1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * PCI Backend - Functions for creating a virtual configuration space for
4 * exported PCI Devices.
5 * It's dangerous to allow PCI Driver Domains to change their
6 * device's resources (memory, i/o ports, interrupts). We need to
7 * restrict changes to certain PCI Configuration registers:
8 * BARs, INTERRUPT_PIN, most registers in the header...
9 *
10 * Author: Ryan Wilson <hap9@epoch.ncsc.mil>
11 */
12
13 #include <linux/kernel.h>
14 #include <linux/moduleparam.h>
15 #include <linux/pci.h>
16 #include "pciback.h"
17 #include "conf_space.h"
18 #include "conf_space_quirks.h"
19
20 bool xen_pcibk_permissive;
21 module_param_named(permissive, xen_pcibk_permissive, bool, 0644);
22
23 /* This is where xen_pcibk_read_config_byte, xen_pcibk_read_config_word,
24 * xen_pcibk_write_config_word, and xen_pcibk_write_config_byte are created. */
25 #define DEFINE_PCI_CONFIG(op, size, type) \
26 int xen_pcibk_##op##_config_##size \
27 (struct pci_dev *dev, int offset, type value, void *data) \
28 { \
29 return pci_##op##_config_##size(dev, offset, value); \
30 }
31
DEFINE_PCI_CONFIG(read,byte,u8 *)32 DEFINE_PCI_CONFIG(read, byte, u8 *)
33 DEFINE_PCI_CONFIG(read, word, u16 *)
34 DEFINE_PCI_CONFIG(read, dword, u32 *)
35
36 DEFINE_PCI_CONFIG(write, byte, u8)
37 DEFINE_PCI_CONFIG(write, word, u16)
38 DEFINE_PCI_CONFIG(write, dword, u32)
39
40 static int conf_space_read(struct pci_dev *dev,
41 const struct config_field_entry *entry,
42 int offset, u32 *value)
43 {
44 int ret = 0;
45 const struct config_field *field = entry->field;
46
47 *value = 0;
48
49 switch (field->size) {
50 case 1:
51 if (field->u.b.read)
52 ret = field->u.b.read(dev, offset, (u8 *) value,
53 entry->data);
54 break;
55 case 2:
56 if (field->u.w.read)
57 ret = field->u.w.read(dev, offset, (u16 *) value,
58 entry->data);
59 break;
60 case 4:
61 if (field->u.dw.read)
62 ret = field->u.dw.read(dev, offset, value, entry->data);
63 break;
64 }
65 return ret;
66 }
67
conf_space_write(struct pci_dev * dev,const struct config_field_entry * entry,int offset,u32 value)68 static int conf_space_write(struct pci_dev *dev,
69 const struct config_field_entry *entry,
70 int offset, u32 value)
71 {
72 int ret = 0;
73 const struct config_field *field = entry->field;
74
75 switch (field->size) {
76 case 1:
77 if (field->u.b.write)
78 ret = field->u.b.write(dev, offset, (u8) value,
79 entry->data);
80 break;
81 case 2:
82 if (field->u.w.write)
83 ret = field->u.w.write(dev, offset, (u16) value,
84 entry->data);
85 break;
86 case 4:
87 if (field->u.dw.write)
88 ret = field->u.dw.write(dev, offset, value,
89 entry->data);
90 break;
91 }
92 return ret;
93 }
94
get_mask(int size)95 static inline u32 get_mask(int size)
96 {
97 if (size == 1)
98 return 0xff;
99 else if (size == 2)
100 return 0xffff;
101 else
102 return 0xffffffff;
103 }
104
valid_request(int offset,int size)105 static inline int valid_request(int offset, int size)
106 {
107 /* Validate request (no un-aligned requests) */
108 if ((size == 1 || size == 2 || size == 4) && (offset % size) == 0)
109 return 1;
110 return 0;
111 }
112
merge_value(u32 val,u32 new_val,u32 new_val_mask,int offset)113 static inline u32 merge_value(u32 val, u32 new_val, u32 new_val_mask,
114 int offset)
115 {
116 if (offset >= 0) {
117 new_val_mask <<= (offset * 8);
118 new_val <<= (offset * 8);
119 } else {
120 new_val_mask >>= (offset * -8);
121 new_val >>= (offset * -8);
122 }
123 val = (val & ~new_val_mask) | (new_val & new_val_mask);
124
125 return val;
126 }
127
xen_pcibios_err_to_errno(int err)128 static int xen_pcibios_err_to_errno(int err)
129 {
130 switch (err) {
131 case PCIBIOS_SUCCESSFUL:
132 return XEN_PCI_ERR_success;
