1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Implementation of the Xen vTPM device frontend
  4 *
  5 * Author:  Daniel De Graaf <dgdegra@tycho.nsa.gov>
 
 
 
 
  6 */
  7#include <linux/errno.h>
  8#include <linux/err.h>
  9#include <linux/interrupt.h>
 10#include <linux/freezer.h>
 11#include <xen/xen.h>
 12#include <xen/events.h>
 13#include <xen/interface/io/tpmif.h>
 14#include <xen/grant_table.h>
 15#include <xen/xenbus.h>
 16#include <xen/page.h>
 17#include "tpm.h"
 18#include <xen/platform_pci.h>
 19
 20struct tpm_private {
 21	struct tpm_chip *chip;
 22	struct xenbus_device *dev;
 23
 24	struct vtpm_shared_page *shr;
 25
 26	unsigned int evtchn;
 27	int ring_ref;
 28	domid_t backend_id;
 29	int irq;
 30	wait_queue_head_t read_queue;
 31};
 32
 33enum status_bits {
 34	VTPM_STATUS_RUNNING  = 0x1,
 35	VTPM_STATUS_IDLE     = 0x2,
 36	VTPM_STATUS_RESULT   = 0x4,
 37	VTPM_STATUS_CANCELED = 0x8,
 38};
 39
 40static bool wait_for_tpm_stat_cond(struct tpm_chip *chip, u8 mask,
 41					bool check_cancel, bool *canceled)
 42{
 43	u8 status = chip->ops->status(chip);
 44
 45	*canceled = false;
 46	if ((status & mask) == mask)
 47		return true;
 48	if (check_cancel && chip->ops->req_canceled(chip, status)) {
 49		*canceled = true;
 50		return true;
 51	}
 52	return false;
 53}
 54
 55static int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask,
 56		unsigned long timeout, wait_queue_head_t *queue,
 57		bool check_cancel)
 58{
 59	unsigned long stop;
 60	long rc;
 61	u8 status;
 62	bool canceled = false;
 63
 64	/* check current status */
 65	status = chip->ops->status(chip);
 66	if ((status & mask) == mask)
 67		return 0;
 68
 69	stop = jiffies + timeout;
 70
 71	if (chip->flags & TPM_CHIP_FLAG_IRQ) {
 72again:
 73		timeout = stop - jiffies;
 74		if ((long)timeout <= 0)
 75			return -ETIME;
 76		rc = wait_event_interruptible_timeout(*queue,
 77			wait_for_tpm_stat_cond(chip, mask, check_cancel,
 78					       &canceled),
 79			timeout);
 80		if (rc > 0) {
 81			if (canceled)
 82				return -ECANCELED;
 83			return 0;
 84		}
 85		if (rc == -ERESTARTSYS && freezing(current)) {
 86			clear_thread_flag(TIF_SIGPENDING);
 87			goto again;
 88		}
 89	} else {
 90		do {
 91			tpm_msleep(TPM_TIMEOUT);
 92			status = chip->ops->status(chip);
 93			if ((status & mask) == mask)
 94				return 0;
 95		} while (time_before(jiffies, stop));
 96	}
 97	return -ETIME;
 98}
 99
100static u8 vtpm_status(struct tpm_chip *chip)
101{
102	struct tpm_private *priv = dev_get_drvdata(&chip->dev);
103	switch (priv->shr->state) {
104	case VTPM_STATE_IDLE:
105		return VTPM_STATUS_IDLE | VTPM_STATUS_CANCELED;
106	case VTPM_STATE_FINISH:
107		return VTPM_STATUS_IDLE | VTPM_STATUS_RESULT;
108	case VTPM_STATE_SUBMIT:
109	case VTPM_STATE_CANCEL: /* cancel requested, not yet canceled */
110		return VTPM_STATUS_RUNNING;
111	default:
112		return 0;
113	}
114}
115
116static bool vtpm_req_canceled(struct tpm_chip *chip, u8 status)
117{
118	return status & VTPM_STATUS_CANCELED;
119}
120
121static void vtpm_cancel(struct tpm_chip *chip)
122{
123	struct tpm_private *priv = dev_get_drvdata(&chip->dev);
124	priv->shr->state = VTPM_STATE_CANCEL;
125	wmb();
126	notify_remote_via_evtchn(priv->evtchn);
