summaryrefslogtreecommitdiff
path: root/drivers/iommu/io-pgfault.c
blob: e5b8b9110c132aa88444e52fd75585aba1945bab (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
// SPDX-License-Identifier: GPL-2.0
/*
 * Handle device page faults
 *
 * Copyright (C) 2020 ARM Ltd.
 */

#include <linux/iommu.h>
#include <linux/list.h>
#include <linux/sched/mm.h>
#include <linux/slab.h>
#include <linux/workqueue.h>

#include "iommu-sva.h"

/**
 * struct iopf_queue - IO Page Fault queue
 * @wq: the fault workqueue
 * @devices: devices attached to this queue
 * @lock: protects the device list
 */
struct iopf_queue {
	struct workqueue_struct		*wq;
	struct list_head		devices;
	struct mutex			lock;
};

/**
 * struct iopf_device_param - IO Page Fault data attached to a device
 * @dev: the device that owns this param
 * @queue: IOPF queue
 * @queue_list: index into queue->devices
 * @partial: faults that are part of a Page Request Group for which the last
 *           request hasn't been submitted yet.
 */
struct iopf_device_param {
	struct device			*dev;
	struct iopf_queue		*queue;
	struct list_head		queue_list;
	struct list_head		partial;
};

struct iopf_fault {
	struct iommu_fault		fault;
	struct list_head		list;
};

struct iopf_group {
	struct iopf_fault		last_fault;
	struct list_head		faults;
	struct work_struct		work;
	struct device			*dev;
};

static int iopf_complete_group(struct device *dev, struct iopf_fault *iopf,
			       enum iommu_page_response_code status)
{
	struct iommu_page_response resp = {
		.version		= IOMMU_PAGE_RESP_VERSION_1,
		.pasid			= iopf->fault.prm.pasid,
		.grpid			= iopf->fault.prm.grpid,
		.code			= status,
	};

	if ((iopf->fault.prm.flags & IOMMU_FAULT_PAGE_REQUEST_PASID_VALID) &&
	    (iopf->fault.prm.flags & IOMMU_FAULT_PAGE_RESPONSE_NEEDS_PASID))
		resp.flags = IOMMU_PAGE_RESP_PASID_VALID;

	return iommu_page_response(dev, &resp);
}

static void iopf_handler(struct work_struct *work)
{
	struct iopf_group *group;
	struct iommu_domain *domain;
	struct iopf_fault *iopf, *next;
	enum iommu_page_response_code status = IOMMU_PAGE_RESP_SUCCESS;

	group = container_of(work, struct iopf_group, work);
	domain = iommu_get_domain_for_dev_pasid(group->dev,
				group->last_fault.fault.prm.pasid, 0);
	if (!domain || !domain->iopf_handler)
		status = IOMMU_PAGE_RESP_INVALID;

	list_for_each_entry_safe(iopf, next, &group->faults, list) {
		/*
		 * For the moment, errors are sticky: don't handle subsequent
		 * faults in the group if there is an error.
		 */
		if (status == IOMMU_PAGE_RESP_SUCCESS)
			status = domain->iopf_handler(&iopf->fault,
						      domain->fault_data);

		if (!(iopf->fault.prm.flags &
		      IOMMU_FAULT_PAGE_REQUEST_LAST_PAGE))
			kfree(iopf);
	}

	iopf_complete_group(group->dev, &group->last_fault, status);
	kfree(group);
}

/**
 * iommu_queue_iopf - IO Page Fault handler
 * @fault: fault event
 * @cookie: struct device, passed to iommu_register_device_fault_handler.
 *
 * Add a fault to the device workqueue, to be handled by mm.
 *
 * This module doesn't handle PCI PASID Stop Marker; IOMMU drivers must discard
 * them before reporting faults. A PASID Stop Marker (LRW = 0b100) doesn't
 * expect a response. It may be generated when disabling a PASID (issuing a
 * PASID stop request) by some PCI devices.
 *
 * The PASID stop request is issued by the device driver before unbind(). Once
 * it completes, no page request is generated for this PASID anymore and
 * outstanding ones have been pushed to the IOMMU (as per PCIe 4.0r1.0 - 6.20.1
 * and 10.4.1.2 - Managing PASID TLP Prefix Usage). Some PCI devices will wait
 * for all outstanding page requests to come back with a response before
 * completing the PASID stop request. Others do not wait for page responses, and
 * instead issue this Stop Marker that tells us when the PASID can be
 * reallocated.
 *
 * It is safe to discard the Stop Marker because it is an optimization.
 * a. Page requests, which are posted requests, have been flushed to the IOMMU
 *    when the stop request completes.
 * b. The IOMMU driver flushes all fault queues on unbind() before freeing the
 *    PASID.
 *
 * So even though the Stop Marker might be issued by the device *after* the stop
 * request completes, outstanding faults will have been dealt with by the time
 * the PASID is freed.
 *
 * Any valid page fault will be eventually routed to an iommu domain and the
 * page fault handler installed there will get called. The users of this
 * handling framework should guarantee that the iommu domain could only be
 * freed after the device has stopped generating page faults (or the iommu
 * hardware has been set to block the page faults) and the pending page faults
 * have been flushed.
 *
 * Return: 0 on success and <0 on error.
 */
int iommu_queue_iopf(struct iommu_fault *fault, void *cookie)
{
	int ret;
	struct iopf_group *group;
	struct iopf_fault *iopf, *next;
	struct iopf_device_param *iopf_param;

