arch/x86/pci/xen.c

   1 /*
   2  * Xen PCI - handle PCI (INTx) and MSI infrastructure calls for PV, HVM and
   3  * initial domain support. We also handle the DSDT _PRT callbacks for GSI's
   4  * used in HVM and initial domain mode (PV does not parse ACPI, so it has no
   5  * concept of GSIs). Under PV we hook under the pnbbios API for IRQs and
   6  * 0xcf8 PCI configuration read/write.
   7  *
   8  *   Author: Ryan Wilson <hap9@epoch.ncsc.mil>
   9  *           Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
  10  *           Stefano Stabellini <stefano.stabellini@eu.citrix.com>
  11  */
  12 #include <linux/module.h>
  13 #include <linux/init.h>
  14 #include <linux/pci.h>
  15 #include <linux/acpi.h>
  16
  17 #include <linux/io.h>
  18 #include <asm/io_apic.h>
  19 #include <asm/pci_x86.h>
  20
  21 #include <asm/xen/hypervisor.h>
  22
  23 #include <xen/features.h>
  24 #include <xen/events.h>
  25 #include <asm/xen/pci.h>
  26 #include <asm/xen/cpuid.h>
  27 #include <asm/apic.h>
  28 #include <asm/i8259.h>
  29
  30 static int xen_pcifront_enable_irq(struct pci_dev *dev)
  31 {
  32         int rc;
  33         int share = 1;
  34         int pirq;
  35         u8 gsi;
  36
  37         rc = pci_read_config_byte(dev, PCI_INTERRUPT_LINE, &gsi);
  38         if (rc < 0) {
  39                 dev_warn(&dev->dev, "Xen PCI: failed to read interrupt line: %d\n",
  40                          rc);
  41                 return rc;
  42         }
  43         /* In PV DomU the Xen PCI backend puts the PIRQ in the interrupt line.*/
  44         pirq = gsi;
  45
  46         if (gsi < nr_legacy_irqs())
  47                 share = 0;
  48
  49         rc = xen_bind_pirq_gsi_to_irq(gsi, pirq, share, "pcifront");
  50         if (rc < 0) {
  51                 dev_warn(&dev->dev, "Xen PCI: failed to bind GSI%d (PIRQ%d) to IRQ: %d\n",
  52                          gsi, pirq, rc);
  53                 return rc;
  54         }
  55
  56         dev->irq = rc;
  57         dev_info(&dev->dev, "Xen PCI mapped GSI%d to IRQ%d\n", gsi, dev->irq);
  58         return 0;
  59 }
  60
  61 #ifdef CONFIG_ACPI
  62 static int xen_register_pirq(u32 gsi, int gsi_override, int triggering,
  63                              bool set_pirq)
  64 {
  65         int rc, pirq = -1, irq = -1;
  66         struct physdev_map_pirq map_irq;
  67         int shareable = 0;
  68         char *name;
  69
  70         irq = xen_irq_from_gsi(gsi);
  71         if (irq > 0)
  72                 return irq;
  73
  74         if (set_pirq)
  75                 pirq = gsi;
  76
  77         map_irq.domid = DOMID_SELF;
  78         map_irq.type = MAP_PIRQ_TYPE_GSI;
  79         map_irq.index = gsi;
  80         map_irq.pirq = pirq;
  81
  82         rc = HYPERVISOR_physdev_op(PHYSDEVOP_map_pirq, &map_irq);
  83         if (rc) {
  84                 printk(KERN_WARNING "xen map irq failed %d\n", rc);
  85                 return -1;
  86         }
  87
  88         if (triggering == ACPI_EDGE_SENSITIVE) {
  89                 shareable = 0;
  90                 name = "ioapic-edge";
  91         } else {
  92                 shareable = 1;
  93                 name = "ioapic-level";
  94         }
  95
  96         if (gsi_override >= 0)
  97                 gsi = gsi_override;
  98
  99         irq = xen_bind_pirq_gsi_to_irq(gsi, map_irq.pirq, shareable, name);
 100         if (irq < 0)
 101                 goto out;
 102
 103         printk(KERN_DEBUG "xen: --> pirq=%d -> irq=%d (gsi=%d)\n", map_irq.pirq, irq, gsi);
 104 out:
 105         return irq;
 106 }
 107
 108 static int acpi_register_gsi_xen_hvm(struct device *dev, u32 gsi,
 109                                      int trigger, int polarity)
 110 {
