[mirror_ubuntu-jammy-kernel.git] / drivers / char / tpm / xen-tpmfront.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Implementation of the Xen vTPM device frontend
 *
 * Author:  Daniel De Graaf <dgdegra@tycho.nsa.gov>
 */
#include <linux/errno.h>
#include <linux/err.h>
#include <linux/interrupt.h>
#include <linux/freezer.h>
#include <xen/xen.h>
#include <xen/events.h>
#include <xen/interface/io/tpmif.h>
#include <xen/grant_table.h>
#include <xen/xenbus.h>
#include <xen/page.h>
#include "tpm.h"
#include <xen/platform_pci.h>

struct tpm_private {
	struct tpm_chip *chip;
	struct xenbus_device *dev;

	struct vtpm_shared_page *shr;

	unsigned int evtchn;
	int ring_ref;
	domid_t backend_id;
	int irq;
	wait_queue_head_t read_queue;
};

enum status_bits {
	VTPM_STATUS_RUNNING  = 0x1,
	VTPM_STATUS_IDLE     = 0x2,
	VTPM_STATUS_RESULT   = 0x4,
	VTPM_STATUS_CANCELED = 0x8,
};

static bool wait_for_tpm_stat_cond(struct tpm_chip *chip, u8 mask,
					bool check_cancel, bool *canceled)
{
	u8 status = chip->ops->status(chip);

	*canceled = false;
	if ((status & mask) == mask)
		return true;
	if (check_cancel && chip->ops->req_canceled(chip, status)) {
		*canceled = true;
		return true;
	}
	return false;
}

static int wait_for_tpm_stat(struct tpm_chip *chip, u8 mask,
		unsigned long timeout, wait_queue_head_t *queue,
		bool check_cancel)
{
	unsigned long stop;
	long rc;
	u8 status;
	bool canceled = false;

	/* check current status */
	status = chip->ops->status(chip);
	if ((status & mask) == mask)
		return 0;

	stop = jiffies + timeout;

	if (chip->flags & TPM_CHIP_FLAG_IRQ) {
again:
		timeout = stop - jiffies;
		if ((long)timeout <= 0)
			return -ETIME;
		rc = wait_event_interruptible_timeout(*queue,
			wait_for_tpm_stat_cond(chip, mask, check_cancel,
					       &canceled),
			timeout);
		if (rc > 0) {
			if (canceled)
				return -ECANCELED;
			return 0;
		}
		if (rc == -ERESTARTSYS && freezing(current)) {
			clear_thread_flag(TIF_SIGPENDING);
			goto again;
		}
	} else {
		do {
			tpm_msleep(TPM_TIMEOUT);
			status = chip->ops->status(chip);
			if ((status & mask) == mask)
				return 0;
		} while (time_before(jiffies, stop));
	}
	return -ETIME;
}

static u8 vtpm_status(struct tpm_chip *chip)
{
	struct tpm_private *priv = dev_get_drvdata(&chip->dev);
	switch (priv->shr->state) {
	case VTPM_STATE_IDLE:
		return VTPM_STATUS_IDLE | VTPM_STATUS_CANCELED;
	case VTPM_STATE_FINISH:
		return VTPM_STATUS_IDLE | VTPM_STATUS_RESULT;
	case VTPM_STATE_SUBMIT:
	case VTPM_STATE_CANCEL: /* cancel requested, not yet canceled */
		return VTPM_STATUS_RUNNING;
	default:
		return 0;
	}
}

static bool vtpm_req_canceled(struct tpm_chip *chip, u8 status)
{
	return status & VTPM_STATUS_CANCELED;
}

static void vtpm_cancel(struct tpm_chip *chip)
{
	struct tpm_private *priv = dev_get_drvdata(&chip->dev);
	priv->shr->state = VTPM_STATE_CANCEL;
	wmb();
	notify_remote_via_evtchn(priv->evtchn);
}

static unsigned int shr_data_offset(struct vtpm_shared_page *shr)
{
	return sizeof(*shr) + sizeof(u32) * shr->nr_extra_pages;
}

static int vtpm_send(struct tpm_chip *chip, u8 *buf, size_t count)
{
	struct tpm_private *priv = dev_get_drvdata(&chip->dev);
	struct vtpm_shared_page *shr = priv->shr;
	unsigned int offset = shr_data_offset(shr);

	u32 ordinal;
	unsigned long duration;

	if (offset > PAGE_SIZE)
		return -EINVAL;

	if (offset + count > PAGE_SIZE)
		return -EINVAL;

