drivers/pci/pcie/err.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * This file implements the error recovery as a core part of PCIe error
   4  * reporting. When a PCIe error is delivered, an error message will be
   5  * collected and printed to console, then, an error recovery procedure
   6  * will be executed by following the PCI error recovery rules.
   7  *
   8  * Copyright (C) 2006 Intel Corp.
   9  *      Tom Long Nguyen (tom.l.nguyen@intel.com)
  10  *      Zhang Yanmin (yanmin.zhang@intel.com)
  11  */
  12
  13 #include <linux/pci.h>
  14 #include <linux/module.h>
  15 #include <linux/pci.h>
  16 #include <linux/kernel.h>
  17 #include <linux/errno.h>
  18 #include <linux/aer.h>
  19 #include "portdrv.h"
  20 #include "../pci.h"
  21
  22 struct aer_broadcast_data {
  23         enum pci_channel_state state;
  24         enum pci_ers_result result;
  25 };
  26
  27 static pci_ers_result_t merge_result(enum pci_ers_result orig,
  28                                   enum pci_ers_result new)
  29 {
  30         if (new == PCI_ERS_RESULT_NO_AER_DRIVER)
  31                 return PCI_ERS_RESULT_NO_AER_DRIVER;
  32
  33         if (new == PCI_ERS_RESULT_NONE)
  34                 return orig;
  35
  36         switch (orig) {
  37         case PCI_ERS_RESULT_CAN_RECOVER:
  38         case PCI_ERS_RESULT_RECOVERED:
  39                 orig = new;
  40                 break;
  41         case PCI_ERS_RESULT_DISCONNECT:
  42                 if (new == PCI_ERS_RESULT_NEED_RESET)
  43                         orig = PCI_ERS_RESULT_NEED_RESET;
  44                 break;
  45         default:
  46                 break;
  47         }
  48
  49         return orig;
  50 }
  51
  52 static int report_error_detected(struct pci_dev *dev, void *data)
  53 {
  54         pci_ers_result_t vote;
  55         const struct pci_error_handlers *err_handler;
  56         struct aer_broadcast_data *result_data;
  57
  58         result_data = (struct aer_broadcast_data *) data;
  59
  60         device_lock(&dev->dev);
  61         dev->error_state = result_data->state;
  62
  63         if (!dev->driver ||
  64                 !dev->driver->err_handler ||
  65                 !dev->driver->err_handler->error_detected) {
  66                 if (result_data->state == pci_channel_io_frozen &&
  67                         dev->hdr_type != PCI_HEADER_TYPE_BRIDGE) {
  68                         /*
  69                          * In case of fatal recovery, if one of down-
  70                          * stream device has no driver. We might be
  71                          * unable to recover because a later insmod
  72                          * of a driver for this device is unaware of
  73                          * its hw state.
  74                          */
  75                         pci_printk(KERN_DEBUG, dev, "device has %s\n",
  76                                    dev->driver ?
  77                                    "no AER-aware driver" : "no driver");
  78                 }
  79
  80                 /*
  81                  * If there's any device in the subtree that does not
  82                  * have an error_detected callback, returning
  83                  * PCI_ERS_RESULT_NO_AER_DRIVER prevents calling of
  84                  * the subsequent mmio_enabled/slot_reset/resume
  85                  * callbacks of "any" device in the subtree. All the
  86                  * devices in the subtree are left in the error state
  87                  * without recovery.
  88                  */
  89
  90                 if (dev->hdr_type != PCI_HEADER_TYPE_BRIDGE)
  91                         vote = PCI_ERS_RESULT_NO_AER_DRIVER;
  92                 else
  93                         vote = PCI_ERS_RESULT_NONE;
  94         } else {
  95                 err_handler = dev->driver->err_handler;
  96                 vote = err_handler->error_detected(dev, result_data->state);
  97                 pci_uevent_ers(dev, PCI_ERS_RESULT_NONE);
  98         }
  99
 100         result_data->result = merge_result(result_data->result, vote);
 101         device_unlock(&dev->dev);
 102         return 0;
 103 }
 104
 105 static int report_mmio_enabled(struct pci_dev *dev, void *data)
 106 {
 107         pci_ers_result_t vote;
 108         const struct pci_error_handlers *err_handler;
 109         struct aer_broadcast_data *result_data;
 110
 111         result_data = (struct aer_broadcast_data *) data;
 112
 113         device_lock(&dev->dev);
 114         if (!dev->driver ||
 115                 !dev->driver->err_handler ||
 116                 !dev->driver->err_handler->mmio_enabled)
 117                 goto out;
 118
 119         err_handler = dev->driver->err_handler;
 120         vote = err_handler->mmio_enabled(dev);
 121         result_data->result = merge_result(result_data->result, vote);
 122 out:
 123         device_unlock(&dev->dev);
 124         return 0;
 125 }
 126
 127 static int report_slot_reset(struct pci_dev *dev, void *data)
 128 {
 129         pci_ers_result_t vote;
 130         const struct pci_error_handlers *err_handler;
 131         struct aer_broadcast_data *result_data;
 132