 111         if (!xen_hvm_domain())
 112                 return -1;
 113
 114         return xen_register_pirq(gsi, -1 /* no GSI override */, trigger,
 115                                  false /* no mapping of GSI to PIRQ */);
 116 }
 117
 118 #ifdef CONFIG_XEN_DOM0
 119 static int xen_register_gsi(u32 gsi, int gsi_override, int triggering, int polarity)
 120 {
 121         int rc, irq;
 122         struct physdev_setup_gsi setup_gsi;
 123
 124         if (!xen_pv_domain())
 125                 return -1;
 126
 127         printk(KERN_DEBUG "xen: registering gsi %u triggering %d polarity %d\n",
 128                         gsi, triggering, polarity);
 129
 130         irq = xen_register_pirq(gsi, gsi_override, triggering, true);
 131
 132         setup_gsi.gsi = gsi;
 133         setup_gsi.triggering = (triggering == ACPI_EDGE_SENSITIVE ? 0 : 1);
 134         setup_gsi.polarity = (polarity == ACPI_ACTIVE_HIGH ? 0 : 1);
 135
 136         rc = HYPERVISOR_physdev_op(PHYSDEVOP_setup_gsi, &setup_gsi);
 137         if (rc == -EEXIST)
 138                 printk(KERN_INFO "Already setup the GSI :%d\n", gsi);
 139         else if (rc) {
 140                 printk(KERN_ERR "Failed to setup GSI :%d, err_code:%d\n",
 141                                 gsi, rc);
 142         }
 143
 144         return irq;
 145 }
 146
 147 static int acpi_register_gsi_xen(struct device *dev, u32 gsi,
 148                                  int trigger, int polarity)
 149 {
 150         return xen_register_gsi(gsi, -1 /* no GSI override */, trigger, polarity);
 151 }
 152 #endif
 153 #endif
 154
 155 #if defined(CONFIG_PCI_MSI)
 156 #include <linux/msi.h>
 157 #include <asm/msidef.h>
 158
 159 struct xen_pci_frontend_ops *xen_pci_frontend;
 160 EXPORT_SYMBOL_GPL(xen_pci_frontend);
 161
 162 static int xen_setup_msi_irqs(struct pci_dev *dev, int nvec, int type)
 163 {
 164         int irq, ret, i;
 165         struct msi_desc *msidesc;
 166         int *v;
 167
 168         if (type == PCI_CAP_ID_MSI && nvec > 1)
 169                 return 1;
 170
 171         v = kzalloc(sizeof(int) * max(1, nvec), GFP_KERNEL);
 172         if (!v)
 173                 return -ENOMEM;
 174
 175         if (type == PCI_CAP_ID_MSIX)
 176                 ret = xen_pci_frontend_enable_msix(dev, v, nvec);
 177         else
 178                 ret = xen_pci_frontend_enable_msi(dev, v);
 179         if (ret)
 180                 goto error;
 181         i = 0;
 182         list_for_each_entry(msidesc, &dev->msi_list, list) {
 183                 irq = xen_bind_pirq_msi_to_irq(dev, msidesc, v[i],
 184                                                (type == PCI_CAP_ID_MSI) ? nvec : 1,
 185                                                (type == PCI_CAP_ID_MSIX) ?
 186                                                "pcifront-msi-x" :
 187                                                "pcifront-msi",
 188                                                 DOMID_SELF);
 189                 if (irq < 0) {
 190                         ret = irq;
 191                         goto free;
 192                 }
 193                 i++;
 194         }
 195         kfree(v);
 196         return 0;
 197
 198 error:
 199         dev_err(&dev->dev, "Xen PCI frontend has not registered MSI/MSI-X support!\n");
 200 free:
 201         kfree(v);
 202         return ret;
 203 }
 204
 205 #define XEN_PIRQ_MSI_DATA  (MSI_DATA_TRIGGER_EDGE | \
 206                 MSI_DATA_LEVEL_ASSERT | (3 << 8) | MSI_DATA_VECTOR(0))
 207
 208 static void xen_msi_compose_msg(struct pci_dev *pdev, unsigned int pirq,
 209                 struct msi_msg *msg)
 210 {
 211         /* We set vector == 0 to tell the hypervisor we don't care about it,
 212          * but we want a pirq setup instead.
