	mutex_lock(&iov->dev->sriov->lock);
 	pci_stop_and_remove_bus_device(virtfn);
 	virtfn_remove_bus(dev->bus, virtfn->bus);
 	mutex_unlock(&iov->dev->sriov->lock);

 	/* balance pci_get_domain_bus_and_slot() */
 	pci_dev_put(virtfn);
 	pci_dev_put(dev);
 }

 static int sriov_enable(struct pci_dev *dev, int nr_virtfn)
 {
 	int rc;
 	int i, j;
 	int nres;
 	u16 offset, stride, initial;
 	struct resource *res;
 	struct pci_dev *pdev;
 	struct pci_sriov *iov = dev->sriov;
 	int bars = 0;

 	if (!nr_virtfn)
 		return 0;

 	if (iov->num_VFs)
 		return -EINVAL;

 	pci_read_config_word(dev, iov->pos + PCI_SRIOV_INITIAL_VF, &initial);
 	if (initial > iov->total_VFs ||
 	    (!(iov->cap & PCI_SRIOV_CAP_VFM) && (initial != iov->total_VFs)))
 		return -EIO;

 	if (nr_virtfn < 0 || nr_virtfn > iov->total_VFs ||
 	    (!(iov->cap & PCI_SRIOV_CAP_VFM) && (nr_virtfn > initial)))
 		return -EINVAL;

 	pci_read_config_word(dev, iov->pos + PCI_SRIOV_VF_OFFSET, &offset);
 	pci_read_config_word(dev, iov->pos + PCI_SRIOV_VF_STRIDE, &stride);
 	if (!offset || (nr_virtfn > 1 && !stride))
 		return -EIO;

 	nres = 0;
 	for (i = 0; i < PCI_SRIOV_NUM_BARS; i++) {
 		bars |= (1 << (i + PCI_IOV_RESOURCES));
 		res = dev->resource + PCI_IOV_RESOURCES + i;
 		if (res->parent)
 			nres++;
 	}
 	if (nres != iov->nres) {
 		dev_err(&dev->dev, "not enough MMIO resources for SR-IOV\n");
 		return -ENOMEM;
 	}

 	iov->offset = offset;
 	iov->stride = stride;

 	if (virtfn_bus(dev, nr_virtfn - 1) > dev->bus->busn_res.end) {
 		dev_err(&dev->dev, "SR-IOV: bus number out of range\n");
 		return -ENOMEM;
 	}

 	if (pci_enable_resources(dev, bars)) {
 		dev_err(&dev->dev, "SR-IOV: IOV BARS not allocated\n");
 		return -ENOMEM;
 	}

 	if (iov->link != dev->devfn) {
 		pdev = pci_get_slot(dev->bus, iov->link);
 		if (!pdev)
 			return -ENODEV;

 		if (!pdev->is_physfn) {
 			pci_dev_put(pdev);
 			return -ENOSYS;
 		}

 		rc = sysfs_create_link(&dev->dev.kobj,
 					&pdev->dev.kobj, "dep_link");
 		pci_dev_put(pdev);
 		if (rc)
 			return rc;
 	}

 	pci_write_config_word(dev, iov->pos + PCI_SRIOV_NUM_VF, nr_virtfn);
 	iov->ctrl |= PCI_SRIOV_CTRL_VFE | PCI_SRIOV_CTRL_MSE;
 	pci_cfg_access_lock(dev);
 	pci_write_config_word(dev, iov->pos + PCI_SRIOV_CTRL, iov->ctrl);
 	msleep(100);
 	pci_cfg_access_unlock(dev);

 	iov->initial_VFs = initial;
 	if (nr_virtfn < initial)
 		initial = nr_virtfn;

 	for (i = 0; i < initial; i++) {
 		rc = virtfn_add(dev, i, 0);
 		if (rc)
 			goto failed;
 	}

 	kobject_uevent(&dev->dev.kobj, KOBJ_CHANGE);
 	iov->num_VFs = nr_virtfn;

 	return 0;

 failed:
 	for (j = 0; j < i; j++)
 		virtfn_remove(dev, j, 0);

 	iov->ctrl &= ~(PCI_SRIOV_CTRL_VFE | PCI_SRIOV_CTRL_MSE);
 	pci_cfg_access_lock(dev);
 	pci_write_config_word(dev, iov->pos + PCI_SRIOV_CTRL, iov->ctrl);
 	pci_write_config_word(dev, iov->pos + PCI_SRIOV_NUM_VF, 0);
 	ssleep(1);
 	pci_cfg_access_unlock(dev);

 	if (iov->link != dev->devfn)
 		sysfs_remove_link(&dev->dev.kobj, "dep_link");

 	return rc;
 }

 static void sriov_disable(struct pci_dev *dev)
 {
 	int i;
 	struct pci_sriov *iov = dev->sriov;

 	if (!iov->num_VFs)
 		return;

 	for (i = 0; i < iov->num_VFs; i++)
 		virtfn_remove(dev, i, 0);

 	iov->ctrl &= ~(PCI_SRIOV_CTRL_VFE | PCI_SRIOV_CTRL_MSE);
 	pci_cfg_access_lock(dev);
 	pci_write_config_word(dev, iov->pos + PCI_SRIOV_CTRL, iov->ctrl);
 	ssleep(1);
 	pci_cfg_access_unlock(dev);