	/* Wait for completion of any existing command or cancellation */
	if (wait_for_tpm_stat(chip, VTPM_STATUS_IDLE, chip->timeout_c,
			&priv->read_queue, true) < 0) {
		vtpm_cancel(chip);
		return -ETIME;
	}

	memcpy(offset + (u8 *)shr, buf, count);
	shr->length = count;
	barrier();
	shr->state = VTPM_STATE_SUBMIT;
	wmb();
	notify_remote_via_evtchn(priv->evtchn);

	ordinal = be32_to_cpu(((struct tpm_header *)buf)->ordinal);
	duration = tpm_calc_ordinal_duration(chip, ordinal);

	if (wait_for_tpm_stat(chip, VTPM_STATUS_IDLE, duration,
			&priv->read_queue, true) < 0) {
		/* got a signal or timeout, try to cancel */
		vtpm_cancel(chip);
		return -ETIME;
	}

	return 0;
}

static int vtpm_recv(struct tpm_chip *chip, u8 *buf, size_t count)
{
	struct tpm_private *priv = dev_get_drvdata(&chip->dev);
	struct vtpm_shared_page *shr = priv->shr;
	unsigned int offset = shr_data_offset(shr);
	size_t length = shr->length;

	if (shr->state == VTPM_STATE_IDLE)
		return -ECANCELED;

	/* In theory the wait at the end of _send makes this one unnecessary */
	if (wait_for_tpm_stat(chip, VTPM_STATUS_RESULT, chip->timeout_c,
			&priv->read_queue, true) < 0) {
		vtpm_cancel(chip);
		return -ETIME;
	}

	if (offset > PAGE_SIZE)
		return -EIO;

	if (offset + length > PAGE_SIZE)
		length = PAGE_SIZE - offset;

	if (length > count)
		length = count;

	memcpy(buf, offset + (u8 *)shr, length);

	return length;
}

static const struct tpm_class_ops tpm_vtpm = {
	.status = vtpm_status,
	.recv = vtpm_recv,
	.send = vtpm_send,
	.cancel = vtpm_cancel,
	.req_complete_mask = VTPM_STATUS_IDLE | VTPM_STATUS_RESULT,
	.req_complete_val  = VTPM_STATUS_IDLE | VTPM_STATUS_RESULT,
	.req_canceled      = vtpm_req_canceled,
};

static irqreturn_t tpmif_interrupt(int dummy, void *dev_id)
{
	struct tpm_private *priv = dev_id;

	switch (priv->shr->state) {
	case VTPM_STATE_IDLE:
	case VTPM_STATE_FINISH:
		wake_up_interruptible(&priv->read_queue);
		break;
	case VTPM_STATE_SUBMIT:
	case VTPM_STATE_CANCEL:
	default:
		break;
	}
	return IRQ_HANDLED;
}

static int setup_chip(struct device *dev, struct tpm_private *priv)
{
	struct tpm_chip *chip;

	chip = tpmm_chip_alloc(dev, &tpm_vtpm);
	if (IS_ERR(chip))
		return PTR_ERR(chip);

	init_waitqueue_head(&priv->read_queue);

	priv->chip = chip;
	dev_set_drvdata(&chip->dev, priv);

	return 0;
}

/* caller must clean up in case of errors */
static int setup_ring(struct xenbus_device *dev, struct tpm_private *priv)
{
	struct xenbus_transaction xbt;
	const char *message = NULL;
	int rv;
	grant_ref_t gref;

	priv->shr = (void *)__get_free_page(GFP_KERNEL|__GFP_ZERO);
	if (!priv->shr) {
		xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
		return -ENOMEM;
	}

	rv = xenbus_grant_ring(dev, priv->shr, 1, &gref);
	if (rv < 0)
		return rv;

	priv->ring_ref = gref;

	rv = xenbus_alloc_evtchn(dev, &priv->evtchn);
	if (rv)
		return rv;