 213          * We use the dest_id field to pass the pirq that we want. */
 214         msg->address_hi = MSI_ADDR_BASE_HI | MSI_ADDR_EXT_DEST_ID(pirq);
 215         msg->address_lo =
 216                 MSI_ADDR_BASE_LO |
 217                 MSI_ADDR_DEST_MODE_PHYSICAL |
 218                 MSI_ADDR_REDIRECTION_CPU |
 219                 MSI_ADDR_DEST_ID(pirq);
 220
 221         msg->data = XEN_PIRQ_MSI_DATA;
 222 }
 223
 224 static int xen_hvm_setup_msi_irqs(struct pci_dev *dev, int nvec, int type)
 225 {
 226         int irq, pirq;
 227         struct msi_desc *msidesc;
 228         struct msi_msg msg;
 229
 230         if (type == PCI_CAP_ID_MSI && nvec > 1)
 231                 return 1;
 232
 233         list_for_each_entry(msidesc, &dev->msi_list, list) {
 234                 __pci_read_msi_msg(msidesc, &msg);
 235                 pirq = MSI_ADDR_EXT_DEST_ID(msg.address_hi) |
 236                         ((msg.address_lo >> MSI_ADDR_DEST_ID_SHIFT) & 0xff);
 237                 if (msg.data != XEN_PIRQ_MSI_DATA ||
 238                     xen_irq_from_pirq(pirq) < 0) {
 239                         pirq = xen_allocate_pirq_msi(dev, msidesc);
 240                         if (pirq < 0) {
 241                                 irq = -ENODEV;
 242                                 goto error;
 243                         }
 244                         xen_msi_compose_msg(dev, pirq, &msg);
 245                         __pci_write_msi_msg(msidesc, &msg);
 246                         dev_dbg(&dev->dev, "xen: msi bound to pirq=%d\n", pirq);
 247                 } else {
 248                         dev_dbg(&dev->dev,
 249                                 "xen: msi already bound to pirq=%d\n", pirq);
 250                 }
 251                 irq = xen_bind_pirq_msi_to_irq(dev, msidesc, pirq,
 252                                                (type == PCI_CAP_ID_MSI) ? nvec : 1,
 253                                                (type == PCI_CAP_ID_MSIX) ?
 254                                                "msi-x" : "msi",
 255                                                DOMID_SELF);
 256                 if (irq < 0)
 257                         goto error;
 258                 dev_dbg(&dev->dev,
 259                         "xen: msi --> pirq=%d --> irq=%d\n", pirq, irq);
 260         }
 261         return 0;
 262
 263 error:
 264         dev_err(&dev->dev,
 265                 "Xen PCI frontend has not registered MSI/MSI-X support!\n");
 266         return irq;
 267 }
 268
 269 #ifdef CONFIG_XEN_DOM0
 270 static bool __read_mostly pci_seg_supported = true;
 271
 272 static int xen_initdom_setup_msi_irqs(struct pci_dev *dev, int nvec, int type)
 273 {
 274         int ret = 0;
 275         struct msi_desc *msidesc;
 276
 277         list_for_each_entry(msidesc, &dev->msi_list, list) {
 278                 struct physdev_map_pirq map_irq;
 279                 domid_t domid;
 280
 281                 domid = ret = xen_find_device_domain_owner(dev);
 282                 /* N.B. Casting int's -ENODEV to uint16_t results in 0xFFED,
 283                  * hence check ret value for < 0. */
 284                 if (ret < 0)
 285                         domid = DOMID_SELF;
 286
 287                 memset(&map_irq, 0, sizeof(map_irq));
 288                 map_irq.domid = domid;
 289                 map_irq.type = MAP_PIRQ_TYPE_MSI_SEG;
 290                 map_irq.index = -1;
 291                 map_irq.pirq = -1;
 292                 map_irq.bus = dev->bus->number |
 293                               (pci_domain_nr(dev->bus) << 16);
 294                 map_irq.devfn = dev->devfn;
 295
 296                 if (type == PCI_CAP_ID_MSI && nvec > 1) {
 297                         map_irq.type = MAP_PIRQ_TYPE_MULTI_MSI;
 298                         map_irq.entry_nr = nvec;
 299                 } else if (type == PCI_CAP_ID_MSIX) {
 300                         int pos;
 301                         u32 table_offset, bir;
 302
 303                         pos = dev->msix_cap;
 304                         pci_read_config_dword(dev, pos + PCI_MSIX_TABLE,
 305                                               &table_offset);
 306                         bir = (u8)(table_offset & PCI_MSIX_TABLE_BIR);
 307
 308                         map_irq.table_base = pci_resource_start(dev, bir);
 309                         map_irq.entry_nr = msidesc->msi_attrib.entry_nr;
 310                 }
 311
 312                 ret = -EINVAL;
 313                 if (pci_seg_supported)
 314                         ret = HYPERVISOR_physdev_op(PHYSDEVOP_map_pirq,
 315                                                     &map_irq);
 316                 if (type == PCI_CAP_ID_MSI && nvec > 1 && ret) {
 317                         /*
 318                          * If MAP_PIRQ_TYPE_MULTI_MSI is not available
 319                          * there's nothing else we can do in this case.
