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 ([email protected])
  10  *      Zhang Yanmin ([email protected])
  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         int rc;
 179
 180         rc = pci_bridge_secondary_bus_reset(dev);
 181         pci_printk(KERN_DEBUG, dev, "downstream link has been reset\n");
 182         return rc ? PCI_ERS_RESULT_DISCONNECT : PCI_ERS_RESULT_RECOVERED;
 183 }
 184
 185 static pci_ers_result_t reset_link(struct pci_dev *dev, u32 service)
 186 {
 187         struct pci_dev *udev;
 188         pci_ers_result_t status;
 189         struct pcie_port_service_driver *driver = NULL;
 190
 191         if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE) {
 192                 /* Reset this port for all subordinates */
 193                 udev = dev;
 194         } else {
 195                 /* Reset the upstream component (likely downstream port) */
 196                 udev = dev->bus->self;
 197         }
 198
 199         /* Use the aer driver of the component firstly */
 200         driver = pcie_port_find_service(udev, service);
 201
 202         if (driver && driver->reset_link) {
 203                 status = driver->reset_link(udev);
 204         } else if (udev->has_secondary_link) {
 205                 status = default_reset_link(udev);
 206         } else {
 207                 pci_printk(KERN_DEBUG, dev, "no link-reset support at upstream device %s\n",
 208                         pci_name(udev));
 209                 return PCI_ERS_RESULT_DISCONNECT;
 210         }
 211
 212         if (status != PCI_ERS_RESULT_RECOVERED) {
 213                 pci_printk(KERN_DEBUG, dev, "link reset at upstream device %s failed\n",
 214                         pci_name(udev));
 215                 return PCI_ERS_RESULT_DISCONNECT;
 216         }
 217
 218         return status;
 219 }
 220
 221 /**
 222  * broadcast_error_message - handle message broadcast to downstream drivers
 223  * @dev: pointer to from where in a hierarchy message is broadcasted down
 224  * @state: error state
 225  * @error_mesg: message to print
 226  * @cb: callback to be broadcasted
 227  *
 228  * Invoked during error recovery process. Once being invoked, the content
 229  * of error severity will be broadcasted to all downstream drivers in a
 230  * hierarchy in question.
 231  */
 232 static pci_ers_result_t broadcast_error_message(struct pci_dev *dev,
 233         enum pci_channel_state state,
 234         char *error_mesg,
 235         int (*cb)(struct pci_dev *, void *))
 236 {
 237         struct aer_broadcast_data result_data;
 238
 239         pci_printk(KERN_DEBUG, dev, "broadcast %s message\n", error_mesg);
 240         result_data.state = state;
 241         if (cb == report_error_detected)
 242                 result_data.result = PCI_ERS_RESULT_CAN_RECOVER;
 243         else
 244                 result_data.result = PCI_ERS_RESULT_RECOVERED;
 245
 246         if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE) {
 247                 /*
 248                  * If the error is reported by a bridge, we think this error
 249                  * is related to the downstream link of the bridge, so we
 250                  * do error recovery on all subordinates of the bridge instead
 251                  * of the bridge and clear the error status of the bridge.
 252                  */
 253                 if (cb == report_error_detected)
 254                         dev->error_state = state;
 255                 pci_walk_bus(dev->subordinate, cb, &result_data);
 256                 if (cb == report_resume) {
 257                         pci_aer_clear_device_status(dev);
 258                         pci_cleanup_aer_uncorrect_error_status(dev);
 259                         dev->error_state = pci_channel_io_normal;
 260                 }
 261         } else {
 262                 /*
 263                  * If the error is reported by an end point, we think this
 264                  * error is related to the upstream link of the end point.
 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         }
 270
 271         return result_data.result;
 272 }
 273
 274 /**
 275  * pcie_do_fatal_recovery - handle fatal error recovery process
 276  * @dev: pointer to a pci_dev data structure of agent detecting an error
 277  *
 278  * Invoked when an error is fatal. Once being invoked, removes the devices
 279  * beneath this AER agent, followed by reset link e.g. secondary bus reset
 280  * followed by re-enumeration of devices.
