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-rw-r--r--mm/memremap.c550
1 files changed, 550 insertions, 0 deletions
diff --git a/mm/memremap.c b/mm/memremap.c
new file mode 100644
index 000000000..08cbf54fe
--- /dev/null
+++ b/mm/memremap.c
@@ -0,0 +1,550 @@
+// 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/memremap.h>
+#include <linux/pfn_t.h>
+#include <linux/swap.h>
+#include <linux/mmzone.h>
+#include <linux/swapops.h>
+#include <linux/types.h>
+#include <linux/wait_bit.h>
+#include <linux/xarray.h>
+#include "internal.h"
+
+static DEFINE_XARRAY(pgmap_array);
+
+/*
+ * The memremap() and memremap_pages() interfaces are alternately used
+ * to map persistent memory namespaces. These interfaces place different
+ * constraints on the alignment and size of the mapping (namespace).
+ * memremap() can map individual PAGE_SIZE pages. memremap_pages() can
+ * only map subsections (2MB), and at least one architecture (PowerPC)
+ * the minimum mapping granularity of memremap_pages() is 16MB.
+ *
+ * The role of memremap_compat_align() is to communicate the minimum
+ * arch supported alignment of a namespace such that it can freely
+ * switch modes without violating the arch constraint. Namely, do not
+ * allow a namespace to be PAGE_SIZE aligned since that namespace may be
+ * reconfigured into a mode that requires SUBSECTION_SIZE alignment.
+ */
+#ifndef CONFIG_ARCH_HAS_MEMREMAP_COMPAT_ALIGN
+unsigned long memremap_compat_align(void)
+{
+ return SUBSECTION_SIZE;
+}
+EXPORT_SYMBOL_GPL(memremap_compat_align);
+#endif
+
+#ifdef CONFIG_FS_DAX
+DEFINE_STATIC_KEY_FALSE(devmap_managed_key);
+EXPORT_SYMBOL(devmap_managed_key);
+
+static void devmap_managed_enable_put(struct dev_pagemap *pgmap)
+{
+ if (pgmap->type == MEMORY_DEVICE_FS_DAX)
+ static_branch_dec(&devmap_managed_key);
+}
+
+static void devmap_managed_enable_get(struct dev_pagemap *pgmap)
+{
+ if (pgmap->type == MEMORY_DEVICE_FS_DAX)
+ static_branch_inc(&devmap_managed_key);
+}
+#else
+static void devmap_managed_enable_get(struct dev_pagemap *pgmap)
+{
+}
+static void devmap_managed_enable_put(struct dev_pagemap *pgmap)
+{
+}
+#endif /* CONFIG_FS_DAX */
+
+static void pgmap_array_delete(struct range *range)
+{
+ xa_store_range(&pgmap_array, PHYS_PFN(range->start), PHYS_PFN(range->end),
+ NULL, GFP_KERNEL);
+ synchronize_rcu();
+}
+
+static unsigned long pfn_first(struct dev_pagemap *pgmap, int range_id)
+{
+ struct range *range = &pgmap->ranges[range_id];
+ unsigned long pfn = PHYS_PFN(range->start);
+
+ if (range_id)
+ return pfn;
+ return pfn + vmem_altmap_offset(pgmap_altmap(pgmap));
+}
+
+bool pgmap_pfn_valid(struct dev_pagemap *pgmap, unsigned long pfn)
+{
+ int i;
+
+ for (i = 0; i < pgmap->nr_range; i++) {
+ struct range *range = &pgmap->ranges[i];
+
+ if (pfn >= PHYS_PFN(range->start) &&
+ pfn <= PHYS_PFN(range->end))
+ return pfn >= pfn_first(pgmap, i);
+ }
+
+ return false;
+}
+
+static unsigned long pfn_end(struct dev_pagemap *pgmap, int range_id)
+{
+ const struct range *range = &pgmap->ranges[range_id];
+
+ return (range->start + range_len(range)) >> PAGE_SHIFT;
+}
+
+static unsigned long pfn_len(struct dev_pagemap *pgmap, unsigned long range_id)
+{
+ return (pfn_end(pgmap, range_id) -
+ pfn_first(pgmap, range_id)) >> pgmap->vmemmap_shift;
+}
+
+static void pageunmap_range(struct dev_pagemap *pgmap, int range_id)
+{
+ struct range *range = &pgmap->ranges[range_id];
+ struct page *first_page;
+
+ /* make sure to access a memmap that was actually initialized */
+ first_page = pfn_to_page(pfn_first(pgmap, range_id));
+
+ /* pages are dead and unused, undo the arch mapping */
+ mem_hotplug_begin();
+ remove_pfn_range_from_zone(page_zone(first_page), PHYS_PFN(range->start),
+ PHYS_PFN(range_len(range)));
+ if (pgmap->type == MEMORY_DEVICE_PRIVATE) {
