1 // SPDX-License-Identifier: GPL-2.0
3 * PCI Peer 2 Peer DMA support.
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.
11 #define pr_fmt(fmt) "pci-p2pdma: " fmt
12 #include <linux/ctype.h>
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>
21 #include <linux/xarray.h>
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,
31 struct gen_pool *pool;
32 bool p2pmem_published;
33 struct xarray map_types;
36 struct pci_p2pdma_pagemap {
37 struct dev_pagemap pgmap;
38 struct pci_dev *provider;
42 static struct pci_p2pdma_pagemap *to_p2p_pgmap(struct dev_pagemap *pgmap)
44 return container_of(pgmap, struct pci_p2pdma_pagemap, pgmap);
47 static ssize_t size_show(struct device *dev, struct device_attribute *attr,
50 struct pci_dev *pdev = to_pci_dev(dev);
53 if (pdev->p2pdma->pool)
54 size = gen_pool_size(pdev->p2pdma->pool);
56 return sysfs_emit(buf, "%zd\n", size);
58 static DEVICE_ATTR_RO(size);
60 static ssize_t available_show(struct device *dev, struct device_attribute *attr,
63 struct pci_dev *pdev = to_pci_dev(dev);
66 if (pdev->p2pdma->pool)
67 avail = gen_pool_avail(pdev->p2pdma->pool);
69 return sysfs_emit(buf, "%zd\n", avail);
71 static DEVICE_ATTR_RO(available);
73 static ssize_t published_show(struct device *dev, struct device_attribute *attr,
76 struct pci_dev *pdev = to_pci_dev(dev);
78 return sysfs_emit(buf, "%d\n", pdev->p2pdma->p2pmem_published);
80 static DEVICE_ATTR_RO(published);
82 static struct attribute *p2pmem_attrs[] = {
84 &dev_attr_available.attr,
85 &dev_attr_published.attr,
89 static const struct attribute_group p2pmem_group = {
90 .attrs = p2pmem_attrs,
94 static void pci_p2pdma_release(void *data)
96 struct pci_dev *pdev = data;
97 struct pci_p2pdma *p2pdma = pdev->p2pdma;
102 /* Flush and disable pci_alloc_p2p_mem() */
106 gen_pool_destroy(p2pdma->pool);
107 sysfs_remove_group(&pdev->dev.kobj, &p2pmem_group);
108 xa_destroy(&p2pdma->map_types);
111 static int pci_p2pdma_setup(struct pci_dev *pdev)
114 struct pci_p2pdma *p2p;
116 p2p = devm_kzalloc(&pdev->dev, sizeof(*p2p), GFP_KERNEL);
120 xa_init(&p2p->map_types);
122 p2p->pool = gen_pool_create(PAGE_SHIFT, dev_to_node(&pdev->dev));
126 error = devm_add_action_or_reset(&pdev->dev, pci_p2pdma_release, pdev);
128 goto out_pool_destroy;
132 error = sysfs_create_group(&pdev->dev.kobj, &p2pmem_group);
134 goto out_pool_destroy;
140 gen_pool_destroy(p2p->pool);
142 devm_kfree(&pdev->dev, p2p);
147 * pci_p2pdma_add_resource - add memory for use as p2p memory
148 * @pdev: the device to add the memory to
149 * @bar: PCI BAR to add
150 * @size: size of the memory to add, may be zero to use the whole BAR
151 * @offset: offset into the PCI BAR
153 * The memory will be given ZONE_DEVICE struct pages so that it may
154 * be used with any DMA request.
