// SPDX-License-Identifier: GPL-2.0
/*
 * PCI Express I/O Virtualization (IOV) support
 *   Single Root IOV 1.0
 *   Address Translation Service 1.0
 *
 * Copyright (C) 2009 Intel Corporation, Yu Zhao <yu.zhao@intel.com>
 */

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

#define VIRTFN_ID_LEN   16

int pci_iov_virtfn_bus(struct pci_dev *dev, int vf_id)
{
        if (!dev->is_physfn)
                return -EINVAL;
        return dev->bus->number + ((dev->devfn + dev->sriov->offset +
                                    dev->sriov->stride * vf_id) >> 8);
}

int pci_iov_virtfn_devfn(struct pci_dev *dev, int vf_id)
{
        if (!dev->is_physfn)
                return -EINVAL;
        return (dev->devfn + dev->sriov->offset +
                dev->sriov->stride * vf_id) & 0xff;
}
EXPORT_SYMBOL_GPL(pci_iov_virtfn_devfn);

/*
 * Per SR-IOV spec sec 3.3.10 and 3.3.11, First VF Offset and VF Stride may
 * change when NumVFs changes.
 *
 * Update iov->offset and iov->stride when NumVFs is written.
 */
static inline void pci_iov_set_numvfs(struct pci_dev *dev, int nr_virtfn)
{
        struct pci_sriov *iov = dev->sriov;

        pci_write_config_word(dev, iov->pos + PCI_SRIOV_NUM_VF, nr_virtfn);
        pci_read_config_word(dev, iov->pos + PCI_SRIOV_VF_OFFSET, &iov->offset);
        pci_read_config_word(dev, iov->pos + PCI_SRIOV_VF_STRIDE, &iov->stride);
}

/*
 * The PF consumes one bus number.  NumVFs, First VF Offset, and VF Stride
 * determine how many additional bus numbers will be consumed by VFs.
 *
 * Iterate over all valid NumVFs, validate offset and stride, and calculate
 * the maximum number of bus numbers that could ever be required.
 */
static int compute_max_vf_buses(struct pci_dev *dev)
{
        struct pci_sriov *iov = dev->sriov;
        int nr_virtfn, busnr, rc = 0;

        for (nr_virtfn = iov->total_VFs; nr_virtfn; nr_virtfn--) {
                pci_iov_set_numvfs(dev, nr_virtfn);
                if (!iov->offset || (nr_virtfn > 1 && !iov->stride)) {
                        rc = -EIO;
                        goto out;
                }

                busnr = pci_iov_virtfn_bus(dev, nr_virtfn - 1);
                if (busnr > iov->max_VF_buses)
                        iov->max_VF_buses = busnr;
        }

out:
        pci_iov_set_numvfs(dev, 0);
        return rc;
}

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);
}

resource_size_t pci_iov_resource_size(struct pci_dev *dev, int resno)
{
        if (!dev->is_physfn)
                return 0;

        return dev->sriov->barsz[resno - PCI_IOV_RESOURCES];
}

static void pci_read_vf_config_common(struct pci_dev *virtfn)
{
        struct pci_dev *physfn = virtfn->physfn;

        /*
         * Some config registers are the same across all associated VFs.
         * Read them once from VF0 so we can skip reading them from the
         * other VFs.
         *
         * PCIe r4.0, sec 9.3.4.1, technically doesn't require all VFs to
         * have the same Revision ID and Subsystem ID, but we assume they
         * do.
         */
        pci_read_config_dword(virtfn, PCI_CLASS_REVISION,
                              &physfn->sriov->class);
        pci_read_config_byte(virtfn, PCI_HEADER_TYPE,
                             &physfn->sriov->hdr_type);
        pci_read_config_word(virtfn, PCI_SUBSYSTEM_VENDOR_ID,
                             &physfn->sriov->subsystem_vendor);
        pci_read_config_word(virtfn, PCI_SUBSYSTEM_ID,
                             &physfn->sriov->subsystem_device);
}

int pci_iov_sysfs_link(struct pci_dev *dev,
                struct pci_dev *virtfn, int id)
{
        char buf[VIRTFN_ID_LEN];
        int rc;