127}
128
129static size_t shr_data_offset(struct vtpm_shared_page *shr)
130{
131	return struct_size(shr, extra_pages, shr->nr_extra_pages);
132}
133
134static int vtpm_send(struct tpm_chip *chip, u8 *buf, size_t count)
135{
136	struct tpm_private *priv = dev_get_drvdata(&chip->dev);
137	struct vtpm_shared_page *shr = priv->shr;
138	size_t offset = shr_data_offset(shr);
139
140	u32 ordinal;
141	unsigned long duration;
142
143	if (offset > PAGE_SIZE)
144		return -EINVAL;
145
146	if (offset + count > PAGE_SIZE)
147		return -EINVAL;
148
149	/* Wait for completion of any existing command or cancellation */
150	if (wait_for_tpm_stat(chip, VTPM_STATUS_IDLE, chip->timeout_c,
151			&priv->read_queue, true) < 0) {
152		vtpm_cancel(chip);
153		return -ETIME;
154	}
155
156	memcpy(offset + (u8 *)shr, buf, count);
157	shr->length = count;
158	barrier();
159	shr->state = VTPM_STATE_SUBMIT;
160	wmb();
161	notify_remote_via_evtchn(priv->evtchn);
162
163	ordinal = be32_to_cpu(((struct tpm_header *)buf)->ordinal);
164	duration = tpm_calc_ordinal_duration(chip, ordinal);
165
166	if (wait_for_tpm_stat(chip, VTPM_STATUS_IDLE, duration,
167			&priv->read_queue, true) < 0) {
168		/* got a signal or timeout, try to cancel */
169		vtpm_cancel(chip);
170		return -ETIME;
171	}
172
173	return 0;
174}
175
176static int vtpm_recv(struct tpm_chip *chip, u8 *buf, size_t count)
177{
178	struct tpm_private *priv = dev_get_drvdata(&chip->dev);
179	struct vtpm_shared_page *shr = priv->shr;
180	size_t offset = shr_data_offset(shr);
181	size_t length = shr->length;
182
183	if (shr->state == VTPM_STATE_IDLE)
184		return -ECANCELED;
185
186	/* In theory the wait at the end of _send makes this one unnecessary */
187	if (wait_for_tpm_stat(chip, VTPM_STATUS_RESULT, chip->timeout_c,
188			&priv->read_queue, true) < 0) {
189		vtpm_cancel(chip);
190		return -ETIME;
191	}
192
193	if (offset > PAGE_SIZE)
194		return -EIO;
195
196	if (offset + length > PAGE_SIZE)
197		length = PAGE_SIZE - offset;
198
199	if (length > count)
200		length = count;
201
202	memcpy(buf, offset + (u8 *)shr, length);
203
204	return length;
205}
206
207static const struct tpm_class_ops tpm_vtpm = {
208	.status = vtpm_status,
209	.recv = vtpm_recv,
210	.send = vtpm_send,
211	.cancel = vtpm_cancel,
212	.req_complete_mask = VTPM_STATUS_IDLE | VTPM_STATUS_RESULT,
213	.req_complete_val  = VTPM_STATUS_IDLE | VTPM_STATUS_RESULT,
214	.req_canceled      = vtpm_req_canceled,
215};
216
217static irqreturn_t tpmif_interrupt(int dummy, void *dev_id)
218{
219	struct tpm_private *priv = dev_id;
220
221	switch (priv->shr->state) {
222	case VTPM_STATE_IDLE:
223	case VTPM_STATE_FINISH:
224		wake_up_interruptible(&priv->read_queue);
225		break;
226	case VTPM_STATE_SUBMIT:
227	case VTPM_STATE_CANCEL:
228	default:
229		break;
230	}
231	return IRQ_HANDLED;
232}
233
234static int setup_chip(struct device *dev, struct tpm_private *priv)
235{
236	struct tpm_chip *chip;
237
238	chip = tpmm_chip_alloc(dev, &tpm_vtpm);
239	if (IS_ERR(chip))
240		return PTR_ERR(chip);
241
242	init_waitqueue_head(&priv->read_queue);
243
244	priv->chip = chip;
245	dev_set_drvdata(&chip->dev, priv);
246
247	return 0;
248}
249
250/* caller must clean up in case of errors */
