drivers/pci/xen-pcifront.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Xen PCI Frontend
   4  *
   5  * Author: Ryan Wilson <hap9@epoch.ncsc.mil>
   6  */
   7 #include <linux/module.h>
   8 #include <linux/init.h>
   9 #include <linux/mm.h>
  10 #include <xen/xenbus.h>
  11 #include <xen/events.h>
  12 #include <xen/grant_table.h>
  13 #include <xen/page.h>
  14 #include <linux/spinlock.h>
  15 #include <linux/pci.h>
  16 #include <linux/msi.h>
  17 #include <xen/interface/io/pciif.h>
  18 #include <asm/xen/pci.h>
  19 #include <linux/interrupt.h>
  20 #include <linux/atomic.h>
  21 #include <linux/workqueue.h>
  22 #include <linux/bitops.h>
  23 #include <linux/time.h>
  24 #include <linux/ktime.h>
  25 #include <linux/swiotlb.h>
  26 #include <xen/platform_pci.h>
  27
  28 #include <asm/xen/swiotlb-xen.h>
  29
  30 #define INVALID_EVTCHN    (-1)
  31
  32 struct pci_bus_entry {
  33         struct list_head list;
  34         struct pci_bus *bus;
  35 };
  36
  37 #define _PDEVB_op_active                (0)
  38 #define PDEVB_op_active                 (1 << (_PDEVB_op_active))
  39
  40 struct pcifront_device {
  41         struct xenbus_device *xdev;
  42         struct list_head root_buses;
  43
  44         int evtchn;
  45         grant_ref_t gnt_ref;
  46
  47         int irq;
  48
  49         /* Lock this when doing any operations in sh_info */
  50         spinlock_t sh_info_lock;
  51         struct xen_pci_sharedinfo *sh_info;
  52         struct work_struct op_work;
  53         unsigned long flags;
  54
  55 };
  56
  57 struct pcifront_sd {
  58         struct pci_sysdata sd;
  59         struct pcifront_device *pdev;
  60 };
  61
  62 static inline struct pcifront_device *
  63 pcifront_get_pdev(struct pcifront_sd *sd)
  64 {
  65         return sd->pdev;
  66 }
  67
  68 static inline void pcifront_init_sd(struct pcifront_sd *sd,
  69                                     unsigned int domain, unsigned int bus,
  70                                     struct pcifront_device *pdev)
  71 {
  72         /* Because we do not expose that information via XenBus. */
  73         sd->sd.node = first_online_node;
  74         sd->sd.domain = domain;
  75         sd->pdev = pdev;
  76 }
  77
  78 static DEFINE_SPINLOCK(pcifront_dev_lock);
  79 static struct pcifront_device *pcifront_dev;
  80
  81 static int errno_to_pcibios_err(int errno)
  82 {
  83         switch (errno) {
  84         case XEN_PCI_ERR_success:
  85                 return PCIBIOS_SUCCESSFUL;
  86
  87         case XEN_PCI_ERR_dev_not_found:
  88                 return PCIBIOS_DEVICE_NOT_FOUND;
  89
  90         case XEN_PCI_ERR_invalid_offset:
  91         case XEN_PCI_ERR_op_failed:
  92                 return PCIBIOS_BAD_REGISTER_NUMBER;
  93
  94         case XEN_PCI_ERR_not_implemented:
  95                 return PCIBIOS_FUNC_NOT_SUPPORTED;
  96
  97         case XEN_PCI_ERR_access_denied:
  98                 return PCIBIOS_SET_FAILED;
  99         }
 100         return errno;
 101 }
 102
 103 static inline void schedule_pcifront_aer_op(struct pcifront_device *pdev)
 104 {
 105         if (test_bit(_XEN_PCIB_active, (unsigned long *)&pdev->sh_info->flags)
 106                 && !test_and_set_bit(_PDEVB_op_active, &pdev->flags)) {
 107                 dev_dbg(&pdev->xdev->dev, "schedule aer frontend job\n");
 108                 schedule_work(&pdev->op_work);
 109         }
 110 }
 111
 112 static int do_pci_op(struct pcifront_device *pdev, struct xen_pci_op *op)
 113 {
 114         int err = 0;
 115         struct xen_pci_op *active_op = &pdev->sh_info->op;
 116         unsigned long irq_flags;
 117         evtchn_port_t port = pdev->evtchn;
 118         unsigned int irq = pdev->irq;
 119         s64 ns, ns_timeout;
 120
 121         spin_lock_irqsave(&pdev->sh_info_lock, irq_flags);
 122
 123         memcpy(active_op, op, sizeof(struct xen_pci_op));
 124
 125         /* Go */
 126         wmb();
 127         set_bit(_XEN_PCIF_active, (unsigned long *)&pdev->sh_info->flags);
 128         notify_remote_via_evtchn(port);
 129
 130         /*
 131          * We set a poll timeout of 3 seconds but give up on return after
 132          * 2 seconds. It is better to time out too late rather than too early
 133          * (in the latter case we end up continually re-executing poll() with a
 134          * timeout in the past). 1s difference gives plenty of slack for error.
