Adding upstream version 4.19.249.upstream/4.19.249upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 748 insertions, 0 deletions

diff --git a/drivers/nvdimm/pfn_devs.c b/drivers/nvdimm/pfn_devs.c
new file mode 100644
index 000000000..86ed09b2a
--- /dev/null
+++ b/drivers/nvdimm/pfn_devs.c
@@ -0,0 +1,748 @@
+/*
+ * Copyright(c) 2013-2016 Intel Corporation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+#include <linux/memremap.h>
+#include <linux/blkdev.h>
+#include <linux/device.h>
+#include <linux/genhd.h>
+#include <linux/sizes.h>
+#include <linux/slab.h>
+#include <linux/fs.h>
+#include <linux/mm.h>
+#include "nd-core.h"
+#include "pfn.h"
+#include "nd.h"
+
+static void nd_pfn_release(struct device *dev)
+{
+	struct nd_region *nd_region = to_nd_region(dev->parent);
+	struct nd_pfn *nd_pfn = to_nd_pfn(dev);
+
+	dev_dbg(dev, "trace\n");
+	nd_detach_ndns(&nd_pfn->dev, &nd_pfn->ndns);
+	ida_simple_remove(&nd_region->pfn_ida, nd_pfn->id);
+	kfree(nd_pfn->uuid);
+	kfree(nd_pfn);
+}
+
+static struct device_type nd_pfn_device_type = {
+	.name = "nd_pfn",
+	.release = nd_pfn_release,
+};
+
+bool is_nd_pfn(struct device *dev)
+{
+	return dev ? dev->type == &nd_pfn_device_type : false;
+}
+EXPORT_SYMBOL(is_nd_pfn);
+
+struct nd_pfn *to_nd_pfn(struct device *dev)
+{
+	struct nd_pfn *nd_pfn = container_of(dev, struct nd_pfn, dev);
+
+	WARN_ON(!is_nd_pfn(dev));
+	return nd_pfn;
+}
+EXPORT_SYMBOL(to_nd_pfn);
+
+static ssize_t mode_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);
+
+	switch (nd_pfn->mode) {
+	case PFN_MODE_RAM:
+		return sprintf(buf, "ram\n");
+	case PFN_MODE_PMEM:
+		return sprintf(buf, "pmem\n");
+	default:
+		return sprintf(buf, "none\n");
+	}
+}
+
+static ssize_t mode_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t len)
+{
+	struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);
+	ssize_t rc = 0;
+
+	device_lock(dev);
+	nvdimm_bus_lock(dev);
+	if (dev->driver)
+		rc = -EBUSY;
+	else {
+		size_t n = len - 1;
+
+		if (strncmp(buf, "pmem\n", n) == 0
+				|| strncmp(buf, "pmem", n) == 0) {
+			nd_pfn->mode = PFN_MODE_PMEM;
+		} else if (strncmp(buf, "ram\n", n) == 0
+				|| strncmp(buf, "ram", n) == 0)
+			nd_pfn->mode = PFN_MODE_RAM;
+		else if (strncmp(buf, "none\n", n) == 0
+				|| strncmp(buf, "none", n) == 0)
+			nd_pfn->mode = PFN_MODE_NONE;
+		else
+			rc = -EINVAL;
+	}
+	dev_dbg(dev, "result: %zd wrote: %s%s", rc, buf,
+			buf[len - 1] == '\n' ? "" : "\n");
+	nvdimm_bus_unlock(dev);
+	device_unlock(dev);
+
+	return rc ? rc : len;
+}
+static DEVICE_ATTR_RW(mode);
+
+static ssize_t align_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);
+
+	return sprintf(buf, "%ld\n", nd_pfn->align);
+}
+
+static const unsigned long *nd_pfn_supported_alignments(void)
+{
+	/*
+	 * This needs to be a non-static variable because the *_SIZE
+	 * macros aren't always constants.
