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52916982 LG |
1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* | |
3 | * PCI Peer 2 Peer DMA support. | |
4 | * | |
5 | * Copyright (c) 2016-2018, Logan Gunthorpe | |
6 | * Copyright (c) 2016-2017, Microsemi Corporation | |
7 | * Copyright (c) 2017, Christoph Hellwig | |
8 | * Copyright (c) 2018, Eideticom Inc. | |
9 | */ | |
10 | ||
2d7bc010 LG |
11 | #define pr_fmt(fmt) "pci-p2pdma: " fmt |
12 | #include <linux/ctype.h> | |
52916982 LG |
13 | #include <linux/pci-p2pdma.h> |
14 | #include <linux/module.h> | |
15 | #include <linux/slab.h> | |
16 | #include <linux/genalloc.h> | |
17 | #include <linux/memremap.h> | |
18 | #include <linux/percpu-refcount.h> | |
19 | #include <linux/random.h> | |
20 | #include <linux/seq_buf.h> | |
110203be | 21 | #include <linux/xarray.h> |
52916982 | 22 | |
72583084 LG |
23 | enum pci_p2pdma_map_type { |
24 | PCI_P2PDMA_MAP_UNKNOWN = 0, | |
25 | PCI_P2PDMA_MAP_NOT_SUPPORTED, | |
26 | PCI_P2PDMA_MAP_BUS_ADDR, | |
27 | PCI_P2PDMA_MAP_THRU_HOST_BRIDGE, | |
28 | }; | |
29 | ||
52916982 | 30 | struct pci_p2pdma { |
52916982 LG |
31 | struct gen_pool *pool; |
32 | bool p2pmem_published; | |
110203be | 33 | struct xarray map_types; |
52916982 LG |
34 | }; |
35 | ||
a6e6fe65 LG |
36 | struct pci_p2pdma_pagemap { |
37 | struct dev_pagemap pgmap; | |
0afea381 | 38 | struct pci_dev *provider; |
a6e6fe65 LG |
39 | u64 bus_offset; |
40 | }; | |
41 | ||
42 | static struct pci_p2pdma_pagemap *to_p2p_pgmap(struct dev_pagemap *pgmap) | |
43 | { | |
44 | return container_of(pgmap, struct pci_p2pdma_pagemap, pgmap); | |
45 | } | |
46 | ||
cbb8ca69 LG |
47 | static ssize_t size_show(struct device *dev, struct device_attribute *attr, |
48 | char *buf) | |
49 | { | |
50 | struct pci_dev *pdev = to_pci_dev(dev); | |
ae21f835 | 51 | struct pci_p2pdma *p2pdma; |
cbb8ca69 LG |
52 | size_t size = 0; |
53 | ||
ae21f835 ED |
54 | rcu_read_lock(); |
55 | p2pdma = rcu_dereference(pdev->p2pdma); | |
56 | if (p2pdma && p2pdma->pool) | |
57 | size = gen_pool_size(p2pdma->pool); | |
58 | rcu_read_unlock(); | |
cbb8ca69 | 59 | |
f8cf6e51 | 60 | return sysfs_emit(buf, "%zd\n", size); |
cbb8ca69 LG |
61 | } |
62 | static DEVICE_ATTR_RO(size); | |
63 | ||
64 | static ssize_t available_show(struct device *dev, struct device_attribute *attr, | |
65 | char *buf) | |
66 | { | |
67 | struct pci_dev *pdev = to_pci_dev(dev); | |
ae21f835 | 68 | struct pci_p2pdma *p2pdma; |
cbb8ca69 LG |
69 | size_t avail = 0; |
70 | ||
ae21f835 ED |
71 | rcu_read_lock(); |
72 | p2pdma = rcu_dereference(pdev->p2pdma); | |
73 | if (p2pdma && p2pdma->pool) | |
74 | avail = gen_pool_avail(p2pdma->pool); | |
75 | rcu_read_unlock(); | |
cbb8ca69 | 76 | |
f8cf6e51 | 77 | return sysfs_emit(buf, "%zd\n", avail); |
cbb8ca69 LG |
78 | } |
79 | static DEVICE_ATTR_RO(available); | |
80 | ||
81 | static ssize_t published_show(struct device *dev, struct device_attribute *attr, | |
82 | char *buf) | |
83 | { | |
84 | struct pci_dev *pdev = to_pci_dev(dev); | |
ae21f835 ED |
85 | struct pci_p2pdma *p2pdma; |
86 | bool published = false; | |
87 | ||
88 | rcu_read_lock(); | |
89 | p2pdma = rcu_dereference(pdev->p2pdma); | |
90 | if (p2pdma) | |
91 | published = p2pdma->p2pmem_published; | |
92 | rcu_read_unlock(); | |
cbb8ca69 | 93 | |
71327000 | 94 | return sysfs_emit(buf, "%d\n", published); |
cbb8ca69 LG |
95 | } |
96 | static DEVICE_ATTR_RO(published); | |
97 | ||
98 | static struct attribute *p2pmem_attrs[] = { | |
99 | &dev_attr_size.attr, | |
100 | &dev_attr_available.attr, | |
101 | &dev_attr_published.attr, | |
102 | NULL, | |
103 | }; | |
104 | ||
105 | static const struct attribute_group p2pmem_group = { | |
106 | .attrs = p2pmem_attrs, | |
107 | .name = "p2pmem", | |
108 | }; | |
109 | ||
52916982 LG |
110 | static void pci_p2pdma_release(void *data) |
111 | { | |
112 | struct pci_dev *pdev = data; | |
ae21f835 | 113 | struct pci_p2pdma *p2pdma; |
52916982 | 114 | |
ae21f835 | 115 | p2pdma = rcu_dereference_protected(pdev->p2pdma, 1); |
1570175a | 116 | if (!p2pdma) |
52916982 LG |
117 | return; |
118 | ||
1570175a DW |
119 | /* Flush and disable pci_alloc_p2p_mem() */ |
120 | pdev->p2pdma = NULL; | |
121 | synchronize_rcu(); | |
52916982 | 122 | |
1570175a | 123 | gen_pool_destroy(p2pdma->pool); |
cbb8ca69 | 124 | sysfs_remove_group(&pdev->dev.kobj, &p2pmem_group); |
110203be | 125 | xa_destroy(&p2pdma->map_types); |
52916982 LG |
126 | } |
127 | ||
128 | static int pci_p2pdma_setup(struct pci_dev *pdev) | |
129 | { | |
130 | int error = -ENOMEM; | |
131 | struct pci_p2pdma *p2p; | |
132 | ||
133 | p2p = devm_kzalloc(&pdev->dev, sizeof(*p2p), GFP_KERNEL); | |
134 | if (!p2p) | |
135 | return -ENOMEM; | |
136 | ||
110203be LG |
137 | xa_init(&p2p->map_types); |
138 | ||
52916982 LG |
