drivers/xen/xen-pciback/vpci.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * PCI Backend - Provides a Virtual PCI bus (with real devices)
   4  *               to the frontend
   5  *
   6  *   Author: Ryan Wilson <hap9@epoch.ncsc.mil>
   7  */
   8
   9 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  10 #define dev_fmt pr_fmt
  11
  12 #include <linux/list.h>
  13 #include <linux/slab.h>
  14 #include <linux/pci.h>
  15 #include <linux/mutex.h>
  16 #include "pciback.h"
  17
  18 #define PCI_SLOT_MAX 32
  19
  20 struct vpci_dev_data {
  21         /* Access to dev_list must be protected by lock */
  22         struct list_head dev_list[PCI_SLOT_MAX];
  23         struct mutex lock;
  24 };
  25
  26 static inline struct list_head *list_first(struct list_head *head)
  27 {
  28         return head->next;
  29 }
  30
  31 static struct pci_dev *__xen_pcibk_get_pci_dev(struct xen_pcibk_device *pdev,
  32                                                unsigned int domain,
  33                                                unsigned int bus,
  34                                                unsigned int devfn)
  35 {
  36         struct pci_dev_entry *entry;
  37         struct pci_dev *dev = NULL;
  38         struct vpci_dev_data *vpci_dev = pdev->pci_dev_data;
  39
  40         if (domain != 0 || bus != 0)
  41                 return NULL;
  42
  43         if (PCI_SLOT(devfn) < PCI_SLOT_MAX) {
  44                 mutex_lock(&vpci_dev->lock);
  45
  46                 list_for_each_entry(entry,
  47                                     &vpci_dev->dev_list[PCI_SLOT(devfn)],
  48                                     list) {
  49                         if (PCI_FUNC(entry->dev->devfn) == PCI_FUNC(devfn)) {
  50                                 dev = entry->dev;
  51                                 break;
  52                         }
  53                 }
  54
  55                 mutex_unlock(&vpci_dev->lock);
  56         }
  57         return dev;
  58 }
  59
  60 static inline int match_slot(struct pci_dev *l, struct pci_dev *r)
  61 {
  62         if (pci_domain_nr(l->bus) == pci_domain_nr(r->bus)
  63             && l->bus == r->bus && PCI_SLOT(l->devfn) == PCI_SLOT(r->devfn))
  64                 return 1;
  65
  66         return 0;
  67 }
  68
  69 static int __xen_pcibk_add_pci_dev(struct xen_pcibk_device *pdev,
  70                                    struct pci_dev *dev, int devid,
  71                                    publish_pci_dev_cb publish_cb)
  72 {
  73         int err = 0, slot, func = -1;
  74         struct pci_dev_entry *t, *dev_entry;
  75         struct vpci_dev_data *vpci_dev = pdev->pci_dev_data;
  76
  77         if ((dev->class >> 24) == PCI_BASE_CLASS_BRIDGE) {
  78                 err = -EFAULT;
  79                 xenbus_dev_fatal(pdev->xdev, err,
  80                                  "Can't export bridges on the virtual PCI bus");
  81                 goto out;
  82         }
  83
  84         dev_entry = kmalloc(sizeof(*dev_entry), GFP_KERNEL);
  85         if (!dev_entry) {
  86                 err = -ENOMEM;
  87                 xenbus_dev_fatal(pdev->xdev, err,
  88                                  "Error adding entry to virtual PCI bus");
  89                 goto out;
  90         }
  91
  92         dev_entry->dev = dev;
  93
  94         mutex_lock(&vpci_dev->lock);
  95
  96         /*
  97          * Keep multi-function devices together on the virtual PCI bus, except
  98          * virtual functions.
  99          */
 100         if (!dev->is_virtfn) {
 101                 for (slot = 0; slot < PCI_SLOT_MAX; slot++) {
 102                         if (list_empty(&vpci_dev->dev_list[slot]))
 103                                 continue;
 104
 105                         t = list_entry(list_first(&vpci_dev->dev_list[slot]),
 106                                        struct pci_dev_entry, list);
 107
 108                         if (match_slot(dev, t->dev)) {
 109                                 dev_info(&dev->dev, "vpci: assign to virtual slot %d func %d\n",
 110                                          slot, PCI_FUNC(dev->devfn));
 111                                 list_add_tail(&dev_entry->list,
 112                                               &vpci_dev->dev_list[slot]);
 113                                 func = PCI_FUNC(dev->devfn);
 114                                 goto unlock;
 115                         }
 116                 }
 117         }
 118
 119         /* Assign to a new slot on the virtual PCI bus */
 120         for (slot = 0; slot < PCI_SLOT_MAX; slot++) {
 121                 if (list_empty(&vpci_dev->dev_list[slot])) {
 122                         dev_info(&dev->dev, "vpci: assign to virtual slot %d\n",
 123                                  slot);
 124                         list_add_tail(&dev_entry->list,
 125                                       &vpci_dev->dev_list[slot]);
 126                         func = dev->is_virtfn ? 0 : PCI_FUNC(dev->devfn);
 127                         goto unlock;
 128                 }
 129         }
 130
 131         err = -ENOMEM;
 132         xenbus_dev_fatal(pdev->xdev, err,
 133                          "No more space on root virtual PCI bus");
