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 
merge_result(enum pci_ers_result orig,enum pci_ers_result new)24 static 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 
report_error_detected(struct pci_dev * dev,pci_channel_state_t state,enum pci_ers_result * result)49 static 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 
pci_pm_runtime_get_sync(struct pci_dev * pdev,void * data)89 static 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 
pci_pm_runtime_put(struct pci_dev * pdev,void * data)95 static int pci_pm_runtime_put(struct pci_dev *pdev, void *data)
96 {
97 	pm_runtime_put(&pdev->dev);
98 	return 0;
99 }
100 
report_frozen_detected(struct pci_dev * dev,void * data)101 static int report_frozen_detected(struct pci_dev *dev, void *data)
102 {
103 	return report_error_detected(dev, pci_channel_io_frozen, data);
104 }
105 
report_normal_detected(struct pci_dev * dev,void * data)106 static int report_normal_detected(struct pci_dev *dev, void *data)
107 {
108 	return report_error_detected(dev, pci_channel_io_normal, data);
109 }
110 
report_mmio_enabled(struct pci_dev * dev,void * data)111 static 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);
125 out:
126 	device_unlock(&dev->dev);
127 	return 0;
128 }
129 
report_slot_reset(struct pci_dev * dev,void * data)130 static 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);
144 out:
145 	device_unlock(&dev->dev);
146 	return 0;
147 }
148 
report_resume(struct pci_dev * dev,void * data)149 static 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);
162 out:
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  */
pci_walk_bridge(struct pci_dev * bridge,int (* cb)(struct pci_dev *,void *),void * userdata)181 static 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 
pcie_do_recovery(struct pci_dev * dev,pci_channel_state_t state,pci_ers_result_t (* reset_subordinates)(struct pci_dev * pdev))191 pci_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 
269 failed:
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 }
279