139 | p2p->pool = gen_pool_create(PAGE_SHIFT, dev_to_node(&pdev->dev)); |
140 | if (!p2p->pool) | |
141 | goto out; | |
142 | ||
52916982 LG |
143 | error = devm_add_action_or_reset(&pdev->dev, pci_p2pdma_release, pdev); |
144 | if (error) | |
145 | goto out_pool_destroy; | |
146 | ||
cbb8ca69 LG |
147 | error = sysfs_create_group(&pdev->dev.kobj, &p2pmem_group); |
148 | if (error) | |
149 | goto out_pool_destroy; | |
150 | ||
ae21f835 | 151 | rcu_assign_pointer(pdev->p2pdma, p2p); |
52916982 LG |
152 | return 0; |
153 | ||
154 | out_pool_destroy: | |
155 | gen_pool_destroy(p2p->pool); | |
156 | out: | |
157 | devm_kfree(&pdev->dev, p2p); | |
158 | return error; | |
159 | } | |
160 | ||
161 | /** | |
162 | * pci_p2pdma_add_resource - add memory for use as p2p memory | |
163 | * @pdev: the device to add the memory to | |
164 | * @bar: PCI BAR to add | |
165 | * @size: size of the memory to add, may be zero to use the whole BAR | |
166 | * @offset: offset into the PCI BAR | |
167 | * | |
168 | * The memory will be given ZONE_DEVICE struct pages so that it may | |
169 | * be used with any DMA request. | |
170 | */ | |
171 | int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar, size_t size, | |
172 | u64 offset) | |
173 | { | |
a6e6fe65 | 174 | struct pci_p2pdma_pagemap *p2p_pgmap; |
52916982 | 175 | struct dev_pagemap *pgmap; |
ae21f835 | 176 | struct pci_p2pdma *p2pdma; |
52916982 LG |
177 | void *addr; |
178 | int error; | |
179 | ||
180 | if (!(pci_resource_flags(pdev, bar) & IORESOURCE_MEM)) | |
181 | return -EINVAL; | |
182 | ||
183 | if (offset >= pci_resource_len(pdev, bar)) | |
184 | return -EINVAL; | |
185 | ||
186 | if (!size) | |
187 | size = pci_resource_len(pdev, bar) - offset; | |
188 | ||
189 | if (size + offset > pci_resource_len(pdev, bar)) | |
190 | return -EINVAL; | |
191 | ||
192 | if (!pdev->p2pdma) { | |
193 | error = pci_p2pdma_setup(pdev); | |
194 | if (error) | |
195 | return error; | |
196 | } | |
197 | ||
a6e6fe65 LG |
198 | p2p_pgmap = devm_kzalloc(&pdev->dev, sizeof(*p2p_pgmap), GFP_KERNEL); |
199 | if (!p2p_pgmap) | |
52916982 | 200 | return -ENOMEM; |
a6e6fe65 LG |
201 | |
202 | pgmap = &p2p_pgmap->pgmap; | |
a4574f63 DW |
203 | pgmap->range.start = pci_resource_start(pdev, bar) + offset; |
204 | pgmap->range.end = pgmap->range.start + size - 1; | |
b7b3c01b | 205 | pgmap->nr_range = 1; |
52916982 | 206 | pgmap->type = MEMORY_DEVICE_PCI_P2PDMA; |
a6e6fe65 | 207 | |
0afea381 | 208 | p2p_pgmap->provider = pdev; |
a6e6fe65 | 209 | p2p_pgmap->bus_offset = pci_bus_address(pdev, bar) - |
977196b8 | 210 | pci_resource_start(pdev, bar); |
52916982 LG |
211 | |
212 | addr = devm_memremap_pages(&pdev->dev, pgmap); | |
213 | if (IS_ERR(addr)) { | |
214 | error = PTR_ERR(addr); | |
50f44ee7 | 215 | goto pgmap_free; |
52916982 LG |
216 | } |
217 | ||
ae21f835 ED |
218 | p2pdma = rcu_dereference_protected(pdev->p2pdma, 1); |
219 | error = gen_pool_add_owner(p2pdma->pool, (unsigned long)addr, | |
52916982 | 220 | pci_bus_address(pdev, bar) + offset, |
a4574f63 | 221 | range_len(&pgmap->range), dev_to_node(&pdev->dev), |
d0b3517d | 222 | pgmap->ref); |
52916982 | 223 | if (error) |
e615a191 | 224 | goto pages_free; |
52916982 | 225 | |
a4574f63 DW |
226 | pci_info(pdev, "added peer-to-peer DMA memory %#llx-%#llx\n", |
227 | pgmap->range.start, pgmap->range.end); | |
52916982 LG |
228 | |
229 | return 0; | |
230 | ||
e615a191 DW |
231 | pages_free: |
232 | devm_memunmap_pages(&pdev->dev, pgmap); | |
52916982 | 233 | pgmap_free: |
d0b3517d | 234 | devm_kfree(&pdev->dev, pgmap); |
52916982 LG |
235 | return error; |
236 | } | |
237 | EXPORT_SYMBOL_GPL(pci_p2pdma_add_resource); | |
238 | ||
239 | /* | |
240 | * Note this function returns the parent PCI device with a | |
f6b6aefe | 241 | * reference taken. It is the caller's responsibility to drop |
52916982 LG |
242 | * the reference. |
243 | */ | |
244 | static struct pci_dev *find_parent_pci_dev(struct device *dev) | |
245 | { | |
246 | struct device *parent; | |
247 | ||
248 | dev = get_device(dev); | |
249 | ||
250 | while (dev) { | |
251 | if (dev_is_pci(dev)) | |
252 | return to_pci_dev(dev); | |
253 | ||
254 | parent = get_device(dev->parent); | |
255 | put_device(dev); | |
256 | dev = parent; | |
257 | } | |
258 | ||
259 | return NULL; | |
260 | } | |
261 | ||
262 | /* | |
263 | * Check if a PCI bridge has its ACS redirection bits set to redirect P2P | |
264 | * TLPs upstream via ACS. Returns 1 if the packets will be redirected | |
265 | * upstream, 0 otherwise. | |
266 | */ | |
267 | static int pci_bridge_has_acs_redir(struct pci_dev *pdev) | |
268 | { | |
269 | int pos; | |
270 | u16 ctrl; | |
271 | ||
52fbf5bd | 272 | pos = pdev->acs_cap; |
52916982 LG |
273 | if (!pos) |
274 | return 0; | |
275 | ||
276 | pci_read_config_word(pdev, pos + PCI_ACS_CTRL, &ctrl); | |
