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 11#define pr_fmt(fmt) "pci-p2pdma: " fmt 12#include <linux/ctype.h> 13#include <linux/dma-map-ops.h> 14#include <linux/pci-p2pdma.h> 15#include <linux/module.h> 16#include <linux/slab.h> 17#include <linux/genalloc.h> 18#include <linux/memremap.h> 19#include <linux/percpu-refcount.h> 20#include <linux/random.h> 21#include <linux/seq_buf.h> 22#include <linux/xarray.h> 23 24struct pci_p2pdma { 25 struct gen_pool *pool; 26 bool p2pmem_published; 27 struct xarray map_types; 28}; 29 30struct pci_p2pdma_pagemap { 31 struct pci_dev *provider; 32 u64 bus_offset; 33 struct dev_pagemap pgmap; 34}; 35 36static struct pci_p2pdma_pagemap *to_p2p_pgmap(struct dev_pagemap *pgmap) 37{ 38 return container_of(pgmap, struct pci_p2pdma_pagemap, pgmap); 39} 40 41static ssize_t size_show(struct device *dev, struct device_attribute *attr, 42 char *buf) 43{ 44 struct pci_dev *pdev = to_pci_dev(dev); 45 struct pci_p2pdma *p2pdma; 46 size_t size = 0; 47 48 rcu_read_lock(); 49 p2pdma = rcu_dereference(pdev->p2pdma); 50 if (p2pdma && p2pdma->pool) 51 size = gen_pool_size(p2pdma->pool); 52 rcu_read_unlock(); 53 54 return sysfs_emit(buf, "%zd\n", size); 55} 56static DEVICE_ATTR_RO(size); 57 58static ssize_t available_show(struct device *dev, struct device_attribute *attr, 59 char *buf) 60{ 61 struct pci_dev *pdev = to_pci_dev(dev); 62 struct pci_p2pdma *p2pdma; 63 size_t avail = 0; 64 65 rcu_read_lock(); 66 p2pdma = rcu_dereference(pdev->p2pdma); 67 if (p2pdma && p2pdma->pool) 68 avail = gen_pool_avail(p2pdma->pool); 69 rcu_read_unlock(); 70 71 return sysfs_emit(buf, "%zd\n", avail); 72} 73static DEVICE_ATTR_RO(available); 74 75static ssize_t published_show(struct device *dev, struct device_attribute *attr, 76 char *buf) 77{ 78 struct pci_dev *pdev = to_pci_dev(dev); 79 struct pci_p2pdma *p2pdma; 80 bool published = false; 81 82 rcu_read_lock(); 83 p2pdma = rcu_dereference(pdev->p2pdma); 84 if (p2pdma) 85 published = p2pdma->p2pmem_published; 86 rcu_read_unlock(); 87 88 return sysfs_emit(buf, "%d\n", published); 89} 90static DEVICE_ATTR_RO(published); 91 92static int p2pmem_alloc_mmap(struct file *filp, struct kobject *kobj, 93 struct bin_attribute *attr, struct vm_area_struct *vma) 94{ 95 struct pci_dev *pdev = to_pci_dev(kobj_to_dev(kobj)); 96 size_t len = vma->vm_end - vma->vm_start; 97 struct pci_p2pdma *p2pdma; 98 struct percpu_ref *ref; 99 unsigned long vaddr; 100 void *kaddr; 101 int ret; 102 103 /* prevent private mappings from being established */ 104 if ((vma->vm_flags & VM_MAYSHARE) != VM_MAYSHARE) { 105 pci_info_ratelimited(pdev, 106 "%s: fail, attempted private mapping\n", 107 current->comm); 108 return -EINVAL; 109 } 110 111 if (vma->vm_pgoff) { 112 pci_info_ratelimited(pdev, 113 "%s: fail, attempted mapping with non-zero offset\n", 114 current->comm); 115 return -EINVAL; 116 } 117 118 rcu_read_lock(); 119 p2pdma = rcu_dereference(pdev->p2pdma); 120 if (!p2pdma) { 121 ret = -ENODEV; 122 goto out; 123 } 124 125 kaddr = (void *)gen_pool_alloc_owner(p2pdma->pool, len, (void **)&ref); 126 if (!kaddr) { 127 ret = -ENOMEM; 128 goto out; 129 } 130 131 /* 132 * vm_insert_page() can sleep, so a reference is taken to mapping 133 * such that rcu_read_unlock() can be done before inserting the 134 * pages 135 */ 136 if (unlikely(!percpu_ref_tryget_live_rcu(ref))) { 137 ret = -ENODEV; 138 goto out_free_mem; 139 } 140 rcu_read_unlock(); 141 142 for (vaddr = vma->vm_start; vaddr < vma->vm_end; vaddr += PAGE_SIZE) { 143 ret = vm_insert_page(vma, vaddr, virt_to_page(kaddr)); 144 if (ret) { 145 gen_pool_free(p2pdma->pool, (uintptr_t)kaddr, len); 146 return ret; 147 } 148 percpu_ref_get(ref); 149 put_page(virt_to_page(kaddr)); 150 kaddr += PAGE_SIZE; 151 len -= PAGE_SIZE; 152 } 153 154 percpu_ref_put(ref); 155 156 return 0; 157out_free_mem: 158 gen_pool_free(p2pdma->pool, (uintptr_t)kaddr, len); 159out: 160 rcu_read_unlock(); 161 return ret; 162} 163 164static struct bin_attribute p2pmem_alloc_attr = { 165 .attr = { .name = "allocate", .mode = 0660 }, 166 .mmap = p2pmem_alloc_mmap, 167 /* 168 * Some places where we want to call mmap (ie. python) will check 169 * that the file size is greater than the mmap size before allowing 170 * the mmap to continue. To work around this, just set the size 171 * to be very large. 