	rv = bind_evtchn_to_irqhandler(priv->evtchn, tpmif_interrupt, 0,
				       "tpmif", priv);
	if (rv <= 0) {
		xenbus_dev_fatal(dev, rv, "allocating TPM irq");
		return rv;
	}
	priv->irq = rv;

 again:
	rv = xenbus_transaction_start(&xbt);
	if (rv) {
		xenbus_dev_fatal(dev, rv, "starting transaction");
		return rv;
	}

	rv = xenbus_printf(xbt, dev->nodename,
			"ring-ref", "%u", priv->ring_ref);
	if (rv) {
		message = "writing ring-ref";
		goto abort_transaction;
	}

	rv = xenbus_printf(xbt, dev->nodename, "event-channel", "%u",
			priv->evtchn);
	if (rv) {
		message = "writing event-channel";
		goto abort_transaction;
	}

	rv = xenbus_printf(xbt, dev->nodename, "feature-protocol-v2", "1");
	if (rv) {
		message = "writing feature-protocol-v2";
		goto abort_transaction;
	}

	rv = xenbus_transaction_end(xbt, 0);
	if (rv == -EAGAIN)
		goto again;
	if (rv) {
		xenbus_dev_fatal(dev, rv, "completing transaction");
		return rv;
	}

	xenbus_switch_state(dev, XenbusStateInitialised);

	return 0;

 abort_transaction:
	xenbus_transaction_end(xbt, 1);
	if (message)
		xenbus_dev_error(dev, rv, "%s", message);

	return rv;
}

static void ring_free(struct tpm_private *priv)
{
	if (!priv)
		return;

	if (priv->ring_ref)
		gnttab_end_foreign_access(priv->ring_ref, 0,
				(unsigned long)priv->shr);
	else
		free_page((unsigned long)priv->shr);

	if (priv->irq)
		unbind_from_irqhandler(priv->irq, priv);

	kfree(priv);
}

static int tpmfront_probe(struct xenbus_device *dev,
		const struct xenbus_device_id *id)
{
	struct tpm_private *priv;
	int rv;

	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
	if (!priv) {
		xenbus_dev_fatal(dev, -ENOMEM, "allocating priv structure");
		return -ENOMEM;
	}

	rv = setup_chip(&dev->dev, priv);
	if (rv) {
		kfree(priv);
		return rv;
	}

	rv = setup_ring(dev, priv);
	if (rv) {
		ring_free(priv);
		return rv;
	}

	tpm_get_timeouts(priv->chip);

	return tpm_chip_register(priv->chip);
}

static int tpmfront_remove(struct xenbus_device *dev)
{
	struct tpm_chip *chip = dev_get_drvdata(&dev->dev);
	struct tpm_private *priv = dev_get_drvdata(&chip->dev);
	tpm_chip_unregister(chip);
	ring_free(priv);
	dev_set_drvdata(&chip->dev, NULL);
	return 0;
}

static int tpmfront_resume(struct xenbus_device *dev)
{
	/* A suspend/resume/migrate will interrupt a vTPM anyway */
	tpmfront_remove(dev);
	return tpmfront_probe(dev, NULL);
}

static void backend_changed(struct xenbus_device *dev,
		enum xenbus_state backend_state)
{
	switch (backend_state) {
	case XenbusStateInitialised:
	case XenbusStateConnected:
		if (dev->state == XenbusStateConnected)
			break;

		if (!xenbus_read_unsigned(dev->otherend, "feature-protocol-v2",
					  0)) {
			xenbus_dev_fatal(dev, -EINVAL,
					"vTPM protocol 2 required");
			return;
		}
		xenbus_switch_state(dev, XenbusStateConnected);
		break;

	case XenbusStateClosing:
	case XenbusStateClosed:
		device_unregister(&dev->dev);
		xenbus_frontend_closed(dev);
		break;
	default:
		break;
	}
}

static const struct xenbus_device_id tpmfront_ids[] = {
	{ "vtpm" },
	{ "" }
};
MODULE_ALIAS("xen:vtpm");

static struct xenbus_driver tpmfront_driver = {
	.ids = tpmfront_ids,
	.probe = tpmfront_probe,
	.remove = tpmfront_remove,
	.resume = tpmfront_resume,
	.otherend_changed = backend_changed,
};

static int __init xen_tpmfront_init(void)
{
	if (!xen_domain())
		return -ENODEV;

	if (!xen_has_pv_devices())
		return -ENODEV;

	return xenbus_register_frontend(&tpmfront_driver);
}
module_init(xen_tpmfront_init);

static void __exit xen_tpmfront_exit(void)
{
	xenbus_unregister_driver(&tpmfront_driver);
}
module_exit(xen_tpmfront_exit);

