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 scnprintf(buf, PAGE_SIZE, "%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 scnprintf(buf, PAGE_SIZE, "%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 scnprintf(buf, PAGE_SIZE, "%d\n",
79 pdev->p2pdma->p2pmem_published);
81 static DEVICE_ATTR_RO(published);
83 static struct attribute *p2pmem_attrs[] = {
85 &dev_attr_available.attr,
86 &dev_attr_published.attr,
90 static const struct attribute_group p2pmem_group = {
91 .attrs = p2pmem_attrs,
95 static void pci_p2pdma_release(void *data)
97 struct pci_dev *pdev = data;
98 struct pci_p2pdma *p2pdma = pdev->p2pdma;
103 /* Flush and disable pci_alloc_p2p_mem() */
107 gen_pool_destroy(p2pdma->pool);
108 sysfs_remove_group(&pdev->dev.kobj, &p2pmem_group);
109 xa_destroy(&p2pdma->map_types);
112 static int pci_p2pdma_setup(struct pci_dev *pdev)
115 struct pci_p2pdma *p2p;
117 p2p = devm_kzalloc(&pdev->dev, sizeof(*p2p), GFP_KERNEL);
121 xa_init(&p2p->map_types);
123 p2p->pool = gen_pool_create(PAGE_SHIFT, dev_to_node(&pdev->dev));
127 error = devm_add_action_or_reset(&pdev->dev, pci_p2pdma_release, pdev);
129 goto out_pool_destroy;
133 error = sysfs_create_group(&pdev->dev.kobj, &p2pmem_group);
135 goto out_pool_destroy;
141 gen_pool_destroy(p2p->pool);
143 devm_kfree(&pdev->dev, p2p);
148 * pci_p2pdma_add_resource - add memory for use as p2p memory
149 * @pdev: the device to add the memory to
150 * @bar: PCI BAR to add
151 * @size: size of the memory to add, may be zero to use the whole BAR
152 * @offset: offset into the PCI BAR
154 * The memory will be given ZONE_DEVICE struct pages so that it may
155 * be used with any DMA request.
157 int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar, size_t size,
160 struct pci_p2pdma_pagemap *p2p_pgmap;
161 struct dev_pagemap *pgmap;
165 if (!(pci_resource_flags(pdev, bar) & IORESOURCE_MEM))
168 if (offset >= pci_resource_len(pdev, bar))
172 size = pci_resource_len(pdev, bar) - offset;
174 if (size + offset > pci_resource_len(pdev, bar))
178 error = pci_p2pdma_setup(pdev);
183 p2p_pgmap = devm_kzalloc(&pdev->dev, sizeof(*p2p_pgmap), GFP_KERNEL);
187 pgmap = &p2p_pgmap->pgmap;
188 pgmap->range.start = pci_resource_start(pdev, bar) + offset;
189 pgmap->range.end = pgmap->range.start + size - 1;
191 pgmap->type = MEMORY_DEVICE_PCI_P2PDMA;
193 p2p_pgmap->provider = pdev;
194 p2p_pgmap->bus_offset = pci_bus_address(pdev, bar) -
195 pci_resource_start(pdev, bar);
197 addr = devm_memremap_pages(&pdev->dev, pgmap);
199 error = PTR_ERR(addr);
203 error = gen_pool_add_owner(pdev->p2pdma->pool, (unsigned long)addr,
204 pci_bus_address(pdev, bar) + offset,
205 range_len(&pgmap->range), dev_to_node(&pdev->dev),
210 pci_info(pdev, "added peer-to-peer DMA memory %#llx-%#llx\n",
211 pgmap->range.start, pgmap->range.end);
216 devm_memunmap_pages(&pdev->dev, pgmap);
218 devm_kfree(&pdev->dev, pgmap);
221 EXPORT_SYMBOL_GPL(pci_p2pdma_add_resource);
224 * Note this function returns the parent PCI device with a
225 * reference taken. It is the caller's responsibility to drop
228 static struct pci_dev *find_parent_pci_dev(struct device *dev)
230 struct device *parent;
232 dev = get_device(dev);
236 return to_pci_dev(dev);
238 parent = get_device(dev->parent);
247 * Check if a PCI bridge has its ACS redirection bits set to redirect P2P
248 * TLPs upstream via ACS. Returns 1 if the packets will be redirected
249 * upstream, 0 otherwise.