 	if (iov->link != dev->devfn)
 		sysfs_remove_link(&dev->dev.kobj, "dep_link");

 	iov->num_VFs = 0;
 	pci_write_config_word(dev, iov->pos + PCI_SRIOV_NUM_VF, 0);
 }

 static int sriov_init(struct pci_dev *dev, int pos)
 {
 	int i;
 	int rc;
 	int nres;
 	u32 pgsz;
 	u16 ctrl, total, offset, stride;
 	struct pci_sriov *iov;
 	struct resource *res;
 	struct pci_dev *pdev;

 	if (pci_pcie_type(dev) != PCI_EXP_TYPE_RC_END &&
 	    pci_pcie_type(dev) != PCI_EXP_TYPE_ENDPOINT)
 		return -ENODEV;

 	pci_read_config_word(dev, pos + PCI_SRIOV_CTRL, &ctrl);
 	if (ctrl & PCI_SRIOV_CTRL_VFE) {
 		pci_write_config_word(dev, pos + PCI_SRIOV_CTRL, 0);
 		ssleep(1);
 	}

 	pci_read_config_word(dev, pos + PCI_SRIOV_TOTAL_VF, &total);
 	if (!total)
 		return 0;

 	ctrl = 0;
 	list_for_each_entry(pdev, &dev->bus->devices, bus_list)
 		if (pdev->is_physfn)
 			goto found;

 	pdev = NULL;
 	if (pci_ari_enabled(dev->bus))
 		ctrl |= PCI_SRIOV_CTRL_ARI;

 found:
 	pci_write_config_word(dev, pos + PCI_SRIOV_CTRL, ctrl);
 	pci_write_config_word(dev, pos + PCI_SRIOV_NUM_VF, 0);
 	pci_read_config_word(dev, pos + PCI_SRIOV_VF_OFFSET, &offset);
 	pci_read_config_word(dev, pos + PCI_SRIOV_VF_STRIDE, &stride);
 	if (!offset || (total > 1 && !stride))
 		return -EIO;

 	pci_read_config_dword(dev, pos + PCI_SRIOV_SUP_PGSIZE, &pgsz);
 	i = PAGE_SHIFT > 12 ? PAGE_SHIFT - 12 : 0;
 	pgsz &= ~((1 << i) - 1);
 	if (!pgsz)
 		return -EIO;

 	pgsz &= ~(pgsz - 1);
 	pci_write_config_dword(dev, pos + PCI_SRIOV_SYS_PGSIZE, pgsz);

 	nres = 0;
 	for (i = 0; i < PCI_SRIOV_NUM_BARS; i++) {
 		res = dev->resource + PCI_IOV_RESOURCES + i;
 		i += __pci_read_base(dev, pci_bar_unknown, res,
 				     pos + PCI_SRIOV_BAR + i * 4);
 		if (!res->flags)
 			continue;
 		if (resource_size(res) & (PAGE_SIZE - 1)) {
 			rc = -EIO;
 			goto failed;
 		}
 		res->end = res->start + resource_size(res) * total - 1;
 		nres++;
 	}

 	iov = kzalloc(sizeof(*iov), GFP_KERNEL);
 	if (!iov) {
 		rc = -ENOMEM;
 		goto failed;
 	}

 	iov->pos = pos;
 	iov->nres = nres;
 	iov->ctrl = ctrl;
 	iov->total_VFs = total;
 	iov->offset = offset;
 	iov->stride = stride;
 	iov->pgsz = pgsz;
 	iov->self = dev;
 	pci_read_config_dword(dev, pos + PCI_SRIOV_CAP, &iov->cap);
 	pci_read_config_byte(dev, pos + PCI_SRIOV_FUNC_LINK, &iov->link);
 	if (pci_pcie_type(dev) == PCI_EXP_TYPE_RC_END)
 		iov->link = PCI_DEVFN(PCI_SLOT(dev->devfn), iov->link);

 	if (pdev)
 		iov->dev = pci_dev_get(pdev);
 	else
 		iov->dev = dev;

 	mutex_init(&iov->lock);

 	dev->sriov = iov;
 	dev->is_physfn = 1;

 	return 0;

 failed:
 	for (i = 0; i < PCI_SRIOV_NUM_BARS; i++) {
 		res = dev->resource + PCI_IOV_RESOURCES + i;
 		res->flags = 0;
 	}

 	return rc;
 }

 static void sriov_release(struct pci_dev *dev)
 {
 	BUG_ON(dev->sriov->num_VFs);

 	if (dev != dev->sriov->dev)
 		pci_dev_put(dev->sriov->dev);

 	mutex_destroy(&dev->sriov->lock);

 	kfree(dev->sriov);
 	dev->sriov = NULL;
 }

 static void sriov_restore_state(struct pci_dev *dev)
 {
 	int i;
 	u16 ctrl;
 	struct pci_sriov *iov = dev->sriov;

 	pci_read_config_word(dev, iov->pos + PCI_SRIOV_CTRL, &ctrl);
 	if (ctrl & PCI_SRIOV_CTRL_VFE)
 		return;

 	for (i = PCI_IOV_RESOURCES; i <= PCI_IOV_RESOURCE_END; i++)
 		pci_update_resource(dev, i);

 	pci_write_config_dword(dev, iov->pos + PCI_SRIOV_SYS_PGSIZE, iov->pgsz);
 	pci_write_config_word(dev, iov->pos + PCI_SRIOV_NUM_VF, iov->num_VFs);
 	pci_write_config_word(dev, iov->pos + PCI_SRIOV_CTRL, iov->ctrl);
 	if (iov->ctrl & PCI_SRIOV_CTRL_VFE)
 		msleep(100);
 }