251static int setup_ring(struct xenbus_device *dev, struct tpm_private *priv)
252{
253	struct xenbus_transaction xbt;
254	const char *message = NULL;
255	int rv;
 
256
257	rv = xenbus_setup_ring(dev, GFP_KERNEL, (void **)&priv->shr, 1,
258			       &priv->ring_ref);
 
 
 
 
 
259	if (rv < 0)
260		return rv;
261
 
 
262	rv = xenbus_alloc_evtchn(dev, &priv->evtchn);
263	if (rv)
264		return rv;
265
266	rv = bind_evtchn_to_irqhandler(priv->evtchn, tpmif_interrupt, 0,
267				       "tpmif", priv);
268	if (rv <= 0) {
269		xenbus_dev_fatal(dev, rv, "allocating TPM irq");
270		return rv;
271	}
272	priv->irq = rv;
273
274 again:
275	rv = xenbus_transaction_start(&xbt);
276	if (rv) {
277		xenbus_dev_fatal(dev, rv, "starting transaction");
278		return rv;
279	}
280
281	rv = xenbus_printf(xbt, dev->nodename,
282			"ring-ref", "%u", priv->ring_ref);
283	if (rv) {
284		message = "writing ring-ref";
285		goto abort_transaction;
286	}
287
288	rv = xenbus_printf(xbt, dev->nodename, "event-channel", "%u",
289			priv->evtchn);
290	if (rv) {
291		message = "writing event-channel";
292		goto abort_transaction;
293	}
294
295	rv = xenbus_printf(xbt, dev->nodename, "feature-protocol-v2", "1");
296	if (rv) {
297		message = "writing feature-protocol-v2";
298		goto abort_transaction;
299	}
300
301	rv = xenbus_transaction_end(xbt, 0);
302	if (rv == -EAGAIN)
303		goto again;
304	if (rv) {
305		xenbus_dev_fatal(dev, rv, "completing transaction");
306		return rv;
307	}
308
309	xenbus_switch_state(dev, XenbusStateInitialised);
310
311	return 0;
312
313 abort_transaction:
314	xenbus_transaction_end(xbt, 1);
315	if (message)
316		xenbus_dev_error(dev, rv, "%s", message);
317
318	return rv;
319}
320
321static void ring_free(struct tpm_private *priv)
322{
323	if (!priv)
324		return;
325
326	xenbus_teardown_ring((void **)&priv->shr, 1, &priv->ring_ref);
 
 
 
 
327
328	if (priv->irq)
329		unbind_from_irqhandler(priv->irq, priv);
330
331	kfree(priv);
332}
333
334static int tpmfront_probe(struct xenbus_device *dev,
335		const struct xenbus_device_id *id)
336{
337	struct tpm_private *priv;
338	int rv;
339
340	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
341	if (!priv) {
342		xenbus_dev_fatal(dev, -ENOMEM, "allocating priv structure");
343		return -ENOMEM;
344	}
345
346	rv = setup_chip(&dev->dev, priv);
347	if (rv) {
348		kfree(priv);
349		return rv;
350	}
351
352	rv = setup_ring(dev, priv);
353	if (rv) {
354		ring_free(priv);
355		return rv;
356	}
357
358	tpm_get_timeouts(priv->chip);
359
360	return tpm_chip_register(priv->chip);
361}
362
363static void tpmfront_remove(struct xenbus_device *dev)
364{
365	struct tpm_chip *chip = dev_get_drvdata(&dev->dev);
366	struct tpm_private *priv = dev_get_drvdata(&chip->dev);
367	tpm_chip_unregister(chip);
368	ring_free(priv);
369	dev_set_drvdata(&chip->dev, NULL);
 
370}
371
372static int tpmfront_resume(struct xenbus_device *dev)
373{
374	/* A suspend/resume/migrate will interrupt a vTPM anyway */
375	tpmfront_remove(dev);
376	return tpmfront_probe(dev, NULL);
377}
378
379static void backend_changed(struct xenbus_device *dev,
380		enum xenbus_state backend_state)
381{
382	switch (backend_state) {
383	case XenbusStateInitialised:
384	case XenbusStateConnected:
385		if (dev->state == XenbusStateConnected)
386			break;
387
388		if (!xenbus_read_unsigned(dev->otherend, "feature-protocol-v2",
389					  0)) {
390			xenbus_dev_fatal(dev, -EINVAL,
391					"vTPM protocol 2 required");
392			return;
393		}
394		xenbus_switch_state(dev, XenbusStateConnected);
395		break;
396
397	case XenbusStateClosing:
398	case XenbusStateClosed:
399		device_unregister(&dev->dev);
400		xenbus_frontend_closed(dev);
401		break;
402	default:
403		break;
404	}
405}
406
407static const struct xenbus_device_id tpmfront_ids[] = {
408	{ "vtpm" },
409	{ "" }
410};
411MODULE_ALIAS("xen:vtpm");
412
413static struct xenbus_driver tpmfront_driver = {
414	.ids = tpmfront_ids,
415	.probe = tpmfront_probe,
416	.remove = tpmfront_remove,
417	.resume = tpmfront_resume,
418	.otherend_changed = backend_changed,
419};
420
421static int __init xen_tpmfront_init(void)
422{
423	if (!xen_domain())
424		return -ENODEV;
425
426	if (!xen_has_pv_devices())
427		return -ENODEV;
428
429	return xenbus_register_frontend(&tpmfront_driver);
430}
431module_init(xen_tpmfront_init);
432
433static void __exit xen_tpmfront_exit(void)
434{
435	xenbus_unregister_driver(&tpmfront_driver);
436}
437module_exit(xen_tpmfront_exit);
438
439MODULE_AUTHOR("Daniel De Graaf <dgdegra@tycho.nsa.gov>");
440MODULE_DESCRIPTION("Xen vTPM Driver");
441MODULE_LICENSE("GPL");

 
  1/*
  2 * Implementation of the Xen vTPM device frontend
  3 *
  4 * Author:  Daniel De Graaf <dgdegra@tycho.nsa.gov>
  5 *
  6 * This program is free software; you can redistribute it and/or modify
  7 * it under the terms of the GNU General Public License version 2,
  8 * as published by the Free Software Foundation.
  9 */
 10#include <linux/errno.h>
 11#include <linux/err.h>
 12#include <linux/interrupt.h>
 13#include <linux/freezer.h>
 14#include <xen/xen.h>
 15#include <xen/events.h>
 16#include <xen/interface/io/tpmif.h>
 17#include <xen/grant_table.h>
 18#include <xen/xenbus.h>
 19#include <xen/page.h>
 20#include "tpm.h"
 21#include <xen/platform_pci.h>
 22
 23struct tpm_private {
 24	struct tpm_chip *chip;
 25	struct xenbus_device *dev;
 26
 27	struct vtpm_shared_page *shr;
 28
 29	unsigned int evtchn;
 30	int ring_ref;
 31	domid_t backend_id;
 32	int irq;
 33	wait_queue_head_t read_queue;
 34};
 35
 36enum status_bits {
 37	VTPM_STATUS_RUNNING  = 0x1,
 38	VTPM_STATUS_IDLE     = 0x2,
 39	VTPM_STATUS_RESULT   = 0x4,
 40	VTPM_STATUS_CANCELED = 0x8,
 41};
 42
 43static bool wait_for_tpm_stat_cond(struct tpm_chip *chip, u8 mask,
 44					bool check_cancel, bool *canceled)
 45{
 46	u8 status = chip->ops->status(chip);
 47
 48	*canceled = false;
 49	if ((status & mask) == mask)
 50		return true;
 51	if (check_cancel && chip->ops->req_canceled(chip, status)) {
 52		*canceled = true;
 53		return true;
 54	}
 55	return false;
 56}
 57
 58static int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask,
 59		unsigned long timeout, wait_queue_head_t *queue,
 60		bool check_cancel)
 61{
 62	unsigned long stop;
 63	long rc;
 64	u8 status;
 65	bool canceled = false;
 66
 67	/* check current status */
 68	status = chip->ops->status(chip);
 69	if ((status & mask) == mask)
 70		return 0;
 71