251 static int pci_bridge_has_acs_redir(struct pci_dev *pdev)
260 pci_read_config_word(pdev, pos + PCI_ACS_CTRL, &ctrl);
262 if (ctrl & (PCI_ACS_RR | PCI_ACS_CR | PCI_ACS_EC))
268 static void seq_buf_print_bus_devfn(struct seq_buf *buf, struct pci_dev *pdev)
273 seq_buf_printf(buf, "%s;", pci_name(pdev));
276 static bool cpu_supports_p2pdma(void)
279 struct cpuinfo_x86 *c = &cpu_data(0);
281 /* Any AMD CPU whose family ID is Zen or newer supports p2pdma */
282 if (c->x86_vendor == X86_VENDOR_AMD && c->x86 >= 0x17)
289 static const struct pci_p2pdma_whitelist_entry {
290 unsigned short vendor;
291 unsigned short device;
293 REQ_SAME_HOST_BRIDGE = 1 << 0,
295 } pci_p2pdma_whitelist[] = {
296 /* Intel Xeon E5/Core i7 */
297 {PCI_VENDOR_ID_INTEL, 0x3c00, REQ_SAME_HOST_BRIDGE},
298 {PCI_VENDOR_ID_INTEL, 0x3c01, REQ_SAME_HOST_BRIDGE},
299 /* Intel Xeon E7 v3/Xeon E5 v3/Core i7 */
300 {PCI_VENDOR_ID_INTEL, 0x2f00, REQ_SAME_HOST_BRIDGE},
301 {PCI_VENDOR_ID_INTEL, 0x2f01, REQ_SAME_HOST_BRIDGE},
302 /* Intel SkyLake-E */
303 {PCI_VENDOR_ID_INTEL, 0x2030, 0},
304 {PCI_VENDOR_ID_INTEL, 0x2031, 0},
305 {PCI_VENDOR_ID_INTEL, 0x2032, 0},
306 {PCI_VENDOR_ID_INTEL, 0x2033, 0},
307 {PCI_VENDOR_ID_INTEL, 0x2020, 0},
312 * This lookup function tries to find the PCI device corresponding to a given
315 * It assumes the host bridge device is the first PCI device in the
316 * bus->devices list and that the devfn is 00.0. These assumptions should hold
317 * for all the devices in the whitelist above.
319 * This function is equivalent to pci_get_slot(host->bus, 0), however it does
320 * not take the pci_bus_sem lock seeing __host_bridge_whitelist() must not
323 * For this to be safe, the caller should hold a reference to a device on the
324 * bridge, which should ensure the host_bridge device will not be freed
325 * or removed from the head of the devices list.
327 static struct pci_dev *pci_host_bridge_dev(struct pci_host_bridge *host)
329 struct pci_dev *root;
331 root = list_first_entry_or_null(&host->bus->devices,
332 struct pci_dev, bus_list);
336 if (root->devfn != PCI_DEVFN(0, 0))
342 static bool __host_bridge_whitelist(struct pci_host_bridge *host,
343 bool same_host_bridge, bool warn)
345 struct pci_dev *root = pci_host_bridge_dev(host);
346 const struct pci_p2pdma_whitelist_entry *entry;
347 unsigned short vendor, device;
352 vendor = root->vendor;
353 device = root->device;
355 for (entry = pci_p2pdma_whitelist; entry->vendor; entry++) {
356 if (vendor != entry->vendor || device != entry->device)
358 if (entry->flags & REQ_SAME_HOST_BRIDGE && !same_host_bridge)
365 pci_warn(root, "Host bridge not in P2PDMA whitelist: %04x:%04x\n",
372 * If we can't find a common upstream bridge take a look at the root
373 * complex and compare it to a whitelist of known good hardware.