277 | ||
278 | if (ctrl & (PCI_ACS_RR | PCI_ACS_CR | PCI_ACS_EC)) | |
279 | return 1; | |
280 | ||
281 | return 0; | |
282 | } | |
283 | ||
284 | static void seq_buf_print_bus_devfn(struct seq_buf *buf, struct pci_dev *pdev) | |
285 | { | |
286 | if (!buf) | |
287 | return; | |
288 | ||
289 | seq_buf_printf(buf, "%s;", pci_name(pdev)); | |
290 | } | |
291 | ||
dea286bb LG |
292 | static bool cpu_supports_p2pdma(void) |
293 | { | |
294 | #ifdef CONFIG_X86 | |
295 | struct cpuinfo_x86 *c = &cpu_data(0); | |
296 | ||
297 | /* Any AMD CPU whose family ID is Zen or newer supports p2pdma */ | |
298 | if (c->x86_vendor == X86_VENDOR_AMD && c->x86 >= 0x17) | |
299 | return true; | |
300 | #endif | |
301 | ||
302 | return false; | |
303 | } | |
304 | ||
494d63b0 LG |
305 | static const struct pci_p2pdma_whitelist_entry { |
306 | unsigned short vendor; | |
307 | unsigned short device; | |
308 | enum { | |
309 | REQ_SAME_HOST_BRIDGE = 1 << 0, | |
310 | } flags; | |
311 | } pci_p2pdma_whitelist[] = { | |
494d63b0 LG |
312 | /* Intel Xeon E5/Core i7 */ |
313 | {PCI_VENDOR_ID_INTEL, 0x3c00, REQ_SAME_HOST_BRIDGE}, | |
314 | {PCI_VENDOR_ID_INTEL, 0x3c01, REQ_SAME_HOST_BRIDGE}, | |
315 | /* Intel Xeon E7 v3/Xeon E5 v3/Core i7 */ | |
316 | {PCI_VENDOR_ID_INTEL, 0x2f00, REQ_SAME_HOST_BRIDGE}, | |
317 | {PCI_VENDOR_ID_INTEL, 0x2f01, REQ_SAME_HOST_BRIDGE}, | |
bc123a51 AB |
318 | /* Intel SkyLake-E */ |
319 | {PCI_VENDOR_ID_INTEL, 0x2030, 0}, | |
7b94b53d AM |
320 | {PCI_VENDOR_ID_INTEL, 0x2031, 0}, |
321 | {PCI_VENDOR_ID_INTEL, 0x2032, 0}, | |
322 | {PCI_VENDOR_ID_INTEL, 0x2033, 0}, | |
bc123a51 | 323 | {PCI_VENDOR_ID_INTEL, 0x2020, 0}, |
494d63b0 LG |
324 | {} |
325 | }; | |
326 | ||
3ec0c3ec LG |
327 | /* |
328 | * This lookup function tries to find the PCI device corresponding to a given | |
329 | * host bridge. | |
330 | * | |
331 | * It assumes the host bridge device is the first PCI device in the | |
332 | * bus->devices list and that the devfn is 00.0. These assumptions should hold | |
333 | * for all the devices in the whitelist above. | |
334 | * | |
335 | * This function is equivalent to pci_get_slot(host->bus, 0), however it does | |
336 | * not take the pci_bus_sem lock seeing __host_bridge_whitelist() must not | |
337 | * sleep. | |
338 | * | |
339 | * For this to be safe, the caller should hold a reference to a device on the | |
340 | * bridge, which should ensure the host_bridge device will not be freed | |
341 | * or removed from the head of the devices list. | |
342 | */ | |
343 | static struct pci_dev *pci_host_bridge_dev(struct pci_host_bridge *host) | |
344 | { | |
345 | struct pci_dev *root; | |
346 | ||
347 | root = list_first_entry_or_null(&host->bus->devices, | |
348 | struct pci_dev, bus_list); | |
349 | ||
350 | if (!root) | |
351 | return NULL; | |
352 | if (root->devfn != PCI_DEVFN(0, 0)) | |
353 | return NULL; | |
354 | ||
355 | return root; | |
356 | } | |
357 | ||
494d63b0 | 358 | static bool __host_bridge_whitelist(struct pci_host_bridge *host, |
cf201bfe | 359 | bool same_host_bridge, bool warn) |
0f97da83 | 360 | { |
3ec0c3ec | 361 | struct pci_dev *root = pci_host_bridge_dev(host); |
494d63b0 | 362 | const struct pci_p2pdma_whitelist_entry *entry; |
0f97da83 CK |
363 | unsigned short vendor, device; |
364 | ||
365 | if (!root) | |
366 | return false; | |
367 | ||
368 | vendor = root->vendor; | |
369 | device = root->device; | |
0f97da83 | 370 | |
494d63b0 LG |
371 | for (entry = pci_p2pdma_whitelist; entry->vendor; entry++) { |
372 | if (vendor != entry->vendor || device != entry->device) | |
373 | continue; | |
374 | if (entry->flags & REQ_SAME_HOST_BRIDGE && !same_host_bridge) | |
375 | return false; | |
376 | ||
0f97da83 | 377 | return true; |
494d63b0 | 378 | } |
0f97da83 | 379 | |
cf201bfe LG |
380 | if (warn) |
381 | pci_warn(root, "Host bridge not in P2PDMA whitelist: %04x:%04x\n", | |
382 | vendor, device); | |
383 | ||
0f97da83 CK |
384 | return false; |
385 | } | |
386 | ||
2c84d818 LG |
387 | /* |
388 | * If we can't find a common upstream bridge take a look at the root | |
389 | * complex and compare it to a whitelist of known good hardware. | |
390 | */ | |
cf201bfe LG |
391 | static bool host_bridge_whitelist(struct pci_dev *a, struct pci_dev *b, |
392 | bool warn) | |
2c84d818 LG |
393 | { |
394 | struct pci_host_bridge *host_a = pci_find_host_bridge(a->bus); | |
395 | struct pci_host_bridge *host_b = pci_find_host_bridge(b->bus); | |
396 | ||
494d63b0 | 397 | if (host_a == host_b) |
cf201bfe | 398 | return __host_bridge_whitelist(host_a, true, warn); |
494d63b0 | 399 | |
cf201bfe LG |
400 | if (__host_bridge_whitelist(host_a, false, warn) && |
401 | __host_bridge_whitelist(host_b, false, warn)) | |
2c84d818 LG |
402 | return true; |
403 | ||
404 | return false; | |
405 | } | |