 135          */
 136         ns_timeout = ktime_get_ns() + 2 * (s64)NSEC_PER_SEC;
 137
 138         xen_clear_irq_pending(irq);
 139
 140         while (test_bit(_XEN_PCIF_active,
 141                         (unsigned long *)&pdev->sh_info->flags)) {
 142                 xen_poll_irq_timeout(irq, jiffies + 3*HZ);
 143                 xen_clear_irq_pending(irq);
 144                 ns = ktime_get_ns();
 145                 if (ns > ns_timeout) {
 146                         dev_err(&pdev->xdev->dev,
 147                                 "pciback not responding!!!\n");
 148                         clear_bit(_XEN_PCIF_active,
 149                                   (unsigned long *)&pdev->sh_info->flags);
 150                         err = XEN_PCI_ERR_dev_not_found;
 151                         goto out;
 152                 }
 153         }
 154
 155         /*
 156          * We might lose backend service request since we
 157          * reuse same evtchn with pci_conf backend response. So re-schedule
 158          * aer pcifront service.
 159          */
 160         if (test_bit(_XEN_PCIB_active,
 161                         (unsigned long *)&pdev->sh_info->flags)) {
 162                 dev_err(&pdev->xdev->dev,
 163                         "schedule aer pcifront service\n");
 164                 schedule_pcifront_aer_op(pdev);
 165         }
 166
 167         memcpy(op, active_op, sizeof(struct xen_pci_op));
 168
 169         err = op->err;
 170 out:
 171         spin_unlock_irqrestore(&pdev->sh_info_lock, irq_flags);
 172         return err;
 173 }
 174
 175 /* Access to this function is spinlocked in drivers/pci/access.c */
 176 static int pcifront_bus_read(struct pci_bus *bus, unsigned int devfn,
 177                              int where, int size, u32 *val)
 178 {
 179         int err = 0;
 180         struct xen_pci_op op = {
 181                 .cmd    = XEN_PCI_OP_conf_read,
 182                 .domain = pci_domain_nr(bus),
 183                 .bus    = bus->number,
 184                 .devfn  = devfn,
 185                 .offset = where,
 186                 .size   = size,
 187         };
 188         struct pcifront_sd *sd = bus->sysdata;
 189         struct pcifront_device *pdev = pcifront_get_pdev(sd);
 190
 191         dev_dbg(&pdev->xdev->dev,
 192                 "read dev=%04x:%02x:%02x.%d - offset %x size %d\n",
 193                 pci_domain_nr(bus), bus->number, PCI_SLOT(devfn),
 194                 PCI_FUNC(devfn), where, size);
 195
 196         err = do_pci_op(pdev, &op);
 197
 198         if (likely(!err)) {
 199                 dev_dbg(&pdev->xdev->dev, "read got back value %x\n",
 200                         op.value);
 201
 202                 *val = op.value;
 203         } else if (err == -ENODEV) {
 204                 /* No device here, pretend that it just returned 0 */
 205                 err = 0;
 206                 *val = 0;
 207         }
 208
 209         return errno_to_pcibios_err(err);
 210 }
 211
 212 /* Access to this function is spinlocked in drivers/pci/access.c */
 213 static int pcifront_bus_write(struct pci_bus *bus, unsigned int devfn,
 214                               int where, int size, u32 val)
 215 {
 216         struct xen_pci_op op = {
 217                 .cmd    = XEN_PCI_OP_conf_write,
 218                 .domain = pci_domain_nr(bus),
 219                 .bus    = bus->number,
 220                 .devfn  = devfn,
 221                 .offset = where,
 222                 .size   = size,
 223                 .value  = val,
 224         };
 225         struct pcifront_sd *sd = bus->sysdata;
 226         struct pcifront_device *pdev = pcifront_get_pdev(sd);
 227
 228         dev_dbg(&pdev->xdev->dev,
 229                 "write dev=%04x:%02x:%02x.%d - offset %x size %d val %x\n",
 230                 pci_domain_nr(bus), bus->number,
 231                 PCI_SLOT(devfn), PCI_FUNC(devfn), where, size, val);
 232
 233         return errno_to_pcibios_err(do_pci_op(pdev, &op));
 234 }
 235
 236 static struct pci_ops pcifront_bus_ops = {
 237         .read = pcifront_bus_read,
 238         .write = pcifront_bus_write,
 239 };
 240
 241 #ifdef CONFIG_PCI_MSI
 242 static int pci_frontend_enable_msix(struct pci_dev *dev,
 243                                     int vector[], int nvec)
 244 {
 245         int err;
 246         int i;
 247         struct xen_pci_op op = {
 248                 .cmd    = XEN_PCI_OP_enable_msix,
 249                 .domain = pci_domain_nr(dev->bus),
 250                 .bus = dev->bus->number,
 251                 .devfn = dev->devfn,
 252                 .value = nvec,
 253         };
 254         struct pcifront_sd *sd = dev->bus->sysdata;
 255         struct pcifront_device *pdev = pcifront_get_pdev(sd);
 256         struct msi_desc *entry;
 257
 258         if (nvec > SH_INFO_MAX_VEC) {
 259                 pci_err(dev, "too many vectors (0x%x) for PCI frontend:"
 260                                    " Increase SH_INFO_MAX_VEC\n", nvec);
 261                 return -EINVAL;
 262         }
 263
 264         i = 0;
 265         msi_for_each_desc(entry, &dev->dev, MSI_DESC_NOTASSOCIATED) {
 266                 op.msix_entries[i].entry = entry->msi_index;
 267                 /* Vector is useless at this point. */
 268                 op.msix_entries[i].vector = -1;
 269                 i++;
 270         }
 271
 272         err = do_pci_op(pdev, &op);
 273
 274         if (likely(!err)) {
 275                 if (likely(!op.value)) {
 276                         /* we get the result */
