drivers/xen/pciback/xenbus.c

   1 /*
   2  * PCI Backend Xenbus Setup - handles setup with frontend and xend
   3  *
   4  *   Author: Ryan Wilson <hap9@epoch.ncsc.mil>
   5  */
   6 #include <linux/module.h>
   7 #include <linux/init.h>
   8 #include <linux/list.h>
   9 #include <linux/vmalloc.h>
  10 #include <xen/xenbus.h>
  11 #include <xen/evtchn.h>
  12 #include "pciback.h"
  13
  14 #define INVALID_EVTCHN_IRQ  (-1)
  15
  16 static struct pciback_device *alloc_pdev(struct xenbus_device *xdev)
  17 {
  18         struct pciback_device *pdev;
  19
  20         pdev = kzalloc(sizeof(struct pciback_device), GFP_KERNEL);
  21         if (pdev == NULL)
  22                 goto out;
  23         dev_dbg(&xdev->dev, "allocated pdev @ 0x%p\n", pdev);
  24
  25         pdev->xdev = xdev;
  26         xdev->dev.driver_data = pdev;
  27
  28         spin_lock_init(&pdev->dev_lock);
  29
  30         pdev->sh_area = NULL;
  31         pdev->sh_info = NULL;
  32         pdev->evtchn_irq = INVALID_EVTCHN_IRQ;
  33         pdev->be_watching = 0;
  34
  35         INIT_WORK(&pdev->op_work, pciback_do_op);
  36
  37         if (pciback_init_devices(pdev)) {
  38                 kfree(pdev);
  39                 pdev = NULL;
  40         }
  41       out:
  42         return pdev;
  43 }
  44
  45 static void free_pdev(struct pciback_device *pdev)
  46 {
  47         if (pdev->be_watching)
  48                 unregister_xenbus_watch(&pdev->be_watch);
  49
  50         /* Ensure the guest can't trigger our handler before removing devices */
  51         if (pdev->evtchn_irq != INVALID_EVTCHN_IRQ)
  52                 unbind_from_irqhandler(pdev->evtchn_irq, pdev);
  53
  54         /* If the driver domain started an op, make sure we complete it or
  55          * delete it before releasing the shared memory */
  56         flush_scheduled_work();
  57
  58         if (pdev->sh_info)
  59                 xenbus_unmap_ring_vfree(pdev->xdev, pdev->sh_area);
  60
  61         pciback_release_devices(pdev);
  62
  63         pdev->xdev->dev.driver_data = NULL;
  64         pdev->xdev = NULL;
  65
  66         kfree(pdev);
  67 }
  68
  69 static int pciback_do_attach(struct pciback_device *pdev, int gnt_ref,
  70                              int remote_evtchn)
  71 {
  72         int err = 0;
  73         struct vm_struct *area;
  74
  75         dev_dbg(&pdev->xdev->dev,
  76                 "Attaching to frontend resources - gnt_ref=%d evtchn=%d\n",
  77                 gnt_ref, remote_evtchn);
  78
  79         area = xenbus_map_ring_valloc(pdev->xdev, gnt_ref);
  80         if (IS_ERR(area)) {
  81                 err = PTR_ERR(area);
  82                 goto out;
  83         }
  84         pdev->sh_area = area;
  85         pdev->sh_info = area->addr;
  86
  87         err = bind_interdomain_evtchn_to_irqhandler(
  88                 pdev->xdev->otherend_id, remote_evtchn, pciback_handle_event,
  89                 SA_SAMPLE_RANDOM, "pciback", pdev);
  90         if (err < 0) {
  91                 xenbus_dev_fatal(pdev->xdev, err,
  92                                  "Error binding event channel to IRQ");
  93                 goto out;
  94         }
  95         pdev->evtchn_irq = err;
  96         err = 0;
  97
  98         dev_dbg(&pdev->xdev->dev, "Attached!\n");
  99       out:
 100         return err;
 101 }
 102
 103 static int pciback_attach(struct pciback_device *pdev)
 104 {
 105         int err = 0;
 106         int gnt_ref, remote_evtchn;
 107         char *magic = NULL;
 108
 109         spin_lock(&pdev->dev_lock);
 110
 111         /* Make sure we only do this setup once */
 112         if (xenbus_read_driver_state(pdev->xdev->nodename) !=
 113             XenbusStateInitialised)
 114                 goto out;
 115
 116         /* Wait for frontend to state that it has published the configuration */
 117         if (xenbus_read_driver_state(pdev->xdev->otherend) !=
 118             XenbusStateInitialised)
 119                 goto out;
 120
 121         dev_dbg(&pdev->xdev->dev, "Reading frontend config\n");
 122
 123         err = xenbus_gather(XBT_NIL, pdev->xdev->otherend,