	struct device *dev = cookie;
	struct dev_iommu *param = dev->iommu;

	lockdep_assert_held(&param->lock);

	if (fault->type != IOMMU_FAULT_PAGE_REQ)
		/* Not a recoverable page fault */
		return -EOPNOTSUPP;

	/*
	 * As long as we're holding param->lock, the queue can't be unlinked
	 * from the device and therefore cannot disappear.
	 */
	iopf_param = param->iopf_param;
	if (!iopf_param)
		return -ENODEV;

	if (!(fault->prm.flags & IOMMU_FAULT_PAGE_REQUEST_LAST_PAGE)) {
		iopf = kzalloc(sizeof(*iopf), GFP_KERNEL);
		if (!iopf)
			return -ENOMEM;

		iopf->fault = *fault;

		/* Non-last request of a group. Postpone until the last one */
		list_add(&iopf->list, &iopf_param->partial);

		return 0;
	}

	group = kzalloc(sizeof(*group), GFP_KERNEL);
	if (!group) {
		/*
		 * The caller will send a response to the hardware. But we do
		 * need to clean up before leaving, otherwise partial faults
		 * will be stuck.
		 */
		ret = -ENOMEM;
		goto cleanup_partial;
	}

	group->dev = dev;
	group->last_fault.fault = *fault;
	INIT_LIST_HEAD(&group->faults);
	list_add(&group->last_fault.list, &group->faults);
	INIT_WORK(&group->work, iopf_handler);

	/* See if we have partial faults for this group */
	list_for_each_entry_safe(iopf, next, &iopf_param->partial, list) {
		if (iopf->fault.prm.grpid == fault->prm.grpid)
			/* Insert *before* the last fault */
			list_move(&iopf->list, &group->faults);
	}

	queue_work(iopf_param->queue->wq, &group->work);
	return 0;

cleanup_partial:
	list_for_each_entry_safe(iopf, next, &iopf_param->partial, list) {
		if (iopf->fault.prm.grpid == fault->prm.grpid) {
			list_del(&iopf->list);
			kfree(iopf);
		}
	}
	return ret;
}
EXPORT_SYMBOL_GPL(iommu_queue_iopf);

/**
 * iopf_queue_flush_dev - Ensure that all queued faults have been processed
 * @dev: the endpoint whose faults need to be flushed.
 *
 * The IOMMU driver calls this before releasing a PASID, to ensure that all
 * pending faults for this PASID have been handled, and won't hit the address
 * space of the next process that uses this PASID. The driver must make sure
 * that no new fault is added to the queue. In particular it must flush its
 * low-level queue before calling this function.
 *
 * Return: 0 on success and <0 on error.
 */
int iopf_queue_flush_dev(struct device *dev)
{
	int ret = 0;
	struct iopf_device_param *iopf_param;
	struct dev_iommu *param = dev->iommu;

	if (!param)
		return -ENODEV;

	mutex_lock(&param->lock);
	iopf_param = param->iopf_param;
	if (iopf_param)
		flush_workqueue(iopf_param->queue->wq);
	else
		ret = -ENODEV;
	mutex_unlock(&param->lock);

	return ret;
}
EXPORT_SYMBOL_GPL(iopf_queue_flush_dev);