 277                         for (i = 0; i < nvec; i++) {
 278                                 if (op.msix_entries[i].vector <= 0) {
 279                                         pci_warn(dev, "MSI-X entry %d is invalid: %d!\n",
 280                                                 i, op.msix_entries[i].vector);
 281                                         err = -EINVAL;
 282                                         vector[i] = -1;
 283                                         continue;
 284                                 }
 285                                 vector[i] = op.msix_entries[i].vector;
 286                         }
 287                 } else {
 288                         pr_info("enable msix get value %x\n", op.value);
 289                         err = op.value;
 290                 }
 291         } else {
 292                 pci_err(dev, "enable msix get err %x\n", err);
 293         }
 294         return err;
 295 }
 296
 297 static void pci_frontend_disable_msix(struct pci_dev *dev)
 298 {
 299         int err;
 300         struct xen_pci_op op = {
 301                 .cmd    = XEN_PCI_OP_disable_msix,
 302                 .domain = pci_domain_nr(dev->bus),
 303                 .bus = dev->bus->number,
 304                 .devfn = dev->devfn,
 305         };
 306         struct pcifront_sd *sd = dev->bus->sysdata;
 307         struct pcifront_device *pdev = pcifront_get_pdev(sd);
 308
 309         err = do_pci_op(pdev, &op);
 310
 311         /* What should do for error ? */
 312         if (err)
 313                 pci_err(dev, "pci_disable_msix get err %x\n", err);
 314 }
 315
 316 static int pci_frontend_enable_msi(struct pci_dev *dev, int vector[])
 317 {
 318         int err;
 319         struct xen_pci_op op = {
 320                 .cmd    = XEN_PCI_OP_enable_msi,
 321                 .domain = pci_domain_nr(dev->bus),
 322                 .bus = dev->bus->number,
 323                 .devfn = dev->devfn,
 324         };
 325         struct pcifront_sd *sd = dev->bus->sysdata;
 326         struct pcifront_device *pdev = pcifront_get_pdev(sd);
 327
 328         err = do_pci_op(pdev, &op);
 329         if (likely(!err)) {
 330                 vector[0] = op.value;
 331                 if (op.value <= 0) {
 332                         pci_warn(dev, "MSI entry is invalid: %d!\n",
 333                                 op.value);
 334                         err = -EINVAL;
 335                         vector[0] = -1;
 336                 }
 337         } else {
 338                 pci_err(dev, "pci frontend enable msi failed for dev "
 339                                     "%x:%x\n", op.bus, op.devfn);
 340                 err = -EINVAL;
 341         }
 342         return err;
 343 }
 344
 345 static void pci_frontend_disable_msi(struct pci_dev *dev)
 346 {
 347         int err;
 348         struct xen_pci_op op = {
 349                 .cmd    = XEN_PCI_OP_disable_msi,
 350                 .domain = pci_domain_nr(dev->bus),
 351                 .bus = dev->bus->number,
 352                 .devfn = dev->devfn,
 353         };
 354         struct pcifront_sd *sd = dev->bus->sysdata;
 355         struct pcifront_device *pdev = pcifront_get_pdev(sd);
 356
 357         err = do_pci_op(pdev, &op);
 358         if (err == XEN_PCI_ERR_dev_not_found) {
 359                 /* XXX No response from backend, what shall we do? */
 360                 pr_info("get no response from backend for disable MSI\n");
 361                 return;
 362         }
 363         if (err)
 364                 /* how can pciback notify us fail? */
 365                 pr_info("get fake response from backend\n");
 366 }
 367
 368 static struct xen_pci_frontend_ops pci_frontend_ops = {
 369         .enable_msi = pci_frontend_enable_msi,
 370         .disable_msi = pci_frontend_disable_msi,
 371         .enable_msix = pci_frontend_enable_msix,
 372         .disable_msix = pci_frontend_disable_msix,
 373 };
 374
 375 static void pci_frontend_registrar(int enable)
 376 {
 377         if (enable)
 378                 xen_pci_frontend = &pci_frontend_ops;
 379         else
 380                 xen_pci_frontend = NULL;
 381 };
 382 #else
 383 static inline void pci_frontend_registrar(int enable) { };
 384 #endif /* CONFIG_PCI_MSI */
 385
 386 /* Claim resources for the PCI frontend as-is, backend won't allow changes */
 387 static int pcifront_claim_resource(struct pci_dev *dev, void *data)
 388 {
 389         struct pcifront_device *pdev = data;
 390         int i;
 391         struct resource *r;
 392
 393         pci_dev_for_each_resource(dev, r, i) {
 394                 if (!r->parent && r->start && r->flags) {
 395                         dev_info(&pdev->xdev->dev, "claiming resource %s/%d\n",
 396                                 pci_name(dev), i);
 397                         if (pci_claim_resource(dev, i)) {
 398                                 dev_err(&pdev->xdev->dev, "Could not claim resource %s/%d! "
 399                                         "Device offline. Try using e820_host=1 in the guest config.\n",
 400                                         pci_name(dev), i);
 401                         }
 402                 }
 403         }
 404
 405         return 0;
 406 }
 407
 408 static int pcifront_scan_bus(struct pcifront_device *pdev,
 409                                 unsigned int domain, unsigned int bus,
 410                                 struct pci_bus *b)
 411 {
 412         struct pci_dev *d;
 413         unsigned int devfn;
 414
 415         /*
 416          * Scan the bus for functions and add.
