1/*
  2 * AMD Cryptographic Coprocessor (CCP) driver
  3 *
  4 * Copyright (C) 2013,2016 Advanced Micro Devices, Inc.
  5 *
  6 * Author: Tom Lendacky <thomas.lendacky@amd.com>
  7 *
  8 * This program is free software; you can redistribute it and/or modify
  9 * it under the terms of the GNU General Public License version 2 as
 10 * published by the Free Software Foundation.
 11 */
 12
 13#include <linux/module.h>
 14#include <linux/kernel.h>
 15#include <linux/kthread.h>
 16#include <linux/sched.h>
 17#include <linux/interrupt.h>
 18#include <linux/spinlock.h>
 19#include <linux/rwlock_types.h>
 20#include <linux/types.h>
 21#include <linux/mutex.h>
 22#include <linux/delay.h>
 23#include <linux/hw_random.h>
 24#include <linux/cpu.h>
 25#ifdef CONFIG_X86
 26#include <asm/cpu_device_id.h>
 27#endif
 28#include <linux/ccp.h>
 29
 30#include "ccp-dev.h"
 31
 32MODULE_AUTHOR("Tom Lendacky <thomas.lendacky@amd.com>");
 33MODULE_LICENSE("GPL");
 34MODULE_VERSION("1.0.0");
 35MODULE_DESCRIPTION("AMD Cryptographic Coprocessor driver");
 36
 37struct ccp_tasklet_data {
 38	struct completion completion;
 39	struct ccp_cmd *cmd;
 40};
 41
 42/* List of CCPs, CCP count, read-write access lock, and access functions
 43 *
 44 * Lock structure: get ccp_unit_lock for reading whenever we need to
 45 * examine the CCP list. While holding it for reading we can acquire
 46 * the RR lock to update the round-robin next-CCP pointer. The unit lock
 47 * must be acquired before the RR lock.
 48 *
 49 * If the unit-lock is acquired for writing, we have total control over
 50 * the list, so there's no value in getting the RR lock.
 51 */
 52static DEFINE_RWLOCK(ccp_unit_lock);
 53static LIST_HEAD(ccp_units);
 54
 55/* Round-robin counter */
 56static DEFINE_SPINLOCK(ccp_rr_lock);
 57static struct ccp_device *ccp_rr;
 58
 59/* Ever-increasing value to produce unique unit numbers */
 60static atomic_t ccp_unit_ordinal;
 61unsigned int ccp_increment_unit_ordinal(void)
 62{
 63	return atomic_inc_return(&ccp_unit_ordinal);
 64}
 65
 66/**
 67 * ccp_add_device - add a CCP device to the list
 68 *
 69 * @ccp: ccp_device struct pointer
 70 *
 71 * Put this CCP on the unit list, which makes it available
 72 * for use.
 73 *
 74 * Returns zero if a CCP device is present, -ENODEV otherwise.
 75 */
 76void ccp_add_device(struct ccp_device *ccp)
 77{
 78	unsigned long flags;
 79
 80	write_lock_irqsave(&ccp_unit_lock, flags);
 81	list_add_tail(&ccp->entry, &ccp_units);
 82	if (!ccp_rr)
 83		/* We already have the list lock (we're first) so this
 84		 * pointer can't change on us. Set its initial value.
 85		 */
 86		ccp_rr = ccp;
 87	write_unlock_irqrestore(&ccp_unit_lock, flags);
 88}
 89
 90/**
 91 * ccp_del_device - remove a CCP device from the list
 92 *
 93 * @ccp: ccp_device struct pointer
 94 *
 95 * Remove this unit from the list of devices. If the next device
 96 * up for use is this one, adjust the pointer. If this is the last
 97 * device, NULL the pointer.
 98 */
 99void ccp_del_device(struct ccp_device *ccp)
100{
101	unsigned long flags;
102
103	write_lock_irqsave(&ccp_unit_lock, flags);
104	if (ccp_rr == ccp) {
105		/* ccp_unit_lock is read/write; any read access
106		 * will be suspended while we make changes to the
107		 * list and RR pointer.