406 | ||
110203be LG |
407 | static unsigned long map_types_idx(struct pci_dev *client) |
408 | { | |
409 | return (pci_domain_nr(client->bus) << 16) | | |
410 | (client->bus->number << 8) | client->devfn; | |
411 | } | |
412 | ||
c6bfaeb5 | 413 | /* |
6389d437 | 414 | * Calculate the P2PDMA mapping type and distance between two PCI devices. |
c6bfaeb5 | 415 | * |
6389d437 LG |
416 | * If the two devices are the same PCI function, return |
417 | * PCI_P2PDMA_MAP_BUS_ADDR and a distance of 0. | |
c6bfaeb5 | 418 | * |
6389d437 LG |
419 | * If they are two functions of the same device, return |
420 | * PCI_P2PDMA_MAP_BUS_ADDR and a distance of 2 (one hop up to the bridge, | |
421 | * then one hop back down to another function of the same device). | |
c6bfaeb5 | 422 | * |
6389d437 LG |
423 | * In the case where two devices are connected to the same PCIe switch, |
424 | * return a distance of 4. This corresponds to the following PCI tree: | |
c6bfaeb5 LG |
425 | * |
426 | * -+ Root Port | |
427 | * \+ Switch Upstream Port | |
6389d437 | 428 | * +-+ Switch Downstream Port 0 |
c6bfaeb5 | 429 | * + \- Device A |
6389d437 | 430 | * \-+ Switch Downstream Port 1 |
c6bfaeb5 LG |
431 | * \- Device B |
432 | * | |
6389d437 LG |
433 | * The distance is 4 because we traverse from Device A to Downstream Port 0 |
434 | * to the common Switch Upstream Port, back down to Downstream Port 1 and | |
435 | * then to Device B. The mapping type returned depends on the ACS | |
436 | * redirection setting of the ports along the path. | |
c6bfaeb5 | 437 | * |
6389d437 LG |
438 | * If ACS redirect is set on any port in the path, traffic between the |
439 | * devices will go through the host bridge, so return | |
440 | * PCI_P2PDMA_MAP_THRU_HOST_BRIDGE; otherwise return | |
441 | * PCI_P2PDMA_MAP_BUS_ADDR. | |
c6bfaeb5 LG |
442 | * |
443 | * Any two devices that have a data path that goes through the host bridge | |
6389d437 LG |
444 | * will consult a whitelist. If the host bridge is in the whitelist, return |
445 | * PCI_P2PDMA_MAP_THRU_HOST_BRIDGE with the distance set to the number of | |
446 | * ports per above. If the device is not in the whitelist, return | |
c6bfaeb5 | 447 | * PCI_P2PDMA_MAP_NOT_SUPPORTED. |
c6bfaeb5 LG |
448 | */ |
449 | static enum pci_p2pdma_map_type | |
6389d437 | 450 | calc_map_type_and_dist(struct pci_dev *provider, struct pci_dev *client, |
d1b8dc09 | 451 | int *dist, bool verbose) |
c6bfaeb5 | 452 | { |
d1b8dc09 CH |
453 | enum pci_p2pdma_map_type map_type = PCI_P2PDMA_MAP_THRU_HOST_BRIDGE; |
454 | struct pci_dev *a = provider, *b = client, *bb; | |
455 | bool acs_redirects = false; | |
ae21f835 | 456 | struct pci_p2pdma *p2pdma; |
d1b8dc09 CH |
457 | struct seq_buf acs_list; |
458 | int acs_cnt = 0; | |
459 | int dist_a = 0; | |
460 | int dist_b = 0; | |
461 | char buf[128]; | |
462 | ||
463 | seq_buf_init(&acs_list, buf, sizeof(buf)); | |
464 | ||
465 | /* | |
466 | * Note, we don't need to take references to devices returned by | |
467 | * pci_upstream_bridge() seeing we hold a reference to a child | |
468 | * device which will already hold a reference to the upstream bridge. | |
469 | */ | |
470 | while (a) { | |
471 | dist_b = 0; | |
472 | ||
473 | if (pci_bridge_has_acs_redir(a)) { | |
474 | seq_buf_print_bus_devfn(&acs_list, a); | |
475 | acs_cnt++; | |
476 | } | |
477 | ||
478 | bb = b; | |
e2cbfbf7 | 479 | |
d1b8dc09 CH |
480 | while (bb) { |
481 | if (a == bb) | |
482 | goto check_b_path_acs; | |
e2cbfbf7 | 483 | |
d1b8dc09 CH |
484 | bb = pci_upstream_bridge(bb); |
485 | dist_b++; | |
486 | } | |
487 | ||
488 | a = pci_upstream_bridge(a); | |
489 | dist_a++; | |
e2cbfbf7 LG |
490 | } |
491 | ||
d1b8dc09 CH |
492 | *dist = dist_a + dist_b; |
493 | goto map_through_host_bridge; | |
110203be | 494 | |
d1b8dc09 CH |
495 | check_b_path_acs: |
496 | bb = b; | |
c6bfaeb5 | 497 | |
d1b8dc09 CH |
498 | while (bb) { |
499 | if (a == bb) | |
500 | break; | |
52916982 | 501 | |
d1b8dc09 CH |
502 | if (pci_bridge_has_acs_redir(bb)) { |
503 | seq_buf_print_bus_devfn(&acs_list, bb); | |
504 | acs_cnt++; | |
505 | } | |
506 | ||
507 | bb = pci_upstream_bridge(bb); | |
508 | } | |
52916982 | 509 | |
d1b8dc09 CH |
510 | *dist = dist_a + dist_b; |
511 | ||
512 | if (!acs_cnt) { | |
513 | map_type = PCI_P2PDMA_MAP_BUS_ADDR; | |
514 | goto done; | |
515 | } | |
516 | ||
517 | if (verbose) { | |
518 | acs_list.buffer[acs_list.len-1] = 0; /* drop final semicolon */ | |
72583084 | 519 | pci_warn(client, "ACS redirect is set between the client and provider (%s)\n", |
52916982 | 520 | pci_name(provider)); |
52916982 LG |
521 | pci_warn(client, "to disable ACS redirect for this path, add the kernel parameter: pci=disable_acs_redir=%s\n", |
522 | acs_list.buffer); | |
72583084 | 523 | } |
d1b8dc09 | 524 | acs_redirects = true; |