 133         result_data = (struct aer_broadcast_data *) data;
 134
 135         device_lock(&dev->dev);
 136         if (!dev->driver ||
 137                 !dev->driver->err_handler ||
 138                 !dev->driver->err_handler->slot_reset)
 139                 goto out;
 140
 141         err_handler = dev->driver->err_handler;
 142         vote = err_handler->slot_reset(dev);
 143         result_data->result = merge_result(result_data->result, vote);
 144 out:
 145         device_unlock(&dev->dev);
 146         return 0;
 147 }
 148
 149 static int report_resume(struct pci_dev *dev, void *data)
 150 {
 151         const struct pci_error_handlers *err_handler;
 152
 153         device_lock(&dev->dev);
 154         dev->error_state = pci_channel_io_normal;
 155
 156         if (!dev->driver ||
 157                 !dev->driver->err_handler ||
 158                 !dev->driver->err_handler->resume)
 159                 goto out;
 160
 161         err_handler = dev->driver->err_handler;
 162         err_handler->resume(dev);
 163         pci_uevent_ers(dev, PCI_ERS_RESULT_RECOVERED);
 164 out:
 165         device_unlock(&dev->dev);
 166         return 0;
 167 }
 168
 169 /**
 170  * default_reset_link - default reset function
 171  * @dev: pointer to pci_dev data structure
 172  *
 173  * Invoked when performing link reset on a Downstream Port or a
 174  * Root Port with no aer driver.
 175  */
 176 static pci_ers_result_t default_reset_link(struct pci_dev *dev)
 177 {
 178         pci_reset_bridge_secondary_bus(dev);
 179         pci_printk(KERN_DEBUG, dev, "downstream link has been reset\n");
 180         return PCI_ERS_RESULT_RECOVERED;
 181 }
 182
 183 static pci_ers_result_t reset_link(struct pci_dev *dev, u32 service)
 184 {
 185         struct pci_dev *udev;
 186         pci_ers_result_t status;
 187         struct pcie_port_service_driver *driver = NULL;
 188
 189         if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE) {
 190                 /* Reset this port for all subordinates */
 191                 udev = dev;
 192         } else {
 193                 /* Reset the upstream component (likely downstream port) */
 194                 udev = dev->bus->self;
 195         }
 196
 197         /* Use the aer driver of the component firstly */
 198         driver = pcie_port_find_service(udev, service);
 199
 200         if (driver && driver->reset_link) {
 201                 status = driver->reset_link(udev);
 202         } else if (udev->has_secondary_link) {
 203                 status = default_reset_link(udev);
 204         } else {
 205                 pci_printk(KERN_DEBUG, dev, "no link-reset support at upstream device %s\n",
 206                         pci_name(udev));
 207                 return PCI_ERS_RESULT_DISCONNECT;
 208         }
 209
 210         if (status != PCI_ERS_RESULT_RECOVERED) {
 211                 pci_printk(KERN_DEBUG, dev, "link reset at upstream device %s failed\n",
 212                         pci_name(udev));
 213                 return PCI_ERS_RESULT_DISCONNECT;
 214         }
 215
 216         return status;
 217 }
 218
 219 /**
 220  * broadcast_error_message - handle message broadcast to downstream drivers
 221  * @dev: pointer to from where in a hierarchy message is broadcasted down
 222  * @state: error state
 223  * @error_mesg: message to print
 224  * @cb: callback to be broadcasted
 225  *
 226  * Invoked during error recovery process. Once being invoked, the content
 227  * of error severity will be broadcasted to all downstream drivers in a
 228  * hierarchy in question.
 229  */
 230 static pci_ers_result_t broadcast_error_message(struct pci_dev *dev,
 231         enum pci_channel_state state,
 232         char *error_mesg,
 233         int (*cb)(struct pci_dev *, void *))
 234 {
 235         struct aer_broadcast_data result_data;
 236
 237         pci_printk(KERN_DEBUG, dev, "broadcast %s message\n", error_mesg);
 238         result_data.state = state;
 239         if (cb == report_error_detected)
 240                 result_data.result = PCI_ERS_RESULT_CAN_RECOVER;
 241         else
 242                 result_data.result = PCI_ERS_RESULT_RECOVERED;
 243
 244         if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE) {
 245                 /*
 246                  * If the error is reported by a bridge, we think this error
 247                  * is related to the downstream link of the bridge, so we
 248                  * do error recovery on all subordinates of the bridge instead
 249                  * of the bridge and clear the error status of the bridge.
 250                  */
 251                 if (cb == report_error_detected)
 252                         dev->error_state = state;
 253                 pci_walk_bus(dev->subordinate, cb, &result_data);
 254                 if (cb == report_resume) {
 255                         pci_cleanup_aer_uncorrect_error_status(dev);
 256                         dev->error_state = pci_channel_io_normal;
 257                 }
 258         } else {
 259                 /*
 260                  * If the error is reported by an end point, we think this
 261                  * error is related to the upstream link of the end point.