+	 */
+	const unsigned long supported_alignments[] = {
+		PAGE_SIZE,
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+		HPAGE_PMD_SIZE,
+#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
+		HPAGE_PUD_SIZE,
+#endif
+#endif
+		0,
+	};
+	static unsigned long data[ARRAY_SIZE(supported_alignments)];
+
+	memcpy(data, supported_alignments, sizeof(data));
+
+	return data;
+}
+
+static ssize_t align_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t len)
+{
+	struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);
+	ssize_t rc;
+
+	device_lock(dev);
+	nvdimm_bus_lock(dev);
+	rc = nd_size_select_store(dev, buf, &nd_pfn->align,
+			nd_pfn_supported_alignments());
+	dev_dbg(dev, "result: %zd wrote: %s%s", rc, buf,
+			buf[len - 1] == '\n' ? "" : "\n");
+	nvdimm_bus_unlock(dev);
+	device_unlock(dev);
+
+	return rc ? rc : len;
+}
+static DEVICE_ATTR_RW(align);
+
+static ssize_t uuid_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);
+
+	if (nd_pfn->uuid)
+		return sprintf(buf, "%pUb\n", nd_pfn->uuid);
+	return sprintf(buf, "\n");
+}
+
+static ssize_t uuid_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t len)
+{
+	struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);
+	ssize_t rc;
+
+	device_lock(dev);
+	rc = nd_uuid_store(dev, &nd_pfn->uuid, buf, len);
+	dev_dbg(dev, "result: %zd wrote: %s%s", rc, buf,
+			buf[len - 1] == '\n' ? "" : "\n");
+	device_unlock(dev);
+
+	return rc ? rc : len;
+}
+static DEVICE_ATTR_RW(uuid);
+
+static ssize_t namespace_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);
+	ssize_t rc;
+
+	nvdimm_bus_lock(dev);
+	rc = sprintf(buf, "%s\n", nd_pfn->ndns
+			? dev_name(&nd_pfn->ndns->dev) : "");
+	nvdimm_bus_unlock(dev);
+	return rc;
+}
+
+static ssize_t namespace_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t len)
+{
+	struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);
+	ssize_t rc;
+
+	device_lock(dev);
+	nvdimm_bus_lock(dev);
+	rc = nd_namespace_store(dev, &nd_pfn->ndns, buf, len);
+	dev_dbg(dev, "result: %zd wrote: %s%s", rc, buf,
+			buf[len - 1] == '\n' ? "" : "\n");
+	nvdimm_bus_unlock(dev);
+	device_unlock(dev);
+
+	return rc;
+}
+static DEVICE_ATTR_RW(namespace);
+
+static ssize_t resource_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);
+	ssize_t rc;
+
+	device_lock(dev);
+	if (dev->driver) {
+		struct nd_pfn_sb *pfn_sb = nd_pfn->pfn_sb;
+		u64 offset = __le64_to_cpu(pfn_sb->dataoff);
+		struct nd_namespace_common *ndns = nd_pfn->ndns;
+		u32 start_pad = __le32_to_cpu(pfn_sb->start_pad);
+		struct nd_namespace_io *nsio = to_nd_namespace_io(&ndns->dev);
+
+		rc = sprintf(buf, "%#llx\n", (unsigned long long) nsio->res.start
+				+ start_pad + offset);
+	} else {
+		/* no address to convey if the pfn instance is disabled */
+		rc = -ENXIO;
+	}
+	device_unlock(dev);
+
+	return rc;
+}
+static DEVICE_ATTR_RO(resource);
+
+static ssize_t size_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct nd_pfn *nd_pfn = to_nd_pfn_safe(dev);
+	ssize_t rc;
+
+	device_lock(dev);
+	if (dev->driver) {
+		struct nd_pfn_sb *pfn_sb = nd_pfn->pfn_sb;