375 static bool host_bridge_whitelist(struct pci_dev *a, struct pci_dev *b,
378 struct pci_host_bridge *host_a = pci_find_host_bridge(a->bus);
379 struct pci_host_bridge *host_b = pci_find_host_bridge(b->bus);
381 if (host_a == host_b)
382 return __host_bridge_whitelist(host_a, true, warn);
384 if (__host_bridge_whitelist(host_a, false, warn) &&
385 __host_bridge_whitelist(host_b, false, warn))
391 static unsigned long map_types_idx(struct pci_dev *client)
393 return (pci_domain_nr(client->bus) << 16) |
394 (client->bus->number << 8) | client->devfn;
398 * Calculate the P2PDMA mapping type and distance between two PCI devices.
400 * If the two devices are the same PCI function, return
401 * PCI_P2PDMA_MAP_BUS_ADDR and a distance of 0.
403 * If they are two functions of the same device, return
404 * PCI_P2PDMA_MAP_BUS_ADDR and a distance of 2 (one hop up to the bridge,
405 * then one hop back down to another function of the same device).
407 * In the case where two devices are connected to the same PCIe switch,
408 * return a distance of 4. This corresponds to the following PCI tree:
411 * \+ Switch Upstream Port
412 * +-+ Switch Downstream Port 0
414 * \-+ Switch Downstream Port 1
417 * The distance is 4 because we traverse from Device A to Downstream Port 0
418 * to the common Switch Upstream Port, back down to Downstream Port 1 and
419 * then to Device B. The mapping type returned depends on the ACS
420 * redirection setting of the ports along the path.
422 * If ACS redirect is set on any port in the path, traffic between the
423 * devices will go through the host bridge, so return
424 * PCI_P2PDMA_MAP_THRU_HOST_BRIDGE; otherwise return
425 * PCI_P2PDMA_MAP_BUS_ADDR.
427 * Any two devices that have a data path that goes through the host bridge
428 * will consult a whitelist. If the host bridge is in the whitelist, return
429 * PCI_P2PDMA_MAP_THRU_HOST_BRIDGE with the distance set to the number of
430 * ports per above. If the device is not in the whitelist, return
431 * PCI_P2PDMA_MAP_NOT_SUPPORTED.
433 static enum pci_p2pdma_map_type
434 calc_map_type_and_dist(struct pci_dev *provider, struct pci_dev *client,
435 int *dist, bool verbose)
437 enum pci_p2pdma_map_type map_type = PCI_P2PDMA_MAP_THRU_HOST_BRIDGE;
438 struct pci_dev *a = provider, *b = client, *bb;
439 bool acs_redirects = false;
440 struct seq_buf acs_list;
446 seq_buf_init(&acs_list, buf, sizeof(buf));
449 * Note, we don't need to take references to devices returned by
450 * pci_upstream_bridge() seeing we hold a reference to a child
451 * device which will already hold a reference to the upstream bridge.
456 if (pci_bridge_has_acs_redir(a)) {
457 seq_buf_print_bus_devfn(&acs_list, a);
465 goto check_b_path_acs;
467 bb = pci_upstream_bridge(bb);
471 a = pci_upstream_bridge(a);
475 *dist = dist_a + dist_b;
476 goto map_through_host_bridge;
485 if (pci_bridge_has_acs_redir(bb)) {
486 seq_buf_print_bus_devfn(&acs_list, bb);
490 bb = pci_upstream_bridge(bb);
493 *dist = dist_a + dist_b;
496 map_type = PCI_P2PDMA_MAP_BUS_ADDR;
501 acs_list.buffer[acs_list.len-1] = 0; /* drop final semicolon */
502 pci_warn(client, "ACS redirect is set between the client and provider (%s)\n",
504 pci_warn(client, "to disable ACS redirect for this path, add the kernel parameter: pci=disable_acs_redir=%s\n",
507 acs_redirects = true;
509 map_through_host_bridge:
510 if (!cpu_supports_p2pdma() &&
511 !host_bridge_whitelist(provider, client, acs_redirects)) {
513 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",
515 map_type = PCI_P2PDMA_MAP_NOT_SUPPORTED;
518 if (provider->p2pdma)
519 xa_store(&provider->p2pdma->map_types, map_types_idx(client),
520 xa_mk_value(map_type), GFP_KERNEL);
525 * pci_p2pdma_distance_many - Determine the cumulative distance between
526 * a p2pdma provider and the clients in use.
