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

/*
 * Implementation of the Xen vTPM device frontend
 *
 * Author:  Daniel De Graaf <dgdegra@tycho.nsa.gov>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2,
 * as published by the Free Software Foundation.
 */
#include <linux/errno.h>
#include <linux/err.h>
#include <linux/interrupt.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"

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;
};

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

static u8 vtpm_status(struct tpm_chip *chip)
{
	struct tpm_private *priv = TPM_VPRIV(chip);
	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 = TPM_VPRIV(chip);
	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 = TPM_VPRIV(chip);
	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->vendor.timeout_c,
			&chip->vendor.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_input_header*)buf)->ordinal);
	duration = tpm_calc_ordinal_duration(chip, ordinal);

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

	return count;
}

static int vtpm_recv(struct tpm_chip *chip, u8 *buf, size_t count)
{
	struct tpm_private *priv = TPM_VPRIV(chip);
	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->vendor.timeout_c,
			&chip->vendor.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;
}

ssize_t tpm_show_locality(struct device *dev, struct device_attribute *attr,
			  char *buf)
{
	struct tpm_chip *chip = dev_get_drvdata(dev);
	struct tpm_private *priv = TPM_VPRIV(chip);
	u8 locality = priv->shr->locality;

	return sprintf(buf, "%d\n", locality);
}

ssize_t tpm_store_locality(struct device *dev, struct device_attribute *attr,
			const char *buf, size_t len)
{
	struct tpm_chip *chip = dev_get_drvdata(dev);
	struct tpm_private *priv = TPM_VPRIV(chip);
	u8 val;

	int rv = kstrtou8(buf, 0, &val);
	if (rv)
		return rv;

	priv->shr->locality = val;

	return len;
}

static const struct file_operations vtpm_ops = {
	.owner = THIS_MODULE,
	.llseek = no_llseek,
	.open = tpm_open,
	.read = tpm_read,
	.write = tpm_write,
	.release = tpm_release,
};

static DEVICE_ATTR(pubek, S_IRUGO, tpm_show_pubek, NULL);
static DEVICE_ATTR(pcrs, S_IRUGO, tpm_show_pcrs, NULL);
static DEVICE_ATTR(enabled, S_IRUGO, tpm_show_enabled, NULL);
static DEVICE_ATTR(active, S_IRUGO, tpm_show_active, NULL);
static DEVICE_ATTR(owned, S_IRUGO, tpm_show_owned, NULL);
static DEVICE_ATTR(temp_deactivated, S_IRUGO, tpm_show_temp_deactivated,
		NULL);
static DEVICE_ATTR(caps, S_IRUGO, tpm_show_caps, NULL);
static DEVICE_ATTR(cancel, S_IWUSR | S_IWGRP, NULL, tpm_store_cancel);
static DEVICE_ATTR(durations, S_IRUGO, tpm_show_durations, NULL);
static DEVICE_ATTR(timeouts, S_IRUGO, tpm_show_timeouts, NULL);
static DEVICE_ATTR(locality, S_IRUGO | S_IWUSR, tpm_show_locality,
		tpm_store_locality);

static struct attribute *vtpm_attrs[] = {
	&dev_attr_pubek.attr,
	&dev_attr_pcrs.attr,
	&dev_attr_enabled.attr,
	&dev_attr_active.attr,
	&dev_attr_owned.attr,
	&dev_attr_temp_deactivated.attr,
	&dev_attr_caps.attr,
	&dev_attr_cancel.attr,
	&dev_attr_durations.attr,
	&dev_attr_timeouts.attr,
	&dev_attr_locality.attr,
	NULL,
};

static struct attribute_group vtpm_attr_grp = {
	.attrs = vtpm_attrs,
};

#define TPM_LONG_TIMEOUT   (10 * 60 * HZ)

static const struct tpm_vendor_specific 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,
	.attr_group = &vtpm_attr_grp,
	.miscdev = {
		.fops = &vtpm_ops,
	},
	.duration = {
		TPM_LONG_TIMEOUT,
		TPM_LONG_TIMEOUT,
		TPM_LONG_TIMEOUT,
	},
};

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->chip->vendor.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 = tpm_register_hardware(dev, &tpm_vtpm);
	if (!chip)
		return -ENODEV;

	init_waitqueue_head(&chip->vendor.read_queue);

	priv->chip = chip;
	TPM_VPRIV(chip) = 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;