156 int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar, size_t size,
159 struct pci_p2pdma_pagemap *p2p_pgmap;
160 struct dev_pagemap *pgmap;
164 if (!(pci_resource_flags(pdev, bar) & IORESOURCE_MEM))
167 if (offset >= pci_resource_len(pdev, bar))
171 size = pci_resource_len(pdev, bar) - offset;
173 if (size + offset > pci_resource_len(pdev, bar))
177 error = pci_p2pdma_setup(pdev);
182 p2p_pgmap = devm_kzalloc(&pdev->dev, sizeof(*p2p_pgmap), GFP_KERNEL);
186 pgmap = &p2p_pgmap->pgmap;
187 pgmap->range.start = pci_resource_start(pdev, bar) + offset;
188 pgmap->range.end = pgmap->range.start + size - 1;
190 pgmap->type = MEMORY_DEVICE_PCI_P2PDMA;
192 p2p_pgmap->provider = pdev;
193 p2p_pgmap->bus_offset = pci_bus_address(pdev, bar) -
194 pci_resource_start(pdev, bar);
196 addr = devm_memremap_pages(&pdev->dev, pgmap);
198 error = PTR_ERR(addr);
202 error = gen_pool_add_owner(pdev->p2pdma->pool, (unsigned long)addr,
203 pci_bus_address(pdev, bar) + offset,
204 range_len(&pgmap->range), dev_to_node(&pdev->dev),
209 pci_info(pdev, "added peer-to-peer DMA memory %#llx-%#llx\n",
210 pgmap->range.start, pgmap->range.end);
215 devm_memunmap_pages(&pdev->dev, pgmap);
217 devm_kfree(&pdev->dev, pgmap);
220 EXPORT_SYMBOL_GPL(pci_p2pdma_add_resource);
223 * Note this function returns the parent PCI device with a
224 * reference taken. It is the caller's responsibility to drop
227 static struct pci_dev *find_parent_pci_dev(struct device *dev)
229 struct device *parent;
231 dev = get_device(dev);
235 return to_pci_dev(dev);
237 parent = get_device(dev->parent);
246 * Check if a PCI bridge has its ACS redirection bits set to redirect P2P
247 * TLPs upstream via ACS. Returns 1 if the packets will be redirected
248 * upstream, 0 otherwise.
250 static int pci_bridge_has_acs_redir(struct pci_dev *pdev)
259 pci_read_config_word(pdev, pos + PCI_ACS_CTRL, &ctrl);
261 if (ctrl & (PCI_ACS_RR | PCI_ACS_CR | PCI_ACS_EC))
267 static void seq_buf_print_bus_devfn(struct seq_buf *buf, struct pci_dev *pdev)
272 seq_buf_printf(buf, "%s;", pci_name(pdev));
275 static bool cpu_supports_p2pdma(void)
278 struct cpuinfo_x86 *c = &cpu_data(0);
280 /* Any AMD CPU whose family ID is Zen or newer supports p2pdma */
281 if (c->x86_vendor == X86_VENDOR_AMD && c->x86 >= 0x17)
288 static const struct pci_p2pdma_whitelist_entry {
289 unsigned short vendor;
290 unsigned short device;
292 REQ_SAME_HOST_BRIDGE = 1 << 0,
294 } pci_p2pdma_whitelist[] = {
295 /* Intel Xeon E5/Core i7 */
296 {PCI_VENDOR_ID_INTEL, 0x3c00, REQ_SAME_HOST_BRIDGE},
297 {PCI_VENDOR_ID_INTEL, 0x3c01, REQ_SAME_HOST_BRIDGE},
298 /* Intel Xeon E7 v3/Xeon E5 v3/Core i7 */
299 {PCI_VENDOR_ID_INTEL, 0x2f00, REQ_SAME_HOST_BRIDGE},
300 {PCI_VENDOR_ID_INTEL, 0x2f01, REQ_SAME_HOST_BRIDGE},
301 /* Intel SkyLake-E */
302 {PCI_VENDOR_ID_INTEL, 0x2030, 0},
303 {PCI_VENDOR_ID_INTEL, 0x2031, 0},
304 {PCI_VENDOR_ID_INTEL, 0x2032, 0},
305 {PCI_VENDOR_ID_INTEL, 0x2033, 0},
306 {PCI_VENDOR_ID_INTEL, 0x2020, 0},
310 static bool __host_bridge_whitelist(struct pci_host_bridge *host,
311 bool same_host_bridge)
313 struct pci_dev *root = pci_get_slot(host->bus, PCI_DEVFN(0, 0));
314 const struct pci_p2pdma_whitelist_entry *entry;
315 unsigned short vendor, device;
320 vendor = root->vendor;
321 device = root->device;
324 for (entry = pci_p2pdma_whitelist; entry->vendor; entry++) {
325 if (vendor != entry->vendor || device != entry->device)
327 if (entry->flags & REQ_SAME_HOST_BRIDGE && !same_host_bridge)
337 * If we can't find a common upstream bridge take a look at the root
338 * complex and compare it to a whitelist of known good hardware.
