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