172 */ 173 .size = SZ_1T, 174}; 175 176static struct attribute *p2pmem_attrs[] = { 177 &dev_attr_size.attr, 178 &dev_attr_available.attr, 179 &dev_attr_published.attr, 180 NULL, 181}; 182 183static struct bin_attribute *p2pmem_bin_attrs[] = { 184 &p2pmem_alloc_attr, 185 NULL, 186}; 187 188static const struct attribute_group p2pmem_group = { 189 .attrs = p2pmem_attrs, 190 .bin_attrs = p2pmem_bin_attrs, 191 .name = "p2pmem", 192}; 193 194static void p2pdma_page_free(struct page *page) 195{ 196 struct pci_p2pdma_pagemap *pgmap = to_p2p_pgmap(page->pgmap); 197 /* safe to dereference while a reference is held to the percpu ref */ 198 struct pci_p2pdma *p2pdma = 199 rcu_dereference_protected(pgmap->provider->p2pdma, 1); 200 struct percpu_ref *ref; 201 202 gen_pool_free_owner(p2pdma->pool, (uintptr_t)page_to_virt(page), 203 PAGE_SIZE, (void **)&ref); 204 percpu_ref_put(ref); 205} 206 207static const struct dev_pagemap_ops p2pdma_pgmap_ops = { 208 .page_free = p2pdma_page_free, 209}; 210 211static void pci_p2pdma_release(void *data) 212{ 213 struct pci_dev *pdev = data; 214 struct pci_p2pdma *p2pdma; 215 216 p2pdma = rcu_dereference_protected(pdev->p2pdma, 1); 217 if (!p2pdma) 218 return; 219 220 /* Flush and disable pci_alloc_p2p_mem() */ 221 pdev->p2pdma = NULL; 222 synchronize_rcu(); 223 224 gen_pool_destroy(p2pdma->pool); 225 sysfs_remove_group(&pdev->dev.kobj, &p2pmem_group); 226 xa_destroy(&p2pdma->map_types); 227} 228 229static int pci_p2pdma_setup(struct pci_dev *pdev) 230{ 231 int error = -ENOMEM; 232 struct pci_p2pdma *p2p; 233 234 p2p = devm_kzalloc(&pdev->dev, sizeof(*p2p), GFP_KERNEL); 235 if (!p2p) 236 return -ENOMEM; 237 238 xa_init(&p2p->map_types); 239 240 p2p->pool = gen_pool_create(PAGE_SHIFT, dev_to_node(&pdev->dev)); 241 if (!p2p->pool) 242 goto out; 243 244 error = devm_add_action_or_reset(&pdev->dev, pci_p2pdma_release, pdev); 245 if (error) 246 goto out_pool_destroy; 247 248 error = sysfs_create_group(&pdev->dev.kobj, &p2pmem_group); 249 if (error) 250 goto out_pool_destroy; 251 252 rcu_assign_pointer(pdev->p2pdma, p2p); 253 return 0; 254 255out_pool_destroy: 256 gen_pool_destroy(p2p->pool); 257out: 258 devm_kfree(&pdev->dev, p2p); 259 return error; 260} 261 262static void pci_p2pdma_unmap_mappings(void *data) 263{ 264 struct pci_dev *pdev = data; 265 266 /* 267 * Removing the alloc attribute from sysfs will call 268 * unmap_mapping_range() on the inode, teardown any existing userspace 269 * mappings and prevent new ones from being created. 270 */ 271 sysfs_remove_file_from_group(&pdev->dev.kobj, &p2pmem_alloc_attr.attr, 272 p2pmem_group.name); 273} 274 275/** 276 * pci_p2pdma_add_resource - add memory for use as p2p memory 277 * @pdev: the device to add the memory to 278 * @bar: PCI BAR to add 279 * @size: size of the memory to add, may be zero to use the whole BAR 280 * @offset: offset into the PCI BAR 281 * 282 * The memory will be given ZONE_DEVICE struct pages so that it may 283 * be used with any DMA request. 284 */ 285int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar, size_t size, 286 u64 offset) 287{ 288 struct pci_p2pdma_pagemap *p2p_pgmap; 289 struct dev_pagemap *pgmap; 290 struct pci_p2pdma *p2pdma; 291 void *addr; 292 int error; 293 294 if (!