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

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

        return 0;

failed1:
        sysfs_remove_link(&dev->dev.kobj, buf);
failed:
        return rc;
}

#ifdef CONFIG_PCI_MSI
static ssize_t sriov_vf_total_msix_show(struct device *dev,
                                        struct device_attribute *attr,
                                        char *buf)
{
        struct pci_dev *pdev = to_pci_dev(dev);
        u32 vf_total_msix = 0;

        device_lock(dev);
        if (!pdev->driver || !pdev->driver->sriov_get_vf_total_msix)
                goto unlock;

        vf_total_msix = pdev->driver->sriov_get_vf_total_msix(pdev);
unlock:
        device_unlock(dev);
        return sysfs_emit(buf, "%u\n", vf_total_msix);
}
static DEVICE_ATTR_RO(sriov_vf_total_msix);

static ssize_t sriov_vf_msix_count_store(struct device *dev,
                                         struct device_attribute *attr,
                                         const char *buf, size_t count)
{
        struct pci_dev *vf_dev = to_pci_dev(dev);
        struct pci_dev *pdev = pci_physfn(vf_dev);
        int val, ret;

        ret = kstrtoint(buf, 0, &val);
        if (ret)
                return ret;

        if (val < 0)
                return -EINVAL;

        device_lock(&pdev->dev);
        if (!pdev->driver || !pdev->driver->sriov_set_msix_vec_count) {
                ret = -EOPNOTSUPP;
                goto err_pdev;
        }

        device_lock(&vf_dev->dev);
        if (vf_dev->driver) {
                /*
                 * A driver is already attached to this VF and has configured
                 * itself based on the current MSI-X vector count. Changing
                 * the vector size could mess up the driver, so block it.
                 */
                ret = -EBUSY;
                goto err_dev;
        }

        ret = pdev->driver->sriov_set_msix_vec_count(vf_dev, val);

err_dev:
        device_unlock(&vf_dev->dev);
err_pdev:
        device_unlock(&pdev->dev);
        return ret ? : count;
}
static DEVICE_ATTR_WO(sriov_vf_msix_count);
#endif

static struct attribute *sriov_vf_dev_attrs[] = {
#ifdef CONFIG_PCI_MSI
        &dev_attr_sriov_vf_msix_count.attr,
#endif
        NULL,
};

static umode_t sriov_vf_attrs_are_visible(struct kobject *kobj,
                                          struct attribute *a, int n)
{
        struct device *dev = kobj_to_dev(kobj);
        struct pci_dev *pdev = to_pci_dev(dev);

        if (!pdev->is_virtfn)
                return 0;

        return a->mode;
}

const struct attribute_group sriov_vf_dev_attr_group = {
        .attrs = sriov_vf_dev_attrs,
        .is_visible = sriov_vf_attrs_are_visible,
};

int pci_iov_add_virtfn(struct pci_dev *dev, int id)
{
        int i;
        int rc = -ENOMEM;
        u64 size;
        struct pci_dev *virtfn;
        struct resource *res;
        struct pci_sriov *iov = dev->sriov;
        struct pci_bus *bus;

        bus = virtfn_add_bus(dev->bus, pci_iov_virtfn_bus(dev, id));
        if (!bus)
                goto failed;

