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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> | |
8702c675 | 13 | #include <xen/xen.h> |
e2683957 DDG |
14 | #include <xen/events.h> |
15 | #include <xen/interface/io/tpmif.h> | |
16 | #include <xen/grant_table.h> | |
17 | #include <xen/xenbus.h> | |
18 | #include <xen/page.h> | |
19 | #include "tpm.h" | |
51c71a3b | 20 | #include <xen/platform_pci.h> |
e2683957 DDG |
21 | |
22 | struct tpm_private { | |
23 | struct tpm_chip *chip; | |
24 | struct xenbus_device *dev; | |
25 | ||
26 | struct vtpm_shared_page *shr; | |
27 | ||
28 | unsigned int evtchn; | |
29 | int ring_ref; | |
30 | domid_t backend_id; | |
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 | ||
40 | static u8 vtpm_status(struct tpm_chip *chip) | |
41 | { | |
42 | struct tpm_private *priv = TPM_VPRIV(chip); | |
43 | switch (priv->shr->state) { | |
44 | case VTPM_STATE_IDLE: | |
45 | return VTPM_STATUS_IDLE | VTPM_STATUS_CANCELED; | |
46 | case VTPM_STATE_FINISH: | |
47 | return VTPM_STATUS_IDLE | VTPM_STATUS_RESULT; | |
48 | case VTPM_STATE_SUBMIT: | |
49 | case VTPM_STATE_CANCEL: /* cancel requested, not yet canceled */ | |
50 | return VTPM_STATUS_RUNNING; | |
51 | default: | |
52 | return 0; | |
53 | } | |
54 | } | |
55 | ||
56 | static bool vtpm_req_canceled(struct tpm_chip *chip, u8 status) | |
57 | { | |
58 | return status & VTPM_STATUS_CANCELED; | |
59 | } | |
60 | ||
61 | static void vtpm_cancel(struct tpm_chip *chip) | |
62 | { | |
63 | struct tpm_private *priv = TPM_VPRIV(chip); | |
64 | priv->shr->state = VTPM_STATE_CANCEL; | |
65 | wmb(); | |
66 | notify_remote_via_evtchn(priv->evtchn); | |
67 | } | |
68 | ||
69 | static unsigned int shr_data_offset(struct vtpm_shared_page *shr) | |
70 | { | |
71 | return sizeof(*shr) + sizeof(u32) * shr->nr_extra_pages; | |
72 | } | |
73 | ||
74 | static int vtpm_send(struct tpm_chip *chip, u8 *buf, size_t count) | |
75 | { | |
76 | struct tpm_private *priv = TPM_VPRIV(chip); | |
77 | struct vtpm_shared_page *shr = priv->shr; | |
78 | unsigned int offset = shr_data_offset(shr); | |
79 | ||
80 | u32 ordinal; | |
81 | unsigned long duration; | |
82 | ||
83 | if (offset > PAGE_SIZE) | |
84 | return -EINVAL; | |
85 | ||
86 | if (offset + count > PAGE_SIZE) | |
87 | return -EINVAL; | |
88 | ||
89 | /* Wait for completion of any existing command or cancellation */ | |
90 | if (wait_for_tpm_stat(chip, VTPM_STATUS_IDLE, chip->vendor.timeout_c, | |
91 | &chip->vendor.read_queue, true) < 0) { | |
92 | vtpm_cancel(chip); | |
93 | return -ETIME; | |
94 | } | |
95 | ||
96 | memcpy(offset + (u8 *)shr, buf, count); | |
97 | shr->length = count; | |
98 | barrier(); | |
99 | shr->state = VTPM_STATE_SUBMIT; | |
100 | wmb(); | |
101 | notify_remote_via_evtchn(priv->evtchn); | |
102 | ||
103 | ordinal = be32_to_cpu(((struct tpm_input_header*)buf)->ordinal); | |
104 | duration = tpm_calc_ordinal_duration(chip, ordinal); | |
105 | ||
106 | if (wait_for_tpm_stat(chip, VTPM_STATUS_IDLE, duration, | |