527 * @provider: p2pdma provider to check against the client list
528 * @clients: array of devices to check (NULL-terminated)
529 * @num_clients: number of clients in the array
530 * @verbose: if true, print warnings for devices when we return -1
532 * Returns -1 if any of the clients are not compatible, otherwise returns a
533 * positive number where a lower number is the preferable choice. (If there's
534 * one client that's the same as the provider it will return 0, which is best
537 * "compatible" means the provider and the clients are either all behind
538 * the same PCI root port or the host bridges connected to each of the devices
539 * are listed in the 'pci_p2pdma_whitelist'.
541 int pci_p2pdma_distance_many(struct pci_dev *provider, struct device **clients,
542 int num_clients, bool verbose)
544 enum pci_p2pdma_map_type map;
545 bool not_supported = false;
546 struct pci_dev *pci_client;
550 if (num_clients == 0)
553 for (i = 0; i < num_clients; i++) {
554 pci_client = find_parent_pci_dev(clients[i]);
558 "cannot be used for peer-to-peer DMA as it is not a PCI device\n");
562 map = calc_map_type_and_dist(provider, pci_client, &distance,
565 pci_dev_put(pci_client);
567 if (map == PCI_P2PDMA_MAP_NOT_SUPPORTED)
568 not_supported = true;
570 if (not_supported && !verbose)
573 total_dist += distance;
581 EXPORT_SYMBOL_GPL(pci_p2pdma_distance_many);
584 * pci_has_p2pmem - check if a given PCI device has published any p2pmem
585 * @pdev: PCI device to check
587 bool pci_has_p2pmem(struct pci_dev *pdev)
589 return pdev->p2pdma && pdev->p2pdma->p2pmem_published;
591 EXPORT_SYMBOL_GPL(pci_has_p2pmem);
594 * pci_p2pmem_find_many - find a peer-to-peer DMA memory device compatible with
595 * the specified list of clients and shortest distance (as determined
596 * by pci_p2pmem_dma())
597 * @clients: array of devices to check (NULL-terminated)
598 * @num_clients: number of client devices in the list
600 * If multiple devices are behind the same switch, the one "closest" to the
601 * client devices in use will be chosen first. (So if one of the providers is
602 * the same as one of the clients, that provider will be used ahead of any
603 * other providers that are unrelated). If multiple providers are an equal
604 * distance away, one will be chosen at random.
606 * Returns a pointer to the PCI device with a reference taken (use pci_dev_put
607 * to return the reference) or NULL if no compatible device is found. The
608 * found provider will also be assigned to the client list.
610 struct pci_dev *pci_p2pmem_find_many(struct device **clients, int num_clients)
612 struct pci_dev *pdev = NULL;
614 int closest_distance = INT_MAX;
615 struct pci_dev **closest_pdevs;
617 const int max_devs = PAGE_SIZE / sizeof(*closest_pdevs);
620 closest_pdevs = kmalloc(PAGE_SIZE, GFP_KERNEL);
624 while ((pdev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, pdev))) {
625 if (!pci_has_p2pmem(pdev))
628 distance = pci_p2pdma_distance_many(pdev, clients,
630 if (distance < 0 || distance > closest_distance)
633 if (distance == closest_distance && dev_cnt >= max_devs)
636 if (distance < closest_distance) {
637 for (i = 0; i < dev_cnt; i++)
638 pci_dev_put(closest_pdevs[i]);
641 closest_distance = distance;
644 closest_pdevs[dev_cnt++] = pci_dev_get(pdev);
648 pdev = pci_dev_get(closest_pdevs[prandom_u32_max(dev_cnt)]);
650 for (i = 0; i < dev_cnt; i++)
651 pci_dev_put(closest_pdevs[i]);
653 kfree(closest_pdevs);
656 EXPORT_SYMBOL_GPL(pci_p2pmem_find_many);
659 * pci_alloc_p2pmem - allocate peer-to-peer DMA memory
660 * @pdev: the device to allocate memory from
661 * @size: number of bytes to allocate
663 * Returns the allocated memory or NULL on error.