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

        virtfn->devfn = pci_iov_virtfn_devfn(dev, id);
        virtfn->vendor = dev->vendor;
        virtfn->device = iov->vf_device;
        virtfn->is_virtfn = 1;
        virtfn->physfn = pci_dev_get(dev);
        virtfn->no_command_memory = 1;

        if (id == 0)
                pci_read_vf_config_common(virtfn);

        rc = pci_setup_device(virtfn);
        if (rc)
                goto failed1;

        virtfn->dev.parent = dev->dev.parent;
        virtfn->multifunction = 0;

        for (i = 0; i < PCI_SRIOV_NUM_BARS; i++) {
                res = &dev->resource[i + PCI_IOV_RESOURCES];
                if (!res->parent)
                        continue;
                virtfn->resource[i].name = pci_name(virtfn);
                virtfn->resource[i].flags = res->flags;
                size = pci_iov_resource_size(dev, i + PCI_IOV_RESOURCES);
                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);
        }

        pci_device_add(virtfn, virtfn->bus);
        rc = pci_iov_sysfs_link(dev, virtfn, id);
        if (rc)
                goto failed1;

        pci_bus_add_device(virtfn);

        return 0;

failed1:
        pci_stop_and_remove_bus_device(virtfn);
        pci_dev_put(dev);
failed0:
        virtfn_remove_bus(dev->bus, bus);
failed:

        return rc;
}

void pci_iov_remove_virtfn(struct pci_dev *dev, int id)
{
        char buf[VIRTFN_ID_LEN];
        struct pci_dev *virtfn;

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

        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");

        pci_stop_and_remove_bus_device(virtfn);
        virtfn_remove_bus(dev->bus, virtfn->bus);

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

static ssize_t sriov_totalvfs_show(struct device *dev,
                                   struct device_attribute *attr,
                                   char *buf)
{
        struct pci_dev *pdev = to_pci_dev(dev);

        return sysfs_emit(buf, "%u\n", pci_sriov_get_totalvfs(pdev));
}

static ssize_t sriov_numvfs_show(struct device *dev,
                                 struct device_attribute *attr,
                                 char *buf)
{
        struct pci_dev *pdev = to_pci_dev(dev);
        u16 num_vfs;

        /* Serialize vs sriov_numvfs_store() so readers see valid num_VFs */
        device_lock(&pdev->dev);
        num_vfs = pdev->sriov->num_VFs;
        device_unlock(&pdev->dev);

        return sysfs_emit(buf, "%u\n", num_vfs);
}

/*
 * num_vfs > 0; number of VFs to enable
 * num_vfs = 0; disable all VFs
 *
 * Note: SRIOV spec does not allow partial VF
 *       disable, so it's all or none.
 */
static ssize_t sriov_numvfs_store(struct device *dev,
                                  struct device_attribute *attr,
                                  const char *buf, size_t count)
{
        struct pci_dev *pdev = to_pci_dev(dev);
        int ret;
        u16 num_vfs;

        ret = kstrtou16(buf, 0, &num_vfs);
        if (ret < 0)
                return ret;

        if (num_vfs > pci_sriov_get_totalvfs(pdev))
                return -ERANGE;

        device_lock(&pdev->dev);

        if (num_vfs == pdev->sriov->num_VFs)
                goto exit;

        /* is PF driver loaded */
        if (!pdev->driver) {
                pci_info(pdev, "no driver bound to device; cannot configure SR-IOV\n");
                ret = -ENOENT;
                goto exit;
        }

        /* is PF driver loaded w/callback */
        if (!pdev->driver->sriov_configure) {
                pci_info(pdev, "driver does not support SR-IOV configuration via sysfs\n");
                ret = -ENOENT;
                goto exit;
        }

        if (num_vfs == 0) {
                /* disable VFs */
                ret = pdev->driver->sriov_configure(pdev, 0);
                goto exit;
        }

        /* enable VFs */
        if (pdev->sriov->num_VFs) {
                pci_warn(pdev, "%d VFs already enabled. Disable before enabling %d VFs\n",
                         pdev->sriov->num_VFs, num_vfs);
                ret = -EBUSY;
                goto exit;
        }

        ret = pdev->driver->sriov_configure(pdev, num_vfs);
        if (ret < 0)
                goto exit;

        if (ret != num_vfs)
                pci_warn(pdev, "%d VFs requested; only %d enabled\n",
                         num_vfs, ret);

exit:
        device_unlock(&pdev->dev);

        if (ret < 0)
                return ret;