107 | &chip->vendor.read_queue, true) < 0) { | |
108 | /* got a signal or timeout, try to cancel */ | |
109 | vtpm_cancel(chip); | |
110 | return -ETIME; | |
111 | } | |
112 | ||
113 | return count; | |
114 | } | |
115 | ||
116 | static int vtpm_recv(struct tpm_chip *chip, u8 *buf, size_t count) | |
117 | { | |
118 | struct tpm_private *priv = TPM_VPRIV(chip); | |
119 | struct vtpm_shared_page *shr = priv->shr; | |
120 | unsigned int offset = shr_data_offset(shr); | |
121 | size_t length = shr->length; | |
122 | ||
123 | if (shr->state == VTPM_STATE_IDLE) | |
124 | return -ECANCELED; | |
125 | ||
126 | /* In theory the wait at the end of _send makes this one unnecessary */ | |
127 | if (wait_for_tpm_stat(chip, VTPM_STATUS_RESULT, chip->vendor.timeout_c, | |
128 | &chip->vendor.read_queue, true) < 0) { | |
129 | vtpm_cancel(chip); | |
130 | return -ETIME; | |
131 | } | |
132 | ||
133 | if (offset > PAGE_SIZE) | |
134 | return -EIO; | |
135 | ||
136 | if (offset + length > PAGE_SIZE) | |
137 | length = PAGE_SIZE - offset; | |
138 | ||
139 | if (length > count) | |
140 | length = count; | |
141 | ||
142 | memcpy(buf, offset + (u8 *)shr, length); | |
143 | ||
144 | return length; | |
145 | } | |
146 | ||
01ad1fa7 | 147 | static const struct tpm_class_ops tpm_vtpm = { |
e2683957 DDG |
148 | .status = vtpm_status, |
149 | .recv = vtpm_recv, | |
150 | .send = vtpm_send, | |
151 | .cancel = vtpm_cancel, | |
152 | .req_complete_mask = VTPM_STATUS_IDLE | VTPM_STATUS_RESULT, | |
153 | .req_complete_val = VTPM_STATUS_IDLE | VTPM_STATUS_RESULT, | |
154 | .req_canceled = vtpm_req_canceled, | |
e2683957 DDG |
155 | }; |
156 | ||
157 | static irqreturn_t tpmif_interrupt(int dummy, void *dev_id) | |
158 | { | |
159 | struct tpm_private *priv = dev_id; | |
160 | ||
161 | switch (priv->shr->state) { | |
162 | case VTPM_STATE_IDLE: | |
163 | case VTPM_STATE_FINISH: | |
164 | wake_up_interruptible(&priv->chip->vendor.read_queue); | |
165 | break; | |
166 | case VTPM_STATE_SUBMIT: | |
167 | case VTPM_STATE_CANCEL: | |
168 | default: | |
169 | break; | |
170 | } | |
171 | return IRQ_HANDLED; | |
172 | } | |
173 | ||
174 | static int setup_chip(struct device *dev, struct tpm_private *priv) | |
175 | { | |
176 | struct tpm_chip *chip; | |
177 | ||
afb5abc2 JS |
178 | chip = tpmm_chip_alloc(dev, &tpm_vtpm); |
179 | if (IS_ERR(chip)) | |
180 | return PTR_ERR(chip); | |
e2683957 DDG |
181 | |
182 | init_waitqueue_head(&chip->vendor.read_queue); | |
183 | ||
184 | priv->chip = chip; | |
185 | TPM_VPRIV(chip) = priv; | |
186 | ||
187 | return 0; | |
188 | } | |
189 | ||
190 | /* caller must clean up in case of errors */ | |
191 | static int setup_ring(struct xenbus_device *dev, struct tpm_private *priv) | |
192 | { | |
193 | struct xenbus_transaction xbt; | |
194 | const char *message = NULL; | |
195 | int rv; | |
ccc9d90a | 196 | grant_ref_t gref; |
e2683957 DDG |
197 | |
198 | priv->shr = (void *)__get_free_page(GFP_KERNEL|__GFP_ZERO); | |
199 | if (!priv->shr) { | |
200 | xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring"); | |