665 void *pci_alloc_p2pmem(struct pci_dev *pdev, size_t size)
668 struct percpu_ref *ref;
671 * Pairs with synchronize_rcu() in pci_p2pdma_release() to
672 * ensure pdev->p2pdma is non-NULL for the duration of the
676 if (unlikely(!pdev->p2pdma))
679 ret = (void *)gen_pool_alloc_owner(pdev->p2pdma->pool, size,
684 if (unlikely(!percpu_ref_tryget_live(ref))) {
685 gen_pool_free(pdev->p2pdma->pool, (unsigned long) ret, size);
693 EXPORT_SYMBOL_GPL(pci_alloc_p2pmem);
696 * pci_free_p2pmem - free peer-to-peer DMA memory
697 * @pdev: the device the memory was allocated from
698 * @addr: address of the memory that was allocated
699 * @size: number of bytes that were allocated
701 void pci_free_p2pmem(struct pci_dev *pdev, void *addr, size_t size)
703 struct percpu_ref *ref;
705 gen_pool_free_owner(pdev->p2pdma->pool, (uintptr_t)addr, size,
709 EXPORT_SYMBOL_GPL(pci_free_p2pmem);
712 * pci_p2pmem_virt_to_bus - return the PCI bus address for a given virtual
713 * address obtained with pci_alloc_p2pmem()
714 * @pdev: the device the memory was allocated from
715 * @addr: address of the memory that was allocated
717 pci_bus_addr_t pci_p2pmem_virt_to_bus(struct pci_dev *pdev, void *addr)
725 * Note: when we added the memory to the pool we used the PCI
726 * bus address as the physical address. So gen_pool_virt_to_phys()
727 * actually returns the bus address despite the misleading name.
729 return gen_pool_virt_to_phys(pdev->p2pdma->pool, (unsigned long)addr);
731 EXPORT_SYMBOL_GPL(pci_p2pmem_virt_to_bus);
734 * pci_p2pmem_alloc_sgl - allocate peer-to-peer DMA memory in a scatterlist
735 * @pdev: the device to allocate memory from
736 * @nents: the number of SG entries in the list
737 * @length: number of bytes to allocate
739 * Return: %NULL on error or &struct scatterlist pointer and @nents on success
741 struct scatterlist *pci_p2pmem_alloc_sgl(struct pci_dev *pdev,
742 unsigned int *nents, u32 length)
744 struct scatterlist *sg;
747 sg = kmalloc(sizeof(*sg), GFP_KERNEL);
751 sg_init_table(sg, 1);
753 addr = pci_alloc_p2pmem(pdev, length);
757 sg_set_buf(sg, addr, length);
765 EXPORT_SYMBOL_GPL(pci_p2pmem_alloc_sgl);
768 * pci_p2pmem_free_sgl - free a scatterlist allocated by pci_p2pmem_alloc_sgl()
769 * @pdev: the device to allocate memory from
770 * @sgl: the allocated scatterlist
772 void pci_p2pmem_free_sgl(struct pci_dev *pdev, struct scatterlist *sgl)
774 struct scatterlist *sg;
777 for_each_sg(sgl, sg, INT_MAX, count) {
781 pci_free_p2pmem(pdev, sg_virt(sg), sg->length);
785 EXPORT_SYMBOL_GPL(pci_p2pmem_free_sgl);
788 * pci_p2pmem_publish - publish the peer-to-peer DMA memory for use by
789 * other devices with pci_p2pmem_find()
790 * @pdev: the device with peer-to-peer DMA memory to publish
791 * @publish: set to true to publish the memory, false to unpublish it
793 * Published memory can be used by other PCI device drivers for
794 * peer-2-peer DMA operations. Non-published memory is reserved for
795 * exclusive use of the device driver that registers the peer-to-peer
798 void pci_p2pmem_publish(struct pci_dev *pdev, bool publish)
801 pdev->p2pdma->p2pmem_published = publish;
803 EXPORT_SYMBOL_GPL(pci_p2pmem_publish);
805 static enum pci_p2pdma_map_type pci_p2pdma_map_type(struct dev_pagemap *pgmap,
808 struct pci_dev *provider = to_p2p_pgmap(pgmap)->provider;
809 struct pci_dev *client;
811 if (!provider->p2pdma)
812 return PCI_P2PDMA_MAP_NOT_SUPPORTED;