        return count;
}

static ssize_t sriov_offset_show(struct device *dev,
                                 struct device_attribute *attr,
                                 char *buf)
{
        struct pci_dev *pdev = to_pci_dev(dev);

        return sysfs_emit(buf, "%u\n", pdev->sriov->offset);
}

static ssize_t sriov_stride_show(struct device *dev,
                                 struct device_attribute *attr,
                                 char *buf)
{
        struct pci_dev *pdev = to_pci_dev(dev);

        return sysfs_emit(buf, "%u\n", pdev->sriov->stride);
}

static ssize_t sriov_vf_device_show(struct device *dev,
                                    struct device_attribute *attr,
                                    char *buf)
{
        struct pci_dev *pdev = to_pci_dev(dev);

        return sysfs_emit(buf, "%x\n", pdev->sriov->vf_device);
}

static ssize_t sriov_drivers_autoprobe_show(struct device *dev,
                                            struct device_attribute *attr,
                                            char *buf)
{
        struct pci_dev *pdev = to_pci_dev(dev);

        return sysfs_emit(buf, "%u\n", pdev->sriov->drivers_autoprobe);
}

static ssize_t sriov_drivers_autoprobe_store(struct device *dev,
                                             struct device_attribute *attr,
                                             const char *buf, size_t count)
{
        struct pci_dev *pdev = to_pci_dev(dev);
        bool drivers_autoprobe;

        if (kstrtobool(buf, &drivers_autoprobe) < 0)
                return -EINVAL;

        pdev->sriov->drivers_autoprobe = drivers_autoprobe;

        return count;
}

static DEVICE_ATTR_RO(sriov_totalvfs);
static DEVICE_ATTR_RW(sriov_numvfs);
static DEVICE_ATTR_RO(sriov_offset);
static DEVICE_ATTR_RO(sriov_stride);
static DEVICE_ATTR_RO(sriov_vf_device);
static DEVICE_ATTR_RW(sriov_drivers_autoprobe);

static struct attribute *sriov_pf_dev_attrs[] = {
        &dev_attr_sriov_totalvfs.attr,
        &dev_attr_sriov_numvfs.attr,
        &dev_attr_sriov_offset.attr,
        &dev_attr_sriov_stride.attr,
        &dev_attr_sriov_vf_device.attr,
        &dev_attr_sriov_drivers_autoprobe.attr,
#ifdef CONFIG_PCI_MSI
        &dev_attr_sriov_vf_total_msix.attr,
#endif
        NULL,
};

static umode_t sriov_pf_attrs_are_visible(struct kobject *kobj,
                                          struct attribute *a, int n)
{
        struct device *dev = kobj_to_dev(kobj);

        if (!dev_is_pf(dev))
                return 0;

        return a->mode;
}

const struct attribute_group sriov_pf_dev_attr_group = {
        .attrs = sriov_pf_dev_attrs,
        .is_visible = sriov_pf_attrs_are_visible,
};

int __weak pcibios_sriov_enable(struct pci_dev *pdev, u16 num_vfs)
{
        return 0;
}

int __weak pcibios_sriov_disable(struct pci_dev *pdev)
{
        return 0;
}

static int sriov_add_vfs(struct pci_dev *dev, u16 num_vfs)
{
        unsigned int i;
        int rc;

        if (dev->no_vf_scan)
                return 0;

        for (i = 0; i < num_vfs; i++) {
                rc = pci_iov_add_virtfn(dev, i);
                if (rc)
                        goto failed;
        }
        return 0;
failed:
        while (i--)
                pci_iov_remove_virtfn(dev, i);

        return rc;
}

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

        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;

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

        bus = pci_iov_virtfn_bus(dev, nr_virtfn - 1);
        if (bus > dev->bus->busn_res.end) {
                pci_err(dev, "can't enable %d VFs (bus %02x out of range of %pR)\n",
                        nr_virtfn, bus, &dev->bus->busn_res);
                return -ENOMEM;
        }

        if (pci_enable_resources(dev, bars)) {
                pci_err(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;
        }