201 | return -ENOMEM; | |
202 | } | |
203 | ||
ccc9d90a | 204 | rv = xenbus_grant_ring(dev, &priv->shr, 1, &gref); |
e2683957 DDG |
205 | if (rv < 0) |
206 | return rv; | |
207 | ||
ccc9d90a | 208 | priv->ring_ref = gref; |
e2683957 DDG |
209 | |
210 | rv = xenbus_alloc_evtchn(dev, &priv->evtchn); | |
211 | if (rv) | |
212 | return rv; | |
213 | ||
214 | rv = bind_evtchn_to_irqhandler(priv->evtchn, tpmif_interrupt, 0, | |
215 | "tpmif", priv); | |
216 | if (rv <= 0) { | |
217 | xenbus_dev_fatal(dev, rv, "allocating TPM irq"); | |
218 | return rv; | |
219 | } | |
220 | priv->chip->vendor.irq = rv; | |
221 | ||
222 | again: | |
223 | rv = xenbus_transaction_start(&xbt); | |
224 | if (rv) { | |
225 | xenbus_dev_fatal(dev, rv, "starting transaction"); | |
226 | return rv; | |
227 | } | |
228 | ||
229 | rv = xenbus_printf(xbt, dev->nodename, | |
230 | "ring-ref", "%u", priv->ring_ref); | |
231 | if (rv) { | |
232 | message = "writing ring-ref"; | |
233 | goto abort_transaction; | |
234 | } | |
235 | ||
236 | rv = xenbus_printf(xbt, dev->nodename, "event-channel", "%u", | |
237 | priv->evtchn); | |
238 | if (rv) { | |
239 | message = "writing event-channel"; | |
240 | goto abort_transaction; | |
241 | } | |
242 | ||
243 | rv = xenbus_printf(xbt, dev->nodename, "feature-protocol-v2", "1"); | |
244 | if (rv) { | |
245 | message = "writing feature-protocol-v2"; | |
246 | goto abort_transaction; | |
247 | } | |
248 | ||
249 | rv = xenbus_transaction_end(xbt, 0); | |
250 | if (rv == -EAGAIN) | |
251 | goto again; | |
252 | if (rv) { | |
253 | xenbus_dev_fatal(dev, rv, "completing transaction"); | |
254 | return rv; | |
255 | } | |
256 | ||
257 | xenbus_switch_state(dev, XenbusStateInitialised); | |
258 | ||
259 | return 0; | |
260 | ||
261 | abort_transaction: | |
262 | xenbus_transaction_end(xbt, 1); | |
263 | if (message) | |
264 | xenbus_dev_error(dev, rv, "%s", message); | |
265 | ||
266 | return rv; | |
267 | } | |
268 | ||
269 | static void ring_free(struct tpm_private *priv) | |
270 | { | |
271 | if (!priv) | |
272 | return; | |
273 | ||
274 | if (priv->ring_ref) | |
275 | gnttab_end_foreign_access(priv->ring_ref, 0, | |
276 | (unsigned long)priv->shr); | |
277 | else | |
278 | free_page((unsigned long)priv->shr); | |
279 | ||
280 | if (priv->chip && priv->chip->vendor.irq) | |
281 | unbind_from_irqhandler(priv->chip->vendor.irq, priv); | |
282 | ||
283 | kfree(priv); | |
284 | } | |
285 | ||
286 | static int tpmfront_probe(struct xenbus_device *dev, | |
287 | const struct xenbus_device_id *id) | |
288 | { | |
289 | struct tpm_private *priv; | |
afb5abc2 | 290 | struct tpm_chip *chip; |
e2683957 DDG |
291 | int rv; |
292 | ||
293 | priv = kzalloc(sizeof(*priv), GFP_KERNEL); | |
294 | if (!priv) { | |
295 | xenbus_dev_fatal(dev, -ENOMEM, "allocating priv structure"); | |
296 | return -ENOMEM; | |
297 | } | |
298 | ||
299 | rv = setup_chip(&dev->dev, priv); | |
300 | if (rv) { | |
301 | kfree(priv); | |
302 | return rv; | |
303 | } | |