108		 */
109		if (list_is_last(&ccp_rr->entry, &ccp_units))
110			ccp_rr = list_first_entry(&ccp_units, struct ccp_device,
111						  entry);
112		else
113			ccp_rr = list_next_entry(ccp_rr, entry);
114	}
115	list_del(&ccp->entry);
116	if (list_empty(&ccp_units))
117		ccp_rr = NULL;
118	write_unlock_irqrestore(&ccp_unit_lock, flags);
119}
120
121static struct ccp_device *ccp_get_device(void)
122{
123	unsigned long flags;
124	struct ccp_device *dp = NULL;
125
126	/* We round-robin through the unit list.
127	 * The (ccp_rr) pointer refers to the next unit to use.
128	 */
129	read_lock_irqsave(&ccp_unit_lock, flags);
130	if (!list_empty(&ccp_units)) {
131		spin_lock(&ccp_rr_lock);
132		dp = ccp_rr;
133		if (list_is_last(&ccp_rr->entry, &ccp_units))
134			ccp_rr = list_first_entry(&ccp_units, struct ccp_device,
135						  entry);
136		else
137			ccp_rr = list_next_entry(ccp_rr, entry);
138		spin_unlock(&ccp_rr_lock);
139	}
140	read_unlock_irqrestore(&ccp_unit_lock, flags);
141
142	return dp;
143}
144
145/**
146 * ccp_present - check if a CCP device is present
147 *
148 * Returns zero if a CCP device is present, -ENODEV otherwise.
149 */
150int ccp_present(void)
151{
152	unsigned long flags;
153	int ret;
154
155	read_lock_irqsave(&ccp_unit_lock, flags);
156	ret = list_empty(&ccp_units);
157	read_unlock_irqrestore(&ccp_unit_lock, flags);
158
159	return ret ? -ENODEV : 0;
160}
161EXPORT_SYMBOL_GPL(ccp_present);
162
163/**
164 * ccp_version - get the version of the CCP device
165 *
166 * Returns the version from the first unit on the list;
167 * otherwise a zero if no CCP device is present
168 */
169unsigned int ccp_version(void)
170{
171	struct ccp_device *dp;
172	unsigned long flags;
173	int ret = 0;
174
175	read_lock_irqsave(&ccp_unit_lock, flags);
176	if (!list_empty(&ccp_units)) {
177		dp = list_first_entry(&ccp_units, struct ccp_device, entry);
178		ret = dp->vdata->version;
179	}
180	read_unlock_irqrestore(&ccp_unit_lock, flags);
181
182	return ret;
183}
184EXPORT_SYMBOL_GPL(ccp_version);
185
186/**
187 * ccp_enqueue_cmd - queue an operation for processing by the CCP
188 *
189 * @cmd: ccp_cmd struct to be processed
190 *
191 * Queue a cmd to be processed by the CCP. If queueing the cmd
192 * would exceed the defined length of the cmd queue the cmd will
193 * only be queued if the CCP_CMD_MAY_BACKLOG flag is set and will
194 * result in a return code of -EBUSY.
195 *
196 * The callback routine specified in the ccp_cmd struct will be
197 * called to notify the caller of completion (if the cmd was not
198 * backlogged) or advancement out of the backlog. If the cmd has
199 * advanced out of the backlog the "err" value of the callback
200 * will be -EINPROGRESS. Any other "err" value during callback is
201 * the result of the operation.