133 case PCIBIOS_DEVICE_NOT_FOUND:
134 return XEN_PCI_ERR_dev_not_found;
135 case PCIBIOS_BAD_REGISTER_NUMBER:
136 return XEN_PCI_ERR_invalid_offset;
137 case PCIBIOS_FUNC_NOT_SUPPORTED:
138 return XEN_PCI_ERR_not_implemented;
139 case PCIBIOS_SET_FAILED:
140 return XEN_PCI_ERR_access_denied;
141 }
142 return err;
143 }
144
xen_pcibk_config_read(struct pci_dev * dev,int offset,int size,u32 * ret_val)145 int xen_pcibk_config_read(struct pci_dev *dev, int offset, int size,
146 u32 *ret_val)
147 {
148 int err = 0;
149 struct xen_pcibk_dev_data *dev_data = pci_get_drvdata(dev);
150 const struct config_field_entry *cfg_entry;
151 const struct config_field *field;
152 int field_start, field_end;
153 /* if read fails for any reason, return 0
154 * (as if device didn't respond) */
155 u32 value = 0, tmp_val;
156
157 if (unlikely(verbose_request))
158 printk(KERN_DEBUG DRV_NAME ": %s: read %d bytes at 0x%x\n",
159 pci_name(dev), size, offset);
160
161 if (!valid_request(offset, size)) {
162 err = XEN_PCI_ERR_invalid_offset;
163 goto out;
164 }
165
166 /* Get the real value first, then modify as appropriate */
167 switch (size) {
168 case 1:
169 err = pci_read_config_byte(dev, offset, (u8 *) &value);
170 break;
171 case 2:
172 err = pci_read_config_word(dev, offset, (u16 *) &value);
173 break;
174 case 4:
175 err = pci_read_config_dword(dev, offset, &value);
176 break;
177 }
178
179 list_for_each_entry(cfg_entry, &dev_data->config_fields, list) {
180 field = cfg_entry->field;
181
182 field_start = OFFSET(cfg_entry);
183 field_end = OFFSET(cfg_entry) + field->size;
184
185 if (offset + size > field_start && field_end > offset) {
186 err = conf_space_read(dev, cfg_entry, field_start,
187 &tmp_val);
188 if (err)
189 goto out;
190
191 value = merge_value(value, tmp_val,
192 get_mask(field->size),
193 field_start - offset);
194 }
195 }
196
197 out:
198 if (unlikely(verbose_request))
199 printk(KERN_DEBUG DRV_NAME ": %s: read %d bytes at 0x%x = %x\n",
200 pci_name(dev), size, offset, value);
201
202 *ret_val = value;
203 return xen_pcibios_err_to_errno(err);
204 }
205
xen_pcibk_config_write(struct pci_dev * dev,int offset,int size,u32 value)206 int xen_pcibk_config_write(struct pci_dev *dev, int offset, int size, u32 value)
207 {
208 int err = 0, handled = 0;
209 struct xen_pcibk_dev_data *dev_data = pci_get_drvdata(dev);
210 const struct config_field_entry *cfg_entry;
211 const struct config_field *field;
212 u32 tmp_val;
213 int field_start, field_end;
214
215 if (unlikely(verbose_request))
216 printk(KERN_DEBUG
217 DRV_NAME ": %s: write request %d bytes at 0x%x = %x\n",
218 pci_name(dev), size, offset, value);
219
220 if (!valid_request(offset, size))
221 return XEN_PCI_ERR_invalid_offset;
222
223 list_for_each_entry(cfg_entry, &dev_data->config_fields, list) {
224 field = cfg_entry->field;
225
226 field_start = OFFSET(cfg_entry);
227 field_end = OFFSET(cfg_entry) + field->size;
228
229 if (offset + size > field_start && field_end > offset) {
230 err = conf_space_read(dev, cfg_entry, field_start,
231 &tmp_val);
232 if (err)
233 break;
234
235 tmp_val = merge_value(tmp_val, value, get_mask(size),
236 offset - field_start);
237
238 err = conf_space_write(dev, cfg_entry, field_start,
239 tmp_val);
240
241 /* handled is set true here, but not every byte
242 * may have been written! Properly detecting if
243 * every byte is handled is unnecessary as the
244 * flag is used to detect devices that need
245 * special helpers to work correctly.
246 */
247 handled = 1;
248 }
249 }
250
251 if (!handled && !err) {
252 /* By default, anything not specificially handled above is
253 * read-only. The permissive flag changes this behavior so
254 * that anything not specifically handled above is writable.