 124                             "pci-op-ref", "%u", &gnt_ref,
 125                             "event-channel", "%u", &remote_evtchn,
 126                             "magic", NULL, &magic, NULL);
 127         if (err) {
 128                 /* If configuration didn't get read correctly, wait longer */
 129                 xenbus_dev_fatal(pdev->xdev, err,
 130                                  "Error reading configuration from frontend");
 131                 goto out;
 132         }
 133
 134         if (magic == NULL || strcmp(magic, XEN_PCI_MAGIC) != 0) {
 135                 xenbus_dev_fatal(pdev->xdev, -EFAULT,
 136                                  "version mismatch (%s/%s) with pcifront - "
 137                                  "halting pciback",
 138                                  magic, XEN_PCI_MAGIC);
 139                 goto out;
 140         }
 141
 142         err = pciback_do_attach(pdev, gnt_ref, remote_evtchn);
 143         if (err)
 144                 goto out;
 145
 146         dev_dbg(&pdev->xdev->dev, "Connecting...\n");
 147
 148         err = xenbus_switch_state(pdev->xdev, XenbusStateConnected);
 149         if (err)
 150                 xenbus_dev_fatal(pdev->xdev, err,
 151                                  "Error switching to connected state!");
 152
 153         dev_dbg(&pdev->xdev->dev, "Connected? %d\n", err);
 154       out:
 155         spin_unlock(&pdev->dev_lock);
 156
 157         if (magic)
 158                 kfree(magic);
 159
 160         return err;
 161 }
 162
 163 static void pciback_frontend_changed(struct xenbus_device *xdev,
 164                                      enum xenbus_state fe_state)
 165 {
 166         struct pciback_device *pdev = xdev->dev.driver_data;
 167
 168         dev_dbg(&xdev->dev, "fe state changed %d\n", fe_state);
 169
 170         switch (fe_state) {
 171         case XenbusStateInitialised:
 172                 pciback_attach(pdev);
 173                 break;
 174
 175         case XenbusStateClosing:
 176                 xenbus_switch_state(xdev, XenbusStateClosing);
 177                 break;
 178
 179         case XenbusStateUnknown:
 180         case XenbusStateClosed:
 181                 dev_dbg(&xdev->dev, "frontend is gone! unregister device\n");
 182                 device_unregister(&xdev->dev);
 183                 break;
 184
 185         default:
 186                 break;
 187         }
 188 }
 189
 190 static int pciback_publish_pci_root(struct pciback_device *pdev,
 191                                     unsigned int domain, unsigned int bus)
 192 {
 193         unsigned int d, b;
 194         int i, root_num, len, err;
 195         char str[64];
 196
 197         dev_dbg(&pdev->xdev->dev, "Publishing pci roots\n");
 198
 199         err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename,
 200                            "root_num", "%d", &root_num);
 201         if (err == 0 || err == -ENOENT)
 202                 root_num = 0;
 203         else if (err < 0)
 204                 goto out;
 205
 206         /* Verify that we haven't already published this pci root */
 207         for (i = 0; i < root_num; i++) {
 208                 len = snprintf(str, sizeof(str), "root-%d", i);
 209                 if (unlikely(len >= (sizeof(str) - 1))) {
 210                         err = -ENOMEM;
 211                         goto out;
 212                 }
 213
 214                 err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename,
 215                                    str, "%x:%x", &d, &b);
 216                 if (err < 0)
 217                         goto out;
 218                 if (err != 2) {
 219                         err = -EINVAL;
 220                         goto out;
 221                 }
 222
 223                 if (d == domain && b == bus) {
 224                         err = 0;
 225                         goto out;
 226                 }
 227         }
 228
 229         len = snprintf(str, sizeof(str), "root-%d", root_num);
 230         if (unlikely(len >= (sizeof(str) - 1))) {
 231                 err = -ENOMEM;
 232                 goto out;
 233         }