340 static bool host_bridge_whitelist(struct pci_dev *a, struct pci_dev *b)
342 struct pci_host_bridge *host_a = pci_find_host_bridge(a->bus);
343 struct pci_host_bridge *host_b = pci_find_host_bridge(b->bus);
345 if (host_a == host_b)
346 return __host_bridge_whitelist(host_a, true);
348 if (__host_bridge_whitelist(host_a, false) &&
349 __host_bridge_whitelist(host_b, false))
355 static enum pci_p2pdma_map_type
356 __upstream_bridge_distance(struct pci_dev *provider, struct pci_dev *client,
357 int *dist, bool *acs_redirects, struct seq_buf *acs_list)
359 struct pci_dev *a = provider, *b = client, *bb;
365 *acs_redirects = false;
368 * Note, we don't need to take references to devices returned by
369 * pci_upstream_bridge() seeing we hold a reference to a child
370 * device which will already hold a reference to the upstream bridge.
376 if (pci_bridge_has_acs_redir(a)) {
377 seq_buf_print_bus_devfn(acs_list, a);
385 goto check_b_path_acs;
387 bb = pci_upstream_bridge(bb);
391 a = pci_upstream_bridge(a);
396 *dist = dist_a + dist_b;
398 return PCI_P2PDMA_MAP_THRU_HOST_BRIDGE;
407 if (pci_bridge_has_acs_redir(bb)) {
408 seq_buf_print_bus_devfn(acs_list, bb);
412 bb = pci_upstream_bridge(bb);
416 *dist = dist_a + dist_b;
420 *acs_redirects = true;
422 return PCI_P2PDMA_MAP_THRU_HOST_BRIDGE;
425 return PCI_P2PDMA_MAP_BUS_ADDR;
428 static unsigned long map_types_idx(struct pci_dev *client)
430 return (pci_domain_nr(client->bus) << 16) |
431 (client->bus->number << 8) | client->devfn;
435 * Find the distance through the nearest common upstream bridge between
438 * If the two devices are the same device then 0 will be returned.
440 * If there are two virtual functions of the same device behind the same
441 * bridge port then 2 will be returned (one step down to the PCIe switch,
442 * then one step back to the same device).
444 * In the case where two devices are connected to the same PCIe switch, the
445 * value 4 will be returned. This corresponds to the following PCI tree:
448 * \+ Switch Upstream Port
449 * +-+ Switch Downstream Port
451 * \-+ Switch Downstream Port
454 * The distance is 4 because we traverse from Device A through the downstream
455 * port of the switch, to the common upstream port, back up to the second
456 * downstream port and then to Device B.
458 * Any two devices that cannot communicate using p2pdma will return
459 * PCI_P2PDMA_MAP_NOT_SUPPORTED.
461 * Any two devices that have a data path that goes through the host bridge
462 * will consult a whitelist. If the host bridges are on the whitelist,
463 * this function will return PCI_P2PDMA_MAP_THRU_HOST_BRIDGE.
465 * If either bridge is not on the whitelist this function returns
466 * PCI_P2PDMA_MAP_NOT_SUPPORTED.
468 * If a bridge which has any ACS redirection bits set is in the path,
469 * acs_redirects will be set to true. In this case, a list of all infringing
470 * bridge addresses will be populated in acs_list (assuming it's non-null)
471 * for printk purposes.