 72	stop = jiffies + timeout;
 73
 74	if (chip->flags & TPM_CHIP_FLAG_IRQ) {
 75again:
 76		timeout = stop - jiffies;
 77		if ((long)timeout <= 0)
 78			return -ETIME;
 79		rc = wait_event_interruptible_timeout(*queue,
 80			wait_for_tpm_stat_cond(chip, mask, check_cancel,
 81					       &canceled),
 82			timeout);
 83		if (rc > 0) {
 84			if (canceled)
 85				return -ECANCELED;
 86			return 0;
 87		}
 88		if (rc == -ERESTARTSYS && freezing(current)) {
 89			clear_thread_flag(TIF_SIGPENDING);
 90			goto again;
 91		}
 92	} else {
 93		do {
 94			tpm_msleep(TPM_TIMEOUT);
 95			status = chip->ops->status(chip);
 96			if ((status & mask) == mask)
 97				return 0;
 98		} while (time_before(jiffies, stop));
 99	}
100	return -ETIME;
101}
102
103static u8 vtpm_status(struct tpm_chip *chip)
104{
105	struct tpm_private *priv = dev_get_drvdata(&chip->dev);
106	switch (priv->shr->state) {
107	case VTPM_STATE_IDLE:
108		return VTPM_STATUS_IDLE | VTPM_STATUS_CANCELED;
109	case VTPM_STATE_FINISH:
110		return VTPM_STATUS_IDLE | VTPM_STATUS_RESULT;
111	case VTPM_STATE_SUBMIT:
112	case VTPM_STATE_CANCEL: /* cancel requested, not yet canceled */
113		return VTPM_STATUS_RUNNING;
114	default:
115		return 0;
116	}
117}
118
119static bool vtpm_req_canceled(struct tpm_chip *chip, u8 status)
120{
121	return status & VTPM_STATUS_CANCELED;
122}
123
124static void vtpm_cancel(struct tpm_chip *chip)
125{
126	struct tpm_private *priv = dev_get_drvdata(&chip->dev);
127	priv->shr->state = VTPM_STATE_CANCEL;
128	wmb();
129	notify_remote_via_evtchn(priv->evtchn);
130}
131
132static unsigned int shr_data_offset(struct vtpm_shared_page *shr)
133{
134	return sizeof(*shr) + sizeof(u32) * shr->nr_extra_pages;
135}
136
137static int vtpm_send(struct tpm_chip *chip, u8 *buf, size_t count)
138{
139	struct tpm_private *priv = dev_get_drvdata(&chip->dev);
140	struct vtpm_shared_page *shr = priv->shr;
141	unsigned int offset = shr_data_offset(shr);
142
143	u32 ordinal;
144	unsigned long duration;
145
146	if (offset > PAGE_SIZE)
147		return -EINVAL;
148
149	if (offset + count > PAGE_SIZE)
150		return -EINVAL;
151
152	/* Wait for completion of any existing command or cancellation */
153	if (wait_for_tpm_stat(chip, VTPM_STATUS_IDLE, chip->timeout_c,
154			&priv->read_queue, true) < 0) {
155		vtpm_cancel(chip);
156		return -ETIME;
157	}
158
159	memcpy(offset + (u8 *)shr, buf, count);
160	shr->length = count;
161	barrier();
162	shr->state = VTPM_STATE_SUBMIT;
163	wmb();
164	notify_remote_via_evtchn(priv->evtchn);
165
166	ordinal = be32_to_cpu(((struct tpm_input_header*)buf)->ordinal);
167	duration = tpm_calc_ordinal_duration(chip, ordinal);
168
169	if (wait_for_tpm_stat(chip, VTPM_STATUS_IDLE, duration,
170			&priv->read_queue, true) < 0) {
171		/* got a signal or timeout, try to cancel */
172		vtpm_cancel(chip);
173		return -ETIME;
174	}
175
176	return count;
177}
178
179static int vtpm_recv(struct tpm_chip *chip, u8 *buf, size_t count)
180{
181	struct tpm_private *priv = dev_get_drvdata(&chip->dev);
182	struct vtpm_shared_page *shr = priv->shr;
183	unsigned int offset = shr_data_offset(shr);
184	size_t length = shr->length;
185
186	if (shr->state == VTPM_STATE_IDLE)
187		return -ECANCELED;
188