 281  */
 282 void pcie_do_fatal_recovery(struct pci_dev *dev, u32 service)
 283 {
 284         struct pci_dev *udev;
 285         struct pci_bus *parent;
 286         struct pci_dev *pdev, *temp;
 287         pci_ers_result_t result;
 288
 289         if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE)
 290                 udev = dev;
 291         else
 292                 udev = dev->bus->self;
 293
 294         parent = udev->subordinate;
 295         pci_lock_rescan_remove();
 296         pci_dev_get(dev);
 297         list_for_each_entry_safe_reverse(pdev, temp, &parent->devices,
 298                                          bus_list) {
 299                 pci_dev_get(pdev);
 300                 pci_dev_set_disconnected(pdev, NULL);
 301                 if (pci_has_subordinate(pdev))
 302                         pci_walk_bus(pdev->subordinate,
 303                                      pci_dev_set_disconnected, NULL);
 304                 pci_stop_and_remove_bus_device(pdev);
 305                 pci_dev_put(pdev);
 306         }
 307
 308         result = reset_link(udev, service);
 309
 310         if ((service == PCIE_PORT_SERVICE_AER) &&
 311             (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE)) {
 312                 /*
 313                  * If the error is reported by a bridge, we think this error
 314                  * is related to the downstream link of the bridge, so we
 315                  * do error recovery on all subordinates of the bridge instead
 316                  * of the bridge and clear the error status of the bridge.
 317                  */
 318                 pci_aer_clear_fatal_status(dev);
 319                 pci_aer_clear_device_status(dev);
 320         }
 321
 322         if (result == PCI_ERS_RESULT_RECOVERED) {
 323                 if (pcie_wait_for_link(udev, true))
 324                         pci_rescan_bus(udev->bus);
 325                 pci_info(dev, "Device recovery from fatal error successful\n");
 326         } else {
 327                 pci_uevent_ers(dev, PCI_ERS_RESULT_DISCONNECT);
 328                 pci_info(dev, "Device recovery from fatal error failed\n");
 329         }
 330
 331         pci_dev_put(dev);
 332         pci_unlock_rescan_remove();
 333 }
 334
 335 /**
 336  * pcie_do_nonfatal_recovery - handle nonfatal error recovery process
 337  * @dev: pointer to a pci_dev data structure of agent detecting an error
 338  *
 339  * Invoked when an error is nonfatal/fatal. Once being invoked, broadcast
 340  * error detected message to all downstream drivers within a hierarchy in
 341  * question and return the returned code.
 342  */
 343 void pcie_do_nonfatal_recovery(struct pci_dev *dev)
 344 {
 345         pci_ers_result_t status;
 346         enum pci_channel_state state;
 347
 348         state = pci_channel_io_normal;
 349
 350         status = broadcast_error_message(dev,
 351                         state,
 352                         "error_detected",
 353                         report_error_detected);
 354
 355         if (status == PCI_ERS_RESULT_CAN_RECOVER)
 356                 status = broadcast_error_message(dev,
 357                                 state,
 358                                 "mmio_enabled",
 359                                 report_mmio_enabled);
 360
 361         if (status == PCI_ERS_RESULT_NEED_RESET) {
 362                 /*
 363                  * TODO: Should call platform-specific
 364                  * functions to reset slot before calling
 365                  * drivers' slot_reset callbacks?
 366                  */
 367                 status = broadcast_error_message(dev,
 368                                 state,
 369                                 "slot_reset",
 370                                 report_slot_reset);
 371         }
 372
 373         if (status != PCI_ERS_RESULT_RECOVERED)
 374                 goto failed;
 375
 376         broadcast_error_message(dev,
 377                                 state,
 378                                 "resume",
 379                                 report_resume);
 380
 381         pci_info(dev, "AER: Device recovery successful\n");
 382         return;
 383
 384 failed:
 385         pci_uevent_ers(dev, PCI_ERS_RESULT_DISCONNECT);
 386
 387         /* TODO: Should kernel panic here? */
 388         pci_info(dev, "AER: Device recovery failed\n");
 389 }