diff options
Diffstat (limited to 'drivers/pci/p2pdma.c')
-rw-r--r-- | drivers/pci/p2pdma.c | 376 |
1 files changed, 204 insertions, 172 deletions
diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c index 196382630363..50cdde3e9a8b 100644 --- a/drivers/pci/p2pdma.c +++ b/drivers/pci/p2pdma.c @@ -48,12 +48,16 @@ static ssize_t size_show(struct device *dev, struct device_attribute *attr, char *buf) { struct pci_dev *pdev = to_pci_dev(dev); + struct pci_p2pdma *p2pdma; size_t size = 0; - if (pdev->p2pdma->pool) - size = gen_pool_size(pdev->p2pdma->pool); + rcu_read_lock(); + p2pdma = rcu_dereference(pdev->p2pdma); + if (p2pdma && p2pdma->pool) + size = gen_pool_size(p2pdma->pool); + rcu_read_unlock(); - return scnprintf(buf, PAGE_SIZE, "%zd\n", size); + return sysfs_emit(buf, "%zd\n", size); } static DEVICE_ATTR_RO(size); @@ -61,12 +65,16 @@ static ssize_t available_show(struct device *dev, struct device_attribute *attr, char *buf) { struct pci_dev *pdev = to_pci_dev(dev); + struct pci_p2pdma *p2pdma; size_t avail = 0; - if (pdev->p2pdma->pool) - avail = gen_pool_avail(pdev->p2pdma->pool); + rcu_read_lock(); + p2pdma = rcu_dereference(pdev->p2pdma); + if (p2pdma && p2pdma->pool) + avail = gen_pool_avail(p2pdma->pool); + rcu_read_unlock(); - return scnprintf(buf, PAGE_SIZE, "%zd\n", avail); + return sysfs_emit(buf, "%zd\n", avail); } static DEVICE_ATTR_RO(available); @@ -74,9 +82,16 @@ static ssize_t published_show(struct device *dev, struct device_attribute *attr, char *buf) { struct pci_dev *pdev = to_pci_dev(dev); + struct pci_p2pdma *p2pdma; + bool published = false; - return scnprintf(buf, PAGE_SIZE, "%d\n", - pdev->p2pdma->p2pmem_published); + rcu_read_lock(); + p2pdma = rcu_dereference(pdev->p2pdma); + if (p2pdma) + published = p2pdma->p2pmem_published; + rcu_read_unlock(); + + return sysfs_emit(buf, "%d\n", published); } static DEVICE_ATTR_RO(published); @@ -95,8 +110,9 @@ static const struct attribute_group p2pmem_group = { static void pci_p2pdma_release(void *data) { struct pci_dev *pdev = data; - struct pci_p2pdma *p2pdma = pdev->p2pdma; + struct pci_p2pdma *p2pdma; + p2pdma = rcu_dereference_protected(pdev->p2pdma, 1); if (!p2pdma) return; @@ -128,16 +144,14 @@ static int pci_p2pdma_setup(struct pci_dev *pdev) if (error) goto out_pool_destroy; - pdev->p2pdma = p2p; - error = sysfs_create_group(&pdev->dev.kobj, &p2pmem_group); if (error) goto out_pool_destroy; + rcu_assign_pointer(pdev->p2pdma, p2p); return 0; out_pool_destroy: - pdev->p2pdma = NULL; gen_pool_destroy(p2p->pool); out: devm_kfree(&pdev->dev, p2p); @@ -159,6 +173,7 @@ int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar, size_t size, { struct pci_p2pdma_pagemap *p2p_pgmap; struct dev_pagemap *pgmap; + struct pci_p2pdma *p2pdma; void *addr; int error; @@ -200,7 +215,8 @@ int pci_p2pdma_add_resource(struct pci_dev *pdev, int bar, size_t size, goto pgmap_free; } - error = gen_pool_add_owner(pdev->p2pdma->pool, (unsigned long)addr, + p2pdma = rcu_dereference_protected(pdev->p2pdma, 1); + error = gen_pool_add_owner(p2pdma->pool, (unsigned long)addr, pci_bus_address(pdev, bar) + offset, range_len(&pgmap->range), dev_to_node(&pdev->dev), pgmap->ref); @@ -308,10 +324,41 @@ static const struct pci_p2pdma_whitelist_entry { {} }; +/* + * This lookup function tries to find the PCI device corresponding to a given + * host bridge. + * + * It assumes the host bridge device is the first PCI device in the + * bus->devices list and that the devfn is 00.0. These assumptions should hold + * for all the devices in the whitelist above. + * + * This function is equivalent to pci_get_slot(host->bus, 0), however it does + * not take the pci_bus_sem lock seeing __host_bridge_whitelist() must not + * sleep. + * + * For this to be safe, the caller should hold a reference to a device on the + * bridge, which should ensure the host_bridge device will not be freed + * or removed from the head of the devices list. + */ +static struct pci_dev *pci_host_bridge_dev(struct pci_host_bridge *host) +{ + struct pci_dev *root; + + root = list_first_entry_or_null(&host->bus->devices, + struct pci_dev, bus_list); + + if (!root) + return NULL; + if (root->devfn != PCI_DEVFN(0, 0)) + return NULL; + + return root; +} + static bool __host_bridge_whitelist(struct pci_host_bridge *host, - bool same_host_bridge) + bool same_host_bridge, bool warn) { - struct pci_dev *root = pci_get_slot(host->bus, PCI_DEVFN(0, 0)); + struct pci_dev *root = pci_host_bridge_dev(host); const struct pci_p2pdma_whitelist_entry *entry; unsigned short vendor, device; @@ -320,7 +367,6 @@ static bool __host_bridge_whitelist(struct pci_host_bridge *host, vendor = root->vendor; device = root->device; - pci_dev_put(root); for (entry = pci_p2pdma_whitelist; entry->vendor; entry++) { if (vendor != entry->vendor || device != entry->device) @@ -331,6 +377,10 @@ static bool __host_bridge_whitelist(struct pci_host_bridge *host, return true; } + if (warn) + pci_warn(root, "Host bridge not in P2PDMA whitelist: %04x:%04x\n", + vendor, device); + return false; } @@ -338,44 +388,90 @@ static bool __host_bridge_whitelist(struct pci_host_bridge *host, * If we can't find a common upstream bridge take a look at the root * complex and compare it to a whitelist of known good hardware. */ -static bool host_bridge_whitelist(struct pci_dev *a, struct pci_dev *b) +static bool host_bridge_whitelist(struct pci_dev *a, struct pci_dev *b, + bool warn) { struct pci_host_bridge *host_a = pci_find_host_bridge(a->bus); struct pci_host_bridge *host_b = pci_find_host_bridge(b->bus); if (host_a == host_b) - return __host_bridge_whitelist(host_a, true); + return __host_bridge_whitelist(host_a, true, warn); - if (__host_bridge_whitelist(host_a, false) && - __host_bridge_whitelist(host_b, false)) + if (__host_bridge_whitelist(host_a, false, warn) && + __host_bridge_whitelist(host_b, false, warn)) return true; return false; } +static unsigned long map_types_idx(struct pci_dev *client) +{ + return (pci_domain_nr(client->bus) << 16) | + (client->bus->number << 8) | client->devfn; +} + +/* + * Calculate the P2PDMA mapping type and distance between two PCI devices. + * + * If the two devices are the same PCI function, return + * PCI_P2PDMA_MAP_BUS_ADDR and a distance of 0. + * + * If they are two functions