255 * This means that some fields may still be read-only because
256 * they have entries in the config_field list that intercept
257 * the write and do nothing. */
258 if (dev_data->permissive || xen_pcibk_permissive) {
259 switch (size) {
260 case 1:
261 err = pci_write_config_byte(dev, offset,
262 (u8) value);
263 break;
264 case 2:
265 err = pci_write_config_word(dev, offset,
266 (u16) value);
267 break;
268 case 4:
269 err = pci_write_config_dword(dev, offset,
270 (u32) value);
271 break;
272 }
273 } else if (!dev_data->warned_on_write) {
274 dev_data->warned_on_write = 1;
275 dev_warn(&dev->dev, "Driver tried to write to a "
276 "read-only configuration space field at offset"
277 " 0x%x, size %d. This may be harmless, but if "
278 "you have problems with your device:\n"
279 "1) see permissive attribute in sysfs\n"
280 "2) report problems to the xen-devel "
281 "mailing list along with details of your "
282 "device obtained from lspci.\n", offset, size);
283 }
284 }
285
286 return xen_pcibios_err_to_errno(err);
287 }
288
xen_pcibk_config_free_dyn_fields(struct pci_dev * dev)289 void xen_pcibk_config_free_dyn_fields(struct pci_dev *dev)
290 {
291 struct xen_pcibk_dev_data *dev_data = pci_get_drvdata(dev);
292 struct config_field_entry *cfg_entry, *t;
293 const struct config_field *field;
294
295 dev_dbg(&dev->dev, "free-ing dynamically allocated virtual "
296 "configuration space fields\n");
297 if (!dev_data)
298 return;
299
300 list_for_each_entry_safe(cfg_entry, t, &dev_data->config_fields, list) {
301 field = cfg_entry->field;
302
303 if (field->clean) {
304 field->clean((struct config_field *)field);
305
306 kfree(cfg_entry->data);
307
308 list_del(&cfg_entry->list);
309 kfree(cfg_entry);
310 }
311
312 }
313 }
314
xen_pcibk_config_reset_dev(struct pci_dev * dev)315 void xen_pcibk_config_reset_dev(struct pci_dev *dev)
316 {
317 struct xen_pcibk_dev_data *dev_data = pci_get_drvdata(dev);
318 const struct config_field_entry *cfg_entry;
319 const struct config_field *field;
320
321 dev_dbg(&dev->dev, "resetting virtual configuration space\n");
322 if (!dev_data)
323 return;
324
325 list_for_each_entry(cfg_entry, &dev_data->config_fields, list) {
326 field = cfg_entry->field;
327
328 if (field->reset)
329 field->reset(dev, OFFSET(cfg_entry), cfg_entry->data);
330 }
331 }
332
xen_pcibk_config_free_dev(struct pci_dev * dev)333 void xen_pcibk_config_free_dev(struct pci_dev *dev)
334 {
335 struct xen_pcibk_dev_data *dev_data = pci_get_drvdata(dev);
336 struct config_field_entry *cfg_entry, *t;
337 const struct config_field *field;
338
339 dev_dbg(&dev->dev, "free-ing virtual configuration space fields\n");
340 if (!dev_data)
341 return;
342
343 list_for_each_entry_safe(cfg_entry, t, &dev_data->config_fields, list) {
344 list_del(&cfg_entry->list);
345
346 field = cfg_entry->field;
347
348 if (field->release)
349 field->release(dev, OFFSET(cfg_entry), cfg_entry->data);
350
351 kfree(cfg_entry);
352 }
353 }
354
xen_pcibk_config_add_field_offset(struct pci_dev * dev,const struct config_field * field,unsigned int base_offset)355 int xen_pcibk_config_add_field_offset(struct pci_dev *dev,
356 const struct config_field *field,
357 unsigned int base_offset)
358 {
359 int err = 0;
360 struct xen_pcibk_dev_data *dev_data = pci_get_drvdata(dev);
361 struct config_field_entry *cfg_entry;
362 void *tmp;
363
364 cfg_entry = kmalloc(sizeof(*cfg_entry), GFP_KERNEL);
365 if (!cfg_entry) {
366 err = -ENOMEM;
367 goto out;
368 }
369
370 cfg_entry->data = NULL;
371 cfg_entry->field = field;
372 cfg_entry->base_offset = base_offset;
373
374 /* silently ignore duplicate fields */
375 err = xen_pcibk_field_is_dup(dev, OFFSET(cfg_entry));
376 if (err)
377 goto out;
378
379 if (field->init) {
380 tmp = field->init(dev, OFFSET(cfg_entry));
381
382 if (IS_ERR(tmp)) {
383 err = PTR_ERR(tmp);
384 goto out;
385 }
386
387 cfg_entry->data = tmp;
388 }
389
390 dev_dbg(&dev->dev, "added config field at offset 0x%02x\n",
391 OFFSET(cfg_entry));
392 list_add_tail(&cfg_entry->list, &dev_data->config_fields);
393
394 out:
395 if (err)
396 kfree(cfg_entry);
397
398 return err;
399 }
400
401 /* This sets up the device's virtual configuration space to keep track of
402 * certain registers (like the base address registers (BARs) so that we can
403 * keep the client from manipulating them directly.
404 */
xen_pcibk_config_init_dev(struct pci_dev * dev)405 int xen_pcibk_config_init_dev(struct pci_dev *dev)
406 {
407 int err = 0;
408 struct xen_pcibk_dev_data *dev_data = pci_get_drvdata(dev);
409
410 dev_dbg(&dev->dev, "initializing virtual configuration space\n");
411
412 INIT_LIST_HEAD(&dev_data->config_fields);
413
414 err = xen_pcibk_config_header_add_fields(dev);
415 if (err)
416 goto out;
417
418 err = xen_pcibk_config_capability_add_fields(dev);
419 if (err)
420 goto out;
421
422 err = xen_pcibk_config_quirks_init(dev);
423
424 out:
425 return err;
426 }
427
xen_pcibk_config_init(void)428 int xen_pcibk_config_init(void)
429 {
430 return xen_pcibk_config_capability_init();
431 }
432