+		u64 offset = __le64_to_cpu(pfn_sb->dataoff);
+		struct nd_namespace_common *ndns = nd_pfn->ndns;
+		u32 start_pad = __le32_to_cpu(pfn_sb->start_pad);
+		u32 end_trunc = __le32_to_cpu(pfn_sb->end_trunc);
+		struct nd_namespace_io *nsio = to_nd_namespace_io(&ndns->dev);
+
+		rc = sprintf(buf, "%llu\n", (unsigned long long)
+				resource_size(&nsio->res) - start_pad
+				- end_trunc - offset);
+	} else {
+		/* no size to convey if the pfn instance is disabled */
+		rc = -ENXIO;
+	}
+	device_unlock(dev);
+
+	return rc;
+}
+static DEVICE_ATTR_RO(size);
+
+static ssize_t supported_alignments_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	return nd_size_select_show(0, nd_pfn_supported_alignments(), buf);
+}
+static DEVICE_ATTR_RO(supported_alignments);
+
+static struct attribute *nd_pfn_attributes[] = {
+	&dev_attr_mode.attr,
+	&dev_attr_namespace.attr,
+	&dev_attr_uuid.attr,
+	&dev_attr_align.attr,
+	&dev_attr_resource.attr,
+	&dev_attr_size.attr,
+	&dev_attr_supported_alignments.attr,
+	NULL,
+};
+
+static umode_t pfn_visible(struct kobject *kobj, struct attribute *a, int n)
+{
+	if (a == &dev_attr_resource.attr)
+		return 0400;
+	return a->mode;
+}
+
+struct attribute_group nd_pfn_attribute_group = {
+	.attrs = nd_pfn_attributes,
+	.is_visible = pfn_visible,
+};
+
+static const struct attribute_group *nd_pfn_attribute_groups[] = {
+	&nd_pfn_attribute_group,
+	&nd_device_attribute_group,
+	&nd_numa_attribute_group,
+	NULL,
+};
+
+struct device *nd_pfn_devinit(struct nd_pfn *nd_pfn,
+		struct nd_namespace_common *ndns)
+{
+	struct device *dev;
+
+	if (!nd_pfn)
+		return NULL;
+
+	nd_pfn->mode = PFN_MODE_NONE;
+	nd_pfn->align = PFN_DEFAULT_ALIGNMENT;
+	dev = &nd_pfn->dev;
+	device_initialize(&nd_pfn->dev);
+	if (ndns && !__nd_attach_ndns(&nd_pfn->dev, ndns, &nd_pfn->ndns)) {
+		dev_dbg(&ndns->dev, "failed, already claimed by %s\n",
+				dev_name(ndns->claim));
+		put_device(dev);
+		return NULL;
+	}
+	return dev;
+}
+
+static struct nd_pfn *nd_pfn_alloc(struct nd_region *nd_region)
+{
+	struct nd_pfn *nd_pfn;
+	struct device *dev;
+
+	nd_pfn = kzalloc(sizeof(*nd_pfn), GFP_KERNEL);
+	if (!nd_pfn)
+		return NULL;
+
+	nd_pfn->id = ida_simple_get(&nd_region->pfn_ida, 0, 0, GFP_KERNEL);
+	if (nd_pfn->id < 0) {
+		kfree(nd_pfn);
+		return NULL;
+	}
+
+	dev = &nd_pfn->dev;
+	dev_set_name(dev, "pfn%d.%d", nd_region->id, nd_pfn->id);
+	dev->groups = nd_pfn_attribute_groups;
+	dev->type = &nd_pfn_device_type;
+	dev->parent = &nd_region->dev;
+
+	return nd_pfn;
+}
+
+struct device *nd_pfn_create(struct nd_region *nd_region)
+{
+	struct nd_pfn *nd_pfn;
+	struct device *dev;
+
+	if (!is_memory(&nd_region->dev))
+		return NULL;
+
+	nd_pfn = nd_pfn_alloc(nd_region);
+	dev = nd_pfn_devinit(nd_pfn, NULL);
+
+	__nd_device_register(dev);
+	return dev;
+}
+
+/**
+ * nd_pfn_validate - read and validate info-block
+ * @nd_pfn: fsdax namespace runtime state / properties
+ * @sig: 'devdax' or 'fsdax' signature
+ *
+ * Upon return the info-block buffer contents (->pfn_sb) are
+ * indeterminate when validation fails, and a coherent info-block
+ * otherwise.