 /**
  * pci_iov_init - initialize the IOV capability
  * @dev: the PCI device
  *
  * Returns 0 on success, or negative on failure.
  */
 int pci_iov_init(struct pci_dev *dev)
 {
 	int pos;

 	if (!pci_is_pcie(dev))
 		return -ENODEV;

 	pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_SRIOV);
 	if (pos)
 		return sriov_init(dev, pos);

 	return -ENODEV;
 }

 /**
  * pci_iov_release - release resources used by the IOV capability
  * @dev: the PCI device
  */
 void pci_iov_release(struct pci_dev *dev)
 {
 	if (dev->is_physfn)
 		sriov_release(dev);
 }

 /**
  * pci_iov_resource_bar - get position of the SR-IOV BAR
  * @dev: the PCI device
  * @resno: the resource number
  * @type: the BAR type to be filled in
  *
  * Returns position of the BAR encapsulated in the SR-IOV capability.
  */
 int pci_iov_resource_bar(struct pci_dev *dev, int resno,
 			 enum pci_bar_type *type)
 {
 	if (resno < PCI_IOV_RESOURCES || resno > PCI_IOV_RESOURCE_END)
 		return 0;

 	BUG_ON(!dev->is_physfn);

 	*type = pci_bar_unknown;

 	return dev->sriov->pos + PCI_SRIOV_BAR +
 		4 * (resno - PCI_IOV_RESOURCES);
 }

 /**
  * pci_sriov_resource_alignment - get resource alignment for VF BAR
  * @dev: the PCI device
  * @resno: the resource number
  *
  * Returns the alignment of the VF BAR found in the SR-IOV capability.
  * This is not the same as the resource size which is defined as
  * the VF BAR size multiplied by the number of VFs.  The alignment
  * is just the VF BAR size.
  */
 resource_size_t pci_sriov_resource_alignment(struct pci_dev *dev, int resno)
 {
 	struct resource tmp;
 	enum pci_bar_type type;
 	int reg = pci_iov_resource_bar(dev, resno, &type);

 	if (!reg)
 		return 0;

 	 __pci_read_base(dev, type, &tmp, reg);
 	return resource_alignment(&tmp);
 }

 /**
  * pci_restore_iov_state - restore the state of the IOV capability
  * @dev: the PCI device
  */
 void pci_restore_iov_state(struct pci_dev *dev)
 {
 	if (dev->is_physfn)
 		sriov_restore_state(dev);
 }

 /**
  * pci_iov_bus_range - find bus range used by Virtual Function
  * @bus: the PCI bus
  *
  * Returns max number of buses (exclude current one) used by Virtual
  * Functions.
  */
 int pci_iov_bus_range(struct pci_bus *bus)
 {
 	int max = 0;
 	u8 busnr;
 	struct pci_dev *dev;

 	list_for_each_entry(dev, &bus->devices, bus_list) {
 		if (!dev->is_physfn)
 			continue;
 		busnr = virtfn_bus(dev, dev->sriov->total_VFs - 1);
 		if (busnr > max)
 			max = busnr;
 	}

 	return max ? max - bus->number : 0;
 }

 /**
  * pci_enable_sriov - enable the SR-IOV capability
  * @dev: the PCI device
  * @nr_virtfn: number of virtual functions to enable
  *
  * Returns 0 on success, or negative on failure.
  */
 int pci_enable_sriov(struct pci_dev *dev, int nr_virtfn)
 {
 	might_sleep();

 	if (!dev->is_physfn)
 		return -ENOSYS;

 	return sriov_enable(dev, nr_virtfn);
 }
 EXPORT_SYMBOL_GPL(pci_enable_sriov);

 /**
  * pci_disable_sriov - disable the SR-IOV capability
  * @dev: the PCI device
  */
 void pci_disable_sriov(struct pci_dev *dev)
 {
 	might_sleep();

 	if (!dev->is_physfn)
 		return;

 	sriov_disable(dev);
 }
 EXPORT_SYMBOL_GPL(pci_disable_sriov);

 /**
  * pci_num_vf - return number of VFs associated with a PF device_release_driver
  * @dev: the PCI device
  *
  * Returns number of VFs, or 0 if SR-IOV is not enabled.
  */
 int pci_num_vf(struct pci_dev *dev)
 {
 	if (!dev->is_physfn)
 		return 0;

 	return dev->sriov->num_VFs;
 }
 EXPORT_SYMBOL_GPL(pci_num_vf);

 /**
  * pci_vfs_assigned - returns number of VFs are assigned to a guest
  * @dev: the PCI device
  *
  * Returns number of VFs belonging to this device that are assigned to a guest.
  * If device is not a physical function returns 0.
  */
 int pci_vfs_assigned(struct pci_dev *dev)
 {
 	struct pci_dev *vfdev;
 	unsigned int vfs_assigned = 0;
 	unsigned short dev_id;