/**
 * iopf_queue_discard_partial - Remove all pending partial fault
 * @queue: the queue whose partial faults need to be discarded
 *
 * When the hardware queue overflows, last page faults in a group may have been
 * lost and the IOMMU driver calls this to discard all partial faults. The
 * driver shouldn't be adding new faults to this queue concurrently.
 *
 * Return: 0 on success and <0 on error.
 */
int iopf_queue_discard_partial(struct iopf_queue *queue)
{
	struct iopf_fault *iopf, *next;
	struct iopf_device_param *iopf_param;

	if (!queue)
		return -EINVAL;

	mutex_lock(&queue->lock);
	list_for_each_entry(iopf_param, &queue->devices, queue_list) {
		list_for_each_entry_safe(iopf, next, &iopf_param->partial,
					 list) {
			list_del(&iopf->list);
			kfree(iopf);
		}
	}
	mutex_unlock(&queue->lock);
	return 0;
}
EXPORT_SYMBOL_GPL(iopf_queue_discard_partial);

/**
 * iopf_queue_add_device - Add producer to the fault queue
 * @queue: IOPF queue
 * @dev: device to add
 *
 * Return: 0 on success and <0 on error.
 */
int iopf_queue_add_device(struct iopf_queue *queue, struct device *dev)
{
	int ret = -EBUSY;
	struct iopf_device_param *iopf_param;
	struct dev_iommu *param = dev->iommu;

	if (!param)
		return -ENODEV;

	iopf_param = kzalloc(sizeof(*iopf_param), GFP_KERNEL);
	if (!iopf_param)
		return -ENOMEM;

	INIT_LIST_HEAD(&iopf_param->partial);
	iopf_param->queue = queue;
	iopf_param->dev = dev;

	mutex_lock(&queue->lock);
	mutex_lock(&param->lock);
	if (!param->iopf_param) {
		list_add(&iopf_param->queue_list, &queue->devices);
		param->iopf_param = iopf_param;
		ret = 0;
	}
	mutex_unlock(&param->lock);
	mutex_unlock(&queue->lock);

	if (ret)
		kfree(iopf_param);

	return ret;
}
EXPORT_SYMBOL_GPL(iopf_queue_add_device);

/**
 * iopf_queue_remove_device - Remove producer from fault queue
 * @queue: IOPF queue
 * @dev: device to remove
 *
 * Caller makes sure that no more faults are reported for this device.
 *
 * Return: 0 on success and <0 on error.
 */
int iopf_queue_remove_device(struct iopf_queue *queue, struct device *dev)
{
	int ret = -EINVAL;
	struct iopf_fault *iopf, *next;
	struct iopf_device_param *iopf_param;
	struct dev_iommu *param = dev->iommu;

	if (!param || !queue)
		return -EINVAL;

	mutex_lock(&queue->lock);
	mutex_lock(&param->lock);
	iopf_param = param->iopf_param;
	if (iopf_param && iopf_param->queue == queue) {
		list_del(&iopf_param->queue_list);
		param->iopf_param = NULL;
		ret = 0;
	}
	mutex_unlock(&param->lock);
	mutex_unlock(&queue->lock);
	if (ret)
		return ret;

	/* Just in case some faults are still stuck */
	list_for_each_entry_safe(iopf, next, &iopf_param->partial, list)
		kfree(iopf);

	kfree(iopf_param);

	return 0;
}
EXPORT_SYMBOL_GPL(iopf_queue_remove_device);

/**
 * iopf_queue_alloc - Allocate and initialize a fault queue
 * @name: a unique string identifying the queue (for workqueue)
 *
 * Return: the queue on success and NULL on error.
 */
struct iopf_queue *iopf_queue_alloc(const char *name)
{
	struct iopf_queue *queue;

	queue = kzalloc(sizeof(*queue), GFP_KERNEL);
	if (!queue)
		return NULL;

	/*
	 * The WQ is unordered because the low-level handler enqueues faults by
	 * group. PRI requests within a group have to be ordered, but once
	 * that's dealt with, the high-level function can handle groups out of
	 * order.
	 */
	queue->wq = alloc_workqueue("iopf_queue/%s", WQ_UNBOUND, 0, name);
	if (!queue->wq) {
		kfree(queue);
		return NULL;
	}

	INIT_LIST_HEAD(&queue->devices);
	mutex_init(&queue->lock);

	return queue;
}
EXPORT_SYMBOL_GPL(iopf_queue_alloc);

/**
 * iopf_queue_free - Free IOPF queue
 * @queue: queue to free
 *
 * Counterpart to iopf_queue_alloc(). The driver must not be queuing faults or
 * adding/removing devices on this queue anymore.
 */
void iopf_queue_free(struct iopf_queue *queue)
{
	struct iopf_device_param *iopf_param, *next;

	if (!queue)
		return;

	list_for_each_entry_safe(iopf_param, next, &queue->devices, queue_list)
		iopf_queue_remove_device(queue, iopf_param->dev);

	destroy_workqueue(queue->wq);
	kfree(queue);
}
EXPORT_SYMBOL_GPL(iopf_queue_free);