 134
 135 unlock:
 136         mutex_unlock(&vpci_dev->lock);
 137
 138         /* Publish this device. */
 139         if (!err)
 140                 err = publish_cb(pdev, 0, 0, PCI_DEVFN(slot, func), devid);
 141         else
 142                 kfree(dev_entry);
 143
 144 out:
 145         return err;
 146 }
 147
 148 static void __xen_pcibk_release_pci_dev(struct xen_pcibk_device *pdev,
 149                                         struct pci_dev *dev, bool lock)
 150 {
 151         int slot;
 152         struct vpci_dev_data *vpci_dev = pdev->pci_dev_data;
 153         struct pci_dev *found_dev = NULL;
 154
 155         mutex_lock(&vpci_dev->lock);
 156
 157         for (slot = 0; slot < PCI_SLOT_MAX; slot++) {
 158                 struct pci_dev_entry *e;
 159
 160                 list_for_each_entry(e, &vpci_dev->dev_list[slot], list) {
 161                         if (e->dev == dev) {
 162                                 list_del(&e->list);
 163                                 found_dev = e->dev;
 164                                 kfree(e);
 165                                 goto out;
 166                         }
 167                 }
 168         }
 169
 170 out:
 171         mutex_unlock(&vpci_dev->lock);
 172
 173         if (found_dev) {
 174                 if (lock)
 175                         device_lock(&found_dev->dev);
 176                 pcistub_put_pci_dev(found_dev);
 177                 if (lock)
 178                         device_unlock(&found_dev->dev);
 179         }
 180 }
 181
 182 static int __xen_pcibk_init_devices(struct xen_pcibk_device *pdev)
 183 {
 184         int slot;
 185         struct vpci_dev_data *vpci_dev;
 186
 187         vpci_dev = kmalloc(sizeof(*vpci_dev), GFP_KERNEL);
 188         if (!vpci_dev)
 189                 return -ENOMEM;
 190
 191         mutex_init(&vpci_dev->lock);
 192
 193         for (slot = 0; slot < PCI_SLOT_MAX; slot++)
 194                 INIT_LIST_HEAD(&vpci_dev->dev_list[slot]);
 195
 196         pdev->pci_dev_data = vpci_dev;
 197
 198         return 0;
 199 }
 200
 201 static int __xen_pcibk_publish_pci_roots(struct xen_pcibk_device *pdev,
 202                                          publish_pci_root_cb publish_cb)
 203 {
 204         /* The Virtual PCI bus has only one root */
 205         return publish_cb(pdev, 0, 0);
 206 }
 207
 208 static void __xen_pcibk_release_devices(struct xen_pcibk_device *pdev)
 209 {
 210         int slot;
 211         struct vpci_dev_data *vpci_dev = pdev->pci_dev_data;
 212
 213         for (slot = 0; slot < PCI_SLOT_MAX; slot++) {
 214                 struct pci_dev_entry *e, *tmp;
 215                 list_for_each_entry_safe(e, tmp, &vpci_dev->dev_list[slot],
 216                                          list) {
 217                         struct pci_dev *dev = e->dev;
 218                         list_del(&e->list);
 219                         device_lock(&dev->dev);
 220                         pcistub_put_pci_dev(dev);
 221                         device_unlock(&dev->dev);
 222                         kfree(e);
 223                 }
 224         }
 225
 226         kfree(vpci_dev);
 227         pdev->pci_dev_data = NULL;
 228 }
 229
 230 static int __xen_pcibk_get_pcifront_dev(struct pci_dev *pcidev,
 231                                         struct xen_pcibk_device *pdev,
 232                                         unsigned int *domain, unsigned int *bus,
 233                                         unsigned int *devfn)
 234 {
 235         struct pci_dev_entry *entry;
 236         struct pci_dev *dev = NULL;
 237         struct vpci_dev_data *vpci_dev = pdev->pci_dev_data;
 238         int found = 0, slot;
 239
 240         mutex_lock(&vpci_dev->lock);
 241         for (slot = 0; slot < PCI_SLOT_MAX; slot++) {
 242                 list_for_each_entry(entry,
 243                             &vpci_dev->dev_list[slot],
 244                             list) {
 245                         dev = entry->dev;
 246                         if (dev && dev->bus->number == pcidev->bus->number
 247                                 && pci_domain_nr(dev->bus) ==
 248                                         pci_domain_nr(pcidev->bus)
 249                                 && dev->devfn == pcidev->devfn) {
 250                                 found = 1;
 251                                 *domain = 0;
 252                                 *bus = 0;
 253                                 *devfn = PCI_DEVFN(slot,
 254                                          PCI_FUNC(pcidev->devfn));
 255                         }
 256                 }
 257         }
 258         mutex_unlock(&vpci_dev->lock);
 259         return found;
 260 }
 261
 262 const struct xen_pcibk_backend xen_pcibk_vpci_backend = {
 263         .name           = "vpci",
 264         .init           = __xen_pcibk_init_devices,
 265         .free           = __xen_pcibk_release_devices,
 266         .find           = __xen_pcibk_get_pcifront_dev,
 267         .publish        = __xen_pcibk_publish_pci_roots,
 268         .release        = __xen_pcibk_release_pci_dev,
 269         .add            = __xen_pcibk_add_pci_dev,
 270         .get            = __xen_pcibk_get_pci_dev,
 271 };