(pci_resource_flags(pdev, bar) & IORESOURCE_MEM)) 295 return -EINVAL; 296 297 if (offset >= pci_resource_len(pdev, bar)) 298 return -EINVAL; 299 300 if (!size) 301 size = pci_resource_len(pdev, bar) - offset; 302 303 if (size + offset > pci_resource_len(pdev, bar)) 304 return -EINVAL; 305 306 if (!pdev->p2pdma) { 307 error = pci_p2pdma_setup(pdev); 308 if (error) 309 return error; 310 } 311 312 p2p_pgmap = devm_kzalloc(&pdev->dev, sizeof(*p2p_pgmap), GFP_KERNEL); 313 if (!p2p_pgmap) 314 return -ENOMEM; 315 316 pgmap = &p2p_pgmap->pgmap; 317 pgmap->range.start = pci_resource_start(pdev, bar) + offset; 318 pgmap->range.end = pgmap->range.start + size - 1; 319 pgmap->nr_range = 1; 320 pgmap->type = MEMORY_DEVICE_PCI_P2PDMA; 321 pgmap->ops = &p2pdma_pgmap_ops; 322 323 p2p_pgmap->provider = pdev; 324 p2p_pgmap->bus_offset = pci_bus_address(pdev, bar) - 325 pci_resource_start(pdev, bar); 326 327 addr = devm_memremap_pages(&pdev->dev, pgmap); 328 if (IS_ERR(addr)) { 329 error = PTR_ERR(addr); 330 goto pgmap_free; 331 } 332 333 error = devm_add_action_or_reset(&pdev->dev, pci_p2pdma_unmap_mappings, 334 pdev); 335 if (error) 336 goto pages_free; 337 338 p2pdma = rcu_dereference_protected(pdev->p2pdma, 1); 339 error = gen_pool_add_owner(p2pdma->pool, (unsigned long)addr, 340 pci_bus_address(pdev, bar) + offset, 341 range_len(&pgmap->range), dev_to_node(&pdev->dev), 342 &pgmap->ref); 343 if (error) 344 goto pages_free; 345 346 pci_info(pdev, "added peer-to-peer DMA memory %#llx-%#llx\n", 347 pgmap->range.start, pgmap->range.end); 348 349 return 0; 350 351pages_free: 352 devm_memunmap_pages(&pdev->dev, pgmap); 353pgmap_free: 354 devm_kfree(&pdev->dev, pgmap); 355 return error; 356} 357EXPORT_SYMBOL_GPL(pci_p2pdma_add_resource); 358 359/* 360 * Note this function returns the parent PCI device with a 361 * reference taken. It is the caller's responsibility to drop 362 * the reference. 363 */ 364static struct pci_dev *find_parent_pci_dev(struct device *dev) 365{ 366 struct device *parent; 367 368 dev = get_device(dev); 369 370 while (dev) { 371 if (dev_is_pci(dev)) 372 return to_pci_dev(dev); 373 374 parent = get_device(dev->parent); 375 put_device(dev); 376 dev = parent; 377 } 378 379 return NULL; 380} 381 382/* 383 * Check if a PCI bridge has its ACS redirection bits set to redirect P2P 384 * TLPs upstream via ACS. Returns 1 if the packets will be redirected 385 * upstream, 0 otherwise. 386 */ 387static int pci_bridge_has_acs_redir(struct pci_dev *pdev) 388{ 389 int pos; 390 u16 ctrl; 391 392 pos = pdev->acs_cap; 393 if (!pos) 394 return 0; 395 396 pci_read_config_word(pdev, pos + PCI_ACS_CTRL, &ctrl); 397 398 if (ctrl & (PCI_ACS_RR | PCI_ACS_CR | PCI_ACS_EC)) 399 return 1; 400 401 return 0; 402} 403 404static void seq_buf_print_bus_devfn(struct seq_buf *buf, struct pci_dev *pdev) 405{ 406 if (!buf) 407 return; 408 409 seq_buf_printf(buf, "%s;", pci_name(pdev)); 410} 411 412static bool cpu_supports_p2pdma(void) 413{ 414#ifdef CONFIG_X86 415 struct cpuinfo_x86 *c = &cpu_data(0); 416 417 /* Any AMD CPU whose family ID is Zen or newer supports p2pdma */ 418 if (c->x86_vendor == X86_VENDOR_AMD && c->x86 >= 0x17) 419 return true; 420#endif 421 422 return false; 423} 424 425static const struct pci_p2pdma_whitelist_entry { 426 unsigned short vendor; 427 unsigned short device; 428 enum { 429 REQ_SAME_HOST_BRIDGE = 1 << 0, 430 } flags; 431} pci_p2pdma_whitelist[] = { 432 /* Intel Xeon E5/Core i7 */ 433 {PCI_VENDOR_ID_INTEL, 0x3c00, REQ_SAME_HOST_BRIDGE}, 434 {PCI_VENDOR_ID_INTEL, 0x3c01, REQ_SAME_HOST_BRIDGE}, 435 /* Intel Xeon E7 v3/Xeon E5 v3/Core i7 */ 436 {PCI_VENDOR_ID_INTEL, 0x2f00, REQ_SAME_HOST_BRIDGE}, 437 {PCI_VENDOR_ID_INTEL, 0x2f01, REQ_SAME_HOST_BRIDGE}, 438 /* Intel Skylake-E */ 439 {PCI_VENDOR_ID_INTEL, 0x2030, 0}, 440 {PCI_VENDOR_ID_INTEL, 0x2031, 0}, 441 {PCI_VENDOR_ID_INTEL, 0x2032, 0}, 442 {PCI_VENDOR_ID_INTEL, 0x2033, 0}, 443 {PCI_VENDOR_ID_INTEL, 0x2020, 0}, 444 {PCI_VENDOR_ID_INTEL, 0x09a2, 0}, 445 {} 446}; 447 448/* 449 * If the first device on host's root bus is either devfn 00.0 or a PCIe 450 * Root Port, return it. Otherwise return NULL. 451 * 452 * We often use a devfn 00.0 "host bridge" in the pci_p2pdma_whitelist[] 453 * (though there is no PCI/PCIe requirement for such a device). On some 454 * platforms, e.g., Intel Skylake, there is no such host bridge device, and 455 * pci_p2pdma_whitelist[] may contain a Root Port at any devfn. 