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 = PCI_FUNC(dev->devfn);
  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          * that we want to keep virtual functions at func 0 on their own. They
  99          * aren't multi-function devices and hence their presence at func 0
 100          * may cause guests to not scan the other functions.
 101          */
 102         if (!dev->is_virtfn || func) {
 103                 for (slot = 0; slot < PCI_SLOT_MAX; slot++) {
 104                         if (list_empty(&vpci_dev->dev_list[slot]))
 105                                 continue;
 106
 107                         t = list_entry(list_first(&vpci_dev->dev_list[slot]),
 108                                        struct pci_dev_entry, list);
 109                         if (t->dev->is_virtfn && !PCI_FUNC(t->dev->devfn))
 110                                 continue;
 111
 112                         if (match_slot(dev, t->dev)) {
 113                                 dev_info(&dev->dev, "vpci: assign to virtual slot %d func %d\n",
 114                                          slot, func);
 115                                 list_add_tail(&dev_entry->list,
 116                                               &vpci_dev->dev_list[slot]);
 117                                 goto unlock;
 118                         }
 119                 }
 120         }
 121
 122         /* Assign to a new slot on the virtual PCI bus */
 123         for (slot = 0; slot < PCI_SLOT_MAX; slot++) {
 124                 if (list_empty(&vpci_dev->dev_list[slot])) {
 125                         dev_info(&dev->dev, "vpci: assign to virtual slot %d\n",
 126                                  slot);
 127                         list_add_tail(&dev_entry->list,
 128                                       &vpci_dev->dev_list[slot]);
 129                         goto unlock;
 130                 }
 131         }
 132
 133         err = -ENOMEM;
 134         xenbus_dev_fatal(pdev->xdev, err,
 135                          "No more space on root virtual PCI bus");
 136
 137 unlock:
 138         mutex_unlock(&vpci_dev->lock);
 139
 140         /* Publish this device. */
 141         if (!err)
 142                 err = publish_cb(pdev, 0, 0, PCI_DEVFN(slot, func), devid);
 143         else
 144                 kfree(dev_entry);
 145
 146 out:
 147         return err;
 148 }
 149
 150 static void __xen_pcibk_release_pci_dev(struct xen_pcibk_device *pdev,
 151                                         struct pci_dev *dev, bool lock)
 152 {
 153         int slot;
 154         struct vpci_dev_data *vpci_dev = pdev->pci_dev_data;
 155         struct pci_dev *found_dev = NULL;
 156
 157         mutex_lock(&vpci_dev->lock);
 158
 159         for (slot = 0; slot < PCI_SLOT_MAX; slot++) {
 160                 struct pci_dev_entry *e;
 161
 162                 list_for_each_entry(e, &vpci_dev->dev_list[slot], list) {
 163                         if (e->dev == dev) {
 164                                 list_del(&e->list);
 165                                 found_dev = e->dev;
 166                                 kfree(e);
 167                                 goto out;
 168                         }
 169                 }
 170         }
 171
 172 out:
 173         mutex_unlock(&vpci_dev->lock);
 174
 175         if (found_dev) {
 176                 if (lock)
 177                         device_lock(&found_dev->dev);
 178                 pcistub_put_pci_dev(found_dev);
 179                 if (lock)
 180                         device_unlock(&found_dev->dev);
 181         }
 182 }
 183
 184 static int __xen_pcibk_init_devices(struct xen_pcibk_device *pdev)
 185 {
 186         int slot;
 187         struct vpci_dev_data *vpci_dev;
 188
 189         vpci_dev = kmalloc(sizeof(*vpci_dev), GFP_KERNEL);
 190         if (!vpci_dev)
 191                 return -ENOMEM;
 192
 193         mutex_init(&vpci_dev->lock);
 194
 195         for (slot = 0; slot < PCI_SLOT_MAX; slot++)
 196                 INIT_LIST_HEAD(&vpci_dev->dev_list[slot]);
 197
 198         pdev->pci_dev_data = vpci_dev;
 199
 200         return 0;
 201 }
 202
 203 static int __xen_pcibk_publish_pci_roots(struct xen_pcibk_device *pdev,
 204                                          publish_pci_root_cb publish_cb)
 205 {
 206         /* The Virtual PCI bus has only one root */
 207         return publish_cb(pdev, 0, 0);
 208 }
 209
 210 static void __xen_pcibk_release_devices(struct xen_pcibk_device *pdev)
 211 {
 212         int slot;
 213         struct vpci_dev_data *vpci_dev = pdev->pci_dev_data;
 214
 215         for (slot = 0; slot < PCI_SLOT_MAX; slot++) {
 216                 struct pci_dev_entry *e, *tmp;
 217                 list_for_each_entry_safe(e, tmp, &vpci_dev->dev_list[slot],
 218                                          list) {
 219                         struct pci_dev *dev = e->dev;
 220                         list_del(&e->list);
 221                         device_lock(&dev->dev);
 222                         pcistub_put_pci_dev(dev);
 223                         device_unlock(&dev->dev);
 224                         kfree(e);
 225                 }
 226         }
 227
 228         kfree(vpci_dev);
 229         pdev->pci_dev_data = NULL;
 230 }
 231
 232 static int __xen_pcibk_get_pcifront_dev(struct pci_dev *pcidev,
 233                                         struct xen_pcibk_device *pdev,
 234                                         unsigned int *domain, unsigned int *bus,
 235                                         unsigned int *devfn)
 236 {
 237         struct pci_dev_entry *entry;
 238         struct vpci_dev_data *vpci_dev = pdev->pci_dev_data;
 239         int found = 0, slot;
 240
 241         mutex_lock(&vpci_dev->lock);
 242         for (slot = 0; slot < PCI_SLOT_MAX; slot++) {
 243                 list_for_each_entry(entry,
 244                             &vpci_dev->dev_list[slot],
 245                             list) {
 246                         if (entry->dev == pcidev) {
 247                                 found = 1;
 248                                 *domain = 0;
 249                                 *bus = 0;
 250                                 *devfn = PCI_DEVFN(slot,
 251                                          PCI_FUNC(pcidev->devfn));
 252                         }
 253                 }
 254         }
 255         mutex_unlock(&vpci_dev->lock);
 256         return found;
 257 }
 258
 259 const struct xen_pcibk_backend xen_pcibk_vpci_backend = {
 260         .name           = "vpci",
 261         .init           = __xen_pcibk_init_devices,
 262         .free           = __xen_pcibk_release_devices,
 263         .find           = __xen_pcibk_get_pcifront_dev,
 264         .publish        = __xen_pcibk_publish_pci_roots,
 265         .release        = __xen_pcibk_release_pci_dev,
 266         .add            = __xen_pcibk_add_pci_dev,
 267         .get            = __xen_pcibk_get_pci_dev,
 268 };