	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, virt_to_mfn(priv->shr));
	if (rv < 0)
		return rv;

	priv->ring_ref = rv;

	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->chip->vendor.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->chip && priv->chip->vendor.irq)
		unbind_from_irqhandler(priv->chip->vendor.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) {
		tpm_remove_hardware(&dev->dev);
		ring_free(priv);
		return rv;
	}

	tpm_get_timeouts(priv->chip);

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

	return rv;
}

static int tpmfront_remove(struct xenbus_device *dev)
{
	struct tpm_chip *chip = dev_get_drvdata(&dev->dev);
	struct tpm_private *priv = TPM_VPRIV(chip);
	tpm_remove_hardware(&dev->dev);
	ring_free(priv);
	TPM_VPRIV(chip) = 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)
{
	int val;

	switch (backend_state) {
	case XenbusStateInitialised:
	case XenbusStateConnected:
		if (dev->state == XenbusStateConnected)
			break;

		if (xenbus_scanf(XBT_NIL, dev->otherend,
				"feature-protocol-v2", "%d", &val) < 0)
			val = 0;
		if (!val) {
			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 DEFINE_XENBUS_DRIVER(tpmfront, ,
		.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;

	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
e2683957 DDG	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 <xen/events.h>
	14	#include <xen/interface/io/tpmif.h>
	15	#include <xen/grant_table.h>
	16	#include <xen/xenbus.h>
	17	#include <xen/page.h>
	18	#include "tpm.h"
	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;
	29	};
	30
	31	enum status_bits {
	32	VTPM_STATUS_RUNNING = 0x1,
	33	VTPM_STATUS_IDLE = 0x2,
	34	VTPM_STATUS_RESULT = 0x4,
	35	VTPM_STATUS_CANCELED = 0x8,
	36	};
	37
	38	static u8 vtpm_status(struct tpm_chip *chip)
	39	{
	40	struct tpm_private *priv = TPM_VPRIV(chip);
	41	switch (priv->shr->state) {
	42	case VTPM_STATE_IDLE:
	43	return VTPM_STATUS_IDLE \| VTPM_STATUS_CANCELED;
	44	case VTPM_STATE_FINISH:
	45	return VTPM_STATUS_IDLE \| VTPM_STATUS_RESULT;
	46	case VTPM_STATE_SUBMIT:
	47	case VTPM_STATE_CANCEL: /* cancel requested, not yet canceled */
	48	return VTPM_STATUS_RUNNING;
	49	default:
	50	return 0;
	51	}
	52	}
	53
	54	static bool vtpm_req_canceled(struct tpm_chip *chip, u8 status)
	55	{
	56	return status & VTPM_STATUS_CANCELED;
	57	}
	58
	59	static void vtpm_cancel(struct tpm_chip *chip)
	60	{
	61	struct tpm_private *priv = TPM_VPRIV(chip);
	62	priv->shr->state = VTPM_STATE_CANCEL;
	63	wmb();
	64	notify_remote_via_evtchn(priv->evtchn);
65	}
66
67	static unsigned int shr_data_offset(struct vtpm_shared_page *shr)
68	{
69	return sizeof(shr) + sizeof(u32) shr->nr_extra_pages;
70	}
71
72	static int vtpm_send(struct tpm_chip chip, u8 buf, size_t count)
73	{
74	struct tpm_private *priv = TPM_VPRIV(chip);
75	struct vtpm_shared_page *shr = priv->shr;
76	unsigned int offset = shr_data_offset(shr);
77
78	u32 ordinal;
79	unsigned long duration;
80
81	if (offset > PAGE_SIZE)
82	return -EINVAL;
83
84	if (offset + count > PAGE_SIZE)
85	return -EINVAL;
86
87	/* Wait for completion of any existing command or cancellation */
88	if (wait_for_tpm_stat(chip, VTPM_STATUS_IDLE, chip->vendor.timeout_c,
89	&chip->vendor.read_queue, true) < 0) {