of the same device, return + * PCI_P2PDMA_MAP_BUS_ADDR and a distance of 2 (one hop up to the bridge, + * then one hop back down to another function of the same device). + * + * In the case where two devices are connected to the same PCIe switch, + * return a distance of 4. This corresponds to the following PCI tree: + * + * -+ Root Port + * \+ Switch Upstream Port + * +-+ Switch Downstream Port 0 + * + \- Device A + * \-+ Switch Downstream Port 1 + * \- Device B + * + * The distance is 4 because we traverse from Device A to Downstream Port 0 + * to the common Switch Upstream Port, back down to Downstream Port 1 and + * then to Device B. The mapping type returned depends on the ACS + * redirection setting of the ports along the path. + * + * If ACS redirect is set on any port in the path, traffic between the + * devices will go through the host bridge, so return + * PCI_P2PDMA_MAP_THRU_HOST_BRIDGE; otherwise return + * PCI_P2PDMA_MAP_BUS_ADDR. + * + * Any two devices that have a data path that goes through the host bridge + * will consult a whitelist. If the host bridge is in the whitelist, return + * PCI_P2PDMA_MAP_THRU_HOST_BRIDGE with the distance set to the number of + * ports per above. If the device is not in the whitelist, return + * PCI_P2PDMA_MAP_NOT_SUPPORTED. + */ static enum pci_p2pdma_map_type -__upstream_bridge_distance(struct pci_dev *provider, struct pci_dev *client, - int *dist, bool *acs_redirects, struct seq_buf *acs_list) +calc_map_type_and_dist(struct pci_dev *provider, struct pci_dev *client, + int *dist, bool verbose) { + enum pci_p2pdma_map_type map_type = PCI_P2PDMA_MAP_THRU_HOST_BRIDGE; struct pci_dev *a = provider, *b = client, *bb; + bool acs_redirects = false; + struct pci_p2pdma *p2pdma; + struct seq_buf acs_list; + int acs_cnt = 0; int dist_a = 0; int dist_b = 0; - int acs_cnt = 0; + char buf[128]; - if (acs_redirects) - *acs_redirects = false; + seq_buf_init(&acs_list, buf, sizeof(buf)); /* * Note, we don't need to take references to devices returned by * pci_upstream_bridge() seeing we hold a reference to a child * device which will already hold a reference to the upstream bridge. */ - while (a) { dist_b = 0; if (pci_bridge_has_acs_redir(a)) { - seq_buf_print_bus_devfn(acs_list, a); + seq_buf_print_bus_devfn(&acs_list, a); acs_cnt++; } @@ -393,10 +489,8 @@ __upstream_bridge_distance(struct pci_dev *provider, struct pci_dev *client, dist_a++; } - if (dist) - *dist = dist_a + dist_b; - - return PCI_P2PDMA_MAP_THRU_HOST_BRIDGE; + *dist = dist_a + dist_b; + goto map_through_host_bridge; check_b_path_acs: bb = b; @@ -406,124 +500,45 @@ check_b_path_acs: break; if (pci_bridge_has_acs_redir(bb)) { - seq_buf_print_bus_devfn(acs_list, bb); + seq_buf_print_bus_devfn(&acs_list, bb); acs_cnt++; } bb = pci_upstream_bridge(bb); } - if (dist) - *dist = dist_a + dist_b; - - if (acs_cnt) { - if (acs_redirects) - *acs_redirects = true; - - return PCI_P2PDMA_MAP_THRU_HOST_BRIDGE; - } - - return PCI_P2PDMA_MAP_BUS_ADDR; -} - -static unsigned long map_types_idx(struct pci_dev *client) -{ - return (pci_domain_nr(client->bus) << 16) | - (client->bus->number << 