473 static enum pci_p2pdma_map_type
474 upstream_bridge_distance(struct pci_dev *provider, struct pci_dev *client,
475 int *dist, bool *acs_redirects, struct seq_buf *acs_list)
477 enum pci_p2pdma_map_type map_type;
479 map_type = __upstream_bridge_distance(provider, client, dist,
480 acs_redirects, acs_list);
482 if (map_type == PCI_P2PDMA_MAP_THRU_HOST_BRIDGE) {
483 if (!cpu_supports_p2pdma() &&
484 !host_bridge_whitelist(provider, client))
485 map_type = PCI_P2PDMA_MAP_NOT_SUPPORTED;
488 if (provider->p2pdma)
489 xa_store(&provider->p2pdma->map_types, map_types_idx(client),
490 xa_mk_value(map_type), GFP_KERNEL);
495 static enum pci_p2pdma_map_type
496 upstream_bridge_distance_warn(struct pci_dev *provider, struct pci_dev *client,
499 struct seq_buf acs_list;
503 seq_buf_init(&acs_list, kmalloc(PAGE_SIZE, GFP_KERNEL), PAGE_SIZE);
504 if (!acs_list.buffer)
507 ret = upstream_bridge_distance(provider, client, dist, &acs_redirects,
510 pci_warn(client, "ACS redirect is set between the client and provider (%s)\n",
512 /* Drop final semicolon */
513 acs_list.buffer[acs_list.len-1] = 0;
514 pci_warn(client, "to disable ACS redirect for this path, add the kernel parameter: pci=disable_acs_redir=%s\n",
518 if (ret == PCI_P2PDMA_MAP_NOT_SUPPORTED) {
519 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",
523 kfree(acs_list.buffer);
529 * pci_p2pdma_distance_many - Determine the cumulative distance between
530 * a p2pdma provider and the clients in use.
531 * @provider: p2pdma provider to check against the client list
532 * @clients: array of devices to check (NULL-terminated)
533 * @num_clients: number of clients in the array
534 * @verbose: if true, print warnings for devices when we return -1
536 * Returns -1 if any of the clients are not compatible, otherwise returns a
537 * positive number where a lower number is the preferable choice. (If there's
538 * one client that's the same as the provider it will return 0, which is best
541 * "compatible" means the provider and the clients are either all behind
542 * the same PCI root port or the host bridges connected to each of the devices
543 * are listed in the 'pci_p2pdma_whitelist'.
545 int pci_p2pdma_distance_many(struct pci_dev *provider, struct device **clients,
546 int num_clients, bool verbose)
548 bool not_supported = false;
549 struct pci_dev *pci_client;
554 if (num_clients == 0)
557 for (i = 0; i < num_clients; i++) {
558 pci_client = find_parent_pci_dev(clients[i]);
562 "cannot be used for peer-to-peer DMA as it is not a PCI device\n");
567 ret = upstream_bridge_distance_warn(provider,
568 pci_client, &distance);
570 ret = upstream_bridge_distance(provider, pci_client,
571 &distance, NULL, NULL);
573 pci_dev_put(pci_client);
575 if (ret == PCI_P2PDMA_MAP_NOT_SUPPORTED)
576 not_supported = true;
578 if (not_supported && !verbose)
581 total_dist += distance;
589 EXPORT_SYMBOL_GPL(pci_p2pdma_distance_many);
592 * pci_has_p2pmem - check if a given PCI device has published any p2pmem
593 * @pdev: PCI device to check
595 bool pci_has_p2pmem(struct pci_dev *pdev)
597 return pdev->p2pdma && pdev->p2pdma->p2pmem_published;
599 EXPORT_SYMBOL_GPL(pci_has_p2pmem);
602 * pci_p2pmem_find_many - find a peer-to-peer DMA memory device compatible with
603 * the specified list of clients and shortest distance (as determined
604 * by pci_p2pmem_dma())
605 * @clients: array of devices to check (NULL-terminated)
606 * @num_clients: number of client devices in the list
608 * If multiple devices are behind the same switch, the one "closest" to the
609 * client devices in use will be chosen first. (So if one of the providers is
610 * the same as one of the clients, that provider will be used ahead of any
611 * other providers that are unrelated). If multiple providers are an equal
612 * distance away, one will be chosen at random.