90	vtpm_cancel(chip);
91	return -ETIME;
92	}
93
94	memcpy(offset + (u8 *)shr, buf, count);
95	shr->length = count;
96	barrier();
97	shr->state = VTPM_STATE_SUBMIT;
98	wmb();
99	notify_remote_via_evtchn(priv->evtchn);
100
101	ordinal = be32_to_cpu(((struct tpm_input_header*)buf)->ordinal);
102	duration = tpm_calc_ordinal_duration(chip, ordinal);
103
104	if (wait_for_tpm_stat(chip, VTPM_STATUS_IDLE, duration,
105	&chip->vendor.read_queue, true) < 0) {
106	/* got a signal or timeout, try to cancel */
107	vtpm_cancel(chip);
108	return -ETIME;
109	}
110
111	return count;
112	}
113
114	static int vtpm_recv(struct tpm_chip chip, u8 buf, size_t count)
115	{
116	struct tpm_private *priv = TPM_VPRIV(chip);
117	struct vtpm_shared_page *shr = priv->shr;
118	unsigned int offset = shr_data_offset(shr);
119	size_t length = shr->length;
120
121	if (shr->state == VTPM_STATE_IDLE)
122	return -ECANCELED;
123
124	/* In theory the wait at the end of _send makes this one unnecessary */
125	if (wait_for_tpm_stat(chip, VTPM_STATUS_RESULT, chip->vendor.timeout_c,
126	&chip->vendor.read_queue, true) < 0) {
127	vtpm_cancel(chip);
128	return -ETIME;
129	}
130
131	if (offset > PAGE_SIZE)
132	return -EIO;
133
134	if (offset + length > PAGE_SIZE)
135	length = PAGE_SIZE - offset;
136
137	if (length > count)
138	length = count;
139
140	memcpy(buf, offset + (u8 *)shr, length);
141
142	return length;
143	}
144
145	ssize_t tpm_show_locality(struct device dev, struct device_attribute attr,
146	char *buf)
147	{
148	struct tpm_chip *chip = dev_get_drvdata(dev);
149	struct tpm_private *priv = TPM_VPRIV(chip);
150	u8 locality = priv->shr->locality;
151
152	return sprintf(buf, "%d\n", locality);
153	}
154
155	ssize_t tpm_store_locality(struct device dev, struct device_attribute attr,
156	const char *buf, size_t len)
157	{
158	struct tpm_chip *chip = dev_get_drvdata(dev);
159	struct tpm_private *priv = TPM_VPRIV(chip);
160	u8 val;
161
162	int rv = kstrtou8(buf, 0, &val);
163	if (rv)
164	return rv;
165
166	priv->shr->locality = val;
167
168	return len;
169	}
170
171	static const struct file_operations vtpm_ops = {
172	.owner = THIS_MODULE,
173	.llseek = no_llseek,
174	.open = tpm_open,
175	.read = tpm_read,
176	.write = tpm_write,
177	.release = tpm_release,
178	};
179
180	static DEVICE_ATTR(pubek, S_IRUGO, tpm_show_pubek, NULL);
181	static DEVICE_ATTR(pcrs, S_IRUGO, tpm_show_pcrs, NULL);
182	static DEVICE_ATTR(enabled, S_IRUGO, tpm_show_enabled, NULL);
183	static DEVICE_ATTR(active, S_IRUGO, tpm_show_active, NULL);
184	static DEVICE_ATTR(owned, S_IRUGO, tpm_show_owned, NULL);
185	static DEVICE_ATTR(temp_deactivated, S_IRUGO, tpm_show_temp_deactivated,
186	NULL);
187	static DEVICE_ATTR(caps, S_IRUGO, tpm_show_caps, NULL);
188	static DEVICE_ATTR(cancel, S_IWUSR \| S_IWGRP, NULL, tpm_store_cancel);
189	static DEVICE_ATTR(durations, S_IRUGO, tpm_show_durations, NULL);
190	static DEVICE_ATTR(timeouts, S_IRUGO, tpm_show_timeouts, NULL);
191	static DEVICE_ATTR(locality, S_IRUGO \| S_IWUSR, tpm_show_locality,
192	tpm_store_locality);
193
194	static struct attribute *vtpm_attrs[] = {
195	&dev_attr_pubek.attr,
196	&dev_attr_pcrs.attr,
197	&dev_attr_enabled.attr,
198	&dev_attr_active.attr,
199	&dev_attr_owned.attr,