 417          * We omit handling of PCI bridge attachment because pciback prevents
 418          * bridges from being exported.
 419          */
 420         for (devfn = 0; devfn < 0x100; devfn++) {
 421                 d = pci_get_slot(b, devfn);
 422                 if (d) {
 423                         /* Device is already known. */
 424                         pci_dev_put(d);
 425                         continue;
 426                 }
 427
 428                 d = pci_scan_single_device(b, devfn);
 429                 if (d)
 430                         dev_info(&pdev->xdev->dev, "New device on "
 431                                  "%04x:%02x:%02x.%d found.\n", domain, bus,
 432                                  PCI_SLOT(devfn), PCI_FUNC(devfn));
 433         }
 434
 435         return 0;
 436 }
 437
 438 static int pcifront_scan_root(struct pcifront_device *pdev,
 439                                  unsigned int domain, unsigned int bus)
 440 {
 441         struct pci_bus *b;
 442         LIST_HEAD(resources);
 443         struct pcifront_sd *sd = NULL;
 444         struct pci_bus_entry *bus_entry = NULL;
 445         int err = 0;
 446         static struct resource busn_res = {
 447                 .start = 0,
 448                 .end = 255,
 449                 .flags = IORESOURCE_BUS,
 450         };
 451
 452 #ifndef CONFIG_PCI_DOMAINS
 453         if (domain != 0) {
 454                 dev_err(&pdev->xdev->dev,
 455                         "PCI Root in non-zero PCI Domain! domain=%d\n", domain);
 456                 dev_err(&pdev->xdev->dev,
 457                         "Please compile with CONFIG_PCI_DOMAINS\n");
 458                 err = -EINVAL;
 459                 goto err_out;
 460         }
 461 #endif
 462
 463         dev_info(&pdev->xdev->dev, "Creating PCI Frontend Bus %04x:%02x\n",
 464                  domain, bus);
 465
 466         bus_entry = kzalloc(sizeof(*bus_entry), GFP_KERNEL);
 467         sd = kzalloc(sizeof(*sd), GFP_KERNEL);
 468         if (!bus_entry || !sd) {
 469                 err = -ENOMEM;
 470                 goto err_out;
 471         }
 472         pci_add_resource(&resources, &ioport_resource);
 473         pci_add_resource(&resources, &iomem_resource);
 474         pci_add_resource(&resources, &busn_res);
 475         pcifront_init_sd(sd, domain, bus, pdev);
 476
 477         pci_lock_rescan_remove();
 478
 479         b = pci_scan_root_bus(&pdev->xdev->dev, bus,
 480                                   &pcifront_bus_ops, sd, &resources);
 481         if (!b) {
 482                 dev_err(&pdev->xdev->dev,
 483                         "Error creating PCI Frontend Bus!\n");
 484                 err = -ENOMEM;
 485                 pci_unlock_rescan_remove();
 486                 pci_free_resource_list(&resources);
 487                 goto err_out;
 488         }
 489
 490         bus_entry->bus = b;
 491
 492         list_add(&bus_entry->list, &pdev->root_buses);
 493
 494         /*
 495          * pci_scan_root_bus skips devices which do not have a
 496          * devfn==0. The pcifront_scan_bus enumerates all devfn.
 497          */
 498         err = pcifront_scan_bus(pdev, domain, bus, b);
 499
 500         /* Claim resources before going "live" with our devices */
 501         pci_walk_bus(b, pcifront_claim_resource, pdev);
 502
 503         /* Create SysFS and notify udev of the devices. Aka: "going live" */
 504         pci_bus_add_devices(b);
 505
 506         pci_unlock_rescan_remove();
 507         return err;
 508
 509 err_out:
 510         kfree(bus_entry);
 511         kfree(sd);
 512
 513         return err;
 514 }
 515
 516 static int pcifront_rescan_root(struct pcifront_device *pdev,
 517                                    unsigned int domain, unsigned int bus)
 518 {
 519         int err;
 520         struct pci_bus *b;
 521
 522         b = pci_find_bus(domain, bus);
 523         if (!b)
 524                 /* If the bus is unknown, create it. */
 525                 return pcifront_scan_root(pdev, domain, bus);
 526
 527         dev_info(&pdev->xdev->dev, "Rescanning PCI Frontend Bus %04x:%02x\n",
 528                  domain, bus);
 529
 530         err = pcifront_scan_bus(pdev, domain, bus, b);
 531
 532         /* Claim resources before going "live" with our devices */
 533         pci_walk_bus(b, pcifront_claim_resource, pdev);
 534
 535         /* Create SysFS and notify udev of the devices. Aka: "going live" */
 536         pci_bus_add_devices(b);
 537
 538         return err;
 539 }
 540
 541 static void free_root_bus_devs(struct pci_bus *bus)
 542 {
 543         struct pci_dev *dev;
 544
 545         while (!list_empty(&bus->devices)) {
 546                 dev = container_of(bus->devices.next, struct pci_dev,
 547                                    bus_list);
 548                 pci_dbg(dev, "removing device\n");
 549                 pci_stop_and_remove_bus_device(dev);
 550         }
 551 }
 552
 553 static void pcifront_free_roots(struct pcifront_device *pdev)
