1 files changed, 148 insertions, 104 deletions

diff --git a/kernel/memremap.c b/kernel/memremap.c
index 1490e63f69a9..6ee03a816d67 100644
--- a/kernel/memremap.c
+++ b/kernel/memremap.c
@@ -11,41 +11,39 @@
 #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)
+#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)
 {
-	struct page *page = device_private_entry_to_page(entry);
-	struct hmm_devmem *devmem;
+	if (atomic_dec_and_test(&devmap_managed_enable))
+		static_branch_disable(&devmap_managed_key);
+}
 
-	devmem = container_of(page->pgmap, typeof(*devmem), pagemap);
+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;
+	}
 
-	/*
-	 * 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);
+	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_DEVICE_PRIVATE */
+#endif /* CONFIG_DEV_PAGEMAP_OPS */
 
 static void pgmap_array_delete(struct resource *res)
 {
@@ -56,14 +54,8 @@ static void pgmap_array_delete(struct resource *res)
 
 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;
+	return PHYS_PFN(pgmap->res.start) +
+		vmem_altmap_offset(pgmap_altmap(pgmap));
 }
 
 static unsigned long pfn_end(struct dev_pagemap *pgmap)
@@ -83,57 +75,80 @@ static unsigned long pfn_next(unsigned long pfn)
 #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);
+	}
+}
+
 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);
+	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 */
-	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));
+	nid = page_to_nid(pfn_to_page(PHYS_PFN(res->start)));
 
 	mem_hotplug_begin();
 	if (pgmap->type == MEMORY_DEVICE_PRIVATE) {
-		pfn = align_start >> PAGE_SHIFT;
+		pfn = PHYS_PFN(res->start);
 		__remove_pages(page_zone(pfn_to_page(pfn)), pfn,
-				align_size >> PAGE_SHIFT, NULL);
+				 PHYS_PFN(resource_size(res)), 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);
+		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(align_start), align_size);
+	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, ref and type members of @pgmap must be initialized
+ * 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 altmap_valid
- *    must be set to true
+ * 2/ The altmap field may optionally be initialized, in which case
+ *    PGMAP_ALTMAP_VALID must be set in pgmap->flags.
  *
- * 3/ pgmap->ref must be 'live' on entry and will be killed at
+ * 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
@@ -142,43 +157,85 @@ static void devm_memremap_pages_release(void *data)
  */
 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;
 	struct mhp_restrictions restrictions = {
 		/*
 		 * We do not want any optional features only our own memmap
-		*/
-		.altmap = altmap,
+		 */
+		.altmap = pgmap_altmap(pgmap),
 	};
 	pgprot_t pgprot = PAGE_KERNEL;
 	int error, nid, is_ram;
+	bool need_devmap_managed = true;
 
-	if (!pgmap->ref || !pgmap->kill)
-		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);
+		}
+		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;
+	}
 
-	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;
+	if (!pgmap->ref) {
+		if (pgmap->ops && (pgmap->ops->kill || pgmap->ops->cleanup))
+			return ERR_PTR(-EINVAL);
 
-	conflict_pgmap = get_dev_pagemap(PHYS_PFN(align_start), NULL);
+		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);
-		return ERR_PTR(-ENOMEM);
+		error = -ENOMEM;
+		goto err_array;
 	}
 
-	conflict_pgmap = get_dev_pagemap(PHYS_PFN(align_end), NULL);
+	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);
-		return ERR_PTR(-ENOMEM);
+		error = -ENOMEM;
+		goto err_array;
 	}
 
-	is_ram = region_intersects(align_start, align_size,
+	is_ram = region_intersects(res->start, resource_size(res),
 		IORESOURCE_SYSTEM_RAM, IORES_DESC_NONE);
 
 	if (is_ram != REGION_DISJOINT) {
@@ -199,8 +256,8 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
 	if (nid < 0)
 		nid = numa_mem_id();
 
-	error = track_pfn_remap(NULL, &pgprot, PHYS_PFN(align_start), 0,
-			align_size);
+	error = track_pfn_remap(NULL, &pgprot, PHYS_PFN(res->start), 0,
+			resource_size(res));
 	if (error)
 		goto err_pfn_remap;
 
@@ -218,16 +275,16 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
 	 * arch_add_memory().
 	 */
 	if (pgmap->type == MEMORY_DEVICE_PRIVATE) {
-		error = add_pages(nid, align_start >> PAGE_SHIFT,
-				align_size >> PAGE_SHIFT, &restrictions);
+		error = add_pages(nid, PHYS_PFN(res->start),
+				PHYS_PFN(resource_size(res)), &restrictions);
 	} else {
-		error = kasan_add_zero_shadow(__va(align_start), align_size);
+		error = kasan_add_zero_shadow(__va(res->start), resource_size(res));
 		if (error) {
 			mem_hotplug_done();
 			goto err_kasan;
 		}
 
-		error = arch_add_memory(nid, align_start, align_size,
+		error = arch_add_memory(nid, res->start, resource_size(res),
 					&restrictions);
 	}
 
@@ -235,8 +292,8 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
 		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);
+		move_pfn_range_to_zone(zone, PHYS_PFN(res->start),
+				PHYS_PFN(resource_size(res)), restrictions.altmap);
 	}
 
 	mem_hotplug_done();
@@ -248,8 +305,8 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
 	 * 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);
+				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,
@@ -260,21 +317,30 @@ void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
 	return __va(res->start);
 
  err_add_memory:
-	kasan_remove_zero_shadow(__va(align_start), align_size);
+	kasan_remove_zero_shadow(__va(res->start), resource_size(res));
  err_kasan:
-	untrack_pfn(NULL, PHYS_PFN(align_start), align_size);
+	untrack_pfn(NULL, PHYS_PFN(res->start), resource_size(res));
  err_pfn_remap:
 	pgmap_array_delete(res);
  err_array:
-	pgmap->kill(pgmap->ref);
+	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 */
-	return altmap->reserve + altmap->free;
+	if (altmap)
+		return altmap->reserve + altmap->free;
+	return 0;
 }
 
 void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns)
@@ -316,28 +382,6 @@ struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
 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);
@@ -353,7 +397,7 @@ void __put_devmap_managed_page(struct page *page)
 
 		mem_cgroup_uncharge(page);
 
-		page->pgmap->page_free(page, page->pgmap->data);
+		page->pgmap->ops->page_free(page);
 	} else if (!count)
 		__put_page(page);
 }