200	&dev_attr_temp_deactivated.attr,
201	&dev_attr_caps.attr,
202	&dev_attr_cancel.attr,
203	&dev_attr_durations.attr,
204	&dev_attr_timeouts.attr,
205	&dev_attr_locality.attr,
206	NULL,
207	};
208
209	static struct attribute_group vtpm_attr_grp = {
210	.attrs = vtpm_attrs,
211	};
212
213	#define TPM_LONG_TIMEOUT (10 * 60 * HZ)
214
215	static const struct tpm_vendor_specific tpm_vtpm = {
216	.status = vtpm_status,
217	.recv = vtpm_recv,
218	.send = vtpm_send,
219	.cancel = vtpm_cancel,
220	.req_complete_mask = VTPM_STATUS_IDLE \| VTPM_STATUS_RESULT,
221	.req_complete_val = VTPM_STATUS_IDLE \| VTPM_STATUS_RESULT,
222	.req_canceled = vtpm_req_canceled,
223	.attr_group = &vtpm_attr_grp,
224	.miscdev = {
225	.fops = &vtpm_ops,
226	},
227	.duration = {
228	TPM_LONG_TIMEOUT,
229	TPM_LONG_TIMEOUT,
230	TPM_LONG_TIMEOUT,
231	},
232	};
233
234	static irqreturn_t tpmif_interrupt(int dummy, void *dev_id)
235	{
236	struct tpm_private *priv = dev_id;
237
238	switch (priv->shr->state) {
239	case VTPM_STATE_IDLE:
240	case VTPM_STATE_FINISH:
241	wake_up_interruptible(&priv->chip->vendor.read_queue);
242	break;
243	case VTPM_STATE_SUBMIT:
244	case VTPM_STATE_CANCEL:
245	default:
246	break;
247	}
248	return IRQ_HANDLED;
249	}
250
251	static int setup_chip(struct device dev, struct tpm_private priv)
252	{
253	struct tpm_chip *chip;
254
255	chip = tpm_register_hardware(dev, &tpm_vtpm);
256	if (!chip)
257	return -ENODEV;
258
259	init_waitqueue_head(&chip->vendor.read_queue);
260
261	priv->chip = chip;
262	TPM_VPRIV(chip) = priv;
263
264	return 0;
265	}
266
267	/* caller must clean up in case of errors */
268	static int setup_ring(struct xenbus_device dev, struct tpm_private priv)
269	{
270	struct xenbus_transaction xbt;
271	const char *message = NULL;
272	int rv;
273
274	priv->shr = (void *)__get_free_page(GFP_KERNEL\|__GFP_ZERO);
275	if (!priv->shr) {
276	xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
277	return -ENOMEM;
278	}
279
280	rv = xenbus_grant_ring(dev, virt_to_mfn(priv->shr));
281	if (rv < 0)
282	return rv;
283
284	priv->ring_ref = rv;
285
286	rv = xenbus_alloc_evtchn(dev, &priv->evtchn);
287	if (rv)
288	return rv;
289
290	rv = bind_evtchn_to_irqhandler(priv->evtchn, tpmif_interrupt, 0,
291	"tpmif", priv);
292	if (rv <= 0) {
293	xenbus_dev_fatal(dev, rv, "allocating TPM irq");
294	return rv;
295	}
296	priv->chip->vendor.irq = rv;
297
298	again:
299	rv = xenbus_transaction_start(&xbt);
300	if (rv) {
301	xenbus_dev_fatal(dev, rv, "starting transaction");
302	return rv;
303	}
304
305	rv = xenbus_printf(xbt, dev->nodename,
306	"ring-ref", "%u", priv->ring_ref);
307	if (rv) {
308	message = "writing ring-ref";
309	goto abort_transaction;
310	}
311
312	rv = xenbus_printf(xbt, dev->nodename, "event-channel", "%u",
313	priv->evtchn);
314	if (rv) {
315	message = "writing event-channel";
316	goto abort_transaction;
317	}
318
319	rv = xenbus_printf(xbt, dev->nodename, "feature-protocol-v2", "1");
320	if (rv) {
321	message = "writing feature-protocol-v2";
322	goto abort_transaction;
323	}
324
325	rv = xenbus_transaction_end(xbt, 0);
326	if (rv == -EAGAIN)
327	goto again;
328	if (rv) {
329	xenbus_dev_fatal(dev, rv, "completing transaction");
330	return rv;
331	}
332