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

        rc = pcibios_sriov_enable(dev, initial);
        if (rc) {
                pci_err(dev, "failure %d from pcibios_sriov_enable()\n", rc);
                goto err_pcibios;
        }

        pci_iov_set_numvfs(dev, 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);

        rc = sriov_add_vfs(dev, initial);
        if (rc)
                goto err_pcibios;

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

        return 0;

err_pcibios:
        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);

        pcibios_sriov_disable(dev);

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

        pci_iov_set_numvfs(dev, 0);
        return rc;
}

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

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

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

        if (!iov->num_VFs)
                return;

        sriov_del_vfs(dev);
        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);

        pcibios_sriov_disable(dev);

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

        iov->num_VFs = 0;
        pci_iov_set_numvfs(dev, 0);
}

static int sriov_init(struct pci_dev *dev, int pos)
{
        int i, bar64;
        int rc;
        int nres;
        u32 pgsz;
        u16 ctrl, total;
        struct pci_sriov *iov;
        struct resource *res;
        struct pci_dev *pdev;

        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);
        }

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

        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);

        iov = kzalloc(sizeof(*iov), GFP_KERNEL);
        if (!iov)
                return -ENOMEM;

        nres = 0;
        for (i = 0; i < PCI_SRIOV_NUM_BARS; i++) {
                res = &dev->resource[i + PCI_IOV_RESOURCES];
                /*
                 * If it is already FIXED, don't change it, something
                 * (perhaps EA or header fixups) wants it this way.
                 */
                if (res->flags & IORESOURCE_PCI_FIXED)
                        bar64 = (res->flags & IORESOURCE_MEM_64) ? 1 : 0;
                else
                        bar64 = __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;
                }
                iov->barsz[i] = resource_size(res);
                res->end = res->start + resource_size(res) * total - 1;
                pci_info(dev, "VF(n) BAR%d space: %pR (contains BAR%d for %d VFs)\n",
                         i, res, i, total);
                i += bar64;
                nres++;
        }

        iov->pos = pos;
        iov->nres = nres;
        iov->ctrl = ctrl;
        iov->total_VFs = total;
        iov->driver_max_VFs = total;
        pci_read_config_word(dev, pos + PCI_SRIOV_VF_DID, &iov->vf_device);
        iov->pgsz = pgsz;
        iov->self = dev;
        iov->drivers_autoprobe = true;
        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;

        dev->sriov = iov;
        dev->is_physfn = 1;
        rc = compute_max_vf_buses(dev);
        if (rc)
                goto fail_max_buses;

        return 0;

fail_max_buses:
        dev->sriov = NULL;
        dev->is_physfn = 0;
failed:
        for (i = 0; i < PCI_SRIOV_NUM_BARS; i++) {
                res = &dev->resource[i + PCI_IOV_RESOURCES];
                res->flags = 0;
        }

        kfree(iov);
        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);

        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;

        /*
         * Restore PCI_SRIOV_CTRL_ARI before pci_iov_set_numvfs() because
         * it reads offset & stride, which depend on PCI_SRIOV_CTRL_ARI.
         */
        ctrl &= ~PCI_SRIOV_CTRL_ARI;
        ctrl |= iov->ctrl & PCI_SRIOV_CTRL_ARI;
        pci_write_config_word(dev, iov->pos + PCI_SRIOV_CTRL, ctrl);

        for (i = 0; i < PCI_SRIOV_NUM_BARS; i++)
                pci_update_resource(dev, i + PCI_IOV_RESOURCES);

        pci_write_config_dword(dev, iov->pos + PCI_SRIOV_SYS_PGSIZE, iov->pgsz);
        pci_iov_set_numvfs(dev, 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_remove - clean up SR-IOV state after PF driver is detached
 * @dev: the PCI device
 */
void pci_iov_remove(struct pci_dev *dev)
{
        struct pci_sriov *iov = dev->sriov;

        if (!dev->is_physfn)
                return;

        iov->driver_max_VFs = iov->total_VFs;
        if (iov->num_VFs)
                pci_warn(dev, "driver left SR-IOV enabled after remove\n");
}