 234
 235         dev_dbg(&pdev->xdev->dev, "writing root %d at %04x:%02x\n",
 236                 root_num, domain, bus);
 237
 238         err = xenbus_printf(XBT_NIL, pdev->xdev->nodename, str,
 239                             "%04x:%02x", domain, bus);
 240         if (err)
 241                 goto out;
 242
 243         err = xenbus_printf(XBT_NIL, pdev->xdev->nodename,
 244                             "root_num", "%d", (root_num + 1));
 245
 246       out:
 247         return err;
 248 }
 249
 250 static int pciback_export_device(struct pciback_device *pdev,
 251                                  int domain, int bus, int slot, int func)
 252 {
 253         struct pci_dev *dev;
 254         int err = 0;
 255
 256         dev_dbg(&pdev->xdev->dev, "exporting dom %x bus %x slot %x func %x\n",
 257                 domain, bus, slot, func);
 258
 259         dev = pcistub_get_pci_dev_by_slot(pdev, domain, bus, slot, func);
 260         if (!dev) {
 261                 err = -EINVAL;
 262                 xenbus_dev_fatal(pdev->xdev, err,
 263                                  "Couldn't locate PCI device "
 264                                  "(%04x:%02x:%02x.%01x)! "
 265                                  "perhaps already in-use?",
 266                                  domain, bus, slot, func);
 267                 goto out;
 268         }
 269
 270         err = pciback_add_pci_dev(pdev, dev);
 271         if (err)
 272                 goto out;
 273
 274         /* TODO: It'd be nice to export a bridge and have all of its children
 275          * get exported with it. This may be best done in xend (which will
 276          * have to calculate resource usage anyway) but we probably want to
 277          * put something in here to ensure that if a bridge gets given to a
 278          * driver domain, that all devices under that bridge are not given
 279          * to other driver domains (as he who controls the bridge can disable
 280          * it and stop the other devices from working).
 281          */
 282       out:
 283         return err;
 284 }
 285
 286 static int pciback_setup_backend(struct pciback_device *pdev)
 287 {
 288         /* Get configuration from xend (if available now) */
 289         int domain, bus, slot, func;
 290         int err = 0;
 291         int i, num_devs;
 292         char dev_str[64];
 293
 294         spin_lock(&pdev->dev_lock);
 295
 296         /* It's possible we could get the call to setup twice, so make sure
 297          * we're not already connected.
 298          */
 299         if (xenbus_read_driver_state(pdev->xdev->nodename) !=
 300             XenbusStateInitWait)
 301                 goto out;
 302
 303         dev_dbg(&pdev->xdev->dev, "getting be setup\n");
 304
 305         err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename, "num_devs", "%d",
 306                            &num_devs);
 307         if (err != 1) {
 308                 if (err >= 0)
 309                         err = -EINVAL;
 310                 xenbus_dev_fatal(pdev->xdev, err,
 311                                  "Error reading number of devices");
 312                 goto out;
 313         }
 314
 315         for (i = 0; i < num_devs; i++) {
 316                 int l = snprintf(dev_str, sizeof(dev_str), "dev-%d", i);
 317                 if (unlikely(l >= (sizeof(dev_str) - 1))) {
 318                         err = -ENOMEM;
 319                         xenbus_dev_fatal(pdev->xdev, err,
 320                                          "String overflow while reading "
 321                                          "configuration");
 322                         goto out;
 323                 }
 324
 325                 err = xenbus_scanf(XBT_NIL, pdev->xdev->nodename, dev_str,
 326                                    "%x:%x:%x.%x", &domain, &bus, &slot, &func);
 327                 if (err < 0) {
 328                         xenbus_dev_fatal(pdev->xdev, err,
 329                                          "Error reading device configuration");
 330                         goto out;
 331                 }
 332                 if (err != 4) {