614 * Returns a pointer to the PCI device with a reference taken (use pci_dev_put
615 * to return the reference) or NULL if no compatible device is found. The
616 * found provider will also be assigned to the client list.
618 struct pci_dev *pci_p2pmem_find_many(struct device **clients, int num_clients)
620 struct pci_dev *pdev = NULL;
622 int closest_distance = INT_MAX;
623 struct pci_dev **closest_pdevs;
625 const int max_devs = PAGE_SIZE / sizeof(*closest_pdevs);
628 closest_pdevs = kmalloc(PAGE_SIZE, GFP_KERNEL);
632 while ((pdev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, pdev))) {
633 if (!pci_has_p2pmem(pdev))
636 distance = pci_p2pdma_distance_many(pdev, clients,
638 if (distance < 0 || distance > closest_distance)
641 if (distance == closest_distance && dev_cnt >= max_devs)
644 if (distance < closest_distance) {
645 for (i = 0; i < dev_cnt; i++)
646 pci_dev_put(closest_pdevs[i]);
649 closest_distance = distance;
652 closest_pdevs[dev_cnt++] = pci_dev_get(pdev);
656 pdev = pci_dev_get(closest_pdevs[prandom_u32_max(dev_cnt)]);
658 for (i = 0; i < dev_cnt; i++)
659 pci_dev_put(closest_pdevs[i]);
661 kfree(closest_pdevs);
664 EXPORT_SYMBOL_GPL(pci_p2pmem_find_many);
667 * pci_alloc_p2pmem - allocate peer-to-peer DMA memory
668 * @pdev: the device to allocate memory from
669 * @size: number of bytes to allocate
671 * Returns the allocated memory or NULL on error.
673 void *pci_alloc_p2pmem(struct pci_dev *pdev, size_t size)
676 struct percpu_ref *ref;
679 * Pairs with synchronize_rcu() in pci_p2pdma_release() to
680 * ensure pdev->p2pdma is non-NULL for the duration of the
684 if (unlikely(!pdev->p2pdma))
687 ret = (void *)gen_pool_alloc_owner(pdev->p2pdma->pool, size,
692 if (unlikely(!percpu_ref_tryget_live(ref))) {
693 gen_pool_free(pdev->p2pdma->pool, (unsigned long) ret, size);
701 EXPORT_SYMBOL_GPL(pci_alloc_p2pmem);
704 * pci_free_p2pmem - free peer-to-peer DMA memory
705 * @pdev: the device the memory was allocated from
706 * @addr: address of the memory that was allocated
707 * @size: number of bytes that were allocated
709 void pci_free_p2pmem(struct pci_dev *pdev, void *addr, size_t size)
711 struct percpu_ref *ref;
713 gen_pool_free_owner(pdev->p2pdma->pool, (uintptr_t)addr, size,
717 EXPORT_SYMBOL_GPL(pci_free_p2pmem);
720 * pci_p2pmem_virt_to_bus - return the PCI bus address for a given virtual
721 * address obtained with pci_alloc_p2pmem()
722 * @pdev: the device the memory was allocated from
723 * @addr: address of the memory that was allocated
725 pci_bus_addr_t pci_p2pmem_virt_to_bus(struct pci_dev *pdev, void *addr)
733 * Note: when we added the memory to the pool we used the PCI
734 * bus address as the physical address. So gen_pool_virt_to_phys()
735 * actually returns the bus address despite the misleading name.
