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#define dev_fmt(fmt) "AER: " fmt
 14
 15#include <linux/pci.h>
 16#include <linux/pm_runtime.h>
 17#include <linux/module.h>
 18#include <linux/kernel.h>
 19#include <linux/errno.h>
 20#include <linux/aer.h>
 21#include "portdrv.h"
 22#include "../pci.h"
 23
 24static pci_ers_result_t merge_result(enum pci_ers_result orig,
 25				  enum pci_ers_result new)
 26{
 27	if (new == PCI_ERS_RESULT_NO_AER_DRIVER)
 28		return PCI_ERS_RESULT_NO_AER_DRIVER;
 29
 30	if (new == PCI_ERS_RESULT_NONE)
 31		return orig;
 32
 33	switch (orig) {
 34	case PCI_ERS_RESULT_CAN_RECOVER:
 35	case PCI_ERS_RESULT_RECOVERED:
 36		orig = new;
 37		break;
 38	case PCI_ERS_RESULT_DISCONNECT:
 39		if (new == PCI_ERS_RESULT_NEED_RESET)
 40			orig = PCI_ERS_RESULT_NEED_RESET;
 41		break;
 42	default:
 43		break;
 44	}
 45
 46	return orig;
 47}
 48
 49static int report_error_detected(struct pci_dev *dev,
 50				 pci_channel_state_t state,
 51				 enum pci_ers_result *result)
 52{
 53	struct pci_driver *pdrv;
 54	pci_ers_result_t vote;
 55	const struct pci_error_handlers *err_handler;
 56
 57	device_lock(&dev->dev);
 58	pdrv = dev->driver;
 59	if (pci_dev_is_disconnected(dev)) {
 60		vote = PCI_ERS_RESULT_DISCONNECT;
 61	} else if (!pci_dev_set_io_state(dev, state)) {
 62		pci_info(dev, "can't recover (state transition %u -> %u invalid)\n",
 63			dev->error_state, state);
 64		vote = PCI_ERS_RESULT_NONE;
 65	} else if (!pdrv || !pdrv->err_handler ||
 66		   !pdrv->err_handler->error_detected) {
 67		/*
 68		 * If any device in the subtree does not have an error_detected
 69		 * callback, PCI_ERS_RESULT_NO_AER_DRIVER prevents subsequent
 70		 * error callbacks of "any" device in the subtree, and will
 71		 * exit in the disconnected error state.
 72		 */
 73		if (dev->hdr_type != PCI_HEADER_TYPE_BRIDGE) {
 74			vote = PCI_ERS_RESULT_NO_AER_DRIVER;
 75			pci_info(dev, "can't recover (no error_detected callback)\n");
 76		} else {
 77			vote = PCI_ERS_RESULT_NONE;
 78		}
 79	} else {
 80		err_handler = pdrv->err_handler;
 81		vote = err_handler->error_detected(dev, state);
 82	}
 83	pci_uevent_ers(dev, vote);
 84	*result = merge_result(*result, vote);
 85	device_unlock(&dev->dev);
 86	return 0;
 87}
 88
 89static int pci_pm_runtime_get_sync(struct pci_dev *pdev, void *data)
 90{
 91	pm_runtime_get_sync(&pdev->dev);
 92	return 0;
 93}
 94
 95static int pci_pm_runtime_put(struct pci_dev *pdev, void *data)
 96{
 97	pm_runtime_put(&pdev->dev);
 98	return 0;
 99}
100
101static int report_frozen_detected(struct pci_dev *dev, void *data)
102{
103	return report_error_detected(dev, pci_channel_io_frozen, data);
104}
105
106static int report_normal_detected(struct pci_dev *dev, void *data)
107{
108	return report_error_detected(dev, pci_channel_io_normal, data);
109}
110
111static int report_mmio_enabled(struct pci_dev *dev, void *data)
112{
113	struct pci_driver *pdrv;
114	pci_ers_result_t vote, *result = data;
115	const struct pci_error_handlers *err_handler;
116
117	device_lock(&dev->dev);
118	pdrv = dev->driver;
119	if (!pdrv || !pdrv->err_handler || !pdrv->err_handler->mmio_enabled)
120		goto out;
121
122	err_handler = pdrv->err_handler;
123	vote = err_handler->mmio_enabled(dev);
124	*result = merge_result(*result, vote);
125out:
126	device_unlock(&dev->dev);
127	return 0;
128}
129
130static int report_slot_reset(struct pci_dev *dev, void *data)
131{
132	struct pci_driver *pdrv;
133	pci_ers_result_t vote, *result = data;
134	const struct pci_error_handlers *err_handler;
135
136	device_lock(&dev->dev);
137	pdrv = dev->driver;
138	if (!pdrv || !pdrv->err_handler || !pdrv->err_handler->slot_reset)
139		goto out;
140
141	err_handler = pdrv->err_handler;
142	vote = err_handler->slot_reset(dev);
143	*result = merge_result(*result, vote);
144out:
145	device_unlock(&dev->dev);
146	return 0;
147}
148
149static int report_resume(struct pci_dev *dev, void *data)
150{
151	struct pci_driver *pdrv;
152	const struct pci_error_handlers *err_handler;
153
154	device_lock(&dev->dev);
155	pdrv = dev->driver;
156	if (!pci_dev_set_io_state(dev, pci_channel_io_normal) ||
157	    !pdrv || !pdrv->err_handler || !pdrv->err_handler->resume)
158		goto out;
159
160	err_handler = pdrv->err_handler;
161	err_handler->resume(dev);
162out:
163	pci_uevent_ers(dev, PCI_ERS_RESULT_RECOVERED);
164	device_unlock(&dev->dev);
165	return 0;
166}
167
168/**
169 * pci_walk_bridge - walk bridges potentially AER affected
170 * @bridge:	bridge which may be a Port, an RCEC, or an RCiEP
171 * @cb:		callback to be called for each device found
172 * @userdata:	arbitrary pointer to be passed to callback
173 *
174 * If the device provided is a bridge, walk the subordinate bus, including
175 * any bridged devices on buses under this bus.  Call the provided callback
176 * on each device found.