456 * 457 * This function is similar to pci_get_slot(host->bus, 0), but it does 458 * not take the pci_bus_sem lock since __host_bridge_whitelist() must not 459 * sleep. 460 * 461 * For this to be safe, the caller should hold a reference to a device on the 462 * bridge, which should ensure the host_bridge device will not be freed 463 * or removed from the head of the devices list. 464 */ 465static struct pci_dev *pci_host_bridge_dev(struct pci_host_bridge *host) 466{ 467 struct pci_dev *root; 468 469 root = list_first_entry_or_null(&host->bus->devices, 470 struct pci_dev, bus_list); 471 472 if (!root) 473 return NULL; 474 475 if (root->devfn == PCI_DEVFN(0, 0)) 476 return root; 477 478 if (pci_pcie_type(root) == PCI_EXP_TYPE_ROOT_PORT) 479 return root; 480 481 return NULL; 482} 483 484static bool __host_bridge_whitelist(struct pci_host_bridge *host, 485 bool same_host_bridge, bool warn) 486{ 487 struct pci_dev *root = pci_host_bridge_dev(host); 488 const struct pci_p2pdma_whitelist_entry *entry; 489 unsigned short vendor, device; 490 491 if (!root) 492 return false; 493 494 vendor = root->vendor; 495 device = root->device; 496 497 for (entry = pci_p2pdma_whitelist; entry->vendor; entry++) { 498 if (vendor != entry->vendor || device != entry->device) 499 continue; 500 if (entry->flags & REQ_SAME_HOST_BRIDGE && !same_host_bridge) 501 return false; 502 503 return true; 504 } 505 506 if (warn) 507 pci_warn(root, "Host bridge not in P2PDMA whitelist: %04x:%04x\n", 508 vendor, device); 509 510 return false; 511} 512 513/* 514 * If we can't find a common upstream bridge take a look at the root 515 * complex and compare it to a whitelist of known good hardware. 516 */ 517static bool host_bridge_whitelist(struct pci_dev *a, struct pci_dev *b, 518 bool warn) 519{ 520 struct pci_host_bridge *host_a = pci_find_host_bridge(a->bus); 521 struct pci_host_bridge *host_b = pci_find_host_bridge(b->bus); 522 523 if (host_a == host_b) 524 return __host_bridge_whitelist(host_a, true, warn); 525 526 if (__host_bridge_whitelist(host_a, false, warn) && 527 __host_bridge_whitelist(host_b, false, warn)) 528 return true; 529 530 return false; 531} 532 533static unsigned long map_types_idx(struct pci_dev *client) 534{ 535 return (pci_domain_nr(client->bus) << 16) | pci_dev_id(client); 536} 537 538/* 539 * Calculate the P2PDMA mapping type and distance between two PCI devices. 540 * 541 * If the two devices are the same PCI function, return 542 * PCI_P2PDMA_MAP_BUS_ADDR and a distance of 0. 543 * 544 * If they are two functions of the same device, return 545 * PCI_P2PDMA_MAP_BUS_ADDR and a distance of 2 (one hop up to the bridge, 546 * then one hop back down to another function of the same device). 547 * 548 * In the case where two devices are connected to the same PCIe switch, 549 * return a distance of 4. This corresponds to the following PCI tree: 550 * 551 * -+ Root Port 552 * \+ Switch Upstream Port 553 * +-+ Switch Downstream Port 0 554 * + \- Device A 555 * \-+ Switch Downstream Port 1 556 * \- Device B 557 * 558 * The distance is 4 because we traverse from Device A to Downstream Port 0 559 * to the common Switch Upstream Port, back down to Downstream Port 1 and 560 * then to Device B. The mapping type returned depends on the ACS 561 * redirection setting of the ports along the path. 562 * 563 * If ACS redirect is set on any port in the path, traffic between the 564 * devices will go through the host bridge, so return 565 * PCI_P2PDMA_MAP_THRU_HOST_BRIDGE; otherwise return 566 * PCI_P2PDMA_MAP_BUS_ADDR. 567 * 568 * Any two devices that have a data path that goes through the host bridge 569 * will consult a whitelist. If the host bridge is in the whitelist, return 570 * PCI_P2PDMA_MAP_THRU_HOST_BRIDGE with the distance set to the number of 571 * ports per above. If the device is not in the whitelist, return 572 * PCI_P2PDMA_MAP_NOT_SUPPORTED. 