 320                          * Just set ret > 0 so driver can retry with
 321                          * single MSI.
 322                          */
 323                         ret = 1;
 324                         goto out;
 325                 }
 326                 if (ret == -EINVAL && !pci_domain_nr(dev->bus)) {
 327                         map_irq.type = MAP_PIRQ_TYPE_MSI;
 328                         map_irq.index = -1;
 329                         map_irq.pirq = -1;
 330                         map_irq.bus = dev->bus->number;
 331                         ret = HYPERVISOR_physdev_op(PHYSDEVOP_map_pirq,
 332                                                     &map_irq);
 333                         if (ret != -EINVAL)
 334                                 pci_seg_supported = false;
 335                 }
 336                 if (ret) {
 337                         dev_warn(&dev->dev, "xen map irq failed %d for %d domain\n",
 338                                  ret, domid);
 339                         goto out;
 340                 }
 341
 342                 ret = xen_bind_pirq_msi_to_irq(dev, msidesc, map_irq.pirq,
 343                                                (type == PCI_CAP_ID_MSI) ? nvec : 1,
 344                                                (type == PCI_CAP_ID_MSIX) ? "msi-x" : "msi",
 345                                                domid);
 346                 if (ret < 0)
 347                         goto out;
 348         }
 349         ret = 0;
 350 out:
 351         return ret;
 352 }
 353
 354 static void xen_initdom_restore_msi_irqs(struct pci_dev *dev)
 355 {
 356         int ret = 0;
 357
 358         if (pci_seg_supported) {
 359                 struct physdev_pci_device restore_ext;
 360
 361                 restore_ext.seg = pci_domain_nr(dev->bus);
 362                 restore_ext.bus = dev->bus->number;
 363                 restore_ext.devfn = dev->devfn;
 364                 ret = HYPERVISOR_physdev_op(PHYSDEVOP_restore_msi_ext,
 365                                         &restore_ext);
 366                 if (ret == -ENOSYS)
 367                         pci_seg_supported = false;
 368                 WARN(ret && ret != -ENOSYS, "restore_msi_ext -> %d\n", ret);
 369         }
 370         if (!pci_seg_supported) {
 371                 struct physdev_restore_msi restore;
 372
 373                 restore.bus = dev->bus->number;
 374                 restore.devfn = dev->devfn;
 375                 ret = HYPERVISOR_physdev_op(PHYSDEVOP_restore_msi, &restore);
 376                 WARN(ret && ret != -ENOSYS, "restore_msi -> %d\n", ret);
 377         }
 378 }
 379 #endif
 380
 381 static void xen_teardown_msi_irqs(struct pci_dev *dev)
 382 {
 383         struct msi_desc *msidesc;
 384
 385         msidesc = list_entry(dev->msi_list.next, struct msi_desc, list);
 386         if (msidesc->msi_attrib.is_msix)
 387                 xen_pci_frontend_disable_msix(dev);
 388         else
 389                 xen_pci_frontend_disable_msi(dev);
 390
 391         /* Free the IRQ's and the msidesc using the generic code. */
 392         default_teardown_msi_irqs(dev);
 393 }
 394
 395 static void xen_teardown_msi_irq(unsigned int irq)
 396 {
 397         xen_destroy_irq(irq);
 398 }
 399
 400 #endif
 401
 402 int __init pci_xen_init(void)
 403 {
 404         if (!xen_pv_domain() || xen_initial_domain())
 405                 return -ENODEV;
 406
 407         printk(KERN_INFO "PCI: setting up Xen PCI frontend stub\n");
 408
 409         pcibios_set_cache_line_size();
 410
 411         pcibios_enable_irq = xen_pcifront_enable_irq;