 333                         err = -EINVAL;
 334                         xenbus_dev_fatal(pdev->xdev, err,
 335                                          "Error parsing pci device "
 336                                          "configuration");
 337                         goto out;
 338                 }
 339
 340                 err = pciback_export_device(pdev, domain, bus, slot, func);
 341                 if (err)
 342                         goto out;
 343         }
 344
 345         err = pciback_publish_pci_roots(pdev, pciback_publish_pci_root);
 346         if (err) {
 347                 xenbus_dev_fatal(pdev->xdev, err,
 348                                  "Error while publish PCI root buses "
 349                                  "for frontend");
 350                 goto out;
 351         }
 352
 353         err = xenbus_switch_state(pdev->xdev, XenbusStateInitialised);
 354         if (err)
 355                 xenbus_dev_fatal(pdev->xdev, err,
 356                                  "Error switching to initialised state!");
 357
 358       out:
 359         spin_unlock(&pdev->dev_lock);
 360
 361         if (!err)
 362                 /* see if pcifront is already configured (if not, we'll wait) */
 363                 pciback_attach(pdev);
 364
 365         return err;
 366 }
 367
 368 static void pciback_be_watch(struct xenbus_watch *watch,
 369                              const char **vec, unsigned int len)
 370 {
 371         struct pciback_device *pdev =
 372             container_of(watch, struct pciback_device, be_watch);
 373
 374         switch (xenbus_read_driver_state(pdev->xdev->nodename)) {
 375         case XenbusStateInitWait:
 376                 pciback_setup_backend(pdev);
 377                 break;
 378
 379         default:
 380                 break;
 381         }
 382 }
 383
 384 static int pciback_xenbus_probe(struct xenbus_device *dev,
 385                                 const struct xenbus_device_id *id)
 386 {
 387         int err = 0;
 388         struct pciback_device *pdev = alloc_pdev(dev);
 389
 390         if (pdev == NULL) {
 391                 err = -ENOMEM;
 392                 xenbus_dev_fatal(dev, err,
 393                                  "Error allocating pciback_device struct");
 394                 goto out;
 395         }
 396
 397         /* wait for xend to configure us */
 398         err = xenbus_switch_state(dev, XenbusStateInitWait);
 399         if (err)
 400                 goto out;
 401
 402         /* watch the backend node for backend configuration information */
 403         err = xenbus_watch_path(dev, dev->nodename, &pdev->be_watch,
 404                                 pciback_be_watch);
 405         if (err)
 406                 goto out;
 407         pdev->be_watching = 1;
 408
 409         /* We need to force a call to our callback here in case
 410          * xend already configured us!
 411          */
 412         pciback_be_watch(&pdev->be_watch, NULL, 0);
 413
 414       out:
 415         return err;
 416 }
 417
 418 static int pciback_xenbus_remove(struct xenbus_device *dev)
 419 {
 420         struct pciback_device *pdev = dev->dev.driver_data;
 421
 422         if (pdev != NULL)
 423                 free_pdev(pdev);
 424
 425         return 0;
 426 }
 427
 428 static struct xenbus_device_id xenpci_ids[] = {
 429         {"pci"},
 430         {{0}},
 431 };
 432
 433 static struct xenbus_driver xenbus_pciback_driver = {
 434         .name                   = "pciback",
 435         .owner                  = THIS_MODULE,
 436         .ids                    = xenpci_ids,
 437         .probe                  = pciback_xenbus_probe,
 438         .remove                 = pciback_xenbus_remove,
 439         .otherend_changed       = pciback_frontend_changed,
 440 };
 441
 442 int __init pciback_xenbus_register(void)
 443 {
 444         if (!is_running_on_xen())
 445                 return -ENODEV;
 446
 447         return xenbus_register_backend(&xenbus_pciback_driver);
 448 }
 449
 450 void __exit pciback_xenbus_unregister(void)
 451 {
 452         xenbus_unregister_driver(&xenbus_pciback_driver);
 453 }