 	/* only search if we are a PF */
 	if (!dev->is_physfn)
 		return 0;

 	/*
 	 * determine the device ID for the VFs, the vendor ID will be the
 	 * same as the PF so there is no need to check for that one
 	 */
 	pci_read_config_word(dev, dev->sriov->pos + PCI_SRIOV_VF_DID, &dev_id);

 	/* loop through all the VFs to see if we own any that are assigned */
 	vfdev = pci_get_device(dev->vendor, dev_id, NULL);
 	while (vfdev) {
 		/*
 		 * It is considered assigned if it is a virtual function with
 		 * our dev as the physical function and the assigned bit is set
 		 */
 		if (vfdev->is_virtfn && (vfdev->physfn == dev) &&
 		    (vfdev->dev_flags & PCI_DEV_FLAGS_ASSIGNED))
 			vfs_assigned++;

 		vfdev = pci_get_device(dev->vendor, dev_id, vfdev);
 	}

 	return vfs_assigned;
 }
 EXPORT_SYMBOL_GPL(pci_vfs_assigned);

 /**
  * pci_sriov_set_totalvfs -- reduce the TotalVFs available
  * @dev: the PCI PF device
  * @numvfs: number that should be used for TotalVFs supported
  *
  * Should be called from PF driver's probe routine with
  * device's mutex held.
  *
  * Returns 0 if PF is an SRIOV-capable device and
  * value of numvfs valid. If not a PF return -ENOSYS;
  * if numvfs is invalid return -EINVAL;
  * if VFs already enabled, return -EBUSY.
  */
 int pci_sriov_set_totalvfs(struct pci_dev *dev, u16 numvfs)
 {
 	if (!dev->is_physfn)
 		return -ENOSYS;
 	if (numvfs > dev->sriov->total_VFs)
 		return -EINVAL;

 	/* Shouldn't change if VFs already enabled */
 	if (dev->sriov->ctrl & PCI_SRIOV_CTRL_VFE)
 		return -EBUSY;
 	else
 		dev->sriov->driver_max_VFs = numvfs;

 	return 0;
 }
 EXPORT_SYMBOL_GPL(pci_sriov_set_totalvfs);

 /**
  * pci_sriov_get_totalvfs -- get total VFs supported on this device
  * @dev: the PCI PF device
  *
  * For a PCIe device with SRIOV support, return the PCIe
  * SRIOV capability value of TotalVFs or the value of driver_max_VFs
  * if the driver reduced it.  Otherwise 0.
  */
 int pci_sriov_get_totalvfs(struct pci_dev *dev)
 {
 	if (!dev->is_physfn)
 		return 0;

 	if (dev->sriov->driver_max_VFs)
 		return dev->sriov->driver_max_VFs;

 	return dev->sriov->total_VFs;
 }
 EXPORT_SYMBOL_GPL(pci_sriov_get_totalvfs);
	/*
	* drivers/pci/iov.c
	*
	* Copyright (C) 2009 Intel Corporation, Yu Zhao <yu.zhao@intel.com>
	*
	* PCI Express I/O Virtualization (IOV) support.
	* Single Root IOV 1.0
	* Address Translation Service 1.0
	*/

	#include <linux/pci.h>
	#include <linux/slab.h>
	#include <linux/mutex.h>
	#include <linux/export.h>
	#include <linux/string.h>
	#include <linux/delay.h>
	#include <linux/pci-ats.h>
	#include "pci.h"

	#define VIRTFN_ID_LEN 16

	static inline u8 virtfn_bus(struct pci_dev *dev, int id)
	{
	return dev->bus->number + ((dev->devfn + dev->sriov->offset +
	dev->sriov->stride * id) >> 8);
	}

	static inline u8 virtfn_devfn(struct pci_dev *dev, int id)
	{
	return (dev->devfn + dev->sriov->offset +
	dev->sriov->stride * id) & 0xff;
	}

	static struct pci_bus virtfn_add_bus(struct pci_bus bus, int busnr)
	{
	struct pci_bus *child;

	if (bus->number == busnr)
	return bus;

	child = pci_find_bus(pci_domain_nr(bus), busnr);
	if (child)
	return child;

	child = pci_add_new_bus(bus, NULL, busnr);
	if (!child)
	return NULL;

	pci_bus_insert_busn_res(child, busnr, busnr);

	return child;
	}

	static void virtfn_remove_bus(struct pci_bus physbus, struct pci_bus virtbus)
	{
	if (physbus != virtbus && list_empty(&virtbus->devices))
	pci_remove_bus(virtbus);
	}

	static int virtfn_add(struct pci_dev *dev, int id, int reset)
	{
	int i;
	int rc = -ENOMEM;
	u64 size;
	char buf[VIRTFN_ID_LEN];
	struct pci_dev *virtfn;
	struct resource *res;
	struct pci_sriov *iov = dev->sriov;
	struct pci_bus *bus;

	mutex_lock(&iov->dev->sriov->lock);
	bus = virtfn_add_bus(dev->bus, virtfn_bus(dev, id));
	if (!bus)
	goto failed;

	virtfn = pci_alloc_dev(bus);
	if (!virtfn)
	goto failed0;