+ __remove_pages(PHYS_PFN(range->start),
+ PHYS_PFN(range_len(range)), NULL);
+ } else {
+ arch_remove_memory(range->start, range_len(range),
+ pgmap_altmap(pgmap));
+ kasan_remove_zero_shadow(__va(range->start), range_len(range));
+ }
+ mem_hotplug_done();
+
+ untrack_pfn(NULL, PHYS_PFN(range->start), range_len(range));
+ pgmap_array_delete(range);
+}
+
+void memunmap_pages(struct dev_pagemap *pgmap)
+{
+ int i;
+
+ percpu_ref_kill(&pgmap->ref);
+ if (pgmap->type != MEMORY_DEVICE_PRIVATE &&
+ pgmap->type != MEMORY_DEVICE_COHERENT)
+ for (i = 0; i < pgmap->nr_range; i++)
+ percpu_ref_put_many(&pgmap->ref, pfn_len(pgmap, i));
+
+ wait_for_completion(&pgmap->done);
+
+ for (i = 0; i < pgmap->nr_range; i++)
+ pageunmap_range(pgmap, i);
+ percpu_ref_exit(&pgmap->ref);
+
+ WARN_ONCE(pgmap->altmap.alloc, "failed to free all reserved pages\n");
+ devmap_managed_enable_put(pgmap);
+}
+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, ref);
+
+ complete(&pgmap->done);
+}
+
+static int pagemap_range(struct dev_pagemap *pgmap, struct mhp_params *params,
+ int range_id, int nid)
+{
+ const bool is_private = pgmap->type == MEMORY_DEVICE_PRIVATE;
+ struct range *range = &pgmap->ranges[range_id];
+ struct dev_pagemap *conflict_pgmap;
+ int error, is_ram;
+
+ if (WARN_ONCE(pgmap_altmap(pgmap) && range_id > 0,
+ "altmap not supported for multiple ranges\n"))
+ return -EINVAL;
+
+ conflict_pgmap = get_dev_pagemap(PHYS_PFN(range->start), NULL);
+ if (conflict_pgmap) {
+ WARN(1, "Conflicting mapping in same section\n");
+ put_dev_pagemap(conflict_pgmap);
+ return -ENOMEM;
+ }
+
+ conflict_pgmap = get_dev_pagemap(PHYS_PFN(range->end), NULL);
+ if (conflict_pgmap) {
+ WARN(1, "Conflicting mapping in same section\n");
+ put_dev_pagemap(conflict_pgmap);
+ return -ENOMEM;
+ }
+
+ is_ram = region_intersects(range->start, range_len(range),
+ IORESOURCE_SYSTEM_RAM, IORES_DESC_NONE);
+
+ if (is_ram != REGION_DISJOINT) {
+ WARN_ONCE(1, "attempted on %s region %#llx-%#llx\n",
+ is_ram == REGION_MIXED ? "mixed" : "ram",
+ range->start, range->end);
+ return -ENXIO;
+ }
+
+ error = xa_err(xa_store_range(&pgmap_array, PHYS_PFN(range->start),
+ PHYS_PFN(range->end), pgmap, GFP_KERNEL));
+ if (error)
+ return error;
+
+ if (nid < 0)
+ nid = numa_mem_id();
+
+ error = track_pfn_remap(NULL, &params->pgprot, PHYS_PFN(range->start), 0,
+ range_len(range));
+ if (error)
+ goto err_pfn_remap;
+
+ if (!mhp_range_allowed(range->start, range_len(range), !is_private)) {
+ error = -EINVAL;
+ goto err_kasan;
+ }
+
+ 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 (is_private) {
+ error = add_pages(nid, PHYS_PFN(range->start),
+ PHYS_PFN(range_len(range)), params);
+ } else {
+ error = kasan_add_zero_shadow(__va(range->start), range_len(range));
+ if (error) {
+ mem_hotplug_done();
+ goto err_kasan;
+ }
+
+ error = arch_add_memory(nid, range->start, range_len(range),
+ params);
+ }
+
+ if (!error) {
+ struct zone *zone;
+
+ zone = &NODE_DATA(nid)->node_zones[ZONE_DEVICE];
+ move_pfn_range_to_zone(zone, PHYS_PFN(range->start),
+ PHYS_PFN(range_len(range)), params->altmap,
+ MIGRATE_MOVABLE);
+ }
+
+ 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(range->start),
+ PHYS_PFN(range_len(range)), pgmap);
+ if (pgmap->type != MEMORY_DEVICE_PRIVATE &&
+ pgmap->type != MEMORY_DEVICE_COHERENT)
+ percpu_ref_get_many(&pgmap->ref, pfn_len(pgmap, range_id));
+ return 0;
+
+err_add_memory:
+ if (!is_private)
+ kasan_remove_zero_shadow(__va(range->start), range_len(range));
+err_kasan:
+ untrack_pfn(NULL, PHYS_PFN(range->start), range_len(range));
+err_pfn_remap:
+ pgmap_array_delete(range);
+ return error;
+}
+
+
+/*
+ * Not device managed version of devm_memremap_pages, undone by
+ * memunmap_pages(). Please use devm_memremap_pages if you have a struct
+ * device available.