573 */ 574static enum pci_p2pdma_map_type 575calc_map_type_and_dist(struct pci_dev *provider, struct pci_dev *client, 576 int *dist, bool verbose) 577{ 578 enum pci_p2pdma_map_type map_type = PCI_P2PDMA_MAP_THRU_HOST_BRIDGE; 579 struct pci_dev *a = provider, *b = client, *bb; 580 bool acs_redirects = false; 581 struct pci_p2pdma *p2pdma; 582 struct seq_buf acs_list; 583 int acs_cnt = 0; 584 int dist_a = 0; 585 int dist_b = 0; 586 char buf[128]; 587 588 seq_buf_init(&acs_list, buf, sizeof(buf)); 589 590 /* 591 * Note, we don't need to take references to devices returned by 592 * pci_upstream_bridge() seeing we hold a reference to a child 593 * device which will already hold a reference to the upstream bridge. 594 */ 595 while (a) { 596 dist_b = 0; 597 598 if (pci_bridge_has_acs_redir(a)) { 599 seq_buf_print_bus_devfn(&acs_list, a); 600 acs_cnt++; 601 } 602 603 bb = b; 604 605 while (bb) { 606 if (a == bb) 607 goto check_b_path_acs; 608 609 bb = pci_upstream_bridge(bb); 610 dist_b++; 611 } 612 613 a = pci_upstream_bridge(a); 614 dist_a++; 615 } 616 617 *dist = dist_a + dist_b; 618 goto map_through_host_bridge; 619 620check_b_path_acs: 621 bb = b; 622 623 while (bb) { 624 if (a == bb) 625 break; 626 627 if (pci_bridge_has_acs_redir(bb)) { 628 seq_buf_print_bus_devfn(&acs_list, bb); 629 acs_cnt++; 630 } 631 632 bb = pci_upstream_bridge(bb); 633 } 634 635 *dist = dist_a + dist_b; 636 637 if (!acs_cnt) { 638 map_type = PCI_P2PDMA_MAP_BUS_ADDR; 639 goto done; 640 } 641 642 if (verbose) { 643 acs_list.buffer[acs_list.len-1] = 0; /* drop final semicolon */ 644 pci_warn(client, "ACS redirect is set between the client and provider (%s)\n", 645 pci_name(provider)); 646 pci_warn(client, "to disable ACS redirect for this path, add the kernel parameter: pci=disable_acs_redir=%s\n", 647 acs_list.buffer); 648 } 649 acs_redirects = true; 650 651map_through_host_bridge: 652 if (!cpu_supports_p2pdma() && 653 !host_bridge_whitelist(provider, client, acs_redirects)) { 654 if (verbose) 655 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", 656 pci_name(provider)); 657 map_type = PCI_P2PDMA_MAP_NOT_SUPPORTED; 658 } 659done: 660 rcu_read_lock(); 661 p2pdma = rcu_dereference(provider->p2pdma); 662 if (p2pdma) 663 xa_store(&p2pdma->map_types, map_types_idx(client), 664 xa_mk_value(map_type), GFP_ATOMIC); 665 rcu_read_unlock(); 666 return map_type; 667} 668 669/** 670 * pci_p2pdma_distance_many - Determine the cumulative distance between 671 * a p2pdma provider and the clients in use. 672 * @provider: p2pdma provider to check against the client list 673 * @clients: array of devices to check (NULL-terminated) 674 * @num_clients: number of clients in the array 675 * @verbose: if true, print warnings for devices when we return -1 676 * 677 * Returns -1 if any of the clients are not compatible, otherwise returns a 678 * positive number where a lower number is the preferable choice. (If there's 679 * one client that's the same as the provider it will return 0, which is best 680 * choice). 681 * 682 * "compatible" means the provider and the clients are either all behind 683 * the same PCI root port or the host bridges connected to each of the devices 684 * are listed in the 'pci_p2pdma_whitelist'. 685 */ 686int pci_p2pdma_distance_many(struct pci_dev *provider, struct device **clients, 687 int num_clients, bool verbose) 688{ 689 enum pci_p2pdma_map_type map; 690 bool not_supported = false; 691 struct pci_dev *pci_client; 692 int total_dist = 0; 693 int i, distance; 694 695 if (num_clients == 0) 696 return -1; 697 698 for (i = 0; i < num_clients; i++) { 699 pci_client = find_parent_pci_dev(clients[i]); 700 if (!pci_client) { 701 if (verbose) 702 dev_warn(clients[i], 703 "cannot be used for peer-to-peer DMA as it is not a PCI device\n"); 704 return -1; 705 } 706 707 map = calc_map_type_and_dist(provider, pci_client, &distance, 708 verbose); 709 710 pci_dev_put(pci_client); 711 712 if (map == PCI_P2PDMA_MAP_NOT_SUPPORTED) 713 not_supported = true; 714 715 if (not_supported && !verbose) 716 break; 717 718 total_dist += distance; 719 } 720 721 if (not_supported) 722 return -1; 723 724 return