189	/* In theory the wait at the end of _send makes this one unnecessary */
190	if (wait_for_tpm_stat(chip, VTPM_STATUS_RESULT, chip->timeout_c,
191			&priv->read_queue, true) < 0) {
192		vtpm_cancel(chip);
193		return -ETIME;
194	}
195
196	if (offset > PAGE_SIZE)
197		return -EIO;
198
199	if (offset + length > PAGE_SIZE)
200		length = PAGE_SIZE - offset;
201
202	if (length > count)
203		length = count;
204
205	memcpy(buf, offset + (u8 *)shr, length);
206
207	return length;
208}
209
210static const struct tpm_class_ops tpm_vtpm = {
211	.status = vtpm_status,
212	.recv = vtpm_recv,
213	.send = vtpm_send,
214	.cancel = vtpm_cancel,
215	.req_complete_mask = VTPM_STATUS_IDLE | VTPM_STATUS_RESULT,
216	.req_complete_val  = VTPM_STATUS_IDLE | VTPM_STATUS_RESULT,
217	.req_canceled      = vtpm_req_canceled,
218};
219
220static irqreturn_t tpmif_interrupt(int dummy, void *dev_id)
221{
222	struct tpm_private *priv = dev_id;
223
224	switch (priv->shr->state) {
225	case VTPM_STATE_IDLE:
226	case VTPM_STATE_FINISH:
227		wake_up_interruptible(&priv->read_queue);
228		break;
229	case VTPM_STATE_SUBMIT:
230	case VTPM_STATE_CANCEL:
231	default:
232		break;
233	}
234	return IRQ_HANDLED;
235}
236
237static int setup_chip(struct device *dev, struct tpm_private *priv)
238{
239	struct tpm_chip *chip;
240
241	chip = tpmm_chip_alloc(dev, &tpm_vtpm);
242	if (IS_ERR(chip))
243		return PTR_ERR(chip);
244
245	init_waitqueue_head(&priv->read_queue);
246
247	priv->chip = chip;
248	dev_set_drvdata(&chip->dev, priv);
249
250	return 0;
251}
252
253/* caller must clean up in case of errors */
254static int setup_ring(struct xenbus_device *dev, struct tpm_private *priv)
255{
256	struct xenbus_transaction xbt;
257	const char *message = NULL;
258	int rv;
259	grant_ref_t gref;
260
261	priv->shr = (void *)__get_free_page(GFP_KERNEL|__GFP_ZERO);
262	if (!priv->shr) {
263		xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
264		return -ENOMEM;
265	}
266
267	rv = xenbus_grant_ring(dev, &priv->shr, 1, &gref);
268	if (rv < 0)
269		return rv;
270
271	priv->ring_ref = gref;
272
273	rv = xenbus_alloc_evtchn(dev, &priv->evtchn);
274	if (rv)
275		return rv;
276
277	rv = bind_evtchn_to_irqhandler(priv->evtchn, tpmif_interrupt, 0,
278				       "tpmif", priv);
279	if (rv <= 0) {
280		xenbus_dev_fatal(dev, rv, "allocating TPM irq");
281		return rv;
282	}
283	priv->irq = rv;
284
285 again:
286	rv = xenbus_transaction_start(&xbt);
287	if (rv) {
288		xenbus_dev_fatal(dev, rv, "starting transaction");
289		return rv;
290	}
291
292	rv = xenbus_printf(xbt, dev->nodename,
293			"ring-ref", "%u", priv->ring_ref);
294	if (rv) {
295		message = "writing ring-ref";
296		goto abort_transaction;
297	}
298
299	rv = xenbus_printf(xbt, dev->nodename, "event-channel", "%u",
300			priv->evtchn);
301	if (rv) {
302		message = "writing event-channel";
303		goto abort_transaction;
304	}
305
306	rv = xenbus_printf(xbt, dev->nodename, "feature-protocol-v2", "1");
307	if (rv) {
308		message = "writing feature-protocol-v2";
309		goto abort_transaction;
310	}
311
312	rv = xenbus_transaction_end(xbt, 0);
313	if (rv == -EAGAIN)
314		goto again;
315	if (rv) {
316		xenbus_dev_fatal(dev, rv, "completing transaction");
317		return rv;
318	}
319