52916982 | 525 | |
d1b8dc09 CH |
526 | map_through_host_bridge: |
527 | if (!cpu_supports_p2pdma() && | |
528 | !host_bridge_whitelist(provider, client, acs_redirects)) { | |
529 | if (verbose) | |
530 | pci_warn(client, "cannot be used for peer-to-peer DMA as the client and provider (%s) do not share an upstream bridge or whitelisted host bridge\n", | |
531 | pci_name(provider)); | |
532 | map_type = PCI_P2PDMA_MAP_NOT_SUPPORTED; | |
52916982 | 533 | } |
d1b8dc09 | 534 | done: |
ae21f835 ED |
535 | rcu_read_lock(); |
536 | p2pdma = rcu_dereference(provider->p2pdma); | |
537 | if (p2pdma) | |
538 | xa_store(&p2pdma->map_types, map_types_idx(client), | |
d1b8dc09 | 539 | xa_mk_value(map_type), GFP_KERNEL); |
ae21f835 | 540 | rcu_read_unlock(); |
d1b8dc09 | 541 | return map_type; |
52916982 LG |
542 | } |
543 | ||
544 | /** | |
f6b6aefe | 545 | * pci_p2pdma_distance_many - Determine the cumulative distance between |
52916982 LG |
546 | * a p2pdma provider and the clients in use. |
547 | * @provider: p2pdma provider to check against the client list | |
548 | * @clients: array of devices to check (NULL-terminated) | |
549 | * @num_clients: number of clients in the array | |
550 | * @verbose: if true, print warnings for devices when we return -1 | |
551 | * | |
27235b15 LG |
552 | * Returns -1 if any of the clients are not compatible, otherwise returns a |
553 | * positive number where a lower number is the preferable choice. (If there's | |
554 | * one client that's the same as the provider it will return 0, which is best | |
555 | * choice). | |
52916982 | 556 | * |
27235b15 LG |
557 | * "compatible" means the provider and the clients are either all behind |
558 | * the same PCI root port or the host bridges connected to each of the devices | |
559 | * are listed in the 'pci_p2pdma_whitelist'. | |
52916982 LG |
560 | */ |
561 | int pci_p2pdma_distance_many(struct pci_dev *provider, struct device **clients, | |
562 | int num_clients, bool verbose) | |
563 | { | |
f9c125b9 | 564 | enum pci_p2pdma_map_type map; |
52916982 LG |
565 | bool not_supported = false; |
566 | struct pci_dev *pci_client; | |
72583084 | 567 | int total_dist = 0; |
f9c125b9 | 568 | int i, distance; |
52916982 LG |
569 | |
570 | if (num_clients == 0) | |
571 | return -1; | |
572 | ||
573 | for (i = 0; i < num_clients; i++) { | |
574 | pci_client = find_parent_pci_dev(clients[i]); | |
575 | if (!pci_client) { | |
576 | if (verbose) | |
577 | dev_warn(clients[i], | |
578 | "cannot be used for peer-to-peer DMA as it is not a PCI device\n"); | |
579 | return -1; | |
580 | } | |
581 | ||
d1b8dc09 CH |
582 | map = calc_map_type_and_dist(provider, pci_client, &distance, |
583 | verbose); | |
52916982 LG |
584 | |
585 | pci_dev_put(pci_client); | |
586 | ||
f9c125b9 | 587 | if (map == PCI_P2PDMA_MAP_NOT_SUPPORTED) |
52916982 LG |
588 | not_supported = true; |
589 | ||
590 | if (not_supported && !verbose) | |
591 | break; | |
592 | ||
72583084 | 593 | total_dist += distance; |
52916982 LG |
594 | } |
595 | ||
596 | if (not_supported) | |
597 | return -1; | |
598 | ||
72583084 | 599 | return total_dist; |
52916982 LG |
600 | } |
601 | EXPORT_SYMBOL_GPL(pci_p2pdma_distance_many); | |
602 | ||
603 | /** | |
604 | * pci_has_p2pmem - check if a given PCI device has published any p2pmem | |
605 | * @pdev: PCI device to check | |
606 | */ | |
607 | bool pci_has_p2pmem(struct pci_dev *pdev) | |
608 | { | |
ae21f835 ED |
609 | struct pci_p2pdma *p2pdma; |
610 | bool res; | |
611 | ||
612 | rcu_read_lock(); | |
613 | p2pdma = rcu_dereference(pdev->p2pdma); | |
614 | res = p2pdma && p2pdma->p2pmem_published; | |
615 | rcu_read_unlock(); | |
616 | ||
617 | return res; | |
52916982 LG |
618 | } |
619 | EXPORT_SYMBOL_GPL(pci_has_p2pmem); | |
620 | ||
621 | /** | |
2f0cd59c | 622 | * pci_p2pmem_find_many - find a peer-to-peer DMA memory device compatible with |
52916982 LG |
623 | * the specified list of clients and shortest distance (as determined |
624 | * by pci_p2pmem_dma()) | |
625 | * @clients: array of devices to check (NULL-terminated) | |
626 | * @num_clients: number of client devices in the list | |
627 | * | |
628 | * If multiple devices are behind the same switch, the one "closest" to the | |
fcf9ab35 | 629 | * client devices in use will be chosen first. (So if one of the providers is |
52916982 LG |
630 | * the same as one of the clients, that provider will be used ahead of any |
631 | * other providers that are unrelated). If multiple providers are an equal | |
632 | * distance away, one will be chosen at random. | |
633 | * | |
634 | * Returns a pointer to the PCI device with a reference taken (use pci_dev_put | |
635 | * to return the reference) or NULL if no compatible device is found. The | |
636 | * found provider will also be assigned to the client list. | |