total_dist; 725} 726EXPORT_SYMBOL_GPL(pci_p2pdma_distance_many); 727 728/** 729 * pci_has_p2pmem - check if a given PCI device has published any p2pmem 730 * @pdev: PCI device to check 731 */ 732bool pci_has_p2pmem(struct pci_dev *pdev) 733{ 734 struct pci_p2pdma *p2pdma; 735 bool res; 736 737 rcu_read_lock(); 738 p2pdma = rcu_dereference(pdev->p2pdma); 739 res = p2pdma && p2pdma->p2pmem_published; 740 rcu_read_unlock(); 741 742 return res; 743} 744EXPORT_SYMBOL_GPL(pci_has_p2pmem); 745 746/** 747 * pci_p2pmem_find_many - find a peer-to-peer DMA memory device compatible with 748 * the specified list of clients and shortest distance 749 * @clients: array of devices to check (NULL-terminated) 750 * @num_clients: number of client devices in the list 751 * 752 * If multiple devices are behind the same switch, the one "closest" to the 753 * client devices in use will be chosen first. (So if one of the providers is 754 * the same as one of the clients, that provider will be used ahead of any 755 * other providers that are unrelated). If multiple providers are an equal 756 * distance away, one will be chosen at random. 757 * 758 * Returns a pointer to the PCI device with a reference taken (use pci_dev_put 759 * to return the reference) or NULL if no compatible device is found. The 760 * found provider will also be assigned to the client list. 761 */ 762struct pci_dev *pci_p2pmem_find_many(struct device **clients, int num_clients) 763{ 764 struct pci_dev *pdev = NULL; 765 int distance; 766 int closest_distance = INT_MAX; 767 struct pci_dev **closest_pdevs; 768 int dev_cnt = 0; 769 const int max_devs = PAGE_SIZE / sizeof(*closest_pdevs); 770 int i; 771 772 closest_pdevs = kmalloc(PAGE_SIZE, GFP_KERNEL); 773 if (!closest_pdevs) 774 return NULL; 775 776 for_each_pci_dev(pdev) { 777 if (!pci_has_p2pmem(pdev)) 778 continue; 779 780 distance = pci_p2pdma_distance_many(pdev, clients, 781 num_clients, false); 782 if (distance < 0 || distance > closest_distance) 783 continue; 784 785 if (distance == closest_distance && dev_cnt >= max_devs) 786 continue; 787 788 if (distance < closest_distance) { 789 for (i = 0; i < dev_cnt; i++) 790 pci_dev_put(closest_pdevs[i]); 791 792 dev_cnt = 0; 793 closest_distance = distance; 794 } 795 796 closest_pdevs[dev_cnt++] = pci_dev_get(pdev); 797 } 798 799 if (dev_cnt) 800 pdev = pci_dev_get(closest_pdevs[get_random_u32_below(dev_cnt)]); 801 802 for (i = 0; i < dev_cnt; i++) 803 pci_dev_put(closest_pdevs[i]); 804 805 kfree(closest_pdevs); 806 return pdev; 807} 808EXPORT_SYMBOL_GPL(pci_p2pmem_find_many); 809 810/** 811 * pci_alloc_p2pmem - allocate peer-to-peer DMA memory 812 * @pdev: the device to allocate memory from 813 * @size: number of bytes to allocate 814 * 815 * Returns the allocated memory or NULL on error. 816 */ 817void *pci_alloc_p2pmem(struct pci_dev *pdev, size_t size) 818{ 819 void *ret = NULL; 820 struct percpu_ref *ref; 821 struct pci_p2pdma *p2pdma; 822 823 /* 824 * Pairs with synchronize_rcu() in pci_p2pdma_release() to 825 * ensure pdev->p2pdma is non-NULL for the duration of the 826 * read-lock. 827 */ 828 rcu_read_lock(); 829 p2pdma = rcu_dereference(pdev->p2pdma); 830 if (unlikely(!p2pdma)) 831 goto out; 832 833 ret = (void *)gen_pool_alloc_owner(p2pdma->pool, size, (void **) &ref); 834 if (!ret) 835 goto out; 836 837 if (unlikely(!percpu_ref_tryget_live_rcu(ref))) { 838 gen_pool_free(p2pdma->pool, (unsigned long) ret, size); 839 ret = NULL; 840 } 841out: 842 rcu_read_unlock(); 843 return ret; 844} 845EXPORT_SYMBOL_GPL(pci_alloc_p2pmem); 846 847/** 848 * pci_free_p2pmem - free peer-to-peer DMA memory 849 * @pdev: the device the memory was allocated from 850 * @addr: address of the memory that was allocated 851 * @size: number of bytes that were allocated 852 */ 853void pci_free_p2pmem(struct pci_dev *pdev, void *addr, size_t size) 854{ 855 struct percpu_ref *ref; 856 struct pci_p2pdma *p2pdma = rcu_dereference_protected(pdev->p2pdma, 1); 857 858 gen_pool_free_owner(p2pdma->pool, (uintptr_t)addr, size, 