+ */
+int nd_pfn_validate(struct nd_pfn *nd_pfn, const char *sig)
+{
+	u64 checksum, offset;
+	enum nd_pfn_mode mode;
+	struct nd_namespace_io *nsio;
+	unsigned long align, start_pad;
+	struct nd_pfn_sb *pfn_sb = nd_pfn->pfn_sb;
+	struct nd_namespace_common *ndns = nd_pfn->ndns;
+	const u8 *parent_uuid = nd_dev_to_uuid(&ndns->dev);
+
+	if (!pfn_sb || !ndns)
+		return -ENODEV;
+
+	if (!is_memory(nd_pfn->dev.parent))
+		return -ENODEV;
+
+	if (nvdimm_read_bytes(ndns, SZ_4K, pfn_sb, sizeof(*pfn_sb), 0))
+		return -ENXIO;
+
+	if (memcmp(pfn_sb->signature, sig, PFN_SIG_LEN) != 0)
+		return -ENODEV;
+
+	checksum = le64_to_cpu(pfn_sb->checksum);
+	pfn_sb->checksum = 0;
+	if (checksum != nd_sb_checksum((struct nd_gen_sb *) pfn_sb))
+		return -ENODEV;
+	pfn_sb->checksum = cpu_to_le64(checksum);
+
+	if (memcmp(pfn_sb->parent_uuid, parent_uuid, 16) != 0)
+		return -ENODEV;
+
+	if (__le16_to_cpu(pfn_sb->version_minor) < 1) {
+		pfn_sb->start_pad = 0;
+		pfn_sb->end_trunc = 0;
+	}
+
+	if (__le16_to_cpu(pfn_sb->version_minor) < 2)
+		pfn_sb->align = 0;
+
+	switch (le32_to_cpu(pfn_sb->mode)) {
+	case PFN_MODE_RAM:
+	case PFN_MODE_PMEM:
+		break;
+	default:
+		return -ENXIO;
+	}
+
+	align = le32_to_cpu(pfn_sb->align);
+	offset = le64_to_cpu(pfn_sb->dataoff);
+	start_pad = le32_to_cpu(pfn_sb->start_pad);
+	if (align == 0)
+		align = 1UL << ilog2(offset);
+	mode = le32_to_cpu(pfn_sb->mode);
+
+	if (!nd_pfn->uuid) {
+		/*
+		 * When probing a namepace via nd_pfn_probe() the uuid
+		 * is NULL (see: nd_pfn_devinit()) we init settings from
+		 * pfn_sb
+		 */
+		nd_pfn->uuid = kmemdup(pfn_sb->uuid, 16, GFP_KERNEL);
+		if (!nd_pfn->uuid)
+			return -ENOMEM;
+		nd_pfn->align = align;
+		nd_pfn->mode = mode;
+	} else {
+		/*
+		 * When probing a pfn / dax instance we validate the
+		 * live settings against the pfn_sb
+		 */
+		if (memcmp(nd_pfn->uuid, pfn_sb->uuid, 16) != 0)
+			return -ENODEV;
+
+		/*
+		 * If the uuid validates, but other settings mismatch
+		 * return EINVAL because userspace has managed to change
+		 * the configuration without specifying new
+		 * identification.
+		 */
+		if (nd_pfn->align != align || nd_pfn->mode != mode) {
+			dev_err(&nd_pfn->dev,
+					"init failed, settings mismatch\n");
+			dev_dbg(&nd_pfn->dev, "align: %lx:%lx mode: %d:%d\n",
+					nd_pfn->align, align, nd_pfn->mode,
+					mode);
+			return -EINVAL;
+		}
+	}
+
+	if (align > nvdimm_namespace_capacity(ndns)) {
+		dev_err(&nd_pfn->dev, "alignment: %lx exceeds capacity %llx\n",
+				align, nvdimm_namespace_capacity(ndns));
+		return -EINVAL;
+	}
+
+	/*
+	 * These warnings are verbose because they can only trigger in
+	 * the case where the physical address alignment of the
+	 * namespace has changed since the pfn superblock was
+	 * established.
