diff options
Diffstat (limited to 'mm/memremap.c')
| -rw-r--r-- | mm/memremap.c | 435 |
1 files changed, 435 insertions, 0 deletions
diff --git a/mm/memremap.c b/mm/memremap.c new file mode 100644 index 000000000000..ed70c4e8e52a --- /dev/null +++ b/mm/memremap.c @@ -0,0 +1,435 @@ +/* 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); +#define SECTION_MASK ~((1UL << PA_SECTION_SHIFT) - 1) +#define SECTION_SIZE (1UL << PA_SECTION_SHIFT) + +#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 *data) +{ + if (atomic_dec_and_test(&devmap_managed_enable)) + static_branch_disable(&devmap_managed_key); +} + +static int devmap_managed_enable_get(struct device *dev, 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 devm_add_action_or_reset(dev, devmap_managed_enable_put, NULL); +} +#else +static int devmap_managed_enable_get(struct device *dev, struct dev_pagemap *pgmap) +{ + return -EINVAL; +} +#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; +} + +static void devm_memremap_pages_release(void *data) +{ + struct dev_pagemap *pgmap = data; + struct device *dev = pgmap->dev; + struct resource *res = &pgmap->res; + 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); + + /* pages are dead and unused, undo the arch mapping */ + nid = page_to_nid(pfn_to_page(PHYS_PFN(res->start))); + + mem_hotplug_begin(); + if (pgmap->type == MEMORY_DEVICE_PRIVATE) { + pfn = PHYS_PFN(res->start); + __remove_pages(page_zone(pfn_to_page(pfn)), pfn, + 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); + dev_WARN_ONCE(dev, pgmap->altmap.alloc, + "%s: failed to free all reserved pages\n", __func__); +} + +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); +} + +/** + * 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) +{ + 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, nid, 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(dev, pgmap); + if (error) + return ERR_PTR(error); + } + + conflict_pgmap = get_dev_pagemap(PHYS_PFN(res->start), NULL); + if (conflict_pgmap) { + dev_WARN(dev, "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) { + dev_WARN(dev, "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; + } + + pgmap->dev = dev; + + error = xa_err(xa_store_range(&pgmap_array, PHYS_PFN(res->start), + PHYS_PFN(res->end), pgmap, GFP_KERNEL)); + if (error) + goto err_array; + + nid = dev_to_node(dev); + 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)); + + error = devm_add_action_or_reset(dev, devm_memremap_pages_release, + pgmap); + if (error) + return ERR_PTR(error); + + 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); + return ERR_PTR(error); +} +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 */ |