859 (void **) &ref); 860 percpu_ref_put(ref); 861} 862EXPORT_SYMBOL_GPL(pci_free_p2pmem); 863 864/** 865 * pci_p2pmem_virt_to_bus - return the PCI bus address for a given virtual 866 * address obtained with pci_alloc_p2pmem() 867 * @pdev: the device the memory was allocated from 868 * @addr: address of the memory that was allocated 869 */ 870pci_bus_addr_t pci_p2pmem_virt_to_bus(struct pci_dev *pdev, void *addr) 871{ 872 struct pci_p2pdma *p2pdma; 873 874 if (!addr) 875 return 0; 876 877 p2pdma = rcu_dereference_protected(pdev->p2pdma, 1); 878 if (!p2pdma) 879 return 0; 880 881 /* 882 * Note: when we added the memory to the pool we used the PCI 883 * bus address as the physical address. So gen_pool_virt_to_phys() 884 * actually returns the bus address despite the misleading name. 885 */ 886 return gen_pool_virt_to_phys(p2pdma->pool, (unsigned long)addr); 887} 888EXPORT_SYMBOL_GPL(pci_p2pmem_virt_to_bus); 889 890/** 891 * pci_p2pmem_alloc_sgl - allocate peer-to-peer DMA memory in a scatterlist 892 * @pdev: the device to allocate memory from 893 * @nents: the number of SG entries in the list 894 * @length: number of bytes to allocate 895 * 896 * Return: %NULL on error or &struct scatterlist pointer and @nents on success 897 */ 898struct scatterlist *pci_p2pmem_alloc_sgl(struct pci_dev *pdev, 899 unsigned int *nents, u32 length) 900{ 901 struct scatterlist *sg; 902 void *addr; 903 904 sg = kmalloc(sizeof(*sg), GFP_KERNEL); 905 if (!sg) 906 return NULL; 907 908 sg_init_table(sg, 1); 909 910 addr = pci_alloc_p2pmem(pdev, length); 911 if (!addr) 912 goto out_free_sg; 913 914 sg_set_buf(sg, addr, length); 915 *nents = 1; 916 return sg; 917 918out_free_sg: 919 kfree(sg); 920 return NULL; 921} 922EXPORT_SYMBOL_GPL(pci_p2pmem_alloc_sgl); 923 924/** 925 * pci_p2pmem_free_sgl - free a scatterlist allocated by pci_p2pmem_alloc_sgl() 926 * @pdev: the device to allocate memory from 927 * @sgl: the allocated scatterlist 928 */ 929void pci_p2pmem_free_sgl(struct pci_dev *pdev, struct scatterlist *sgl) 930{ 931 struct scatterlist *sg; 932 int count; 933 934 for_each_sg(sgl, sg, INT_MAX, count) { 935 if (!sg) 936 break; 937 938 pci_free_p2pmem(pdev, sg_virt(sg), sg->length); 939 } 940 kfree(sgl); 941} 942EXPORT_SYMBOL_GPL(pci_p2pmem_free_sgl); 943 944/** 945 * pci_p2pmem_publish - publish the peer-to-peer DMA memory for use by 946 * other devices with pci_p2pmem_find() 947 * @pdev: the device with peer-to-peer DMA memory to publish 948 * @publish: set to true to publish the memory, false to unpublish it 949 * 950 * Published memory can be used by other PCI device drivers for 951 * peer-2-peer DMA operations. Non-published memory is reserved for 952 * exclusive use of the device driver that registers the peer-to-peer 953 * memory. 954 */ 955void pci_p2pmem_publish(struct pci_dev *pdev, bool publish) 956{ 957 struct pci_p2pdma *p2pdma; 958 959 rcu_read_lock(); 960 p2pdma = rcu_dereference(pdev->p2pdma); 961 if (p2pdma) 962 p2pdma->p2pmem_published = publish; 963 rcu_read_unlock(); 964} 965EXPORT_SYMBOL_GPL(pci_p2pmem_publish); 966 967static enum pci_p2pdma_map_type pci_p2pdma_map_type(struct dev_pagemap *pgmap, 968 struct device *dev) 969{ 970 enum pci_p2pdma_map_type type = PCI_P2PDMA_MAP_NOT_SUPPORTED; 971 struct pci_dev *provider = to_p2p_pgmap(pgmap)->provider; 972 struct pci_dev *client; 973 struct pci_p2pdma *p2pdma; 974 int dist; 975 976 if (!provider->p2pdma) 977 return PCI_P2PDMA_MAP_NOT_SUPPORTED; 978 979 if (!dev_is_pci(dev)) 980 return PCI_P2PDMA_MAP_NOT_SUPPORTED; 981 982 client = to_pci_dev(dev); 983 984 rcu_read_lock(); 985 p2pdma = rcu_dereference(provider->p2pdma); 986 987 if (p2pdma) 988 type = xa_to_value(xa_load(&p2pdma->map_types, 989 map_types_idx(client))); 990 rcu_read_unlock(); 991 992 if (type == PCI_P2PDMA_MAP_UNKNOWN) 993 return calc_map_type_and_dist(provider, client, &dist, true); 994 995 return type; 996} 997 998/** 999 * pci_p2pdma_map_segment - map an sg segment determining the mapping type 1000 * @state: State structure that should be declared outside of the for_each_sg() 1001 * loop and initialized to zero. 1002 * @dev: DMA device that's doing the mapping operation 1003 * @sg: scatterlist segment to map 1004 * 1005 * This is a helper to be used by non-IOMMU dma_map_sg() implementations where 1006 * the sg segment is the same for the page_link and the dma_address. 