/* SPDX-License-Identifier: GPL-2.0 */ /* Copyright(c) 2015 Intel Corporation. All rights reserved. */ #include <linux/device.h> #include <linux/io.h> #include <linux/kasan.h> #include <linux/memory_hotplug.h> #include <linux/mm.h> #include <linux/pfn_t.h> #include <linux/swap.h> #include <linux/swapops.h> #include <linux/types.h> #include <linux/wait_bit.h> #include <linux/xarray.h> static DEFINE_XARRAY(pgmap_array); #ifdef CONFIG_DEV_PAGEMAP_OPS DEFINE_STATIC_KEY_FALSE(devmap_managed_key); EXPORT_SYMBOL(devmap_managed_key); static atomic_t devmap_managed_enable; static void devmap_managed_enable_put(void) { if (atomic_dec_and_test(&devmap_managed_enable)) static_branch_disable(&devmap_managed_key); } static int devmap_managed_enable_get(struct dev_pagemap *pgmap) { if (!pgmap->ops || !pgmap->ops->page_free) { WARN(1, "Missing page_free method\n"); return -EINVAL; } if (atomic_inc_return(&devmap_managed_enable) == 1) static_branch_enable(&devmap_managed_key); return 0; } #else static int devmap_managed_enable_get(struct dev_pagemap *pgmap) { return -EINVAL; } static void devmap_managed_enable_put(void) { } #endif /* CONFIG_DEV_PAGEMAP_OPS */ static void pgmap_array_delete(struct resource *res) { xa_store_range(&pgmap_array, PHYS_PFN(res->start), PHYS_PFN(res->end), NULL, GFP_KERNEL); synchronize_rcu(); } static unsigned long pfn_first(struct dev_pagemap *pgmap) { return PHYS_PFN(pgmap->res.start) + vmem_altmap_offset(pgmap_altmap(pgmap)); } static unsigned long pfn_end(struct dev_pagemap *pgmap) { const struct resource *res = &pgmap->res; return (res->start + resource_size(res)) >> PAGE_SHIFT; } static unsigned long pfn_next(unsigned long pfn) { if (pfn % 1024 == 0) cond_resched(); return pfn + 1; } #define for_each_device_pfn(pfn, map) \ for (pfn = pfn_first(map); pfn < pfn_end(map); pfn = pfn_next(pfn)) static void dev_pagemap_kill(struct dev_pagemap *pgmap) { if (pgmap->ops && pgmap->ops->kill) pgmap->ops->kill(pgmap); else percpu_ref_kill(pgmap->ref); } static void dev_pagemap_cleanup(struct dev_pagemap *pgmap) { if (pgmap->ops && pgmap->ops->cleanup) { pgmap->ops->cleanup(pgmap); } else { wait_for_completion(&pgmap->done); percpu_ref_exit(pgmap->ref); } /* * Undo the pgmap ref assignment for the internal case as the * caller may re-enable the same pgmap. */ if (pgmap->ref == &pgmap->internal_ref) pgmap->ref = NULL; } void memunmap_pages(struct dev_pagemap *pgmap) { struct resource *res = &pgmap->res; struct page *first_page; unsigned long pfn; int nid; dev_pagemap_kill(pgmap); for_each_device_pfn(pfn, pgmap) put_page(pfn_to_page(pfn)); dev_pagemap_cleanup(pgmap); /* make sure to access a memmap that was actually initialized */ first_page = pfn_to_page(pfn_first(pgmap)); /* pages are dead and unused, undo the arch mapping */ nid = page_to_nid(first_page); mem_hotplug_begin(); if (pgmap->type == MEMORY_DEVICE_PRIVATE) { __remove_pages(PHYS_PFN(res->start), PHYS_PFN(resource_size(res)), NULL); } else { arch_remove_memory(nid, res->start, resource_size(res), pgmap_altmap(pgmap)); kasan_remove_zero_shadow(__va(res->start), resource_size(res)); } mem_hotplug_done(); untrack_pfn(NULL, PHYS_PFN(res->start), resource_size(res)); pgmap_array_delete(res); WARN_ONCE(pgmap->altmap.alloc, "failed to free all reserved pages\n"); devmap_managed_enable_put(); } EXPORT_SYMBOL_GPL(memunmap_pages); static void devm_memremap_pages_release(void *data) { memunmap_pages(data); } static void dev_pagemap_percpu_release(struct percpu_ref *ref) { struct dev_pagemap *pgmap = container_of(ref, struct dev_pagemap, internal_ref); complete(&pgmap->done); } /* * Not device managed version of dev_memremap_pages, undone by * memunmap_pages(). Please use dev_memremap_pages if you have a struct * device available. */ void *memremap_pages(struct dev_pagemap *pgmap, int nid) { struct resource *res = &pgmap->res; struct dev_pagemap *conflict_pgmap; struct mhp_restrictions restrictions = { /* * We do not want any optional features only our own memmap */ .altmap = pgmap_altmap(pgmap), }; pgprot_t pgprot = PAGE_KERNEL; int error, is_ram; bool need_devmap_managed = true; switch (pgmap->type) { case MEMORY_DEVICE_PRIVATE: if (!IS_ENABLED(CONFIG_DEVICE_PRIVATE)) { WARN(1, "Device private memory not supported\n"); return ERR_PTR(-EINVAL); } if (!pgmap->ops || !pgmap->ops->migrate_to_ram) { WARN(1, "Missing migrate_to_ram method\n"); return ERR_PTR(-EINVAL); } break; case MEMORY_DEVICE_FS_DAX: if (!IS_ENABLED(CONFIG_ZONE_DEVICE) || IS_ENABLED(CONFIG_FS_DAX_LIMITED)) { WARN(1, "File system DAX not supported\n"); return ERR_PTR(-EINVAL); } break; case MEMORY_DEVICE_DEVDAX: case MEMORY_DEVICE_PCI_P2PDMA: need_devmap_managed = false; break; default: WARN(1, "Invalid pgmap type %d\n", pgmap->type); break; } if (!pgmap->ref) { if (pgmap->ops && (pgmap->ops->kill || pgmap->ops->cleanup)) return ERR_PTR(-EINVAL); init_completion(&pgmap->done); error = percpu_ref_init(&pgmap->internal_ref, dev_pagemap_percpu_release, 0, GFP_KERNEL); if (error) return ERR_PTR(error); pgmap->ref = &pgmap->internal_ref; } else { if (!pgmap->ops || !pgmap->ops->kill || !pgmap->ops->cleanup) { WARN(1, "Missing reference count teardown definition\n"); return ERR_PTR(-EINVAL); } } if (need_devmap_managed) { error = devmap_managed_enable_get(pgmap); if (error) return ERR_PTR(error); } conflict_pgmap = get_dev_pagemap(PHYS_PFN(res->start), NULL); if (conflict_pgmap) { WARN(1, "Conflicting mapping in same section\n"); put_dev_pagemap(conflict_pgmap); error = -ENOMEM; goto err_array; } conflict_pgmap = get_dev_pagemap(PHYS_PFN(res->end), NULL); if (conflict_pgmap) { WARN(1, "Conflicting mapping in same section\n"); put_dev_pagemap(conflict_pgmap); error = -ENOMEM; goto err_array; } is_ram = region_intersects(res->start, resource_size(res), IORESOURCE_SYSTEM_RAM, IORES_DESC_NONE); if (is_ram != REGION_DISJOINT) { WARN_ONCE(1, "%s attempted on %s region %pr\n", __func__, is_ram == REGION_MIXED ? "mixed" : "ram", res); error = -ENXIO; goto err_array; } error = xa_err(xa_store_range(&pgmap_array, PHYS_PFN(res->start), PHYS_PFN(res->end), pgmap, GFP_KERNEL)); if (error) goto err_array; if (nid < 0) nid = numa_mem_id(); error = track_pfn_remap(NULL, &pgprot, PHYS_PFN(res->start), 0, resource_size(res)); if (error) goto err_pfn_remap; mem_hotplug_begin(); /* * For device private memory we call add_pages() as we only need to * allocate and initialize struct page for the device memory. More- * over the device memory is un-accessible thus we do not want to * create a linear mapping for the memory like arch_add_memory() * would do. * * For all other device memory types, which are accessible by * the CPU, we do want the linear mapping and thus use * arch_add_memory(). */ if (pgmap->type == MEMORY_DEVICE_PRIVATE) { error = add_pages(nid, PHYS_PFN(res->start), PHYS_PFN(resource_size(res)), &restrictions); } else { error = kasan_add_zero_shadow(__va(res->start), resource_size(res)); if (error) { mem_hotplug_done(); goto err_kasan; } error = arch_add_memory(nid, res->start, resource_size(res), &restrictions); } if (!error) { struct zone *zone; zone = &NODE_DATA(nid)->node_zones[ZONE_DEVICE]; move_pfn_range_to_zone(zone, PHYS_PFN(res->start), PHYS_PFN(resource_size(res)), restrictions.altmap); } mem_hotplug_done(); if (error) goto err_add_memory; /* * Initialization of the pages has been deferred until now in order * to allow us to do the work while not holding the hotplug lock. */ memmap_init_zone_device(&NODE_DATA(nid)->node_zones[ZONE_DEVICE], PHYS_PFN(res->start), PHYS_PFN(resource_size(res)), pgmap); percpu_ref_get_many(pgmap->ref, pfn_end(pgmap) - pfn_first(pgmap)); return __va(res->start); err_add_memory: kasan_remove_zero_shadow(__va(res->start), resource_size(res)); err_kasan: untrack_pfn(NULL, PHYS_PFN(res->start), resource_size(res)); err_pfn_remap: pgmap_array_delete(res); err_array: dev_pagemap_kill(pgmap); dev_pagemap_cleanup(pgmap); devmap_managed_enable_put(); return ERR_PTR(error); } EXPORT_SYMBOL_GPL(memremap_pages); /** * devm_memremap_pages - remap and provide memmap backing for the given resource * @dev: hosting device for @res * @pgmap: pointer to a struct dev_pagemap * * Notes: * 1/ At a minimum the res and type members of @pgmap must be initialized * by the caller before passing it to this function * * 2/ The altmap field may optionally be initialized, in which case * PGMAP_ALTMAP_VALID must be set in pgmap->flags. * * 3/ The ref field may optionally be provided, in which pgmap->ref must be * 'live' on entry and will be killed and reaped at * devm_memremap_pages_release() time, or if this routine fails. * * 4/ res is expected to be a host memory range that could feasibly be * treated as a "System RAM" range, i.e. not a device mmio range, but * this is not enforced. */ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap) { int error; void *ret; ret = memremap_pages(pgmap, dev_to_node(dev)); if (IS_ERR(ret)) return ret; error = devm_add_action_or_reset(dev, devm_memremap_pages_release, pgmap); if (error) return ERR_PTR(error); return ret; } EXPORT_SYMBOL_GPL(devm_memremap_pages); void devm_memunmap_pages(struct device *dev, struct dev_pagemap *pgmap) { devm_release_action(dev, devm_memremap_pages_release, pgmap); } EXPORT_SYMBOL_GPL(devm_memunmap_pages); unsigned long vmem_altmap_offset(struct vmem_altmap *altmap) { /* number of pfns from base where pfn_to_page() is valid */ if (altmap) return altmap->reserve + altmap->free; return 0; } void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns) { altmap->alloc -= nr_pfns; } /** * get_dev_pagemap() - take a new live reference on the dev_pagemap for @pfn * @pfn: page frame number to lookup page_map * @pgmap: optional known pgmap that already has a reference * * If @pgmap is non-NULL and covers @pfn it will be returned as-is. If @pgmap * is non-NULL but does not cover @pfn the reference to it will be released. */ struct dev_pagemap *get_dev_pagemap(unsigned long pfn, struct dev_pagemap *pgmap) { resource_size_t phys = PFN_PHYS(pfn); /* * In the cached case we're already holding a live reference. */ if (pgmap) { if (phys >= pgmap->res.start && phys <= pgmap->res.end) return pgmap; put_dev_pagemap(pgmap); } /* fall back to slow path lookup */ rcu_read_lock(); pgmap = xa_load(&pgmap_array, PHYS_PFN(phys)); if (pgmap && !percpu_ref_tryget_live(pgmap->ref)) pgmap = NULL; rcu_read_unlock(); return pgmap; } EXPORT_SYMBOL_GPL(get_dev_pagemap); #ifdef CONFIG_DEV_PAGEMAP_OPS void __put_devmap_managed_page(struct page *page) { int count = page_ref_dec_return(page); /* * If refcount is 1 then page is freed and refcount is stable as nobody * holds a reference on the page. */ if (count == 1) { /* Clear Active bit in case of parallel mark_page_accessed */ __ClearPageActive(page); __ClearPageWaiters(page); mem_cgroup_uncharge(page); /* * When a device_private page is freed, the page->mapping field * may still contain a (stale) mapping value. For example, the * lower bits of page->mapping may still identify the page as * an anonymous page. Ultimately, this entire field is just * stale and wrong, and it will cause errors if not cleared. * One example is: * * migrate_vma_pages() * migrate_vma_insert_page() * page_add_new_anon_rmap() * __page_set_anon_rmap() * ...checks page->mapping, via PageAnon(page) call, * and incorrectly concludes that the page is an * anonymous page. Therefore, it incorrectly, * silently fails to set up the new anon rmap. * * For other types of ZONE_DEVICE pages, migration is either * handled differently or not done at all, so there is no need * to clear page->mapping. */ if (is_device_private_page(page)) page->mapping = NULL; page->pgmap->ops->page_free(page); } else if (!count) __put_page(page); } EXPORT_SYMBOL(__put_devmap_managed_page); #endif /* CONFIG_DEV_PAGEMAP_OPS */