637 | */ | |
638 | struct pci_dev *pci_p2pmem_find_many(struct device **clients, int num_clients) | |
639 | { | |
640 | struct pci_dev *pdev = NULL; | |
641 | int distance; | |
642 | int closest_distance = INT_MAX; | |
643 | struct pci_dev **closest_pdevs; | |
644 | int dev_cnt = 0; | |
645 | const int max_devs = PAGE_SIZE / sizeof(*closest_pdevs); | |
646 | int i; | |
647 | ||
648 | closest_pdevs = kmalloc(PAGE_SIZE, GFP_KERNEL); | |
649 | if (!closest_pdevs) | |
650 | return NULL; | |
651 | ||
652 | while ((pdev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, pdev))) { | |
653 | if (!pci_has_p2pmem(pdev)) | |
654 | continue; | |
655 | ||
656 | distance = pci_p2pdma_distance_many(pdev, clients, | |
657 | num_clients, false); | |
658 | if (distance < 0 || distance > closest_distance) | |
659 | continue; | |
660 | ||
661 | if (distance == closest_distance && dev_cnt >= max_devs) | |
662 | continue; | |
663 | ||
664 | if (distance < closest_distance) { | |
665 | for (i = 0; i < dev_cnt; i++) | |
666 | pci_dev_put(closest_pdevs[i]); | |
667 | ||
668 | dev_cnt = 0; | |
669 | closest_distance = distance; | |
670 | } | |
671 | ||
672 | closest_pdevs[dev_cnt++] = pci_dev_get(pdev); | |
673 | } | |
674 | ||
675 | if (dev_cnt) | |
676 | pdev = pci_dev_get(closest_pdevs[prandom_u32_max(dev_cnt)]); | |
677 | ||
678 | for (i = 0; i < dev_cnt; i++) | |
679 | pci_dev_put(closest_pdevs[i]); | |
680 | ||
681 | kfree(closest_pdevs); | |
682 | return pdev; | |
683 | } | |
684 | EXPORT_SYMBOL_GPL(pci_p2pmem_find_many); | |
685 | ||
686 | /** | |
2f0cd59c | 687 | * pci_alloc_p2pmem - allocate peer-to-peer DMA memory |
52916982 LG |
688 | * @pdev: the device to allocate memory from |
689 | * @size: number of bytes to allocate | |
690 | * | |
691 | * Returns the allocated memory or NULL on error. | |
692 | */ | |
693 | void *pci_alloc_p2pmem(struct pci_dev *pdev, size_t size) | |
694 | { | |
1570175a DW |
695 | void *ret = NULL; |
696 | struct percpu_ref *ref; | |
ae21f835 | 697 | struct pci_p2pdma *p2pdma; |
52916982 | 698 | |
1570175a DW |
699 | /* |
700 | * Pairs with synchronize_rcu() in pci_p2pdma_release() to | |
701 | * ensure pdev->p2pdma is non-NULL for the duration of the | |
702 | * read-lock. | |
703 | */ | |
704 | rcu_read_lock(); | |
ae21f835 ED |
705 | p2pdma = rcu_dereference(pdev->p2pdma); |
706 | if (unlikely(!p2pdma)) | |
1570175a | 707 | goto out; |
52916982 | 708 | |
ae21f835 | 709 | ret = (void *)gen_pool_alloc_owner(p2pdma->pool, size, (void **) &ref); |
1570175a DW |
710 | if (!ret) |
711 | goto out; | |
52916982 | 712 | |
1570175a | 713 | if (unlikely(!percpu_ref_tryget_live(ref))) { |
ae21f835 | 714 | gen_pool_free(p2pdma->pool, (unsigned long) ret, size); |
1570175a DW |
715 | ret = NULL; |
716 | goto out; | |
717 | } | |
718 | out: | |
719 | rcu_read_unlock(); | |
52916982 LG |
720 | return ret; |
721 | } | |
722 | EXPORT_SYMBOL_GPL(pci_alloc_p2pmem); | |
723 | ||
724 | /** | |
725 | * pci_free_p2pmem - free peer-to-peer DMA memory | |
726 | * @pdev: the device the memory was allocated from | |
727 | * @addr: address of the memory that was allocated | |
fcf9ab35 | 728 | * @size: number of bytes that were allocated |
52916982 LG |
729 | */ |
730 | void pci_free_p2pmem(struct pci_dev *pdev, void *addr, size_t size) | |
731 | { | |
1570175a | 732 | struct percpu_ref *ref; |
ae21f835 | 733 | struct pci_p2pdma *p2pdma = rcu_dereference_protected(pdev->p2pdma, 1); |
1570175a | 734 | |
ae21f835 | 735 | gen_pool_free_owner(p2pdma->pool, (uintptr_t)addr, size, |
1570175a DW |
736 | (void **) &ref); |
737 | percpu_ref_put(ref); | |
52916982 LG |
738 | } |
739 | EXPORT_SYMBOL_GPL(pci_free_p2pmem); | |
740 | ||
741 | /** | |
2f0cd59c | 742 | * pci_p2pmem_virt_to_bus - return the PCI bus address for a given virtual |
52916982 LG |
743 | * address obtained with pci_alloc_p2pmem() |
744 | * @pdev: the device the memory was allocated from | |
745 | * @addr: address of the memory that was allocated | |
746 | */ | |
747 | pci_bus_addr_t pci_p2pmem_virt_to_bus(struct pci_dev *pdev, void *addr) | |
748 | { | |
ae21f835 ED |
749 | struct pci_p2pdma *p2pdma; |
750 | ||
52916982 LG |
751 | if (!addr) |
752 | return 0; | |
ae21f835 ED |
753 | |
754 | p2pdma = rcu_dereference_protected(pdev->p2pdma, 1); | |
755 | if (!p2pdma) | |
52916982 LG |
756 | return 0; |
757 | ||
758 | /* | |
759 | * Note: when we added the memory to the pool we used the PCI | |
760 | * bus address as the physical address. So gen_pool_virt_to_phys() | |
761 | * actually returns the bus address despite the misleading name. | |
762 | */ | |
ae21f835 | 763 | return gen_pool_virt_to_phys(p2pdma->pool, (unsigned long)addr); |
52916982 LG |
764 | } |
765 | EXPORT_SYMBOL_GPL(pci_p2pmem_virt_to_bus); | |
766 | ||
767 | /** | |