 554 {
 555         struct pci_bus_entry *bus_entry, *t;
 556
 557         dev_dbg(&pdev->xdev->dev, "cleaning up root buses\n");
 558
 559         pci_lock_rescan_remove();
 560         list_for_each_entry_safe(bus_entry, t, &pdev->root_buses, list) {
 561                 list_del(&bus_entry->list);
 562
 563                 free_root_bus_devs(bus_entry->bus);
 564
 565                 kfree(bus_entry->bus->sysdata);
 566
 567                 device_unregister(bus_entry->bus->bridge);
 568                 pci_remove_bus(bus_entry->bus);
 569
 570                 kfree(bus_entry);
 571         }
 572         pci_unlock_rescan_remove();
 573 }
 574
 575 static pci_ers_result_t pcifront_common_process(int cmd,
 576                                                 struct pcifront_device *pdev,
 577                                                 pci_channel_state_t state)
 578 {
 579         struct pci_driver *pdrv;
 580         int bus = pdev->sh_info->aer_op.bus;
 581         int devfn = pdev->sh_info->aer_op.devfn;
 582         int domain = pdev->sh_info->aer_op.domain;
 583         struct pci_dev *pcidev;
 584
 585         dev_dbg(&pdev->xdev->dev,
 586                 "pcifront AER process: cmd %x (bus:%x, devfn%x)",
 587                 cmd, bus, devfn);
 588
 589         pcidev = pci_get_domain_bus_and_slot(domain, bus, devfn);
 590         if (!pcidev || !pcidev->dev.driver) {
 591                 dev_err(&pdev->xdev->dev, "device or AER driver is NULL\n");
 592                 pci_dev_put(pcidev);
 593                 return PCI_ERS_RESULT_NONE;
 594         }
 595         pdrv = to_pci_driver(pcidev->dev.driver);
 596
 597         if (pdrv->err_handler && pdrv->err_handler->error_detected) {
 598                 pci_dbg(pcidev, "trying to call AER service\n");
 599                 switch (cmd) {
 600                 case XEN_PCI_OP_aer_detected:
 601                         return pdrv->err_handler->error_detected(pcidev, state);
 602                 case XEN_PCI_OP_aer_mmio:
 603                         return pdrv->err_handler->mmio_enabled(pcidev);
 604                 case XEN_PCI_OP_aer_slotreset:
 605                         return pdrv->err_handler->slot_reset(pcidev);
 606                 case XEN_PCI_OP_aer_resume:
 607                         pdrv->err_handler->resume(pcidev);
 608                         return PCI_ERS_RESULT_NONE;
 609                 default:
 610                         dev_err(&pdev->xdev->dev,
 611                                 "bad request in aer recovery operation!\n");
 612                 }
 613         }
 614
 615         return PCI_ERS_RESULT_NONE;
 616 }
 617
 618
 619 static void pcifront_do_aer(struct work_struct *data)
 620 {
 621         struct pcifront_device *pdev =
 622                 container_of(data, struct pcifront_device, op_work);
 623         int cmd = pdev->sh_info->aer_op.cmd;
 624         pci_channel_state_t state =
 625                 (pci_channel_state_t)pdev->sh_info->aer_op.err;
 626
 627         /*
 628          * If a pci_conf op is in progress, we have to wait until it is done
 629          * before service aer op
 630          */
 631         dev_dbg(&pdev->xdev->dev,
 632                 "pcifront service aer bus %x devfn %x\n",
 633                 pdev->sh_info->aer_op.bus, pdev->sh_info->aer_op.devfn);
 634
 635         pdev->sh_info->aer_op.err = pcifront_common_process(cmd, pdev, state);
 636
 637         /* Post the operation to the guest. */
 638         wmb();
 639         clear_bit(_XEN_PCIB_active, (unsigned long *)&pdev->sh_info->flags);
 640         notify_remote_via_evtchn(pdev->evtchn);
 641
 642         /*in case of we lost an aer request in four lines time_window*/
 643         smp_mb__before_atomic();
 644         clear_bit(_PDEVB_op_active, &pdev->flags);
 645         smp_mb__after_atomic();
 646
 647         schedule_pcifront_aer_op(pdev);
 648
 649 }
 650
 651 static irqreturn_t pcifront_handler_aer(int irq, void *dev)
 652 {
 653         struct pcifront_device *pdev = dev;
 654
 655         schedule_pcifront_aer_op(pdev);
 656         return IRQ_HANDLED;
 657 }
 658 static int pcifront_connect_and_init_dma(struct pcifront_device *pdev)
 659 {
 660         int err = 0;
 661
 662         spin_lock(&pcifront_dev_lock);
 663
 664         if (!pcifront_dev) {
 665                 dev_info(&pdev->xdev->dev, "Installing PCI frontend\n");
 666                 pcifront_dev = pdev;
 667         } else
 668                 err = -EEXIST;
 669
 670         spin_unlock(&pcifront_dev_lock);
 671
 672         if (!err && !is_swiotlb_active(&pdev->xdev->dev)) {
 673                 err = pci_xen_swiotlb_init_late();
 674                 if (err)
 675                         dev_err(&pdev->xdev->dev, "Could not setup SWIOTLB!\n");
 676         }
 677         return err;
 678 }
 679
 680 static void pcifront_disconnect(struct pcifront_device *pdev)
 681 {
 682         spin_lock(&pcifront_dev_lock);
 683
 684         if (pdev == pcifront_dev) {