737 return gen_pool_virt_to_phys(pdev->p2pdma->pool, (unsigned long)addr);
739 EXPORT_SYMBOL_GPL(pci_p2pmem_virt_to_bus);
742 * pci_p2pmem_alloc_sgl - allocate peer-to-peer DMA memory in a scatterlist
743 * @pdev: the device to allocate memory from
744 * @nents: the number of SG entries in the list
745 * @length: number of bytes to allocate
747 * Return: %NULL on error or &struct scatterlist pointer and @nents on success
749 struct scatterlist *pci_p2pmem_alloc_sgl(struct pci_dev *pdev,
750 unsigned int *nents, u32 length)
752 struct scatterlist *sg;
755 sg = kmalloc(sizeof(*sg), GFP_KERNEL);
759 sg_init_table(sg, 1);
761 addr = pci_alloc_p2pmem(pdev, length);
765 sg_set_buf(sg, addr, length);
773 EXPORT_SYMBOL_GPL(pci_p2pmem_alloc_sgl);
776 * pci_p2pmem_free_sgl - free a scatterlist allocated by pci_p2pmem_alloc_sgl()
777 * @pdev: the device to allocate memory from
778 * @sgl: the allocated scatterlist
780 void pci_p2pmem_free_sgl(struct pci_dev *pdev, struct scatterlist *sgl)
782 struct scatterlist *sg;
785 for_each_sg(sgl, sg, INT_MAX, count) {
789 pci_free_p2pmem(pdev, sg_virt(sg), sg->length);
793 EXPORT_SYMBOL_GPL(pci_p2pmem_free_sgl);
796 * pci_p2pmem_publish - publish the peer-to-peer DMA memory for use by
797 * other devices with pci_p2pmem_find()
798 * @pdev: the device with peer-to-peer DMA memory to publish
799 * @publish: set to true to publish the memory, false to unpublish it
801 * Published memory can be used by other PCI device drivers for
802 * peer-2-peer DMA operations. Non-published memory is reserved for
803 * exclusive use of the device driver that registers the peer-to-peer
806 void pci_p2pmem_publish(struct pci_dev *pdev, bool publish)
809 pdev->p2pdma->p2pmem_published = publish;
811 EXPORT_SYMBOL_GPL(pci_p2pmem_publish);
813 static enum pci_p2pdma_map_type pci_p2pdma_map_type(struct pci_dev *provider,
814 struct pci_dev *client)
816 if (!provider->p2pdma)
817 return PCI_P2PDMA_MAP_NOT_SUPPORTED;
819 return xa_to_value(xa_load(&provider->p2pdma->map_types,
820 map_types_idx(client)));
823 static int __pci_p2pdma_map_sg(struct pci_p2pdma_pagemap *p2p_pgmap,
824 struct device *dev, struct scatterlist *sg, int nents)
826 struct scatterlist *s;
829 for_each_sg(sg, s, nents, i) {
830 s->dma_address = sg_phys(s) - p2p_pgmap->bus_offset;
831 sg_dma_len(s) = s->length;
838 * pci_p2pdma_map_sg_attrs - map a PCI peer-to-peer scatterlist for DMA
839 * @dev: device doing the DMA request
840 * @sg: scatter list to map
841 * @nents: elements in the scatterlist
842 * @dir: DMA direction
843 * @attrs: DMA attributes passed to dma_map_sg() (if called)
845 * Scatterlists mapped with this function should be unmapped using
846 * pci_p2pdma_unmap_sg_attrs().
848 * Returns the number of SG entries mapped or 0 on error.