202 *
203 * The cmd has been successfully queued if:
204 *   the return code is -EINPROGRESS or
205 *   the return code is -EBUSY and CCP_CMD_MAY_BACKLOG flag is set
206 */
207int ccp_enqueue_cmd(struct ccp_cmd *cmd)
208{
209	struct ccp_device *ccp = ccp_get_device();
210	unsigned long flags;
211	unsigned int i;
212	int ret;
213
214	if (!ccp)
215		return -ENODEV;
216
217	/* Caller must supply a callback routine */
218	if (!cmd->callback)
219		return -EINVAL;
220
221	cmd->ccp = ccp;
222
223	spin_lock_irqsave(&ccp->cmd_lock, flags);
224
225	i = ccp->cmd_q_count;
226
227	if (ccp->cmd_count >= MAX_CMD_QLEN) {
228		ret = -EBUSY;
229		if (cmd->flags & CCP_CMD_MAY_BACKLOG)
230			list_add_tail(&cmd->entry, &ccp->backlog);
231	} else {
232		ret = -EINPROGRESS;
233		ccp->cmd_count++;
234		list_add_tail(&cmd->entry, &ccp->cmd);
235
236		/* Find an idle queue */
237		if (!ccp->suspending) {
238			for (i = 0; i < ccp->cmd_q_count; i++) {
239				if (ccp->cmd_q[i].active)
240					continue;
241
242				break;
243			}
244		}
245	}
246
247	spin_unlock_irqrestore(&ccp->cmd_lock, flags);
248
249	/* If we found an idle queue, wake it up */
250	if (i < ccp->cmd_q_count)
251		wake_up_process(ccp->cmd_q[i].kthread);
252
253	return ret;
254}
255EXPORT_SYMBOL_GPL(ccp_enqueue_cmd);
256
257static void ccp_do_cmd_backlog(struct work_struct *work)
258{
259	struct ccp_cmd *cmd = container_of(work, struct ccp_cmd, work);
260	struct ccp_device *ccp = cmd->ccp;
261	unsigned long flags;
262	unsigned int i;
263
264	cmd->callback(cmd->data, -EINPROGRESS);
265
266	spin_lock_irqsave(&ccp->cmd_lock, flags);
267
268	ccp->cmd_count++;
269	list_add_tail(&cmd->entry, &ccp->cmd);
270
271	/* Find an idle queue */
272	for (i = 0; i < ccp->cmd_q_count; i++) {
273		if (ccp->cmd_q[i].active)
274			continue;
275
276		break;
277	}
278
279	spin_unlock_irqrestore(&ccp->cmd_lock, flags);
280
281	/* If we found an idle queue, wake it up */
282	if (i < ccp->cmd_q_count)
283		wake_up_process(ccp->cmd_q[i].kthread);
284}
285
286static struct ccp_cmd *ccp_dequeue_cmd(struct ccp_cmd_queue *cmd_q)
287{
288	struct ccp_device *ccp = cmd_q->ccp;
289	struct ccp_cmd *cmd = NULL;
290	struct ccp_cmd *backlog = NULL;
291	unsigned long flags;
292
293	spin_lock_irqsave(&ccp->cmd_lock, flags);
294
295	cmd_q->active = 0;
296
297	if (ccp->suspending) {
298		cmd_q->suspended = 1;
299
300		spin_unlock_irqrestore(&ccp->cmd_lock, flags);
301		wake_up_interruptible(&ccp->suspend_queue);
302
303		return NULL;
304	}
305
306	if (ccp->cmd_count) {
307		cmd_q->active = 1;
308
309		cmd = list_first_entry(&ccp->cmd, struct ccp_cmd, entry);
310		list_del(&cmd->entry);
311
312		ccp->cmd_count--;
313	}
314
315	if (!list_empty(&ccp->backlog)) {
316		backlog = list_first_entry(&ccp->backlog, struct ccp_cmd,
317					   entry);
318		list_del(&backlog->entry);
319	}
320
321	spin_unlock_irqrestore(&ccp->cmd_lock, flags);
322
323	if (backlog) {
324		INIT_WORK(&backlog->work, ccp_do_cmd_backlog);
325		schedule_work(&backlog->work);
326	}
327
328	return cmd;
329}
330
331static void ccp_do_cmd_complete(unsigned long data)
332{
333	struct ccp_tasklet_data *tdata = (struct ccp_tasklet_data *)data;