MODULE_AUTHOR("Daniel De Graaf <dgdegra@tycho.nsa.gov>");
MODULE_DESCRIPTION("Xen vTPM Driver");
MODULE_LICENSE("GPL");
Commit	Line	Data
d2912cb1	1	// SPDX-License-Identifier: GPL-2.0-only
e2683957 DDG	2	/*
	3	* Implementation of the Xen vTPM device frontend
	4	*
	5	* Author: Daniel De Graaf <dgdegra@tycho.nsa.gov>
e2683957 DDG	6	*/
	7	#include <linux/errno.h>
	8	#include <linux/err.h>
	9	#include <linux/interrupt.h>
87cdfdd1	10	#include <linux/freezer.h>
8702c675	11	#include <xen/xen.h>
e2683957 DDG	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"
51c71a3b	18	#include <xen/platform_pci.h>
e2683957 DDG	19
	20	struct 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;
570a3609	29	int irq;
6e599f6f	30	wait_queue_head_t read_queue;
e2683957 DDG	31	};
	32
	33	enum status_bits {
	34	VTPM_STATUS_RUNNING = 0x1,
	35	VTPM_STATUS_IDLE = 0x2,
	36	VTPM_STATUS_RESULT = 0x4,
	37	VTPM_STATUS_CANCELED = 0x8,
	38	};
	39
87cdfdd1 NJ	40	static 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
	55	static 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) {
	72	again:
	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
e2683957 DDG	100	static u8 vtpm_status(struct tpm_chip *chip)
e2683957 DDG	101	{
9e0d39d8	102	struct tpm_private *priv = dev_get_drvdata(&chip->dev);
e2683957 DDG	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
	116	static bool vtpm_req_canceled(struct tpm_chip *chip, u8 status)
	117	{
	118	return status & VTPM_STATUS_CANCELED;
	119	}
	120
	121	static void vtpm_cancel(struct tpm_chip *chip)
	122	{
9e0d39d8	123	struct tpm_private *priv = dev_get_drvdata(&chip->dev);
e2683957 DDG	124	priv->shr->state = VTPM_STATE_CANCEL;
	125	wmb();
	126	notify_remote_via_evtchn(priv->evtchn);
	127	}
	128
	129	static unsigned int shr_data_offset(struct vtpm_shared_page *shr)
	130	{
	131	return sizeof(shr) + sizeof(u32) shr->nr_extra_pages;
	132	}
	133
	134	static int vtpm_send(struct tpm_chip chip, u8 buf, size_t count)
	135	{
9e0d39d8	136	struct tpm_private *priv = dev_get_drvdata(&chip->dev);
e2683957 DDG	137	struct vtpm_shared_page *shr = priv->shr;
	138	unsigned int 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 */
af782f33	150	if (wait_for_tpm_stat(chip, VTPM_STATUS_IDLE, chip->timeout_c,
6e599f6f	151	&priv->read_queue, true) < 0) {
e2683957 DDG	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
b34b77a9	163	ordinal = be32_to_cpu(((struct tpm_header *)buf)->ordinal);
e2683957 DDG	164	duration = tpm_calc_ordinal_duration(chip, ordinal);
	165
	166	if (wait_for_tpm_stat(chip, VTPM_STATUS_IDLE, duration,
6e599f6f	167	&priv->read_queue, true) < 0) {
e2683957 DDG	168	/* got a signal or timeout, try to cancel */
	169	vtpm_cancel(chip);
	170	return -ETIME;
	171	}
	172
f5595f5b	173	return 0;
e2683957 DDG	174	}
	175
	176	static int vtpm_recv(struct tpm_chip chip, u8 buf, size_t count)
	177	{
9e0d39d8	178	struct tpm_private *priv = dev_get_drvdata(&chip->dev);
e2683957 DDG	179	struct vtpm_shared_page *shr = priv->shr;
	180	unsigned int 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 */
af782f33	187	if (wait_for_tpm_stat(chip, VTPM_STATUS_RESULT, chip->timeout_c,