8) | client->devfn; -} - -/* - * Find the distance through the nearest common upstream bridge between - * two PCI devices. - * - * If the two devices are the same device then 0 will be returned. - * - * If there are two virtual functions of the same device behind the same - * bridge port then 2 will be returned (one step down to the PCIe switch, - * then one step back to the same device). - * - * In the case where two devices are connected to the same PCIe switch, the - * value 4 will be returned. This corresponds to the following PCI tree: - * - * -+ Root Port - * \+ Switch Upstream Port - * +-+ Switch Downstream Port - * + \- Device A - * \-+ Switch Downstream Port - * \- Device B - * - * The distance is 4 because we traverse from Device A through the downstream - * port of the switch, to the common upstream port, back up to the second - * downstream port and then to Device B. - * - * Any two devices that cannot communicate using p2pdma will return - * PCI_P2PDMA_MAP_NOT_SUPPORTED. - * - * Any two devices that have a data path that goes through the host bridge - * will consult a whitelist. If the host bridges are on the whitelist, - * this function will return PCI_P2PDMA_MAP_THRU_HOST_BRIDGE. - * - * If either bridge is not on the whitelist this function returns - * PCI_P2PDMA_MAP_NOT_SUPPORTED. - * - * If a bridge which has any ACS redirection bits set is in the path, - * acs_redirects will be set to true. In this case, a list of all infringing - * bridge addresses will be populated in acs_list (assuming it's non-null) - * for printk purposes. - */ -static enum pci_p2pdma_map_type -upstream_bridge_distance(struct pci_dev *provider, struct pci_dev *client, - int *dist, bool *acs_redirects, struct seq_buf *acs_list) -{ - enum pci_p2pdma_map_type map_type; - - map_type = __upstream_bridge_distance(provider, client, dist, - acs_redirects, acs_list); + *dist = dist_a + dist_b; - if (map_type == PCI_P2PDMA_MAP_THRU_HOST_BRIDGE) { - if (!cpu_supports_p2pdma() && - !host_bridge_whitelist(provider, client)) - map_type = PCI_P2PDMA_MAP_NOT_SUPPORTED; + if (!acs_cnt) { + map_type = PCI_P2PDMA_MAP_BUS_ADDR; + goto done; } - if (provider->p2pdma) - xa_store(&provider->p2pdma->map_types, map_types_idx(client), - xa_mk_value(map_type), GFP_KERNEL); - - return map_type; -} - -static enum pci_p2pdma_map_type -upstream_bridge_distance_warn(struct pci_dev *provider, struct pci_dev *client, - int *dist) -{ - struct seq_buf acs_list; - bool acs_redirects; - int ret; - - seq_buf_init(&acs_list, kmalloc(PAGE_SIZE, GFP_KERNEL), PAGE_SIZE); - if (!acs_list.buffer) - return -ENOMEM; - - ret = upstream_bridge_distance(provider, client, dist, &acs_redirects, - &acs_list); - if (acs_redirects) { + if (verbose) { + acs_list.buffer[acs_list.len-1] = 0; /* drop final semicolon */ pci_warn(client, "ACS redirect is set between the client and provider (%s)\n", pci_name(provider)); - /* Drop final semicolon */ - acs_list.buffer[acs_list.len-1] = 0; pci_warn(client, "to disable ACS redirect for this path, add the kernel parameter: pci=disable_acs_redir=%s\n", acs_list.buffer); } + acs_redirects = true; - if (ret == PCI_P2PDMA_MAP_NOT_SUPPORTED) { - 