	virtfn->devfn = virtfn_devfn(dev, id);
	virtfn->vendor = dev->vendor;
	pci_read_config_word(dev, iov->pos + PCI_SRIOV_VF_DID, &virtfn->device);
	pci_setup_device(virtfn);
	virtfn->dev.parent = dev->dev.parent;
	virtfn->physfn = pci_dev_get(dev);
	virtfn->is_virtfn = 1;
	virtfn->multifunction = 0;

	for (i = 0; i < PCI_SRIOV_NUM_BARS; i++) {
	res = dev->resource + PCI_IOV_RESOURCES + i;
	if (!res->parent)
	continue;
	virtfn->resource[i].name = pci_name(virtfn);
	virtfn->resource[i].flags = res->flags;
	size = resource_size(res);
	do_div(size, iov->total_VFs);
	virtfn->resource[i].start = res->start + size * id;
	virtfn->resource[i].end = virtfn->resource[i].start + size - 1;
	rc = request_resource(res, &virtfn->resource[i]);
	BUG_ON(rc);
	}

	if (reset)
	__pci_reset_function(virtfn);

	pci_device_add(virtfn, virtfn->bus);
	mutex_unlock(&iov->dev->sriov->lock);

	pci_bus_add_device(virtfn);
	sprintf(buf, "virtfn%u", id);
	rc = sysfs_create_link(&dev->dev.kobj, &virtfn->dev.kobj, buf);
	if (rc)
	goto failed1;
	rc = sysfs_create_link(&virtfn->dev.kobj, &dev->dev.kobj, "physfn");
	if (rc)
	goto failed2;

	kobject_uevent(&virtfn->dev.kobj, KOBJ_CHANGE);

	return 0;

	failed2:
	sysfs_remove_link(&dev->dev.kobj, buf);
	failed1:
	pci_dev_put(dev);
	mutex_lock(&iov->dev->sriov->lock);
	pci_stop_and_remove_bus_device(virtfn);
	failed0:
	virtfn_remove_bus(dev->bus, bus);
	failed:
	mutex_unlock(&iov->dev->sriov->lock);

	return rc;
	}

	static void virtfn_remove(struct pci_dev *dev, int id, int reset)
	{
	char buf[VIRTFN_ID_LEN];
	struct pci_dev *virtfn;
	struct pci_sriov *iov = dev->sriov;

	virtfn = pci_get_domain_bus_and_slot(pci_domain_nr(dev->bus),
	virtfn_bus(dev, id),
	virtfn_devfn(dev, id));
	if (!virtfn)
	return;

	if (reset) {
	device_release_driver(&virtfn->dev);
	__pci_reset_function(virtfn);
	}

	sprintf(buf, "virtfn%u", id);
	sysfs_remove_link(&dev->dev.kobj, buf);
	/*
	* pci_stop_dev() could have been called for this virtfn already,
	* so the directory for the virtfn may have been removed before.
	* Double check to avoid spurious sysfs warnings.
	*/
	if (virtfn->dev.kobj.sd)
	sysfs_remove_link(&virtfn->dev.kobj, "physfn");

	mutex_lock(&iov->dev->sriov->lock);
	pci_stop_and_remove_bus_device(virtfn);
	virtfn_remove_bus(dev->bus, virtfn->bus);
	mutex_unlock(&iov->dev->sriov->lock);

	/* balance pci_get_domain_bus_and_slot() */
	pci_dev_put(virtfn);
	pci_dev_put(dev);
	}

	static int sriov_enable(struct pci_dev *dev, int nr_virtfn)
	{
	int rc;
	int i, j;
	int nres;
	u16 offset, stride, initial;
	struct resource *res;
	struct pci_dev *pdev;
	struct pci_sriov *iov = dev->sriov;
	int bars = 0;

	if (!nr_virtfn)
	return 0;

	if (iov->num_VFs)
	return -EINVAL;

	pci_read_config_word(dev, iov->pos + PCI_SRIOV_INITIAL_VF, &initial);
	if (initial > iov->total_VFs \|\|
	(!(iov->cap & PCI_SRIOV_CAP_VFM) && (initial != iov->total_VFs)))
	return -EIO;

	if (nr_virtfn < 0 \|\| nr_virtfn > iov->total_VFs \|\|
	(!(iov->cap & PCI_SRIOV_CAP_VFM) && (nr_virtfn > initial)))
	return -EINVAL;

	pci_read_config_word(dev, iov->pos + PCI_SRIOV_VF_OFFSET, &offset);
	pci_read_config_word(dev, iov->pos + PCI_SRIOV_VF_STRIDE, &stride);
	if (!offset \|\| (nr_virtfn > 1 && !stride))
	return -EIO;

	nres = 0;
	for (i = 0; i < PCI_SRIOV_NUM_BARS; i++) {
	bars \|= (1 << (i + PCI_IOV_RESOURCES));
	res = dev->resource + PCI_IOV_RESOURCES + i;
	if (res->parent)
	nres++;
	}
	if (nres != iov->nres) {
	dev_err(&dev->dev, "not enough MMIO resources for SR-IOV\n");
	return -ENOMEM;
	}

	iov->offset = offset;
	iov->stride = stride;

	if (virtfn_bus(dev, nr_virtfn - 1) > dev->bus->busn_res.end) {
	dev_err(&dev->dev, "SR-IOV: bus number out of range\n");
	return -ENOMEM;
	}