6e599f6f	188	&priv->read_queue, true) < 0) {
e2683957 DDG	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
01ad1fa7	207	static const struct tpm_class_ops tpm_vtpm = {
e2683957 DDG	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,
e2683957 DDG	215	};
	216
	217	static 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:
6e599f6f	224	wake_up_interruptible(&priv->read_queue);
e2683957 DDG	225	break;
	226	case VTPM_STATE_SUBMIT:
	227	case VTPM_STATE_CANCEL:
	228	default:
	229	break;
	230	}
	231	return IRQ_HANDLED;
	232	}
	233
	234	static int setup_chip(struct device dev, struct tpm_private priv)
	235	{
	236	struct tpm_chip *chip;
	237
afb5abc2 JS	238	chip = tpmm_chip_alloc(dev, &tpm_vtpm);
	239	if (IS_ERR(chip))
	240	return PTR_ERR(chip);
e2683957	241
6e599f6f	242	init_waitqueue_head(&priv->read_queue);
e2683957 DDG	243
e2683957 DDG	244	priv->chip = chip;
9e0d39d8	245	dev_set_drvdata(&chip->dev, priv);
e2683957 DDG	246
	247	return 0;
	248	}
	249
	250	/* caller must clean up in case of errors */
	251	static 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;
ccc9d90a	256	grant_ref_t gref;
e2683957 DDG	257
	258	priv->shr = (void *)__get_free_page(GFP_KERNEL\|__GFP_ZERO);
	259	if (!priv->shr) {
	260	xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
	261	return -ENOMEM;
	262	}
	263
e487a0f5	264	rv = xenbus_grant_ring(dev, priv->shr, 1, &gref);
e2683957 DDG	265	if (rv < 0)
	266	return rv;
	267
ccc9d90a	268	priv->ring_ref = gref;
e2683957 DDG	269
	270	rv = xenbus_alloc_evtchn(dev, &priv->evtchn);
	271	if (rv)
	272	return rv;
	273
	274	rv = bind_evtchn_to_irqhandler(priv->evtchn, tpmif_interrupt, 0,
	275	"tpmif", priv);
	276	if (rv <= 0) {
	277	xenbus_dev_fatal(dev, rv, "allocating TPM irq");
	278	return rv;
	279	}
570a3609	280	priv->irq = rv;
e2683957 DDG	281
	282	again:
	283	rv = xenbus_transaction_start(&xbt);
	284	if (rv) {
	285	xenbus_dev_fatal(dev, rv, "starting transaction");
	286	return rv;
	287	}
	288
	289	rv = xenbus_printf(xbt, dev->nodename,
	290	"ring-ref", "%u", priv->ring_ref);
	291	if (rv) {
	292	message = "writing ring-ref";
	293	goto abort_transaction;
	294	}
	295
	296	rv = xenbus_printf(xbt, dev->nodename, "event-channel", "%u",
	297	priv->evtchn);
	298	if (rv) {
	299	message = "writing event-channel";
	300	goto abort_transaction;
	301	}
	302
	303	rv = xenbus_printf(xbt, dev->nodename, "feature-protocol-v2", "1");
	304	if (rv) {
	305	message = "writing feature-protocol-v2";
	306	goto abort_transaction;
	307	}
	308
	309	rv = xenbus_transaction_end(xbt, 0);
	310	if (rv == -EAGAIN)
	311	goto again;
	312	if (rv) {
	313	xenbus_dev_fatal(dev, rv, "completing transaction");
	314	return rv;
	315	}
	316
	317	xenbus_switch_state(dev, XenbusStateInitialised);
	318
	319	return 0;
	320
	321	abort_transaction:
	322	xenbus_transaction_end(xbt, 1);
	323	if (message)
	324	xenbus_dev_error(dev, rv, "%s", message);
	325
	326	return rv;
	327	}
	328
	329	static void ring_free(struct tpm_private *priv)
	330	{
	331	if (!priv)
	332	return;
	333
	334	if (priv->ring_ref)
	335	gnttab_end_foreign_access(priv->ring_ref, 0,
	336	(unsigned long)priv->shr);