333	xenbus_switch_state(dev, XenbusStateInitialised);
334
335	return 0;
336
337	abort_transaction:
338	xenbus_transaction_end(xbt, 1);
339	if (message)
340	xenbus_dev_error(dev, rv, "%s", message);
341
342	return rv;
343	}
344
345	static void ring_free(struct tpm_private *priv)
346	{
347	if (!priv)
348	return;
349
350	if (priv->ring_ref)
351	gnttab_end_foreign_access(priv->ring_ref, 0,
352	(unsigned long)priv->shr);
353	else
354	free_page((unsigned long)priv->shr);
355
356	if (priv->chip && priv->chip->vendor.irq)
357	unbind_from_irqhandler(priv->chip->vendor.irq, priv);
358
359	kfree(priv);
360	}
361
362	static int tpmfront_probe(struct xenbus_device *dev,
363	const struct xenbus_device_id *id)
364	{
365	struct tpm_private *priv;
366	int rv;
367
368	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
369	if (!priv) {
370	xenbus_dev_fatal(dev, -ENOMEM, "allocating priv structure");
371	return -ENOMEM;
372	}
373
374	rv = setup_chip(&dev->dev, priv);
375	if (rv) {
376	kfree(priv);
377	return rv;
378	}
379
380	rv = setup_ring(dev, priv);
381	if (rv) {
382	tpm_remove_hardware(&dev->dev);
383	ring_free(priv);
384	return rv;
385	}
386
387	tpm_get_timeouts(priv->chip);
388
389	dev_set_drvdata(&dev->dev, priv->chip);
390
391	return rv;
392	}
393
394	static int tpmfront_remove(struct xenbus_device *dev)
395	{
396	struct tpm_chip *chip = dev_get_drvdata(&dev->dev);
397	struct tpm_private *priv = TPM_VPRIV(chip);
398	tpm_remove_hardware(&dev->dev);
399	ring_free(priv);
400	TPM_VPRIV(chip) = NULL;
401	return 0;
402	}
403
404	static int tpmfront_resume(struct xenbus_device *dev)
405	{
406	/* A suspend/resume/migrate will interrupt a vTPM anyway */
407	tpmfront_remove(dev);
408	return tpmfront_probe(dev, NULL);
409	}
410
411	static void backend_changed(struct xenbus_device *dev,
412	enum xenbus_state backend_state)
413	{
414	int val;
415
416	switch (backend_state) {
417	case XenbusStateInitialised:
418	case XenbusStateConnected:
419	if (dev->state == XenbusStateConnected)
420	break;
421
422	if (xenbus_scanf(XBT_NIL, dev->otherend,
423	"feature-protocol-v2", "%d", &val) < 0)
424	val = 0;
425	if (!val) {
426	xenbus_dev_fatal(dev, -EINVAL,
427	"vTPM protocol 2 required");
428	return;
429	}
430	xenbus_switch_state(dev, XenbusStateConnected);
431	break;
432
433	case XenbusStateClosing:
434	case XenbusStateClosed:
435	device_unregister(&dev->dev);
436	xenbus_frontend_closed(dev);
437	break;
438	default:
439	break;
440	}
441	}
442
443	static const struct xenbus_device_id tpmfront_ids[] = {
444	{ "vtpm" },
445	{ "" }
446	};
447	MODULE_ALIAS("xen:vtpm");
448
449	static DEFINE_XENBUS_DRIVER(tpmfront, ,
450	.probe = tpmfront_probe,
451	.remove = tpmfront_remove,
452	.resume = tpmfront_resume,
453	.otherend_changed = backend_changed,
454	);
455
456	static int __init xen_tpmfront_init(void)
457	{
458	if (!xen_domain())
459	return -ENODEV;
460
461	return xenbus_register_frontend(&tpmfront_driver);
462	}
463	module_init(xen_tpmfront_init);
464
465	static void __exit xen_tpmfront_exit(void)
466	{
467	xenbus_unregister_driver(&tpmfront_driver);
468	}
469	module_exit(xen_tpmfront_exit);
470
471	MODULE_AUTHOR("Daniel De Graaf <dgdegra@tycho.nsa.gov>");
472	MODULE_DESCRIPTION("Xen vTPM Driver");
473	MODULE_LICENSE("GPL");