1007 * 1008 * Attempt to map a single segment in an SGL with the PCI bus address. 1009 * The segment must point to a PCI P2PDMA page and thus must be 1010 * wrapped in a is_pci_p2pdma_page(sg_page(sg)) check. 1011 * 1012 * Returns the type of mapping used and maps the page if the type is 1013 * PCI_P2PDMA_MAP_BUS_ADDR. 1014 */ 1015enum pci_p2pdma_map_type 1016pci_p2pdma_map_segment(struct pci_p2pdma_map_state *state, struct device *dev, 1017 struct scatterlist *sg) 1018{ 1019 if (state->pgmap != sg_page(sg)->pgmap) { 1020 state->pgmap = sg_page(sg)->pgmap; 1021 state->map = pci_p2pdma_map_type(state->pgmap, dev); 1022 state->bus_off = to_p2p_pgmap(state->pgmap)->bus_offset; 1023 } 1024 1025 if (state->map == PCI_P2PDMA_MAP_BUS_ADDR) { 1026 sg->dma_address = sg_phys(sg) + state->bus_off; 1027 sg_dma_len(sg) = sg->length; 1028 sg_dma_mark_bus_address(sg); 1029 } 1030 1031 return state->map; 1032} 1033 1034/** 1035 * pci_p2pdma_enable_store - parse a configfs/sysfs attribute store 1036 * to enable p2pdma 1037 * @page: contents of the value to be stored 1038 * @p2p_dev: returns the PCI device that was selected to be used 1039 * (if one was specified in the stored value) 1040 * @use_p2pdma: returns whether to enable p2pdma or not 1041 * 1042 * Parses an attribute value to decide whether to enable p2pdma. 1043 * The value can select a PCI device (using its full BDF device 1044 * name) or a boolean (in any format kstrtobool() accepts). A false 1045 * value disables p2pdma, a true value expects the caller 1046 * to automatically find a compatible device and specifying a PCI device 1047 * expects the caller to use the specific provider. 1048 * 1049 * pci_p2pdma_enable_show() should be used as the show operation for 1050 * the attribute. 1051 * 1052 * Returns 0 on success 1053 */ 1054int pci_p2pdma_enable_store(const char *page, struct pci_dev **p2p_dev, 1055 bool *use_p2pdma) 1056{ 1057 struct device *dev; 1058 1059 dev = bus_find_device_by_name(&pci_bus_type, NULL, page); 1060 if (dev) { 1061 *use_p2pdma = true; 1062 *p2p_dev = to_pci_dev(dev); 1063 1064 if (!pci_has_p2pmem(*p2p_dev)) { 1065 pci_err(*p2p_dev, 1066 "PCI device has no peer-to-peer memory: %s\n", 1067 page); 1068 pci_dev_put(*p2p_dev); 1069 return -ENODEV; 1070 } 1071 1072 return 0; 1073 } else if ((page[0] == '0' || page[0] == '1') && !iscntrl(page[1])) { 1074 /* 1075 * If the user enters a PCI device that doesn't exist 1076 * like "0000:01:00.1", we don't want kstrtobool to think 1077 * it's a '0' when it's clearly not what the user wanted. 1078 * So we require 0's and 1's to be exactly one character. 1079 */ 1080 } else if (!kstrtobool(page, use_p2pdma)) { 1081 return 0; 1082 } 1083 1084 pr_err("No such PCI device: %.*s\n", (int)strcspn(page, "\n"), page); 1085 return -ENODEV; 1086} 1087EXPORT_SYMBOL_GPL(pci_p2pdma_enable_store); 1088 1089/** 1090 * pci_p2pdma_enable_show - show a configfs/sysfs attribute indicating 1091 * whether p2pdma is enabled 1092 * @page: contents of the stored value 1093 * @p2p_dev: the selected p2p device (NULL if no device is selected) 1094 * @use_p2pdma: whether p2pdma has been enabled 1095 * 1096 * Attributes that use pci_p2pdma_enable_store() should use this function 1097 * to show the value of the attribute. 1098 * 1099 * Returns 0 on success 1100 */ 1101ssize_t pci_p2pdma_enable_show(char *page, struct pci_dev *p2p_dev, 1102 bool use_p2pdma) 1103{ 1104 if (!use_p2pdma) 1105 return sprintf(page, "0\n"); 1106 1107 if (!p2p_dev) 1108 return sprintf(page, "1\n"); 1109 1110 return sprintf(page, "%s\n", pci_name(p2p_dev)); 1111} 1112EXPORT_SYMBOL_GPL(pci_p2pdma_enable_show); 1113