/**
 * pci_iov_update_resource - update a VF BAR
 * @dev: the PCI device
 * @resno: the resource number
 *
 * Update a VF BAR in the SR-IOV capability of a PF.
 */
void pci_iov_update_resource(struct pci_dev *dev, int resno)
{
        struct pci_sriov *iov = dev->is_physfn ? dev->sriov : NULL;
        struct resource *res = dev->resource + resno;
        int vf_bar = resno - PCI_IOV_RESOURCES;
        struct pci_bus_region region;
        u16 cmd;
        u32 new;
        int reg;

        /*
         * The generic pci_restore_bars() path calls this for all devices,
         * including VFs and non-SR-IOV devices.  If this is not a PF, we
         * have nothing to do.
         */
        if (!iov)
                return;

        pci_read_config_word(dev, iov->pos + PCI_SRIOV_CTRL, &cmd);
        if ((cmd & PCI_SRIOV_CTRL_VFE) && (cmd & PCI_SRIOV_CTRL_MSE)) {
                dev_WARN(&dev->dev, "can't update enabled VF BAR%d %pR\n",
                         vf_bar, res);
                return;
        }

        /*
         * Ignore unimplemented BARs, unused resource slots for 64-bit
         * BARs, and non-movable resources, e.g., those described via
         * Enhanced Allocation.
         */
        if (!res->flags)
                return;

        if (res->flags & IORESOURCE_UNSET)
                return;

        if (res->flags & IORESOURCE_PCI_FIXED)
                return;

        pcibios_resource_to_bus(dev->bus, &region, res);
        new = region.start;
        new |= res->flags & ~PCI_BASE_ADDRESS_MEM_MASK;

        reg = iov->pos + PCI_SRIOV_BAR + 4 * vf_bar;
        pci_write_config_dword(dev, reg, new);
        if (res->flags & IORESOURCE_MEM_64) {
                new = region.start >> 16 >> 16;
                pci_write_config_dword(dev, reg + 4, new);
        }
}

resource_size_t __weak pcibios_iov_resource_alignment(struct pci_dev *dev,
                                                      int resno)
{
        return pci_iov_resource_size(dev, resno);
}

/**
 * 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)
{
        return pcibios_iov_resource_alignment(dev, resno);
}

/**
 * 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_vf_drivers_autoprobe - set PF property drivers_autoprobe for VFs
 * @dev: the PCI device
 * @auto_probe: set VF drivers auto probe flag
 */
void pci_vf_drivers_autoprobe(struct pci_dev *dev, bool auto_probe)
{
        if (dev->is_physfn)
                dev->sriov->drivers_autoprobe = auto_probe;
}

/**
 * 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;
        struct pci_dev *dev;

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

        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
         */
        dev_id = dev->sriov->vf_device;

        /* 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) &&
                        pci_is_dev_assigned(vfdev))
                        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;

        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;

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

/**
 * pci_sriov_configure_simple - helper to configure SR-IOV
 * @dev: the PCI device
 * @nr_virtfn: number of virtual functions to enable, 0 to disable
 *
 * Enable or disable SR-IOV for devices that don't require any PF setup
 * before enabling SR-IOV.  Return value is negative on error, or number of
 * VFs allocated on success.
 */
int pci_sriov_configure_simple(struct pci_dev *dev, int nr_virtfn)
{
        int rc;

        might_sleep();

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

        if (pci_vfs_assigned(dev)) {
                pci_warn(dev, "Cannot modify SR-IOV while VFs are assigned\n");
                return -EPERM;
        }

        if (nr_virtfn == 0) {
                sriov_disable(dev);
                return 0;
        }

        rc = sriov_enable(dev, nr_virtfn);
        if (rc < 0)
                return rc;

        return nr_virtfn;
}
EXPORT_SYMBOL_GPL(pci_sriov_configure_simple);