304 | ||
305 | rv = setup_ring(dev, priv); | |
306 | if (rv) { | |
afb5abc2 JS |
307 | chip = dev_get_drvdata(&dev->dev); |
308 | tpm_chip_unregister(chip); | |
e2683957 DDG |
309 | ring_free(priv); |
310 | return rv; | |
311 | } | |
312 | ||
313 | tpm_get_timeouts(priv->chip); | |
314 | ||
afb5abc2 | 315 | return tpm_chip_register(priv->chip); |
e2683957 DDG |
316 | } |
317 | ||
318 | static int tpmfront_remove(struct xenbus_device *dev) | |
319 | { | |
320 | struct tpm_chip *chip = dev_get_drvdata(&dev->dev); | |
321 | struct tpm_private *priv = TPM_VPRIV(chip); | |
afb5abc2 | 322 | tpm_chip_unregister(chip); |
e2683957 DDG |
323 | ring_free(priv); |
324 | TPM_VPRIV(chip) = NULL; | |
325 | return 0; | |
326 | } | |
327 | ||
328 | static int tpmfront_resume(struct xenbus_device *dev) | |
329 | { | |
330 | /* A suspend/resume/migrate will interrupt a vTPM anyway */ | |
331 | tpmfront_remove(dev); | |
332 | return tpmfront_probe(dev, NULL); | |
333 | } | |
334 | ||
335 | static void backend_changed(struct xenbus_device *dev, | |
336 | enum xenbus_state backend_state) | |
337 | { | |
338 | int val; | |
339 | ||
340 | switch (backend_state) { | |
341 | case XenbusStateInitialised: | |
342 | case XenbusStateConnected: | |
343 | if (dev->state == XenbusStateConnected) | |
344 | break; | |
345 | ||
346 | if (xenbus_scanf(XBT_NIL, dev->otherend, | |
347 | "feature-protocol-v2", "%d", &val) < 0) | |
348 | val = 0; | |
349 | if (!val) { | |
350 | xenbus_dev_fatal(dev, -EINVAL, | |
351 | "vTPM protocol 2 required"); | |
352 | return; | |
353 | } | |
354 | xenbus_switch_state(dev, XenbusStateConnected); | |
355 | break; | |
356 | ||
357 | case XenbusStateClosing: | |
358 | case XenbusStateClosed: | |
359 | device_unregister(&dev->dev); | |
360 | xenbus_frontend_closed(dev); | |
361 | break; | |
362 | default: | |
363 | break; | |
364 | } | |
365 | } | |
366 | ||
367 | static const struct xenbus_device_id tpmfront_ids[] = { | |
368 | { "vtpm" }, | |
369 | { "" } | |
370 | }; | |
371 | MODULE_ALIAS("xen:vtpm"); | |
372 | ||
95afae48 DV |
373 | static struct xenbus_driver tpmfront_driver = { |
374 | .ids = tpmfront_ids, | |
375 | .probe = tpmfront_probe, | |
376 | .remove = tpmfront_remove, | |
377 | .resume = tpmfront_resume, | |
378 | .otherend_changed = backend_changed, | |
379 | }; | |
e2683957 DDG |
380 | |
381 | static int __init xen_tpmfront_init(void) | |
382 | { | |
383 | if (!xen_domain()) | |
384 | return -ENODEV; | |
385 | ||
51c71a3b KRW |
386 | if (!xen_has_pv_devices()) |
387 | return -ENODEV; | |
388 | ||
e2683957 DDG |
389 | return xenbus_register_frontend(&tpmfront_driver); |
390 | } | |
391 | module_init(xen_tpmfront_init); | |
392 | ||
393 | static void __exit xen_tpmfront_exit(void) | |
394 | { | |
395 | xenbus_unregister_driver(&tpmfront_driver); | |
396 | } | |
397 | module_exit(xen_tpmfront_exit); | |
398 | ||
399 | MODULE_AUTHOR("Daniel De Graaf <dgdegra@tycho.nsa.gov>"); | |
400 | MODULE_DESCRIPTION("Xen vTPM Driver"); | |
401 | MODULE_LICENSE("GPL"); |