	if (pci_enable_resources(dev, bars)) {
	dev_err(&dev->dev, "SR-IOV: IOV BARS not allocated\n");
	return -ENOMEM;
	}

	if (iov->link != dev->devfn) {
	pdev = pci_get_slot(dev->bus, iov->link);
	if (!pdev)
	return -ENODEV;

	if (!pdev->is_physfn) {
	pci_dev_put(pdev);
	return -ENOSYS;
	}

	rc = sysfs_create_link(&dev->dev.kobj,
	&pdev->dev.kobj, "dep_link");
	pci_dev_put(pdev);
	if (rc)
	return rc;
	}

	pci_write_config_word(dev, iov->pos + PCI_SRIOV_NUM_VF, nr_virtfn);
	iov->ctrl \|= PCI_SRIOV_CTRL_VFE \| PCI_SRIOV_CTRL_MSE;
	pci_cfg_access_lock(dev);
	pci_write_config_word(dev, iov->pos + PCI_SRIOV_CTRL, iov->ctrl);
	msleep(100);
	pci_cfg_access_unlock(dev);

	iov->initial_VFs = initial;
	if (nr_virtfn < initial)
	initial = nr_virtfn;

	for (i = 0; i < initial; i++) {
	rc = virtfn_add(dev, i, 0);
	if (rc)
	goto failed;
	}

	kobject_uevent(&dev->dev.kobj, KOBJ_CHANGE);
	iov->num_VFs = nr_virtfn;

	return 0;

	failed:
	for (j = 0; j < i; j++)
	virtfn_remove(dev, j, 0);

	iov->ctrl &= ~(PCI_SRIOV_CTRL_VFE \| PCI_SRIOV_CTRL_MSE);
	pci_cfg_access_lock(dev);
	pci_write_config_word(dev, iov->pos + PCI_SRIOV_CTRL, iov->ctrl);
	pci_write_config_word(dev, iov->pos + PCI_SRIOV_NUM_VF, 0);
	ssleep(1);
	pci_cfg_access_unlock(dev);

	if (iov->link != dev->devfn)
	sysfs_remove_link(&dev->dev.kobj, "dep_link");

	return rc;
	}

	static void sriov_disable(struct pci_dev *dev)
	{
	int i;
	struct pci_sriov *iov = dev->sriov;

	if (!iov->num_VFs)
	return;

	for (i = 0; i < iov->num_VFs; i++)
	virtfn_remove(dev, i, 0);

	iov->ctrl &= ~(PCI_SRIOV_CTRL_VFE \| PCI_SRIOV_CTRL_MSE);
	pci_cfg_access_lock(dev);
	pci_write_config_word(dev, iov->pos + PCI_SRIOV_CTRL, iov->ctrl);
	ssleep(1);
	pci_cfg_access_unlock(dev);

	if (iov->link != dev->devfn)
	sysfs_remove_link(&dev->dev.kobj, "dep_link");

	iov->num_VFs = 0;
	pci_write_config_word(dev, iov->pos + PCI_SRIOV_NUM_VF, 0);
	}

	static int sriov_init(struct pci_dev *dev, int pos)
	{
	int i;
	int rc;
	int nres;
	u32 pgsz;
	u16 ctrl, total, offset, stride;
	struct pci_sriov *iov;
	struct resource *res;
	struct pci_dev *pdev;

	if (pci_pcie_type(dev) != PCI_EXP_TYPE_RC_END &&
	pci_pcie_type(dev) != PCI_EXP_TYPE_ENDPOINT)
	return -ENODEV;

	pci_read_config_word(dev, pos + PCI_SRIOV_CTRL, &ctrl);
	if (ctrl & PCI_SRIOV_CTRL_VFE) {
	pci_write_config_word(dev, pos + PCI_SRIOV_CTRL, 0);
	ssleep(1);
	}

	pci_read_config_word(dev, pos + PCI_SRIOV_TOTAL_VF, &total);
	if (!total)
	return 0;

	ctrl = 0;
	list_for_each_entry(pdev, &dev->bus->devices, bus_list)
	if (pdev->is_physfn)
	goto found;

	pdev = NULL;
	if (pci_ari_enabled(dev->bus))
	ctrl \|= PCI_SRIOV_CTRL_ARI;

	found:
	pci_write_config_word(dev, pos + PCI_SRIOV_CTRL, ctrl);
	pci_write_config_word(dev, pos + PCI_SRIOV_NUM_VF, 0);
	pci_read_config_word(dev, pos + PCI_SRIOV_VF_OFFSET, &offset);
	pci_read_config_word(dev, pos + PCI_SRIOV_VF_STRIDE, &stride);
	if (!offset \|\| (total > 1 && !stride))
	return -EIO;

	pci_read_config_dword(dev, pos + PCI_SRIOV_SUP_PGSIZE, &pgsz);
	i = PAGE_SHIFT > 12 ? PAGE_SHIFT - 12 : 0;
	pgsz &= ~((1 << i) - 1);
	if (!pgsz)
	return -EIO;

	pgsz &= ~(pgsz - 1);
	pci_write_config_dword(dev, pos + PCI_SRIOV_SYS_PGSIZE, pgsz);