768 | * pci_p2pmem_alloc_sgl - allocate peer-to-peer DMA memory in a scatterlist | |
769 | * @pdev: the device to allocate memory from | |
770 | * @nents: the number of SG entries in the list | |
771 | * @length: number of bytes to allocate | |
772 | * | |
fcf9ab35 | 773 | * Return: %NULL on error or &struct scatterlist pointer and @nents on success |
52916982 LG |
774 | */ |
775 | struct scatterlist *pci_p2pmem_alloc_sgl(struct pci_dev *pdev, | |
776 | unsigned int *nents, u32 length) | |
777 | { | |
778 | struct scatterlist *sg; | |
779 | void *addr; | |
780 | ||
eec240e2 | 781 | sg = kmalloc(sizeof(*sg), GFP_KERNEL); |
52916982 LG |
782 | if (!sg) |
783 | return NULL; | |
784 | ||
785 | sg_init_table(sg, 1); | |
786 | ||
787 | addr = pci_alloc_p2pmem(pdev, length); | |
788 | if (!addr) | |
789 | goto out_free_sg; | |
790 | ||
791 | sg_set_buf(sg, addr, length); | |
792 | *nents = 1; | |
793 | return sg; | |
794 | ||
795 | out_free_sg: | |
796 | kfree(sg); | |
797 | return NULL; | |
798 | } | |
799 | EXPORT_SYMBOL_GPL(pci_p2pmem_alloc_sgl); | |
800 | ||
801 | /** | |
802 | * pci_p2pmem_free_sgl - free a scatterlist allocated by pci_p2pmem_alloc_sgl() | |
803 | * @pdev: the device to allocate memory from | |
804 | * @sgl: the allocated scatterlist | |
805 | */ | |
806 | void pci_p2pmem_free_sgl(struct pci_dev *pdev, struct scatterlist *sgl) | |
807 | { | |
808 | struct scatterlist *sg; | |
809 | int count; | |
810 | ||
811 | for_each_sg(sgl, sg, INT_MAX, count) { | |
812 | if (!sg) | |
813 | break; | |
814 | ||
815 | pci_free_p2pmem(pdev, sg_virt(sg), sg->length); | |
816 | } | |
817 | kfree(sgl); | |
818 | } | |
819 | EXPORT_SYMBOL_GPL(pci_p2pmem_free_sgl); | |
820 | ||
821 | /** | |
822 | * pci_p2pmem_publish - publish the peer-to-peer DMA memory for use by | |
823 | * other devices with pci_p2pmem_find() | |
824 | * @pdev: the device with peer-to-peer DMA memory to publish | |
825 | * @publish: set to true to publish the memory, false to unpublish it | |
826 | * | |
827 | * Published memory can be used by other PCI device drivers for | |
828 | * peer-2-peer DMA operations. Non-published memory is reserved for | |
fcf9ab35 | 829 | * exclusive use of the device driver that registers the peer-to-peer |
52916982 LG |
830 | * memory. |
831 | */ | |
832 | void pci_p2pmem_publish(struct pci_dev *pdev, bool publish) | |
833 | { | |
ae21f835 ED |
834 | struct pci_p2pdma *p2pdma; |
835 | ||
836 | rcu_read_lock(); | |
837 | p2pdma = rcu_dereference(pdev->p2pdma); | |
838 | if (p2pdma) | |
839 | p2pdma->p2pmem_published = publish; | |
840 | rcu_read_unlock(); | |
52916982 LG |
841 | } |
842 | EXPORT_SYMBOL_GPL(pci_p2pmem_publish); | |
977196b8 | 843 | |
7e2faa17 LG |
844 | static enum pci_p2pdma_map_type pci_p2pdma_map_type(struct dev_pagemap *pgmap, |
845 | struct device *dev) | |
5d52e1ab | 846 | { |
ae21f835 | 847 | enum pci_p2pdma_map_type type = PCI_P2PDMA_MAP_NOT_SUPPORTED; |
7e2faa17 LG |
848 | struct pci_dev *provider = to_p2p_pgmap(pgmap)->provider; |
849 | struct pci_dev *client; | |
ae21f835 | 850 | struct pci_p2pdma *p2pdma; |
7e2faa17 | 851 | |
5d52e1ab LG |
852 | if (!provider->p2pdma) |
853 | return PCI_P2PDMA_MAP_NOT_SUPPORTED; | |
854 | ||
7e2faa17 LG |
855 | if (!dev_is_pci(dev)) |
856 | return PCI_P2PDMA_MAP_NOT_SUPPORTED; | |
857 | ||
858 | client = to_pci_dev(dev); | |
859 | ||
ae21f835 ED |
860 | rcu_read_lock(); |
861 | p2pdma = rcu_dereference(provider->p2pdma); | |
862 | ||
863 | if (p2pdma) | |
864 | type = xa_to_value(xa_load(&p2pdma->map_types, | |
865 | map_types_idx(client))); | |
866 | rcu_read_unlock(); | |
867 | return type; | |
5d52e1ab LG |
868 | } |
869 | ||
142c242e LG |
870 | static int __pci_p2pdma_map_sg(struct pci_p2pdma_pagemap *p2p_pgmap, |
871 | struct device *dev, struct scatterlist *sg, int nents) | |
977196b8 | 872 | { |
977196b8 | 873 | struct scatterlist *s; |
977196b8 LG |
874 | int i; |
875 | ||
977196b8 | 876 | for_each_sg(sg, s, nents, i) { |
73063ec5 | 877 | s->dma_address = sg_phys(s) - p2p_pgmap->bus_offset; |
977196b8 LG |
878 | sg_dma_len(s) = s->length; |
879 | } | |
880 | ||
881 | return nents; | |
882 | } | |
142c242e LG |
883 | |
884 | /** | |
2f0cd59c | 885 | * pci_p2pdma_map_sg_attrs - map a PCI peer-to-peer scatterlist for DMA |
142c242e LG |
886 | * @dev: device doing the DMA request |
887 | * @sg: scatter list to map | |
888 | * @nents: elements in the scatterlist | |
889 | * @dir: DMA direction | |
890 | * @attrs: DMA attributes passed to dma_map_sg() (if called) | |
891 | * | |
892 | * Scatterlists mapped with this function should be unmapped using | |
893 | * pci_p2pdma_unmap_sg_attrs(). | |
894 | * | |
895 | * Returns the number of SG entries mapped or 0 on error. | |
896 | */ | |
897 | int pci_p2pdma_map_sg_attrs(struct device *dev, struct scatterlist *sg, | |
898 | int nents, enum dma_data_direction dir, unsigned long attrs) | |