 685                 dev_info(&pdev->xdev->dev,
 686                          "Disconnecting PCI Frontend Buses\n");
 687                 pcifront_dev = NULL;
 688         }
 689
 690         spin_unlock(&pcifront_dev_lock);
 691 }
 692 static struct pcifront_device *alloc_pdev(struct xenbus_device *xdev)
 693 {
 694         struct pcifront_device *pdev;
 695
 696         pdev = kzalloc(sizeof(struct pcifront_device), GFP_KERNEL);
 697         if (pdev == NULL)
 698                 goto out;
 699
 700         if (xenbus_setup_ring(xdev, GFP_KERNEL, (void **)&pdev->sh_info, 1,
 701                               &pdev->gnt_ref)) {
 702                 kfree(pdev);
 703                 pdev = NULL;
 704                 goto out;
 705         }
 706         pdev->sh_info->flags = 0;
 707
 708         /*Flag for registering PV AER handler*/
 709         set_bit(_XEN_PCIB_AERHANDLER, (void *)&pdev->sh_info->flags);
 710
 711         dev_set_drvdata(&xdev->dev, pdev);
 712         pdev->xdev = xdev;
 713
 714         INIT_LIST_HEAD(&pdev->root_buses);
 715
 716         spin_lock_init(&pdev->sh_info_lock);
 717
 718         pdev->evtchn = INVALID_EVTCHN;
 719         pdev->irq = -1;
 720
 721         INIT_WORK(&pdev->op_work, pcifront_do_aer);
 722
 723         dev_dbg(&xdev->dev, "Allocated pdev @ 0x%p pdev->sh_info @ 0x%p\n",
 724                 pdev, pdev->sh_info);
 725 out:
 726         return pdev;
 727 }
 728
 729 static void free_pdev(struct pcifront_device *pdev)
 730 {
 731         dev_dbg(&pdev->xdev->dev, "freeing pdev @ 0x%p\n", pdev);
 732
 733         pcifront_free_roots(pdev);
 734
 735         cancel_work_sync(&pdev->op_work);
 736
 737         if (pdev->irq >= 0)
 738                 unbind_from_irqhandler(pdev->irq, pdev);
 739
 740         if (pdev->evtchn != INVALID_EVTCHN)
 741                 xenbus_free_evtchn(pdev->xdev, pdev->evtchn);
 742
 743         xenbus_teardown_ring((void **)&pdev->sh_info, 1, &pdev->gnt_ref);
 744
 745         dev_set_drvdata(&pdev->xdev->dev, NULL);
 746
 747         kfree(pdev);
 748 }
 749
 750 static int pcifront_publish_info(struct pcifront_device *pdev)
 751 {
 752         int err = 0;
 753         struct xenbus_transaction trans;
 754
 755         err = xenbus_alloc_evtchn(pdev->xdev, &pdev->evtchn);
 756         if (err)
 757                 goto out;
 758
 759         err = bind_evtchn_to_irqhandler(pdev->evtchn, pcifront_handler_aer,
 760                 0, "pcifront", pdev);
 761
 762         if (err < 0)
 763                 return err;
 764
 765         pdev->irq = err;
 766
 767 do_publish:
 768         err = xenbus_transaction_start(&trans);
 769         if (err) {
 770                 xenbus_dev_fatal(pdev->xdev, err,
 771                                  "Error writing configuration for backend "
 772                                  "(start transaction)");
 773                 goto out;
 774         }
 775
 776         err = xenbus_printf(trans, pdev->xdev->nodename,
 777                             "pci-op-ref", "%u", pdev->gnt_ref);
 778         if (!err)
 779                 err = xenbus_printf(trans, pdev->xdev->nodename,
 780                                     "event-channel", "%u", pdev->evtchn);
 781         if (!err)
 782                 err = xenbus_printf(trans, pdev->xdev->nodename,
 783                                     "magic", XEN_PCI_MAGIC);
 784
 785         if (err) {
 786                 xenbus_transaction_end(trans, 1);
 787                 xenbus_dev_fatal(pdev->xdev, err,
 788                                  "Error writing configuration for backend");
 789                 goto out;
 790         } else {
 791                 err = xenbus_transaction_end(trans, 0);
 792                 if (err == -EAGAIN)
 793                         goto do_publish;
 794                 else if (err) {
 795                         xenbus_dev_fatal(pdev->xdev, err,
 796                                          "Error completing transaction "
 797                                          "for backend");
 798                         goto out;
 799                 }
 800         }
 801
 802         xenbus_switch_state(pdev->xdev, XenbusStateInitialised);
 803
 804         dev_dbg(&pdev->xdev->dev, "publishing successful!\n");
 805
 806 out:
 807         return err;
 808 }
 809
 810 static void pcifront_connect(struct pcifront_device *pdev)
 811 {
 812         int err;
 813         int i, num_roots, len;
 814         char str[64];
 815         unsigned int domain, bus;
 816
 817         err = xenbus_scanf(XBT_NIL, pdev->xdev->otherend,
 818                            "root_num", "%d", &num_roots);
 819         if (err == -ENOENT) {
 820                 xenbus_dev_error(pdev->xdev, err,
 821                                  "No PCI Roots found, trying 0000:00");
 822                 err = pcifront_rescan_root(pdev, 0, 0);
 823                 if (err) {
 824                         xenbus_dev_fatal(pdev->xdev, err,
 825                                          "Error scanning PCI root 0000:00");