 412         pcibios_disable_irq = NULL;
 413
 414 #ifdef CONFIG_ACPI
 415         /* Keep ACPI out of the picture */
 416         acpi_noirq = 1;
 417 #endif
 418
 419 #ifdef CONFIG_PCI_MSI
 420         x86_msi.setup_msi_irqs = xen_setup_msi_irqs;
 421         x86_msi.teardown_msi_irq = xen_teardown_msi_irq;
 422         x86_msi.teardown_msi_irqs = xen_teardown_msi_irqs;
 423         pci_msi_ignore_mask = 1;
 424 #endif
 425         return 0;
 426 }
 427
 428 #ifdef CONFIG_PCI_MSI
 429 void __init xen_msi_init(void)
 430 {
 431         if (!disable_apic) {
 432                 /*
 433                  * If hardware supports (x2)APIC virtualization (as indicated
 434                  * by hypervisor's leaf 4) then we don't need to use pirqs/
 435                  * event channels for MSI handling and instead use regular
 436                  * APIC processing
 437                  */
 438                 uint32_t eax = cpuid_eax(xen_cpuid_base() + 4);
 439
 440                 if (((eax & XEN_HVM_CPUID_X2APIC_VIRT) && x2apic_mode) ||
 441                     ((eax & XEN_HVM_CPUID_APIC_ACCESS_VIRT) && cpu_has_apic))
 442                         return;
 443         }
 444
 445         x86_msi.setup_msi_irqs = xen_hvm_setup_msi_irqs;
 446         x86_msi.teardown_msi_irq = xen_teardown_msi_irq;
 447 }
 448 #endif
 449
 450 int __init pci_xen_hvm_init(void)
 451 {
 452         if (!xen_have_vector_callback || !xen_feature(XENFEAT_hvm_pirqs))
 453                 return 0;
 454
 455 #ifdef CONFIG_ACPI
 456         /*
 457          * We don't want to change the actual ACPI delivery model,
 458          * just how GSIs get registered.
 459          */
 460         __acpi_register_gsi = acpi_register_gsi_xen_hvm;
 461 #endif
 462
 463 #ifdef CONFIG_PCI_MSI
 464         /*
 465          * We need to wait until after x2apic is initialized
 466          * before we can set MSI IRQ ops.
 467          */
 468         x86_platform.apic_post_init = xen_msi_init;
 469 #endif
 470         return 0;
 471 }
 472
 473 #ifdef CONFIG_XEN_DOM0
 474 static __init void xen_setup_acpi_sci(void)
 475 {
 476         int rc;
 477         int trigger, polarity;
 478         int gsi = acpi_sci_override_gsi;
 479         int irq = -1;
 480         int gsi_override = -1;
 481
 482         if (!gsi)
 483                 return;
 484
 485         rc = acpi_get_override_irq(gsi, &trigger, &polarity);
 486         if (rc) {
 487                 printk(KERN_WARNING "xen: acpi_get_override_irq failed for acpi"
 488                                 " sci, rc=%d\n", rc);
 489                 return;
 490         }
 491         trigger = trigger ? ACPI_LEVEL_SENSITIVE : ACPI_EDGE_SENSITIVE;
 492         polarity = polarity ? ACPI_ACTIVE_LOW : ACPI_ACTIVE_HIGH;
 493
 494         printk(KERN_INFO "xen: sci override: global_irq=%d trigger=%d "
 495                         "polarity=%d\n", gsi, trigger, polarity);
 496
 497         /* Before we bind the GSI to a Linux IRQ, check whether
 498          * we need to override it with bus_irq (IRQ) value. Usually for
 499          * IRQs below IRQ_LEGACY_IRQ this holds IRQ == GSI, as so:
 500          *  ACPI: INT_SRC_OVR (bus 0 bus_irq 9 global_irq 9 low level)
 501          * but there are oddballs where the IRQ != GSI:
 502          *  ACPI: INT_SRC_OVR (bus 0 bus_irq 9 global_irq 20 low level)
 503          * which ends up being: gsi_to_irq[9] == 20
 504          * (which is what acpi_gsi_to_irq ends up calling when starting the
 505          * the ACPI interpreter and keels over since IRQ 9 has not been
 506          * setup as we had setup IRQ 20 for it).