+ */
+void *memremap_pages(struct dev_pagemap *pgmap, int nid)
+{
+ struct mhp_params params = {
+ .altmap = pgmap_altmap(pgmap),
+ .pgmap = pgmap,
+ .pgprot = PAGE_KERNEL,
+ };
+ const int nr_range = pgmap->nr_range;
+ int error, i;
+
+ if (WARN_ONCE(!nr_range, "nr_range must be specified\n"))
+ return ERR_PTR(-EINVAL);
+
+ 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);
+ }
+ if (!pgmap->ops->page_free) {
+ WARN(1, "Missing page_free method\n");
+ return ERR_PTR(-EINVAL);
+ }
+ if (!pgmap->owner) {
+ WARN(1, "Missing owner\n");
+ return ERR_PTR(-EINVAL);
+ }
+ break;
+ case MEMORY_DEVICE_COHERENT:
+ if (!pgmap->ops->page_free) {
+ WARN(1, "Missing page_free method\n");
+ return ERR_PTR(-EINVAL);
+ }
+ if (!pgmap->owner) {
+ WARN(1, "Missing owner\n");
+ return ERR_PTR(-EINVAL);
+ }
+ break;
+ case MEMORY_DEVICE_FS_DAX:
+ if (IS_ENABLED(CONFIG_FS_DAX_LIMITED)) {
+ WARN(1, "File system DAX not supported\n");
+ return ERR_PTR(-EINVAL);
+ }
+ params.pgprot = pgprot_decrypted(params.pgprot);
+ break;
+ case MEMORY_DEVICE_GENERIC:
+ break;
+ case MEMORY_DEVICE_PCI_P2PDMA:
+ params.pgprot = pgprot_noncached(params.pgprot);
+ break;
+ default:
+ WARN(1, "Invalid pgmap type %d\n", pgmap->type);
+ break;
+ }
+
+ init_completion(&pgmap->done);
+ error = percpu_ref_init(&pgmap->ref, dev_pagemap_percpu_release, 0,
+ GFP_KERNEL);
+ if (error)
+ return ERR_PTR(error);
+
+ devmap_managed_enable_get(pgmap);
+
+ /*
+ * Clear the pgmap nr_range as it will be incremented for each
+ * successfully processed range. This communicates how many
+ * regions to unwind in the abort case.
+ */
+ pgmap->nr_range = 0;
+ error = 0;
+ for (i = 0; i < nr_range; i++) {
+ error = pagemap_range(pgmap, &params, i, nid);
+ if (error)
+ break;
+ pgmap->nr_range++;
+ }
+
+ if (i < nr_range) {
+ memunmap_pages(pgmap);
+ pgmap->nr_range = nr_range;
+ return ERR_PTR(error);
+ }
+
+ return __va(pgmap->ranges[0].start);
+}
+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/ range 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->range.start && phys <= pgmap->range.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_rcu(&pgmap->ref))
+ pgmap = NULL;
+ rcu_read_unlock();
+
+ return pgmap;
+}
+EXPORT_SYMBOL_GPL(get_dev_pagemap);
+
+void free_zone_device_page(struct page *page)
+{
+ if (WARN_ON_ONCE(!page->pgmap->ops || !page->pgmap->ops->page_free))
+ return;
+
+ mem_cgroup_uncharge(page_folio(page));
+
+ /*
+ * Note: we don't expect anonymous compound pages yet. Once supported
+ * and we could PTE-map them similar to THP, we'd have to clear
+ * PG_anon_exclusive on all tail pages.
+ */
+ VM_BUG_ON_PAGE(PageAnon(page) && PageCompound(page), page);
+ if (PageAnon(page))
+ __ClearPageAnonExclusive(page);
+
+ /*
+ * When a device managed 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.
+ */
+ page->mapping = NULL;
+ page->pgmap->ops->page_free(page);
+
+ if (page->pgmap->type != MEMORY_DEVICE_PRIVATE &&
+ page->pgmap->type != MEMORY_DEVICE_COHERENT)
+ /*
+ * Reset the page count to 1 to prepare for handing out the page
+ * again.
+ */
+ set_page_count(page, 1);
+ else
+ put_dev_pagemap(page->pgmap);
+}
+
+void zone_device_page_init(struct page *page)
+{
+ /*
+ * Drivers shouldn't be allocating pages after calling
+ * memunmap_pages().
+ */
+ WARN_ON_ONCE(!percpu_ref_tryget_live(&page->pgmap->ref));
+ set_page_count(page, 1);
+ lock_page(page);
+}
+EXPORT_SYMBOL_GPL(zone_device_page_init);
+
+#ifdef CONFIG_FS_DAX
+bool __put_devmap_managed_page_refs(struct page *page, int refs)
+{
+ if (page->pgmap->type != MEMORY_DEVICE_FS_DAX)
+ return false;
+
+ /*
+ * fsdax page refcounts are 1-based, rather than 0-based: if
+ * refcount is 1, then the page is free and the refcount is
+ * stable because nobody holds a reference on the page.
+ */
+ if (page_ref_sub_return(page, refs) == 1)
+ wake_up_var(&page->_refcount);
+ return true;
+}
+EXPORT_SYMBOL(__put_devmap_managed_page_refs);
+#endif /* CONFIG_FS_DAX */