+	 */
+	nsio = to_nd_namespace_io(&ndns->dev);
+	if (offset >= resource_size(&nsio->res)) {
+		dev_err(&nd_pfn->dev, "pfn array size exceeds capacity of %s\n",
+				dev_name(&ndns->dev));
+		return -EBUSY;
+	}
+
+	if ((align && !IS_ALIGNED(nsio->res.start + offset + start_pad, align))
+			|| !IS_ALIGNED(offset, PAGE_SIZE)) {
+		dev_err(&nd_pfn->dev,
+				"bad offset: %#llx dax disabled align: %#lx\n",
+				offset, align);
+		return -ENXIO;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(nd_pfn_validate);
+
+int nd_pfn_probe(struct device *dev, struct nd_namespace_common *ndns)
+{
+	int rc;
+	struct nd_pfn *nd_pfn;
+	struct device *pfn_dev;
+	struct nd_pfn_sb *pfn_sb;
+	struct nd_region *nd_region = to_nd_region(ndns->dev.parent);
+
+	if (ndns->force_raw)
+		return -ENODEV;
+
+	switch (ndns->claim_class) {
+	case NVDIMM_CCLASS_NONE:
+	case NVDIMM_CCLASS_PFN:
+		break;
+	default:
+		return -ENODEV;
+	}
+
+	nvdimm_bus_lock(&ndns->dev);
+	nd_pfn = nd_pfn_alloc(nd_region);
+	pfn_dev = nd_pfn_devinit(nd_pfn, ndns);
+	nvdimm_bus_unlock(&ndns->dev);
+	if (!pfn_dev)
+		return -ENOMEM;
+	pfn_sb = devm_kmalloc(dev, sizeof(*pfn_sb), GFP_KERNEL);
+	nd_pfn = to_nd_pfn(pfn_dev);
+	nd_pfn->pfn_sb = pfn_sb;
+	rc = nd_pfn_validate(nd_pfn, PFN_SIG);
+	dev_dbg(dev, "pfn: %s\n", rc == 0 ? dev_name(pfn_dev) : "<none>");
+	if (rc < 0) {
+		nd_detach_ndns(pfn_dev, &nd_pfn->ndns);
+		put_device(pfn_dev);
+	} else
+		__nd_device_register(pfn_dev);
+
+	return rc;
+}
+EXPORT_SYMBOL(nd_pfn_probe);
+
+/*
+ * We hotplug memory at section granularity, pad the reserved area from
+ * the previous section base to the namespace base address.
+ */
+static unsigned long init_altmap_base(resource_size_t base)
+{
+	unsigned long base_pfn = PHYS_PFN(base);
+
+	return PFN_SECTION_ALIGN_DOWN(base_pfn);
+}
+
+static unsigned long init_altmap_reserve(resource_size_t base)
+{
+	unsigned long reserve = PFN_UP(SZ_8K);
+	unsigned long base_pfn = PHYS_PFN(base);
+
+	reserve += base_pfn - PFN_SECTION_ALIGN_DOWN(base_pfn);
+	return reserve;
+}
+
+static int __nvdimm_setup_pfn(struct nd_pfn *nd_pfn, struct dev_pagemap *pgmap)
+{
+	struct resource *res = &pgmap->res;
+	struct vmem_altmap *altmap = &pgmap->altmap;
+	struct nd_pfn_sb *pfn_sb = nd_pfn->pfn_sb;
+	u64 offset = le64_to_cpu(pfn_sb->dataoff);
+	u32 start_pad = __le32_to_cpu(pfn_sb->start_pad);
+	u32 end_trunc = __le32_to_cpu(pfn_sb->end_trunc);
+	struct nd_namespace_common *ndns = nd_pfn->ndns;
+	struct nd_namespace_io *nsio = to_nd_namespace_io(&ndns->dev);
+	resource_size_t base = nsio->res.start + start_pad;
+	struct vmem_altmap __altmap = {
+		.base_pfn = init_altmap_base(base),
+		.reserve = init_altmap_reserve(base),
+	};
+
+	memcpy(res, &nsio->res, sizeof(*res));
+	res->start += start_pad;
+	res->end -= end_trunc;
+
+	if (nd_pfn->mode == PFN_MODE_RAM) {
+		if (offset < SZ_8K)
+			return -EINVAL;
+		nd_pfn->npfns = le64_to_cpu(pfn_sb->npfns);
+		pgmap->altmap_valid = false;
+	} else if (nd_pfn->mode == PFN_MODE_PMEM) {
+		nd_pfn->npfns = PFN_SECTION_ALIGN_UP((resource_size(res)
+					- offset) / PAGE_SIZE);
+		if (le64_to_cpu(nd_pfn->pfn_sb->npfns) > nd_pfn->npfns)
+			dev_info(&nd_pfn->dev,
+					"number of pfns truncated from %lld to %ld\n",