 507          */
 508         if (acpi_gsi_to_irq(gsi, &irq) == 0) {
 509                 /* Use the provided value if it's valid. */
 510                 if (irq >= 0)
 511                         gsi_override = irq;
 512         }
 513
 514         gsi = xen_register_gsi(gsi, gsi_override, trigger, polarity);
 515         printk(KERN_INFO "xen: acpi sci %d\n", gsi);
 516
 517         return;
 518 }
 519
 520 int __init pci_xen_initial_domain(void)
 521 {
 522         int irq;
 523
 524 #ifdef CONFIG_PCI_MSI
 525         x86_msi.setup_msi_irqs = xen_initdom_setup_msi_irqs;
 526         x86_msi.teardown_msi_irq = xen_teardown_msi_irq;
 527         x86_msi.restore_msi_irqs = xen_initdom_restore_msi_irqs;
 528         pci_msi_ignore_mask = 1;
 529 #endif
 530         xen_setup_acpi_sci();
 531         __acpi_register_gsi = acpi_register_gsi_xen;
 532         /* Pre-allocate legacy irqs */
 533         for (irq = 0; irq < nr_legacy_irqs(); irq++) {
 534                 int trigger, polarity;
 535
 536                 if (acpi_get_override_irq(irq, &trigger, &polarity) == -1)
 537                         continue;
 538
 539                 xen_register_pirq(irq, -1 /* no GSI override */,
 540                         trigger ? ACPI_LEVEL_SENSITIVE : ACPI_EDGE_SENSITIVE,
 541                         true /* Map GSI to PIRQ */);
 542         }
 543         if (0 == nr_ioapics) {
 544                 for (irq = 0; irq < nr_legacy_irqs(); irq++)
 545                         xen_bind_pirq_gsi_to_irq(irq, irq, 0, "xt-pic");
 546         }
 547         return 0;
 548 }
 549
 550 struct xen_device_domain_owner {
 551         domid_t domain;
 552         struct pci_dev *dev;
 553         struct list_head list;
 554 };
 555
 556 static DEFINE_SPINLOCK(dev_domain_list_spinlock);
 557 static struct list_head dev_domain_list = LIST_HEAD_INIT(dev_domain_list);
 558
 559 static struct xen_device_domain_owner *find_device(struct pci_dev *dev)
 560 {
 561         struct xen_device_domain_owner *owner;
 562
 563         list_for_each_entry(owner, &dev_domain_list, list) {
 564                 if (owner->dev == dev)
 565                         return owner;
 566         }
 567         return NULL;
 568 }
 569
 570 int xen_find_device_domain_owner(struct pci_dev *dev)
 571 {
 572         struct xen_device_domain_owner *owner;
 573         int domain = -ENODEV;
 574
 575         spin_lock(&dev_domain_list_spinlock);
 576         owner = find_device(dev);
 577         if (owner)
 578                 domain = owner->domain;
 579         spin_unlock(&dev_domain_list_spinlock);
 580         return domain;
 581 }
 582 EXPORT_SYMBOL_GPL(xen_find_device_domain_owner);
 583
 584 int xen_register_device_domain_owner(struct pci_dev *dev, uint16_t domain)
 585 {
 586         struct xen_device_domain_owner *owner;
 587
 588         owner = kzalloc(sizeof(struct xen_device_domain_owner), GFP_KERNEL);
 589         if (!owner)
 590                 return -ENODEV;
 591
 592         spin_lock(&dev_domain_list_spinlock);
 593         if (find_device(dev)) {
 594                 spin_unlock(&dev_domain_list_spinlock);
 595                 kfree(owner);
 596                 return -EEXIST;
 597         }
 598         owner->domain = domain;
 599         owner->dev = dev;
 600         list_add_tail(&owner->list, &dev_domain_list);
 601         spin_unlock(&dev_domain_list_spinlock);
 602         return 0;
 603 }
 604 EXPORT_SYMBOL_GPL(xen_register_device_domain_owner);
 605
 606 int xen_unregister_device_domain_owner(struct pci_dev *dev)
 607 {
 608         struct xen_device_domain_owner *owner;
 609
 610         spin_lock(&dev_domain_list_spinlock);
 611         owner = find_device(dev);
 612         if (!owner) {
 613                 spin_unlock(&dev_domain_list_spinlock);
 614                 return -ENODEV;
 615         }
 616         list_del(&owner->list);
 617         spin_unlock(&dev_domain_list_spinlock);
 618         kfree(owner);
 619         return 0;
 620 }
 621 EXPORT_SYMBOL_GPL(xen_unregister_device_domain_owner);
 622 #endif