	337	else
	338	free_page((unsigned long)priv->shr);
	339
570a3609 CR	340	if (priv->irq)
570a3609 CR	341	unbind_from_irqhandler(priv->irq, priv);
e2683957 DDG	342
	343	kfree(priv);
	344	}
	345
	346	static int tpmfront_probe(struct xenbus_device *dev,
	347	const struct xenbus_device_id *id)
	348	{
	349	struct tpm_private *priv;
	350	int rv;
	351
	352	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
	353	if (!priv) {
	354	xenbus_dev_fatal(dev, -ENOMEM, "allocating priv structure");
	355	return -ENOMEM;
	356	}
	357
	358	rv = setup_chip(&dev->dev, priv);
	359	if (rv) {
	360	kfree(priv);
	361	return rv;
	362	}
	363
	364	rv = setup_ring(dev, priv);
	365	if (rv) {
e2683957 DDG	366	ring_free(priv);
	367	return rv;
	368	}
	369
	370	tpm_get_timeouts(priv->chip);
	371
afb5abc2	372	return tpm_chip_register(priv->chip);
e2683957 DDG	373	}
	374
	375	static int tpmfront_remove(struct xenbus_device *dev)
	376	{
	377	struct tpm_chip *chip = dev_get_drvdata(&dev->dev);
9e0d39d8	378	struct tpm_private *priv = dev_get_drvdata(&chip->dev);
afb5abc2	379	tpm_chip_unregister(chip);
e2683957	380	ring_free(priv);
9e0d39d8	381	dev_set_drvdata(&chip->dev, NULL);
e2683957 DDG	382	return 0;
	383	}
	384
	385	static int tpmfront_resume(struct xenbus_device *dev)
	386	{
	387	/* A suspend/resume/migrate will interrupt a vTPM anyway */
	388	tpmfront_remove(dev);
	389	return tpmfront_probe(dev, NULL);
	390	}
	391
	392	static void backend_changed(struct xenbus_device *dev,
	393	enum xenbus_state backend_state)
	394	{
e2683957 DDG	395	switch (backend_state) {
	396	case XenbusStateInitialised:
	397	case XenbusStateConnected:
	398	if (dev->state == XenbusStateConnected)
	399	break;
	400
02409334 JG	401	if (!xenbus_read_unsigned(dev->otherend, "feature-protocol-v2",
02409334 JG	402	0)) {
e2683957 DDG	403	xenbus_dev_fatal(dev, -EINVAL,
	404	"vTPM protocol 2 required");
	405	return;
	406	}
	407	xenbus_switch_state(dev, XenbusStateConnected);
	408	break;
	409
	410	case XenbusStateClosing:
	411	case XenbusStateClosed:
	412	device_unregister(&dev->dev);
	413	xenbus_frontend_closed(dev);
	414	break;
	415	default:
	416	break;
	417	}
	418	}
	419
	420	static const struct xenbus_device_id tpmfront_ids[] = {
	421	{ "vtpm" },
	422	{ "" }
	423	};
	424	MODULE_ALIAS("xen:vtpm");
	425
95afae48 DV	426	static struct xenbus_driver tpmfront_driver = {
	427	.ids = tpmfront_ids,
	428	.probe = tpmfront_probe,
	429	.remove = tpmfront_remove,
	430	.resume = tpmfront_resume,
	431	.otherend_changed = backend_changed,
	432	};
e2683957 DDG	433
	434	static int __init xen_tpmfront_init(void)
	435	{
	436	if (!xen_domain())
	437	return -ENODEV;
	438
51c71a3b KRW	439	if (!xen_has_pv_devices())
	440	return -ENODEV;
	441
e2683957 DDG	442	return xenbus_register_frontend(&tpmfront_driver);
	443	}
	444	module_init(xen_tpmfront_init);
	445
	446	static void __exit xen_tpmfront_exit(void)
	447	{
	448	xenbus_unregister_driver(&tpmfront_driver);
	449	}
	450	module_exit(xen_tpmfront_exit);
	451
	452	MODULE_AUTHOR("Daniel De Graaf <dgdegra@tycho.nsa.gov>");
	453	MODULE_DESCRIPTION("Xen vTPM Driver");
	454	MODULE_LICENSE("GPL");