vpci.c

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/*
 * PCI Backend - Provides a Virtual PCI bus (with real devices)
 *               to the frontend
 *
 *   Author: Ryan Wilson <[email protected]>
 */

#include <linux/list.h>
#include <linux/slab.h>
#include <linux/pci.h>
#include <linux/mutex.h>
#include "pciback.h"

#define PCI_SLOT_MAX 32

struct vpci_dev_data {
    /* Access to dev_list must be protected by lock */
    struct list_head dev_list[PCI_SLOT_MAX];
    struct mutex lock;
};

static inline struct list_head *list_first(struct list_head *head)
{
    return head->next;
}

static struct pci_dev *__xen_pcibk_get_pci_dev(struct xen_pcibk_device *pdev,
                           unsigned int domain,
                           unsigned int bus,
                           unsigned int devfn)
{
    struct pci_dev_entry *entry;
    struct pci_dev *dev = NULL;
    struct vpci_dev_data *vpci_dev = pdev->pci_dev_data;

    if (domain != 0 || bus != 0)
        return NULL;

    if (PCI_SLOT(devfn) < PCI_SLOT_MAX) {
        mutex_lock(&vpci_dev->lock);

        list_for_each_entry(entry,
                    &vpci_dev->dev_list[PCI_SLOT(devfn)],
                    list) {
            if (PCI_FUNC(entry->dev->devfn) == PCI_FUNC(devfn)) {
                dev = entry->dev;
                break;
            }
        }

        mutex_unlock(&vpci_dev->lock);
    }
    return dev;
}

static inline int match_slot(struct pci_dev *l, struct pci_dev *r)
{
    if (pci_domain_nr(l->bus) == pci_domain_nr(r->bus)
        && l->bus == r->bus && PCI_SLOT(l->devfn) == PCI_SLOT(r->devfn))
        return 1;

    return 0;
}

static int __xen_pcibk_add_pci_dev(struct xen_pcibk_device *pdev,
                   struct pci_dev *dev, int devid,
                   publish_pci_dev_cb publish_cb)
{
    int err = 0, slot, func = -1;
    struct pci_dev_entry *t, *dev_entry;
    struct vpci_dev_data *vpci_dev = pdev->pci_dev_data;

    if ((dev->class >> 24) == PCI_BASE_CLASS_BRIDGE) {
        err = -EFAULT;
        xenbus_dev_fatal(pdev->xdev, err,
                 "Can't export bridges on the virtual PCI bus");
        goto out;
    }

    dev_entry = kmalloc(sizeof(*dev_entry), GFP_KERNEL);
    if (!dev_entry) {
        err = -ENOMEM;
        xenbus_dev_fatal(pdev->xdev, err,
                 "Error adding entry to virtual PCI bus");
        goto out;
    }

    dev_entry->dev = dev;

    mutex_lock(&vpci_dev->lock);

    /*
     * Keep multi-function devices together on the virtual PCI bus, except
     * virtual functions.
     */
    if (!dev->is_virtfn) {
        for (slot = 0; slot < PCI_SLOT_MAX; slot++) {
            if (list_empty(&vpci_dev->dev_list[slot]))
                continue;

            t = list_entry(list_first(&vpci_dev->dev_list[slot]),
                       struct pci_dev_entry, list);

            if (match_slot(dev, t->dev)) {
                pr_info(DRV_NAME ": vpci: %s: "
                    "assign to virtual slot %d func %d\n",
                    pci_name(dev), slot,
                    PCI_FUNC(dev->devfn));
                list_add_tail(&dev_entry->list,
                          &vpci_dev->dev_list[slot]);
                func = PCI_FUNC(dev->devfn);
                goto unlock;
            }
        }
    }

    /* Assign to a new slot on the virtual PCI bus */
    for (slot = 0; slot < PCI_SLOT_MAX; slot++) {
        if (list_empty(&vpci_dev->dev_list[slot])) {
            printk(KERN_INFO DRV_NAME
                   ": vpci: %s: assign to virtual slot %d\n",
                   pci_name(dev), slot);
            list_add_tail(&dev_entry->list,
                      &vpci_dev->dev_list[slot]);
            func = dev->is_virtfn ? 0 : PCI_FUNC(dev->devfn);
            goto unlock;
        }
    }

    err = -ENOMEM;
    xenbus_dev_fatal(pdev->xdev, err,
             "No more space on root virtual PCI bus");

unlock:
    mutex_unlock(&vpci_dev->lock);