 826                         return;
 827                 }
 828                 num_roots = 0;
 829         } else if (err != 1) {
 830                 xenbus_dev_fatal(pdev->xdev, err >= 0 ? -EINVAL : err,
 831                                  "Error reading number of PCI roots");
 832                 return;
 833         }
 834
 835         for (i = 0; i < num_roots; i++) {
 836                 len = snprintf(str, sizeof(str), "root-%d", i);
 837                 if (unlikely(len >= (sizeof(str) - 1)))
 838                         return;
 839
 840                 err = xenbus_scanf(XBT_NIL, pdev->xdev->otherend, str,
 841                                    "%x:%x", &domain, &bus);
 842                 if (err != 2) {
 843                         xenbus_dev_fatal(pdev->xdev, err >= 0 ? -EINVAL : err,
 844                                          "Error reading PCI root %d", i);
 845                         return;
 846                 }
 847
 848                 err = pcifront_rescan_root(pdev, domain, bus);
 849                 if (err) {
 850                         xenbus_dev_fatal(pdev->xdev, err,
 851                                          "Error scanning PCI root %04x:%02x",
 852                                          domain, bus);
 853                         return;
 854                 }
 855         }
 856
 857         xenbus_switch_state(pdev->xdev, XenbusStateConnected);
 858 }
 859
 860 static void pcifront_try_connect(struct pcifront_device *pdev)
 861 {
 862         int err;
 863
 864         /* Only connect once */
 865         if (xenbus_read_driver_state(pdev->xdev->nodename) !=
 866             XenbusStateInitialised)
 867                 return;
 868
 869         err = pcifront_connect_and_init_dma(pdev);
 870         if (err && err != -EEXIST) {
 871                 xenbus_dev_fatal(pdev->xdev, err,
 872                                  "Error setting up PCI Frontend");
 873                 return;
 874         }
 875
 876         pcifront_connect(pdev);
 877 }
 878
 879 static int pcifront_try_disconnect(struct pcifront_device *pdev)
 880 {
 881         int err = 0;
 882         enum xenbus_state prev_state;
 883
 884
 885         prev_state = xenbus_read_driver_state(pdev->xdev->nodename);
 886
 887         if (prev_state >= XenbusStateClosing)
 888                 goto out;
 889
 890         if (prev_state == XenbusStateConnected) {
 891                 pcifront_free_roots(pdev);
 892                 pcifront_disconnect(pdev);
 893         }
 894
 895         err = xenbus_switch_state(pdev->xdev, XenbusStateClosed);
 896
 897 out:
 898
 899         return err;
 900 }
 901
 902 static void pcifront_attach_devices(struct pcifront_device *pdev)
 903 {
 904         if (xenbus_read_driver_state(pdev->xdev->nodename) ==
 905             XenbusStateReconfiguring)
 906                 pcifront_connect(pdev);
 907 }
 908
 909 static int pcifront_detach_devices(struct pcifront_device *pdev)
 910 {
 911         int err = 0;
 912         int i, num_devs;
 913         enum xenbus_state state;
 914         unsigned int domain, bus, slot, func;
 915         struct pci_dev *pci_dev;
 916         char str[64];
 917
 918         state = xenbus_read_driver_state(pdev->xdev->nodename);
 919         if (state == XenbusStateInitialised) {
 920                 dev_dbg(&pdev->xdev->dev, "Handle skipped connect.\n");
 921                 /* We missed Connected and need to initialize. */
 922                 err = pcifront_connect_and_init_dma(pdev);
 923                 if (err && err != -EEXIST) {
 924                         xenbus_dev_fatal(pdev->xdev, err,
 925                                          "Error setting up PCI Frontend");
 926                         goto out;
 927                 }
 928
 929                 goto out_switch_state;
 930         } else if (state != XenbusStateConnected) {
 931                 goto out;
 932         }
 933
 934         err = xenbus_scanf(XBT_NIL, pdev->xdev->otherend, "num_devs", "%d",
 935                            &num_devs);
 936         if (err != 1) {
 937                 if (err >= 0)
 938                         err = -EINVAL;
 939                 xenbus_dev_fatal(pdev->xdev, err,
 940                                  "Error reading number of PCI devices");
 941                 goto out;
 942         }
 943
 944         /* Find devices being detached and remove them. */
 945         for (i = 0; i < num_devs; i++) {
 946                 int l, state;
 947
 948                 l = snprintf(str, sizeof(str), "state-%d", i);
 949                 if (unlikely(l >= (sizeof(str) - 1))) {
 950                         err = -ENOMEM;
 951                         goto out;
 952                 }
 953                 state = xenbus_read_unsigned(pdev->xdev->otherend, str,
 954                                              XenbusStateUnknown);
 955
 956                 if (state != XenbusStateClosing)
 957                         continue;
 958
 959                 /* Remove device. */