+					le64_to_cpu(nd_pfn->pfn_sb->npfns),
+					nd_pfn->npfns);
+		memcpy(altmap, &__altmap, sizeof(*altmap));
+		altmap->free = PHYS_PFN(offset - SZ_8K);
+		altmap->alloc = 0;
+		pgmap->altmap_valid = true;
+	} else
+		return -ENXIO;
+
+	return 0;
+}
+
+static u64 phys_pmem_align_down(struct nd_pfn *nd_pfn, u64 phys)
+{
+	return min_t(u64, PHYS_SECTION_ALIGN_DOWN(phys),
+			ALIGN_DOWN(phys, nd_pfn->align));
+}
+
+/*
+ * Check if pmem collides with 'System RAM', or other regions when
+ * section aligned.  Trim it accordingly.
+ */
+static void trim_pfn_device(struct nd_pfn *nd_pfn, u32 *start_pad, u32 *end_trunc)
+{
+	struct nd_namespace_common *ndns = nd_pfn->ndns;
+	struct nd_namespace_io *nsio = to_nd_namespace_io(&ndns->dev);
+	struct nd_region *nd_region = to_nd_region(nd_pfn->dev.parent);
+	const resource_size_t start = nsio->res.start;
+	const resource_size_t end = start + resource_size(&nsio->res);
+	resource_size_t adjust, size;
+
+	*start_pad = 0;
+	*end_trunc = 0;
+
+	adjust = start - PHYS_SECTION_ALIGN_DOWN(start);
+	size = resource_size(&nsio->res) + adjust;
+	if (region_intersects(start - adjust, size, IORESOURCE_SYSTEM_RAM,
+				IORES_DESC_NONE) == REGION_MIXED
+			|| nd_region_conflict(nd_region, start - adjust, size))
+		*start_pad = PHYS_SECTION_ALIGN_UP(start) - start;
+
+	/* Now check that end of the range does not collide. */
+	adjust = PHYS_SECTION_ALIGN_UP(end) - end;
+	size = resource_size(&nsio->res) + adjust;
+	if (region_intersects(start, size, IORESOURCE_SYSTEM_RAM,
+				IORES_DESC_NONE) == REGION_MIXED
+			|| !IS_ALIGNED(end, nd_pfn->align)
+			|| nd_region_conflict(nd_region, start, size))
+		*end_trunc = end - phys_pmem_align_down(nd_pfn, end);
+}
+
+static int nd_pfn_init(struct nd_pfn *nd_pfn)
+{
+	u32 dax_label_reserve = is_nd_dax(&nd_pfn->dev) ? SZ_128K : 0;
+	struct nd_namespace_common *ndns = nd_pfn->ndns;
+	struct nd_namespace_io *nsio = to_nd_namespace_io(&ndns->dev);
+	resource_size_t start, size;
+	struct nd_region *nd_region;
+	u32 start_pad, end_trunc;
+	struct nd_pfn_sb *pfn_sb;
+	unsigned long npfns;
+	phys_addr_t offset;
+	const char *sig;
+	u64 checksum;
+	int rc;
+
+	pfn_sb = devm_kmalloc(&nd_pfn->dev, sizeof(*pfn_sb), GFP_KERNEL);
+	if (!pfn_sb)
+		return -ENOMEM;
+
+	nd_pfn->pfn_sb = pfn_sb;
+	if (is_nd_dax(&nd_pfn->dev))
+		sig = DAX_SIG;
+	else
+		sig = PFN_SIG;
+
+	rc = nd_pfn_validate(nd_pfn, sig);
+	if (rc != -ENODEV)
+		return rc;
+
+	/* no info block, do init */;
+	memset(pfn_sb, 0, sizeof(*pfn_sb));
+
+	nd_region = to_nd_region(nd_pfn->dev.parent);
+	if (nd_region->ro) {
+		dev_info(&nd_pfn->dev,
+				"%s is read-only, unable to init metadata\n",
+				dev_name(&nd_region->dev));
+		return -ENXIO;
+	}
+
+	memset(pfn_sb, 0, sizeof(*pfn_sb));
+
+	trim_pfn_device(nd_pfn, &start_pad, &end_trunc);
+	if (start_pad + end_trunc)
+		dev_info(&nd_pfn->dev, "%s alignment collision, truncate %d bytes\n",
+				dev_name(&ndns->dev), start_pad + end_trunc);
+
+	/*
+	 * Note, we use 64 here for the standard size of struct page,
+	 * debugging options may cause it to be larger in which case the
+	 * implementation will limit the pfns advertised through
+	 * ->direct_access() to those that are included in the memmap.