814 if (!dev_is_pci(dev))
815 return PCI_P2PDMA_MAP_NOT_SUPPORTED;
817 client = to_pci_dev(dev);
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);
856 switch (pci_p2pdma_map_type(sg_page(sg)->pgmap, dev)) {
857 case PCI_P2PDMA_MAP_THRU_HOST_BRIDGE:
858 return dma_map_sg_attrs(dev, sg, nents, dir, attrs);
859 case PCI_P2PDMA_MAP_BUS_ADDR:
860 return __pci_p2pdma_map_sg(p2p_pgmap, dev, sg, nents);
866 EXPORT_SYMBOL_GPL(pci_p2pdma_map_sg_attrs);
869 * pci_p2pdma_unmap_sg_attrs - unmap a PCI peer-to-peer scatterlist that was
870 * mapped with pci_p2pdma_map_sg()
871 * @dev: device doing the DMA request
872 * @sg: scatter list to map
873 * @nents: number of elements returned by pci_p2pdma_map_sg()
874 * @dir: DMA direction
875 * @attrs: DMA attributes passed to dma_unmap_sg() (if called)
877 void pci_p2pdma_unmap_sg_attrs(struct device *dev, struct scatterlist *sg,
878 int nents, enum dma_data_direction dir, unsigned long attrs)
880 enum pci_p2pdma_map_type map_type;
882 map_type = pci_p2pdma_map_type(sg_page(sg)->pgmap, dev);
884 if (map_type == PCI_P2PDMA_MAP_THRU_HOST_BRIDGE)
885 dma_unmap_sg_attrs(dev, sg, nents, dir, attrs);
887 EXPORT_SYMBOL_GPL(pci_p2pdma_unmap_sg_attrs);
890 * pci_p2pdma_enable_store - parse a configfs/sysfs attribute store
892 * @page: contents of the value to be stored
893 * @p2p_dev: returns the PCI device that was selected to be used
894 * (if one was specified in the stored value)
895 * @use_p2pdma: returns whether to enable p2pdma or not
897 * Parses an attribute value to decide whether to enable p2pdma.
898 * The value can select a PCI device (using its full BDF device
899 * name) or a boolean (in any format strtobool() accepts). A false
900 * value disables p2pdma, a true value expects the caller
901 * to automatically find a compatible device and specifying a PCI device
902 * expects the caller to use the specific provider.
904 * pci_p2pdma_enable_show() should be used as the show operation for
907 * Returns 0 on success
909 int pci_p2pdma_enable_store(const char *page, struct pci_dev **p2p_dev,
914 dev = bus_find_device_by_name(&pci_bus_type, NULL, page);
917 *p2p_dev = to_pci_dev(dev);
919 if (!pci_has_p2pmem(*p2p_dev)) {
921 "PCI device has no peer-to-peer memory: %s\n",
923 pci_dev_put(*p2p_dev);
928 } else if ((page[0] == '0' || page[0] == '1') && !iscntrl(page[1])) {
930 * If the user enters a PCI device that doesn't exist
931 * like "0000:01:00.1", we don't want strtobool to think
932 * it's a '0' when it's clearly not what the user wanted.
933 * So we require 0's and 1's to be exactly one character.
935 } else if (!strtobool(page, use_p2pdma)) {
939 pr_err("No such PCI device: %.*s\n", (int)strcspn(page, "\n"), page);
942 EXPORT_SYMBOL_GPL(pci_p2pdma_enable_store);
945 * pci_p2pdma_enable_show - show a configfs/sysfs attribute indicating
946 * whether p2pdma is enabled
947 * @page: contents of the stored value
948 * @p2p_dev: the selected p2p device (NULL if no device is selected)
949 * @use_p2pdma: whether p2pdma has been enabled
951 * Attributes that use pci_p2pdma_enable_store() should use this function
952 * to show the value of the attribute.
954 * Returns 0 on success
956 ssize_t pci_p2pdma_enable_show(char *page, struct pci_dev *p2p_dev,
960 return sprintf(page, "0\n");
963 return sprintf(page, "1\n");
965 return sprintf(page, "%s\n", pci_name(p2p_dev));
967 EXPORT_SYMBOL_GPL(pci_p2pdma_enable_show);