/* 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> #include <linux/hmm.h> static DEFINE_XARRAY(pgmap_array); #define SECTION_MASK ~((1UL << PA_SECTION_SHIFT) - 1) #define SECTION_SIZE (1UL << PA_SECTION_SHIFT) #if IS_ENABLED(CONFIG_DEVICE_PRIVATE) vm_fault_t device_private_entry_fault(struct vm_area_struct *vma, unsigned long addr, swp_entry_t entry, unsigned int flags, pmd_t *pmdp) { struct page *page = device_private_entry_to_page(entry); struct hmm_devmem *devmem; devmem = container_of(page->pgmap, typeof(*devmem), pagemap); /* * The page_fault() callback must migrate page back to system memory * so that CPU can access it. This might fail for various reasons * (device issue, device was unsafely unplugged, ...). When such * error conditions happen, the callback must return VM_FAULT_SIGBUS. * * Note that because memory cgroup charges are accounted to the device * memory, this should never fail because of memory restrictions (but * allocation of regular system page might still fail because we are * out of memory). * * There is a more in-depth description of what that callback can and * cannot do, in include/linux/memremap.h */ return devmem->page_fault(vma, addr, page, flags, pmdp); } EXPORT_SYMBOL(device_private_entry_fault); #endif /* CONFIG_DEVICE_PRIVATE */ 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) { const struct resource *res = &pgmap->res; struct vmem_altmap *altmap = &pgmap->altmap; unsigned long pfn; pfn = res->start >> PAGE_SHIFT; if (pgmap->altmap_valid) pfn += vmem_altmap_offset(altmap); return pfn; } 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 devm_memremap_pages_release(void *data) { struct dev_pagemap *pgmap = data; struct device *dev = pgmap->dev; struct resource *res = &pgmap->res; resource_size_t align_start, align_size; unsigned long pfn; int nid; pgmap->kill(pgmap->ref); for_each_device_pfn(pfn, pgmap) put_page(pfn_to_page(pfn)); /* pages are dead and unused, undo the arch mapping */ align_start = res->start & ~(SECTION_SIZE - 1); align_size = ALIGN(res->start + resource_size(res), SECTION_SIZE) - align_start; nid = page_to_nid(pfn_to_page(align_start >> PAGE_SHIFT)); mem_hotplug_begin(); if (pgmap->type == MEMORY_DEVICE_PRIVATE) { pfn = align_start >> PAGE_SHIFT; __remove_pages(page_zone(pfn_to_page(pfn)), pfn, align_size >> PAGE_SHIFT, NULL); } else { arch_remove_memory(nid, align_start, align_size, pgmap->altmap_valid ? &pgmap->altmap : NULL); kasan_remove_zero_shadow(__va(align_start), align_size); } mem_hotplug_done(); untrack_pfn(NULL, PHYS_PFN(align_start), align_size); pgmap_array_delete(res); dev_WARN_ONCE(dev, pgmap->altmap.alloc, "%s: failed to free all reserved pages\n", __func__); } /** * 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, ref 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 altmap_valid * must be set to true * * 3/ pgmap->ref must be 'live' on entry and will be killed 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) { resource_size_t align_start, align_size, align_end; struct vmem_altmap *altmap = pgmap->altmap_valid ? &pgmap->altmap : NULL; struct resource *res = &pgmap->res; struct dev_pagemap *conflict_pgmap; pgprot_t pgprot = PAGE_KERNEL; int error, nid, is_ram; if (!pgmap->ref || !pgmap->kill) return ERR_PTR(-EINVAL); align_start = res->start & ~(SECTION_SIZE - 1); align_size = ALIGN(res->start + resource_size(res), SECTION_SIZE) - align_start; align_end = align_start + align_size - 1; conflict_pgmap = get_dev_pagemap(PHYS_PFN(align_start), NULL); if (conflict_pgmap) { dev_WARN(dev, "Conflicting mapping in same section\n"); put_dev_pagemap(conflict_pgmap); return ERR_PTR(-ENOMEM); } conflict_pgmap = get_dev_pagemap(PHYS_PFN(align_end), NULL); if (conflict_pgmap) { dev_WARN(dev, "Conflicting mapping in same section\n"); put_dev_pagemap(conflict_pgmap); return ERR_PTR(-ENOMEM); } is_ram = region_intersects(align_start, align_size, 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(align_start), 0, align_size); 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, align_start >> PAGE_SHIFT, align_size >> PAGE_SHIFT, NULL, false); } else { error = kasan_add_zero_shadow(__va(align_start), align_size); if (error) { mem_hotplug_done(); goto err_kasan; } error = arch_add_memory(nid, align_start, align_size, altmap, false); } if (!error) { struct zone *zone; zone = &NODE_DATA(nid)->node_zones[ZONE_DEVICE]; move_pfn_range_to_zone(zone, align_start >> PAGE_SHIFT, align_size >> PAGE_SHIFT, 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], align_start >> PAGE_SHIFT, align_size >> PAGE_SHIFT, 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(align_start), align_size); err_kasan: untrack_pfn(NULL, PHYS_PFN(align_start), align_size); err_pfn_remap: pgmap_array_delete(res); err_array: pgmap->kill(pgmap->ref); return ERR_PTR(error); } EXPORT_SYMBOL_GPL(devm_memremap_pages); unsigned long vmem_altmap_offset(struct vmem_altmap *altmap) { /* number of pfns from base where pfn_to_page() is valid */ return altmap->reserve + altmap->free; } 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 DEFINE_STATIC_KEY_FALSE(devmap_managed_key); EXPORT_SYMBOL(devmap_managed_key); static atomic_t devmap_enable; /* * Toggle the static key for ->page_free() callbacks when dev_pagemap * pages go idle. */ void dev_pagemap_get_ops(void) { if (atomic_inc_return(&devmap_enable) == 1) static_branch_enable(&devmap_managed_key); } EXPORT_SYMBOL_GPL(dev_pagemap_get_ops); void dev_pagemap_put_ops(void) { if (atomic_dec_and_test(&devmap_enable)) static_branch_disable(&devmap_managed_key); } EXPORT_SYMBOL_GPL(dev_pagemap_put_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); page->pgmap->page_free(page, page->pgmap->data); } else if (!count) __put_page(page); } EXPORT_SYMBOL(__put_devmap_managed_page); #endif /* CONFIG_DEV_PAGEMAP_OPS */