	nres = 0;
	for (i = 0; i < PCI_SRIOV_NUM_BARS; i++) {
	res = dev->resource + PCI_IOV_RESOURCES + i;
	i += __pci_read_base(dev, pci_bar_unknown, res,
	pos + PCI_SRIOV_BAR + i * 4);
	if (!res->flags)
	continue;
	if (resource_size(res) & (PAGE_SIZE - 1)) {
	rc = -EIO;
	goto failed;
	}
	res->end = res->start + resource_size(res) * total - 1;
	nres++;
	}

	iov = kzalloc(sizeof(*iov), GFP_KERNEL);
	if (!iov) {
	rc = -ENOMEM;
	goto failed;
	}

	iov->pos = pos;
	iov->nres = nres;
	iov->ctrl = ctrl;
	iov->total_VFs = total;
	iov->offset = offset;
	iov->stride = stride;
	iov->pgsz = pgsz;
	iov->self = dev;
	pci_read_config_dword(dev, pos + PCI_SRIOV_CAP, &iov->cap);
	pci_read_config_byte(dev, pos + PCI_SRIOV_FUNC_LINK, &iov->link);
	if (pci_pcie_type(dev) == PCI_EXP_TYPE_RC_END)
	iov->link = PCI_DEVFN(PCI_SLOT(dev->devfn), iov->link);

	if (pdev)
	iov->dev = pci_dev_get(pdev);
	else
	iov->dev = dev;

	mutex_init(&iov->lock);

	dev->sriov = iov;
	dev->is_physfn = 1;

	return 0;

	failed:
	for (i = 0; i < PCI_SRIOV_NUM_BARS; i++) {
	res = dev->resource + PCI_IOV_RESOURCES + i;
	res->flags = 0;
	}

	return rc;
	}

	static void sriov_release(struct pci_dev *dev)
	{
	BUG_ON(dev->sriov->num_VFs);

	if (dev != dev->sriov->dev)
	pci_dev_put(dev->sriov->dev);

	mutex_destroy(&dev->sriov->lock);

	kfree(dev->sriov);
	dev->sriov = NULL;
	}

	static void sriov_restore_state(struct pci_dev *dev)
	{
	int i;
	u16 ctrl;
	struct pci_sriov *iov = dev->sriov;

	pci_read_config_word(dev, iov->pos + PCI_SRIOV_CTRL, &ctrl);
	if (ctrl & PCI_SRIOV_CTRL_VFE)
	return;

	for (i = PCI_IOV_RESOURCES; i <= PCI_IOV_RESOURCE_END; i++)
	pci_update_resource(dev, i);

	pci_write_config_dword(dev, iov->pos + PCI_SRIOV_SYS_PGSIZE, iov->pgsz);
	pci_write_config_word(dev, iov->pos + PCI_SRIOV_NUM_VF, iov->num_VFs);
	pci_write_config_word(dev, iov->pos + PCI_SRIOV_CTRL, iov->ctrl);
	if (iov->ctrl & PCI_SRIOV_CTRL_VFE)
	msleep(100);
	}

	/**
	* pci_iov_init - initialize the IOV capability
	* @dev: the PCI device
	*
	* Returns 0 on success, or negative on failure.
	*/
	int pci_iov_init(struct pci_dev *dev)
	{
	int pos;

	if (!pci_is_pcie(dev))
	return -ENODEV;

	pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_SRIOV);
	if (pos)
	return sriov_init(dev, pos);

	return -ENODEV;
	}

	/**
	* pci_iov_release - release resources used by the IOV capability
	* @dev: the PCI device
	*/
	void pci_iov_release(struct pci_dev *dev)
	{
	if (dev->is_physfn)
	sriov_release(dev);
	}

	/**
	* pci_iov_resource_bar - get position of the SR-IOV BAR
	* @dev: the PCI device
	* @resno: the resource number
	* @type: the BAR type to be filled in
	*
	* Returns position of the BAR encapsulated in the SR-IOV capability.
	*/
	int pci_iov_resource_bar(struct pci_dev *dev, int resno,
	enum pci_bar_type *type)
	{
	if (resno < PCI_IOV_RESOURCES \|\| resno > PCI_IOV_RESOURCE_END)
	return 0;

	BUG_ON(!dev->is_physfn);

	*type = pci_bar_unknown;

	return dev->sriov->pos + PCI_SRIOV_BAR +
	4 * (resno - PCI_IOV_RESOURCES);
	}

	/**
	* pci_sriov_resource_alignment - get resource alignment for VF BAR
	* @dev: the PCI device
	* @resno: the resource number
	*
	* Returns the alignment of the VF BAR found in the SR-IOV capability.
	* This is not the same as the resource size which is defined as
	* the VF BAR size multiplied by the number of VFs. The alignment
	* is just the VF BAR size.
	*/
	resource_size_t pci_sriov_resource_alignment(struct pci_dev *dev, int resno)
	{
	struct resource tmp;
	enum pci_bar_type type;
	int reg = pci_iov_resource_bar(dev, resno, &type);

	if (!reg)
	return 0;

	__pci_read_base(dev, type, &tmp, reg);
	return resource_alignment(&tmp);
	}

	/**
	* pci_restore_iov_state - restore the state of the IOV capability
	* @dev: the PCI device
	*/
	void pci_restore_iov_state(struct pci_dev *dev)
	{
	if (dev->is_physfn)
	sriov_restore_state(dev);
	}