334	struct ccp_cmd *cmd = tdata->cmd;
335
336	cmd->callback(cmd->data, cmd->ret);
337	complete(&tdata->completion);
338}
339
340/**
341 * ccp_cmd_queue_thread - create a kernel thread to manage a CCP queue
342 *
343 * @data: thread-specific data
344 */
345int ccp_cmd_queue_thread(void *data)
346{
347	struct ccp_cmd_queue *cmd_q = (struct ccp_cmd_queue *)data;
348	struct ccp_cmd *cmd;
349	struct ccp_tasklet_data tdata;
350	struct tasklet_struct tasklet;
351
352	tasklet_init(&tasklet, ccp_do_cmd_complete, (unsigned long)&tdata);
353
354	set_current_state(TASK_INTERRUPTIBLE);
355	while (!kthread_should_stop()) {
356		schedule();
357
358		set_current_state(TASK_INTERRUPTIBLE);
359
360		cmd = ccp_dequeue_cmd(cmd_q);
361		if (!cmd)
362			continue;
363
364		__set_current_state(TASK_RUNNING);
365
366		/* Execute the command */
367		cmd->ret = ccp_run_cmd(cmd_q, cmd);
368
369		/* Schedule the completion callback */
370		tdata.cmd = cmd;
371		init_completion(&tdata.completion);
372		tasklet_schedule(&tasklet);
373		wait_for_completion(&tdata.completion);
374	}
375
376	__set_current_state(TASK_RUNNING);
377
378	return 0;
379}
380
381/**
382 * ccp_alloc_struct - allocate and initialize the ccp_device struct
383 *
384 * @dev: device struct of the CCP
385 */
386struct ccp_device *ccp_alloc_struct(struct device *dev)
387{
388	struct ccp_device *ccp;
389
390	ccp = devm_kzalloc(dev, sizeof(*ccp), GFP_KERNEL);
391	if (!ccp)
392		return NULL;
393	ccp->dev = dev;
394
395	INIT_LIST_HEAD(&ccp->cmd);
396	INIT_LIST_HEAD(&ccp->backlog);
397
398	spin_lock_init(&ccp->cmd_lock);
399	mutex_init(&ccp->req_mutex);
400	mutex_init(&ccp->ksb_mutex);
401	ccp->ksb_count = KSB_COUNT;
402	ccp->ksb_start = 0;
403
404	ccp->ord = ccp_increment_unit_ordinal();
405	snprintf(ccp->name, MAX_CCP_NAME_LEN, "ccp-%u", ccp->ord);
406	snprintf(ccp->rngname, MAX_CCP_NAME_LEN, "ccp-%u-rng", ccp->ord);
407
408	return ccp;
409}
410
411#ifdef CONFIG_PM
412bool ccp_queues_suspended(struct ccp_device *ccp)
413{
414	unsigned int suspended = 0;
415	unsigned long flags;
416	unsigned int i;
417
418	spin_lock_irqsave(&ccp->cmd_lock, flags);
419
420	for (i = 0; i < ccp->cmd_q_count; i++)
421		if (ccp->cmd_q[i].suspended)
422			suspended++;
423
424	spin_unlock_irqrestore(&ccp->cmd_lock, flags);
425
426	return ccp->cmd_q_count == suspended;
427}
428#endif
429
430static int __init ccp_mod_init(void)
431{
432#ifdef CONFIG_X86
433	int ret;
434
435	ret = ccp_pci_init();
436	if (ret)
437		return ret;
438
439	/* Don't leave the driver loaded if init failed */
440	if (ccp_present() != 0) {
441		ccp_pci_exit();
442		return -ENODEV;
443	}
444
445	return 0;
446#endif
447
448#ifdef CONFIG_ARM64
449	int ret;
450
451	ret = ccp_platform_init();
452	if (ret)
453		return ret;
454
455	/* Don't leave the driver loaded if init failed */
456	if (ccp_present() != 0) {
457		ccp_platform_exit();
458		return -ENODEV;
459	}
460
461	return 0;
462#endif
463
464	return -ENODEV;
465}
466
467static void __exit ccp_mod_exit(void)
468{
469#ifdef CONFIG_X86
470	ccp_pci_exit();
471#endif
472
473#ifdef CONFIG_ARM64
474	ccp_platform_exit();
475#endif
476}
477
478module_init(ccp_mod_init);
479module_exit(ccp_mod_exit);