320	xenbus_switch_state(dev, XenbusStateInitialised);
321
322	return 0;
323
324 abort_transaction:
325	xenbus_transaction_end(xbt, 1);
326	if (message)
327		xenbus_dev_error(dev, rv, "%s", message);
328
329	return rv;
330}
331
332static void ring_free(struct tpm_private *priv)
333{
334	if (!priv)
335		return;
336
337	if (priv->ring_ref)
338		gnttab_end_foreign_access(priv->ring_ref, 0,
339				(unsigned long)priv->shr);
340	else
341		free_page((unsigned long)priv->shr);
342
343	if (priv->irq)
344		unbind_from_irqhandler(priv->irq, priv);
345
346	kfree(priv);
347}
348
349static int tpmfront_probe(struct xenbus_device *dev,
350		const struct xenbus_device_id *id)
351{
352	struct tpm_private *priv;
353	int rv;
354
355	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
356	if (!priv) {
357		xenbus_dev_fatal(dev, -ENOMEM, "allocating priv structure");
358		return -ENOMEM;
359	}
360
361	rv = setup_chip(&dev->dev, priv);
362	if (rv) {
363		kfree(priv);
364		return rv;
365	}
366
367	rv = setup_ring(dev, priv);
368	if (rv) {
369		ring_free(priv);
370		return rv;
371	}
372
373	tpm_get_timeouts(priv->chip);
374
375	return tpm_chip_register(priv->chip);
376}
377
378static int tpmfront_remove(struct xenbus_device *dev)
379{
380	struct tpm_chip *chip = dev_get_drvdata(&dev->dev);
381	struct tpm_private *priv = dev_get_drvdata(&chip->dev);
382	tpm_chip_unregister(chip);
383	ring_free(priv);
384	dev_set_drvdata(&chip->dev, NULL);
385	return 0;
386}
387
388static int tpmfront_resume(struct xenbus_device *dev)
389{
390	/* A suspend/resume/migrate will interrupt a vTPM anyway */
391	tpmfront_remove(dev);
392	return tpmfront_probe(dev, NULL);
393}
394
395static void backend_changed(struct xenbus_device *dev,
396		enum xenbus_state backend_state)
397{
398	switch (backend_state) {
399	case XenbusStateInitialised:
400	case XenbusStateConnected:
401		if (dev->state == XenbusStateConnected)
402			break;
403
404		if (!xenbus_read_unsigned(dev->otherend, "feature-protocol-v2",
405					  0)) {
406			xenbus_dev_fatal(dev, -EINVAL,
407					"vTPM protocol 2 required");
408			return;
409		}
410		xenbus_switch_state(dev, XenbusStateConnected);
411		break;
412
413	case XenbusStateClosing:
414	case XenbusStateClosed:
415		device_unregister(&dev->dev);
416		xenbus_frontend_closed(dev);
417		break;
418	default:
419		break;
420	}
421}
422
423static const struct xenbus_device_id tpmfront_ids[] = {
424	{ "vtpm" },
425	{ "" }
426};
427MODULE_ALIAS("xen:vtpm");
428
429static struct xenbus_driver tpmfront_driver = {
430	.ids = tpmfront_ids,
431	.probe = tpmfront_probe,
432	.remove = tpmfront_remove,
433	.resume = tpmfront_resume,
434	.otherend_changed = backend_changed,
435};
436
437static int __init xen_tpmfront_init(void)
438{
439	if (!xen_domain())
440		return -ENODEV;
441
442	if (!xen_has_pv_devices())
443		return -ENODEV;
444
445	return xenbus_register_frontend(&tpmfront_driver);
446}
447module_init(xen_tpmfront_init);
448
449static void __exit xen_tpmfront_exit(void)
450{
451	xenbus_unregister_driver(&tpmfront_driver);
452}
453module_exit(xen_tpmfront_exit);
454
455MODULE_AUTHOR("Daniel De Graaf <dgdegra@tycho.nsa.gov>");
456MODULE_DESCRIPTION("Xen vTPM Driver");
457MODULE_LICENSE("GPL");