899 | { | |
900 | struct pci_p2pdma_pagemap *p2p_pgmap = | |
901 | to_p2p_pgmap(sg_page(sg)->pgmap); | |
5d52e1ab | 902 | |
7e2faa17 | 903 | switch (pci_p2pdma_map_type(sg_page(sg)->pgmap, dev)) { |
5d52e1ab LG |
904 | case PCI_P2PDMA_MAP_THRU_HOST_BRIDGE: |
905 | return dma_map_sg_attrs(dev, sg, nents, dir, attrs); | |
906 | case PCI_P2PDMA_MAP_BUS_ADDR: | |
907 | return __pci_p2pdma_map_sg(p2p_pgmap, dev, sg, nents); | |
908 | default: | |
909 | WARN_ON_ONCE(1); | |
910 | return 0; | |
911 | } | |
142c242e | 912 | } |
2b9f4bb2 | 913 | EXPORT_SYMBOL_GPL(pci_p2pdma_map_sg_attrs); |
2d7bc010 | 914 | |
7f73eac3 | 915 | /** |
2f0cd59c | 916 | * pci_p2pdma_unmap_sg_attrs - unmap a PCI peer-to-peer scatterlist that was |
7f73eac3 LG |
917 | * mapped with pci_p2pdma_map_sg() |
918 | * @dev: device doing the DMA request | |
919 | * @sg: scatter list to map | |
920 | * @nents: number of elements returned by pci_p2pdma_map_sg() | |
921 | * @dir: DMA direction | |
922 | * @attrs: DMA attributes passed to dma_unmap_sg() (if called) | |
923 | */ | |
924 | void pci_p2pdma_unmap_sg_attrs(struct device *dev, struct scatterlist *sg, | |
925 | int nents, enum dma_data_direction dir, unsigned long attrs) | |
926 | { | |
5d52e1ab | 927 | enum pci_p2pdma_map_type map_type; |
5d52e1ab | 928 | |
7e2faa17 | 929 | map_type = pci_p2pdma_map_type(sg_page(sg)->pgmap, dev); |
5d52e1ab LG |
930 | |
931 | if (map_type == PCI_P2PDMA_MAP_THRU_HOST_BRIDGE) | |
932 | dma_unmap_sg_attrs(dev, sg, nents, dir, attrs); | |
7f73eac3 LG |
933 | } |
934 | EXPORT_SYMBOL_GPL(pci_p2pdma_unmap_sg_attrs); | |
935 | ||
2d7bc010 LG |
936 | /** |
937 | * pci_p2pdma_enable_store - parse a configfs/sysfs attribute store | |
938 | * to enable p2pdma | |
939 | * @page: contents of the value to be stored | |
940 | * @p2p_dev: returns the PCI device that was selected to be used | |
941 | * (if one was specified in the stored value) | |
942 | * @use_p2pdma: returns whether to enable p2pdma or not | |
943 | * | |
944 | * Parses an attribute value to decide whether to enable p2pdma. | |
fcf9ab35 | 945 | * The value can select a PCI device (using its full BDF device |
2d7bc010 LG |
946 | * name) or a boolean (in any format strtobool() accepts). A false |
947 | * value disables p2pdma, a true value expects the caller | |
948 | * to automatically find a compatible device and specifying a PCI device | |
949 | * expects the caller to use the specific provider. | |
950 | * | |
951 | * pci_p2pdma_enable_show() should be used as the show operation for | |
952 | * the attribute. | |
953 | * | |
954 | * Returns 0 on success | |
955 | */ | |
956 | int pci_p2pdma_enable_store(const char *page, struct pci_dev **p2p_dev, | |
957 | bool *use_p2pdma) | |
958 | { | |
959 | struct device *dev; | |
960 | ||
961 | dev = bus_find_device_by_name(&pci_bus_type, NULL, page); | |
962 | if (dev) { | |
963 | *use_p2pdma = true; | |
964 | *p2p_dev = to_pci_dev(dev); | |
965 | ||
966 | if (!pci_has_p2pmem(*p2p_dev)) { | |
967 | pci_err(*p2p_dev, | |
968 | "PCI device has no peer-to-peer memory: %s\n", | |
969 | page); | |
970 | pci_dev_put(*p2p_dev); | |
971 | return -ENODEV; | |
972 | } | |
973 | ||
974 | return 0; | |
975 | } else if ((page[0] == '0' || page[0] == '1') && !iscntrl(page[1])) { | |
976 | /* | |
977 | * If the user enters a PCI device that doesn't exist | |
978 | * like "0000:01:00.1", we don't want strtobool to think | |
979 | * it's a '0' when it's clearly not what the user wanted. | |
980 | * So we require 0's and 1's to be exactly one character. | |
981 | */ | |
982 | } else if (!strtobool(page, use_p2pdma)) { | |
983 | return 0; | |
984 | } | |
985 | ||
986 | pr_err("No such PCI device: %.*s\n", (int)strcspn(page, "\n"), page); | |
987 | return -ENODEV; | |
988 | } | |
989 | EXPORT_SYMBOL_GPL(pci_p2pdma_enable_store); | |
990 | ||
991 | /** | |
992 | * pci_p2pdma_enable_show - show a configfs/sysfs attribute indicating | |
993 | * whether p2pdma is enabled | |
994 | * @page: contents of the stored value | |
995 | * @p2p_dev: the selected p2p device (NULL if no device is selected) | |
fcf9ab35 | 996 | * @use_p2pdma: whether p2pdma has been enabled |
2d7bc010 LG |
997 | * |
998 | * Attributes that use pci_p2pdma_enable_store() should use this function | |
999 | * to show the value of the attribute. | |
1000 | * | |
1001 | * Returns 0 on success | |
1002 | */ | |
1003 | ssize_t pci_p2pdma_enable_show(char *page, struct pci_dev *p2p_dev, | |
1004 | bool use_p2pdma) | |
1005 | { | |
1006 | if (!use_p2pdma) | |
1007 | return sprintf(page, "0\n"); | |
1008 | ||
1009 | if (!p2p_dev) | |
1010 | return sprintf(page, "1\n"); | |
1011 | ||
1012 | return sprintf(page, "%s\n", pci_name(p2p_dev)); | |
1013 | } | |
1014 | EXPORT_SYMBOL_GPL(pci_p2pdma_enable_show); |