 960                 l = snprintf(str, sizeof(str), "vdev-%d", i);
 961                 if (unlikely(l >= (sizeof(str) - 1))) {
 962                         err = -ENOMEM;
 963                         goto out;
 964                 }
 965                 err = xenbus_scanf(XBT_NIL, pdev->xdev->otherend, str,
 966                                    "%x:%x:%x.%x", &domain, &bus, &slot, &func);
 967                 if (err != 4) {
 968                         if (err >= 0)
 969                                 err = -EINVAL;
 970                         xenbus_dev_fatal(pdev->xdev, err,
 971                                          "Error reading PCI device %d", i);
 972                         goto out;
 973                 }
 974
 975                 pci_dev = pci_get_domain_bus_and_slot(domain, bus,
 976                                 PCI_DEVFN(slot, func));
 977                 if (!pci_dev) {
 978                         dev_dbg(&pdev->xdev->dev,
 979                                 "Cannot get PCI device %04x:%02x:%02x.%d\n",
 980                                 domain, bus, slot, func);
 981                         continue;
 982                 }
 983                 pci_lock_rescan_remove();
 984                 pci_stop_and_remove_bus_device(pci_dev);
 985                 pci_dev_put(pci_dev);
 986                 pci_unlock_rescan_remove();
 987
 988                 dev_dbg(&pdev->xdev->dev,
 989                         "PCI device %04x:%02x:%02x.%d removed.\n",
 990                         domain, bus, slot, func);
 991         }
 992
 993  out_switch_state:
 994         err = xenbus_switch_state(pdev->xdev, XenbusStateReconfiguring);
 995
 996 out:
 997         return err;
 998 }
 999
1000 static void pcifront_backend_changed(struct xenbus_device *xdev,
1001                                                   enum xenbus_state be_state)
1002 {
1003         struct pcifront_device *pdev = dev_get_drvdata(&xdev->dev);
1004
1005         switch (be_state) {
1006         case XenbusStateUnknown:
1007         case XenbusStateInitialising:
1008         case XenbusStateInitWait:
1009         case XenbusStateInitialised:
1010                 break;
1011
1012         case XenbusStateConnected:
1013                 pcifront_try_connect(pdev);
1014                 break;
1015
1016         case XenbusStateClosed:
1017                 if (xdev->state == XenbusStateClosed)
1018                         break;
1019                 fallthrough;    /* Missed the backend's CLOSING state */
1020         case XenbusStateClosing:
1021                 dev_warn(&xdev->dev, "backend going away!\n");
1022                 pcifront_try_disconnect(pdev);
1023                 break;
1024
1025         case XenbusStateReconfiguring:
1026                 pcifront_detach_devices(pdev);
1027                 break;
1028
1029         case XenbusStateReconfigured:
1030                 pcifront_attach_devices(pdev);
1031                 break;
1032         }
1033 }
1034
1035 static int pcifront_xenbus_probe(struct xenbus_device *xdev,
1036                                  const struct xenbus_device_id *id)
1037 {
1038         int err = 0;
1039         struct pcifront_device *pdev = alloc_pdev(xdev);
1040
1041         if (pdev == NULL) {
1042                 err = -ENOMEM;
1043                 xenbus_dev_fatal(xdev, err,
1044                                  "Error allocating pcifront_device struct");
1045                 goto out;
1046         }
1047
1048         err = pcifront_publish_info(pdev);
1049         if (err)
1050                 free_pdev(pdev);
1051
1052 out:
1053         return err;
1054 }
1055
1056 static void pcifront_xenbus_remove(struct xenbus_device *xdev)
1057 {
1058         struct pcifront_device *pdev = dev_get_drvdata(&xdev->dev);
1059
1060         if (pdev)
1061                 free_pdev(pdev);
1062 }
1063
1064 static const struct xenbus_device_id xenpci_ids[] = {
1065         {"pci"},
1066         {""},
1067 };
1068
1069 static struct xenbus_driver xenpci_driver = {
1070         .name                   = "pcifront",
1071         .ids                    = xenpci_ids,
1072         .probe                  = pcifront_xenbus_probe,
1073         .remove                 = pcifront_xenbus_remove,
1074         .otherend_changed       = pcifront_backend_changed,
1075 };
1076
1077 static int __init pcifront_init(void)
1078 {
1079         if (!xen_pv_domain() || xen_initial_domain())
1080                 return -ENODEV;
1081
1082         if (!xen_has_pv_devices())
1083                 return -ENODEV;
1084
1085         pci_frontend_registrar(1 /* enable */);
1086
1087         return xenbus_register_frontend(&xenpci_driver);
1088 }
1089
1090 static void __exit pcifront_cleanup(void)
1091 {
1092         xenbus_unregister_driver(&xenpci_driver);
1093         pci_frontend_registrar(0 /* disable */);
1094 }
1095 module_init(pcifront_init);
1096 module_exit(pcifront_cleanup);
1097
1098 MODULE_DESCRIPTION("Xen PCI passthrough frontend.");
1099 MODULE_LICENSE("GPL");
1100 MODULE_ALIAS("xen:pci");