177 *
178 * If the device provided has no subordinate bus, e.g., an RCEC or RCiEP,
179 * call the callback on the device itself.
180 */
181static void pci_walk_bridge(struct pci_dev *bridge,
182			    int (*cb)(struct pci_dev *, void *),
183			    void *userdata)
184{
185	if (bridge->subordinate)
186		pci_walk_bus(bridge->subordinate, cb, userdata);
187	else
188		cb(bridge, userdata);
189}
190
191pci_ers_result_t pcie_do_recovery(struct pci_dev *dev,
192		pci_channel_state_t state,
193		pci_ers_result_t (*reset_subordinates)(struct pci_dev *pdev))
194{
195	int type = pci_pcie_type(dev);
196	struct pci_dev *bridge;
197	pci_ers_result_t status = PCI_ERS_RESULT_CAN_RECOVER;
198	struct pci_host_bridge *host = pci_find_host_bridge(dev->bus);
199
200	/*
201	 * If the error was detected by a Root Port, Downstream Port, RCEC,
202	 * or RCiEP, recovery runs on the device itself.  For Ports, that
203	 * also includes any subordinate devices.
204	 *
205	 * If it was detected by another device (Endpoint, etc), recovery
206	 * runs on the device and anything else under the same Port, i.e.,
207	 * everything under "bridge".
208	 */
209	if (type == PCI_EXP_TYPE_ROOT_PORT ||
210	    type == PCI_EXP_TYPE_DOWNSTREAM ||
211	    type == PCI_EXP_TYPE_RC_EC ||
212	    type == PCI_EXP_TYPE_RC_END)
213		bridge = dev;
214	else
215		bridge = pci_upstream_bridge(dev);
216
217	pci_walk_bridge(bridge, pci_pm_runtime_get_sync, NULL);
218
219	pci_dbg(bridge, "broadcast error_detected message\n");
220	if (state == pci_channel_io_frozen) {
221		pci_walk_bridge(bridge, report_frozen_detected, &status);
222		if (reset_subordinates(bridge) != PCI_ERS_RESULT_RECOVERED) {
223			pci_warn(bridge, "subordinate device reset failed\n");
224			goto failed;
225		}
226	} else {
227		pci_walk_bridge(bridge, report_normal_detected, &status);
228	}
229
230	if (status == PCI_ERS_RESULT_CAN_RECOVER) {
231		status = PCI_ERS_RESULT_RECOVERED;
232		pci_dbg(bridge, "broadcast mmio_enabled message\n");
233		pci_walk_bridge(bridge, report_mmio_enabled, &status);
234	}
235
236	if (status == PCI_ERS_RESULT_NEED_RESET) {
237		/*
238		 * TODO: Should call platform-specific
239		 * functions to reset slot before calling
240		 * drivers' slot_reset callbacks?
241		 */
242		status = PCI_ERS_RESULT_RECOVERED;
243		pci_dbg(bridge, "broadcast slot_reset message\n");
244		pci_walk_bridge(bridge, report_slot_reset, &status);
245	}
246
247	if (status != PCI_ERS_RESULT_RECOVERED)
248		goto failed;
249
250	pci_dbg(bridge, "broadcast resume message\n");
251	pci_walk_bridge(bridge, report_resume, &status);
252
253	/*
254	 * If we have native control of AER, clear error status in the device
255	 * that detected the error.  If the platform retained control of AER,
256	 * it is responsible for clearing this status.  In that case, the
257	 * signaling device may not even be visible to the OS.
258	 */
259	if (host->native_aer || pcie_ports_native) {
260		pcie_clear_device_status(dev);
261		pci_aer_clear_nonfatal_status(dev);
262	}
263
264	pci_walk_bridge(bridge, pci_pm_runtime_put, NULL);
265
266	pci_info(bridge, "device recovery successful\n");
267	return status;
268
269failed:
270	pci_walk_bridge(bridge, pci_pm_runtime_put, NULL);
271
272	pci_uevent_ers(bridge, PCI_ERS_RESULT_DISCONNECT);
273
274	/* TODO: Should kernel panic here? */
275	pci_info(bridge, "device recovery failed\n");
276
277	return status;
278}