+	 */
+	start = nsio->res.start + start_pad;
+	size = resource_size(&nsio->res);
+	npfns = PFN_SECTION_ALIGN_UP((size - start_pad - end_trunc - SZ_8K)
+			/ PAGE_SIZE);
+	if (nd_pfn->mode == PFN_MODE_PMEM) {
+		/*
+		 * The altmap should be padded out to the block size used
+		 * when populating the vmemmap. This *should* be equal to
+		 * PMD_SIZE for most architectures.
+		 */
+		offset = ALIGN(start + SZ_8K + 64 * npfns + dax_label_reserve,
+				max(nd_pfn->align, PMD_SIZE)) - start;
+	} else if (nd_pfn->mode == PFN_MODE_RAM)
+		offset = ALIGN(start + SZ_8K + dax_label_reserve,
+				nd_pfn->align) - start;
+	else
+		return -ENXIO;
+
+	if (offset + start_pad + end_trunc >= size) {
+		dev_err(&nd_pfn->dev, "%s unable to satisfy requested alignment\n",
+				dev_name(&ndns->dev));
+		return -ENXIO;
+	}
+
+	npfns = (size - offset - start_pad - end_trunc) / SZ_4K;
+	pfn_sb->mode = cpu_to_le32(nd_pfn->mode);
+	pfn_sb->dataoff = cpu_to_le64(offset);
+	pfn_sb->npfns = cpu_to_le64(npfns);
+	memcpy(pfn_sb->signature, sig, PFN_SIG_LEN);
+	memcpy(pfn_sb->uuid, nd_pfn->uuid, 16);
+	memcpy(pfn_sb->parent_uuid, nd_dev_to_uuid(&ndns->dev), 16);
+	pfn_sb->version_major = cpu_to_le16(1);
+	pfn_sb->version_minor = cpu_to_le16(3);
+	pfn_sb->start_pad = cpu_to_le32(start_pad);
+	pfn_sb->end_trunc = cpu_to_le32(end_trunc);
+	pfn_sb->align = cpu_to_le32(nd_pfn->align);
+	checksum = nd_sb_checksum((struct nd_gen_sb *) pfn_sb);
+	pfn_sb->checksum = cpu_to_le64(checksum);
+
+	return nvdimm_write_bytes(ndns, SZ_4K, pfn_sb, sizeof(*pfn_sb), 0);
+}
+
+/*
+ * Determine the effective resource range and vmem_altmap from an nd_pfn
+ * instance.
+ */
+int nvdimm_setup_pfn(struct nd_pfn *nd_pfn, struct dev_pagemap *pgmap)
+{
+	int rc;
+
+	if (!nd_pfn->uuid || !nd_pfn->ndns)
+		return -ENODEV;
+
+	rc = nd_pfn_init(nd_pfn);
+	if (rc)
+		return rc;
+
+	/* we need a valid pfn_sb before we can init a dev_pagemap */
+	return __nvdimm_setup_pfn(nd_pfn, pgmap);
+}
+EXPORT_SYMBOL_GPL(nvdimm_setup_pfn);