850 int pci_p2pdma_map_sg_attrs(struct device *dev, struct scatterlist *sg,
851 int nents, enum dma_data_direction dir, unsigned long attrs)
853 struct pci_p2pdma_pagemap *p2p_pgmap =
854 to_p2p_pgmap(sg_page(sg)->pgmap);
855 struct pci_dev *client;
857 if (WARN_ON_ONCE(!dev_is_pci(dev)))
860 client = to_pci_dev(dev);
862 switch (pci_p2pdma_map_type(p2p_pgmap->provider, client)) {
863 case PCI_P2PDMA_MAP_THRU_HOST_BRIDGE:
864 return dma_map_sg_attrs(dev, sg, nents, dir, attrs);
865 case PCI_P2PDMA_MAP_BUS_ADDR:
866 return __pci_p2pdma_map_sg(p2p_pgmap, dev, sg, nents);
872 EXPORT_SYMBOL_GPL(pci_p2pdma_map_sg_attrs);
875 * pci_p2pdma_unmap_sg_attrs - unmap a PCI peer-to-peer scatterlist that was
876 * mapped with pci_p2pdma_map_sg()
877 * @dev: device doing the DMA request
878 * @sg: scatter list to map
879 * @nents: number of elements returned by pci_p2pdma_map_sg()
880 * @dir: DMA direction
881 * @attrs: DMA attributes passed to dma_unmap_sg() (if called)
883 void pci_p2pdma_unmap_sg_attrs(struct device *dev, struct scatterlist *sg,
884 int nents, enum dma_data_direction dir, unsigned long attrs)
886 struct pci_p2pdma_pagemap *p2p_pgmap =
887 to_p2p_pgmap(sg_page(sg)->pgmap);
888 enum pci_p2pdma_map_type map_type;
889 struct pci_dev *client;
891 if (WARN_ON_ONCE(!dev_is_pci(dev)))
894 client = to_pci_dev(dev);
896 map_type = pci_p2pdma_map_type(p2p_pgmap->provider, client);
898 if (map_type == PCI_P2PDMA_MAP_THRU_HOST_BRIDGE)
899 dma_unmap_sg_attrs(dev, sg, nents, dir, attrs);
901 EXPORT_SYMBOL_GPL(pci_p2pdma_unmap_sg_attrs);
904 * pci_p2pdma_enable_store - parse a configfs/sysfs attribute store
906 * @page: contents of the value to be stored
907 * @p2p_dev: returns the PCI device that was selected to be used
908 * (if one was specified in the stored value)
909 * @use_p2pdma: returns whether to enable p2pdma or not
911 * Parses an attribute value to decide whether to enable p2pdma.
912 * The value can select a PCI device (using its full BDF device
913 * name) or a boolean (in any format strtobool() accepts). A false
914 * value disables p2pdma, a true value expects the caller
915 * to automatically find a compatible device and specifying a PCI device
916 * expects the caller to use the specific provider.
918 * pci_p2pdma_enable_show() should be used as the show operation for
921 * Returns 0 on success
923 int pci_p2pdma_enable_store(const char *page, struct pci_dev **p2p_dev,
928 dev = bus_find_device_by_name(&pci_bus_type, NULL, page);
931 *p2p_dev = to_pci_dev(dev);
933 if (!pci_has_p2pmem(*p2p_dev)) {
935 "PCI device has no peer-to-peer memory: %s\n",
937 pci_dev_put(*p2p_dev);
942 } else if ((page[0] == '0' || page[0] == '1') && !iscntrl(page[1])) {
944 * If the user enters a PCI device that doesn't exist
945 * like "0000:01:00.1", we don't want strtobool to think
946 * it's a '0' when it's clearly not what the user wanted.
947 * So we require 0's and 1's to be exactly one character.
949 } else if (!strtobool(page, use_p2pdma)) {
953 pr_err("No such PCI device: %.*s\n", (int)strcspn(page, "\n"), page);
956 EXPORT_SYMBOL_GPL(pci_p2pdma_enable_store);
959 * pci_p2pdma_enable_show - show a configfs/sysfs attribute indicating
960 * whether p2pdma is enabled
961 * @page: contents of the stored value
962 * @p2p_dev: the selected p2p device (NULL if no device is selected)
963 * @use_p2pdma: whether p2pdma has been enabled
965 * Attributes that use pci_p2pdma_enable_store() should use this function
966 * to show the value of the attribute.
968 * Returns 0 on success
970 ssize_t pci_p2pdma_enable_show(char *page, struct pci_dev *p2p_dev,
974 return sprintf(page, "0\n");
977 return sprintf(page, "1\n");
979 return sprintf(page, "%s\n", pci_name(p2p_dev));
981 EXPORT_SYMBOL_GPL(pci_p2pdma_enable_show);