	/**
	* pci_iov_bus_range - find bus range used by Virtual Function
	* @bus: the PCI bus
	*
	* Returns max number of buses (exclude current one) used by Virtual
	* Functions.
	*/
	int pci_iov_bus_range(struct pci_bus *bus)
	{
	int max = 0;
	u8 busnr;
	struct pci_dev *dev;

	list_for_each_entry(dev, &bus->devices, bus_list) {
	if (!dev->is_physfn)
	continue;
	busnr = virtfn_bus(dev, dev->sriov->total_VFs - 1);
	if (busnr > max)
	max = busnr;
	}

	return max ? max - bus->number : 0;
	}

	/**
	* pci_enable_sriov - enable the SR-IOV capability
	* @dev: the PCI device
	* @nr_virtfn: number of virtual functions to enable
	*
	* Returns 0 on success, or negative on failure.
	*/
	int pci_enable_sriov(struct pci_dev *dev, int nr_virtfn)
	{
	might_sleep();

	if (!dev->is_physfn)
	return -ENOSYS;

	return sriov_enable(dev, nr_virtfn);
	}
	EXPORT_SYMBOL_GPL(pci_enable_sriov);

	/**
	* pci_disable_sriov - disable the SR-IOV capability
	* @dev: the PCI device
	*/
	void pci_disable_sriov(struct pci_dev *dev)
	{
	might_sleep();

	if (!dev->is_physfn)
	return;

	sriov_disable(dev);
	}
	EXPORT_SYMBOL_GPL(pci_disable_sriov);

	/**
	* pci_num_vf - return number of VFs associated with a PF device_release_driver
	* @dev: the PCI device
	*
	* Returns number of VFs, or 0 if SR-IOV is not enabled.
	*/
	int pci_num_vf(struct pci_dev *dev)
	{
	if (!dev->is_physfn)
	return 0;

	return dev->sriov->num_VFs;
	}
	EXPORT_SYMBOL_GPL(pci_num_vf);

	/**
	* pci_vfs_assigned - returns number of VFs are assigned to a guest
	* @dev: the PCI device
	*
	* Returns number of VFs belonging to this device that are assigned to a guest.
	* If device is not a physical function returns 0.
	*/
	int pci_vfs_assigned(struct pci_dev *dev)
	{
	struct pci_dev *vfdev;
	unsigned int vfs_assigned = 0;
	unsigned short dev_id;

	/* only search if we are a PF */
	if (!dev->is_physfn)
	return 0;

	/*
	* determine the device ID for the VFs, the vendor ID will be the
	* same as the PF so there is no need to check for that one
	*/
	pci_read_config_word(dev, dev->sriov->pos + PCI_SRIOV_VF_DID, &dev_id);

	/* loop through all the VFs to see if we own any that are assigned */
	vfdev = pci_get_device(dev->vendor, dev_id, NULL);
	while (vfdev) {
	/*
	* It is considered assigned if it is a virtual function with
	* our dev as the physical function and the assigned bit is set
	*/
	if (vfdev->is_virtfn && (vfdev->physfn == dev) &&
	(vfdev->dev_flags & PCI_DEV_FLAGS_ASSIGNED))
	vfs_assigned++;

	vfdev = pci_get_device(dev->vendor, dev_id, vfdev);
	}

	return vfs_assigned;
	}
	EXPORT_SYMBOL_GPL(pci_vfs_assigned);

	/**
	* pci_sriov_set_totalvfs -- reduce the TotalVFs available
	* @dev: the PCI PF device
	* @numvfs: number that should be used for TotalVFs supported
	*
	* Should be called from PF driver's probe routine with
	* device's mutex held.
	*
	* Returns 0 if PF is an SRIOV-capable device and
	* value of numvfs valid. If not a PF return -ENOSYS;
	* if numvfs is invalid return -EINVAL;
	* if VFs already enabled, return -EBUSY.
	*/
	int pci_sriov_set_totalvfs(struct pci_dev *dev, u16 numvfs)
	{
	if (!dev->is_physfn)
	return -ENOSYS;
	if (numvfs > dev->sriov->total_VFs)
	return -EINVAL;

	/* Shouldn't change if VFs already enabled */
	if (dev->sriov->ctrl & PCI_SRIOV_CTRL_VFE)
	return -EBUSY;
	else
	dev->sriov->driver_max_VFs = numvfs;

	return 0;
	}
	EXPORT_SYMBOL_GPL(pci_sriov_set_totalvfs);

	/**
	* pci_sriov_get_totalvfs -- get total VFs supported on this device
	* @dev: the PCI PF device
	*
	* For a PCIe device with SRIOV support, return the PCIe
	* SRIOV capability value of TotalVFs or the value of driver_max_VFs
	* if the driver reduced it. Otherwise 0.
	*/
	int pci_sriov_get_totalvfs(struct pci_dev *dev)
	{
	if (!dev->is_physfn)
	return 0;

	if (dev->sriov->driver_max_VFs)
	return dev->sriov->driver_max_VFs;

	return dev->sriov->total_VFs;
	}
	EXPORT_SYMBOL_GPL(pci_sriov_get_totalvfs);