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", - pci_name(provider)); +map_through_host_bridge: + if (!cpu_supports_p2pdma() && + !host_bridge_whitelist(provider, client, acs_redirects)) { + if (verbose) + 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", + pci_name(provider)); + map_type = PCI_P2PDMA_MAP_NOT_SUPPORTED; } - - kfree(acs_list.buffer); - - return ret; +done: + rcu_read_lock(); + p2pdma = rcu_dereference(provider->p2pdma); + if (p2pdma) + xa_store(&p2pdma->map_types, map_types_idx(client), + xa_mk_value(map_type), GFP_KERNEL); + rcu_read_unlock(); + return map_type; } /** @@ -546,11 +561,11 @@ upstream_bridge_distance_warn(struct pci_dev *provider, struct pci_dev *client, int pci_p2pdma_distance_many(struct pci_dev *provider, struct device **clients, int num_clients, bool verbose) { + enum pci_p2pdma_map_type map; bool not_supported = false; struct pci_dev *pci_client; int total_dist = 0; - int distance; - int i, ret; + int i, distance; if (num_clients == 0) return -1; @@ -564,16 +579,12 @@ int pci_p2pdma_distance_many(struct pci_dev *provider, struct device **clients, return -1; } - if (verbose) - ret = upstream_bridge_distance_warn(provider, - pci_client, &distance); - else - ret = upstream_bridge_distance(provider, pci_client, - &distance, NULL, NULL); + map = calc_map_type_and_dist(provider, pci_client, &distance, + verbose); pci_dev_put(pci_client); - if (ret == PCI_P2PDMA_MAP_NOT_SUPPORTED) + if (map == PCI_P2PDMA_MAP_NOT_SUPPORTED) not_supported = true; if (not_supported && !verbose) @@ -595,7 +606,15 @@ EXPORT_SYMBOL_GPL(pci_p2pdma_distance_many); */ bool pci_has_p2pmem(struct pci_dev *pdev) { - return pdev->p2pdma && pdev->p2pdma->p2pmem_published; + struct pci_p2pdma *p2pdma; + bool res; + + rcu_read_lock(); + p2pdma = rcu_dereference(pdev->p2pdma); + res = p2pdma && p2pdma->p2pmem_published; + rcu_read_unlock(); + + return res; } EXPORT_SYMBOL_GPL(pci_has_p2pmem); @@ -675,6 +694,7 @@ void *pci_alloc_p2pmem(struct pci_dev *pdev, size_t size) { void *ret = NULL; struct percpu_ref *ref; + struct pci_p2pdma *p2pdma; /* * Pairs with synchronize_rcu() in pci_p2pdma_release() to @@ -682,16 +702,16 @@ void *pci_alloc_p2pmem(struct pci_dev *pdev, size_t size) * read-lock. */ rcu_read_lock(); - if (unlikely(!pdev->p2pdma)) + p2pdma = rcu_dereference(pdev->p2pdma); + if (unlikely(!p2pdma)) goto out; - ret = (void *)gen_pool_alloc_owner(pdev->p2pdma->pool, size, - (void **) &ref); + ret = (void *)gen_pool_alloc_owner(p2pdma->pool, size, (void **) &ref); if (!ret) goto out; if (unlikely(!percpu_ref_tryget_live(ref))) { - gen_pool_free(pdev->p2pdma->pool, (unsigned long) ret, size); + gen_pool_free(p2pdma->pool, (unsigned long) ret, size); ret = NULL; goto out; } @@ -710,8 +730,9 @@ EXPORT_SYMBOL_GPL(pci_alloc_p2pmem); void pci_free_p2pmem(struct pci_dev *pdev, void *addr, size_t size) { struct percpu_ref *ref; + struct pci_p2pdma *p2pdma = rcu_dereference_protected(pdev->p2pdma, 1); - gen_pool_free_owner(pdev->p2pdma->pool, (uintptr_t)addr, size, + gen_pool_free_owner(p2pdma->pool, (uintptr_t)addr, size, (void **) &ref); percpu_ref_put(ref); } @@ -725,9 +746,13 @@ EXPORT_SYMBOL_GPL(pci_free_p2pmem); */ pci_bus_addr_t pci_p2pmem_virt_to_bus(struct pci_dev *pdev, void *addr) { + struct pci_p2pdma *p2pdma; + if (!addr) return 0; - if (!pdev->p2pdma) + + p2pdma = rcu_dereference_protected(pdev->p2pdma, 1); + if (!p2pdma) return 0; /* @@ -735,7 +760,7 @@ pci_bus_addr_t pci_p2pmem_virt_to_bus(struct pci_dev *pdev, void *addr) * bus address as the physical address. So gen_pool_virt_to_phys() * actually returns the bus address despite the misleading name. */ - return gen_pool_virt_to_phys(pdev->p2pdma->pool, (unsigned long)addr); + return gen_pool_virt_to_phys(p2pdma->pool, (unsigned long)addr); } EXPORT_SYMBOL_GPL(pci_p2pmem_virt_to_bus); @@ -806,19 +831,40 @@ EXPORT_SYMBOL_GPL(pci_p2pmem_free_sgl); */ void pci_p2pmem_publish(struct pci_dev *pdev, bool publish) { - if (pdev->p2pdma) - pdev->p2pdma->p2pmem_published = publish; + struct pci_p2pdma *p2pdma; + + rcu_read_lock(); + p2pdma = rcu_dereference(pdev->p2pdma); + if (p2pdma) + p2pdma->p2pmem_published = publish; + rcu_read_unlock(); } EXPORT_SYMBOL_GPL(pci_p2pmem_publish); -static enum pci_p2pdma_map_type pci_p2pdma_map_type(struct pci_dev *provider, - struct pci_dev *client) +static enum pci_p2pdma_map_type pci_p2pdma_map_type(struct dev_pagemap *pgmap, + struct device *dev) { + enum pci_p2pdma_map_type type = PCI_P2PDMA_MAP_NOT_SUPPORTED; + struct pci_dev *provider = to_p2p_pgmap(pgmap)->provider; + struct pci_dev *client; + struct pci_p2pdma *p2pdma; + if (!provider->p2pdma) return PCI_P2PDMA_MAP_NOT_SUPPORTED; - return xa_to_value(xa_load(&provider->p2pdma->map_types, - map_types_idx(client))); + if (!dev_is_pci(dev)) + return PCI_P2PDMA_MAP_NOT_SUPPORTED; + + client = to_pci_dev(dev); + + rcu_read_lock(); + p2pdma = rcu_dereference(provider->p2pdma); + + if (p2pdma) + type = xa_to_value(xa_load(&p2pdma->map_types, + map_types_idx(client))); + rcu_read_unlock(); + return type; } static int __pci_p2pdma_map_sg(struct pci_p2pdma_pagemap *p2p_pgmap, @@ -853,14 +899,8 @@ int pci_p2pdma_map_sg_attrs(struct device *dev, struct scatterlist *sg, { struct pci_p2pdma_pagemap *p2p_pgmap = to_p2p_pgmap(sg_page(sg)->pgmap); - struct pci_dev *client; - - if (WARN_ON_ONCE(!dev_is_pci(dev))) - return 0; - client = to_pci_dev(dev); - - switch (pci_p2pdma_map_type(p2p_pgmap->provider, client)) { + switch (pci_p2pdma_map_type(sg_page(sg)->pgmap, dev)) { case PCI_P2PDMA_MAP_THRU_HOST_BRIDGE: return dma_map_sg_attrs(dev, sg, nents, dir, attrs); case PCI_P2PDMA_MAP_BUS_ADDR: @@ -884,17 +924,9 @@ EXPORT_SYMBOL_GPL(pci_p2pdma_map_sg_attrs); void pci_p2pdma_unmap_sg_attrs(struct device *dev, struct scatterlist *sg, int nents, enum dma_data_direction dir, unsigned long attrs) { - struct pci_p2pdma_pagemap *p2p_pgmap = - to_p2p_pgmap(sg_page(sg)->pgmap); enum pci_p2pdma_map_type map_type; - struct pci_dev *client; - - if (WARN_ON_ONCE(!dev_is_pci(dev))) - return; - - client = to_pci_dev(dev); - map_type = pci_p2pdma_map_type(p2p_pgmap->provider, client); + map_type = pci_p2pdma_map_type(sg_page(sg)->pgmap, dev); if (map_type == PCI_P2PDMA_MAP_THRU_HOST_BRIDGE) dma_unmap_sg_attrs(dev, sg, nents, dir, attrs); |