    /* Publish this device. */
    if (!err)
        err = publish_cb(pdev, 0, 0, PCI_DEVFN(slot, func), devid);

out:
    return err;
}

static void __xen_pcibk_release_pci_dev(struct xen_pcibk_device *pdev,
                    struct pci_dev *dev)
{
    int slot;
    struct vpci_dev_data *vpci_dev = pdev->pci_dev_data;
    struct pci_dev *found_dev = NULL;

    mutex_lock(&vpci_dev->lock);

    for (slot = 0; slot < PCI_SLOT_MAX; slot++) {
        struct pci_dev_entry *e;

        list_for_each_entry(e, &vpci_dev->dev_list[slot], list) {
            if (e->dev == dev) {
                list_del(&e->list);
                found_dev = e->dev;
                kfree(e);
                goto out;
            }
        }
    }

out:
    mutex_unlock(&vpci_dev->lock);

    if (found_dev)
        pcistub_put_pci_dev(found_dev);
}

static int __xen_pcibk_init_devices(struct xen_pcibk_device *pdev)
{
    int slot;
    struct vpci_dev_data *vpci_dev;

    vpci_dev = kmalloc(sizeof(*vpci_dev), GFP_KERNEL);
    if (!vpci_dev)
        return -ENOMEM;

    mutex_init(&vpci_dev->lock);

    for (slot = 0; slot < PCI_SLOT_MAX; slot++)
        INIT_LIST_HEAD(&vpci_dev->dev_list[slot]);

    pdev->pci_dev_data = vpci_dev;

    return 0;
}

static int __xen_pcibk_publish_pci_roots(struct xen_pcibk_device *pdev,
                     publish_pci_root_cb publish_cb)
{
    /* The Virtual PCI bus has only one root */
    return publish_cb(pdev, 0, 0);
}

static void __xen_pcibk_release_devices(struct xen_pcibk_device *pdev)
{
    int slot;
    struct vpci_dev_data *vpci_dev = pdev->pci_dev_data;

    for (slot = 0; slot < PCI_SLOT_MAX; slot++) {
        struct pci_dev_entry *e, *tmp;
        list_for_each_entry_safe(e, tmp, &vpci_dev->dev_list[slot],
                     list) {
            list_del(&e->list);
            pcistub_put_pci_dev(e->dev);
            kfree(e);
        }
    }

    kfree(vpci_dev);
    pdev->pci_dev_data = NULL;
}

static int __xen_pcibk_get_pcifront_dev(struct pci_dev *pcidev,
                    struct xen_pcibk_device *pdev,
                    unsigned int *domain, unsigned int *bus,
                    unsigned int *devfn)
{
    struct pci_dev_entry *entry;
    struct pci_dev *dev = NULL;
    struct vpci_dev_data *vpci_dev = pdev->pci_dev_data;
    int found = 0, slot;

    mutex_lock(&vpci_dev->lock);
    for (slot = 0; slot < PCI_SLOT_MAX; slot++) {
        list_for_each_entry(entry,
                &vpci_dev->dev_list[slot],
                list) {
            dev = entry->dev;
            if (dev && dev->bus->number == pcidev->bus->number
                && pci_domain_nr(dev->bus) ==
                    pci_domain_nr(pcidev->bus)
                && dev->devfn == pcidev->devfn) {
                found = 1;
                *domain = 0;
                *bus = 0;
                *devfn = PCI_DEVFN(slot,
                     PCI_FUNC(pcidev->devfn));
            }
        }
    }
    mutex_unlock(&vpci_dev->lock);
    return found;
}

const struct xen_pcibk_backend xen_pcibk_vpci_backend = {
    .name       = "vpci",
    .init       = __xen_pcibk_init_devices,
    .free       = __xen_pcibk_release_devices,
    .find       = __xen_pcibk_get_pcifront_dev,
    .publish    = __xen_pcibk_publish_pci_roots,
    .release    = __xen_pcibk_release_pci_dev,
    .add        = __xen_pcibk_add_pci_dev,
    .get        = __xen_pcibk_get_pci_dev,
};