 262                  */
 263                 if (state == pci_channel_io_normal)
 264                         /*
 265                          * the error is non fatal so the bus is ok, just invoke
 266                          * the callback for the function that logged the error.
 267                          */
 268                         cb(dev, &result_data);
 269                 else
 270                         pci_walk_bus(dev->bus, cb, &result_data);
 271         }
 272
 273         return result_data.result;
 274 }
 275
 276 /**
 277  * pcie_do_fatal_recovery - handle fatal error recovery process
 278  * @dev: pointer to a pci_dev data structure of agent detecting an error
 279  *
 280  * Invoked when an error is fatal. Once being invoked, removes the devices
 281  * beneath this AER agent, followed by reset link e.g. secondary bus reset
 282  * followed by re-enumeration of devices.
 283  */
 284 void pcie_do_fatal_recovery(struct pci_dev *dev, u32 service)
 285 {
 286         struct pci_dev *udev;
 287         struct pci_bus *parent;
 288         struct pci_dev *pdev, *temp;
 289         pci_ers_result_t result;
 290
 291         if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE)
 292                 udev = dev;
 293         else
 294                 udev = dev->bus->self;
 295
 296         parent = udev->subordinate;
 297         pci_lock_rescan_remove();
 298         pci_dev_get(dev);
 299         list_for_each_entry_safe_reverse(pdev, temp, &parent->devices,
 300                                          bus_list) {
 301                 pci_dev_get(pdev);
 302                 pci_dev_set_disconnected(pdev, NULL);
 303                 if (pci_has_subordinate(pdev))
 304                         pci_walk_bus(pdev->subordinate,
 305                                      pci_dev_set_disconnected, NULL);
 306                 pci_stop_and_remove_bus_device(pdev);
 307                 pci_dev_put(pdev);
 308         }
 309
 310         result = reset_link(udev, service);
 311
 312         if ((service == PCIE_PORT_SERVICE_AER) &&
 313             (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE)) {
 314                 /*
 315                  * If the error is reported by a bridge, we think this error
 316                  * is related to the downstream link of the bridge, so we
 317                  * do error recovery on all subordinates of the bridge instead
 318                  * of the bridge and clear the error status of the bridge.
 319                  */
 320                 pci_cleanup_aer_uncorrect_error_status(dev);
 321         }
 322
 323         if (result == PCI_ERS_RESULT_RECOVERED) {
 324                 if (pcie_wait_for_link(udev, true))
 325                         pci_rescan_bus(udev->bus);
 326                 pci_info(dev, "Device recovery from fatal error successful\n");
 327         } else {
 328                 pci_uevent_ers(dev, PCI_ERS_RESULT_DISCONNECT);
 329                 pci_info(dev, "Device recovery from fatal error failed\n");
 330         }
 331
 332         pci_dev_put(dev);
 333         pci_unlock_rescan_remove();
 334 }
 335
 336 /**
 337  * pcie_do_nonfatal_recovery - handle nonfatal error recovery process
 338  * @dev: pointer to a pci_dev data structure of agent detecting an error
 339  *
 340  * Invoked when an error is nonfatal/fatal. Once being invoked, broadcast
 341  * error detected message to all downstream drivers within a hierarchy in
 342  * question and return the returned code.
 343  */
 344 void pcie_do_nonfatal_recovery(struct pci_dev *dev)
 345 {
 346         pci_ers_result_t status;
 347         enum pci_channel_state state;
 348
 349         state = pci_channel_io_normal;
 350
 351         status = broadcast_error_message(dev,
 352                         state,
 353                         "error_detected",
 354                         report_error_detected);
 355
 356         if (status == PCI_ERS_RESULT_CAN_RECOVER)
 357                 status = broadcast_error_message(dev,
 358                                 state,
 359                                 "mmio_enabled",
 360                                 report_mmio_enabled);
 361
 362         if (status == PCI_ERS_RESULT_NEED_RESET) {
 363                 /*
 364                  * TODO: Should call platform-specific
 365                  * functions to reset slot before calling
 366                  * drivers' slot_reset callbacks?
 367                  */
 368                 status = broadcast_error_message(dev,
 369                                 state,
 370                                 "slot_reset",
 371                                 report_slot_reset);
 372         }
 373
 374         if (status != PCI_ERS_RESULT_RECOVERED)
 375                 goto failed;
 376
 377         broadcast_error_message(dev,
 378                                 state,
 379                                 "resume",
 380                                 report_resume);
 381
 382         pci_info(dev, "AER: Device recovery successful\n");
 383         return;
 384
 385 failed:
 386         pci_uevent_ers(dev, PCI_ERS_RESULT_DISCONNECT);
 387
 388         /* TODO: Should kernel panic here? */
 389         pci_info(dev, "AER: Device recovery failed\n");
 390 }