1// SPDX-License-Identifier: GPL-2.0
  2/* Copyright(c) 2016-2019 Intel Corporation. All rights reserved. */
  3#include <linux/memremap.h>
  4#include <linux/pagemap.h>
  5#include <linux/memory.h>
  6#include <linux/module.h>
  7#include <linux/device.h>
  8#include <linux/pfn_t.h>
  9#include <linux/slab.h>
 10#include <linux/dax.h>
 11#include <linux/fs.h>
 12#include <linux/mm.h>
 13#include <linux/mman.h>
 14#include "dax-private.h"
 15#include "bus.h"
 16
 17int dev_dax_kmem_probe(struct device *dev)
 18{
 19	struct dev_dax *dev_dax = to_dev_dax(dev);
 20	struct resource *res = &dev_dax->region->res;
 21	resource_size_t kmem_start;
 22	resource_size_t kmem_size;
 23	resource_size_t kmem_end;
 24	struct resource *new_res;
 25	int numa_node;
 26	int rc;
 27
 28	/*
 29	 * Ensure good NUMA information for the persistent memory.
 30	 * Without this check, there is a risk that slow memory
 31	 * could be mixed in a node with faster memory, causing
 32	 * unavoidable performance issues.
 33	 */
 34	numa_node = dev_dax->target_node;
 35	if (numa_node < 0) {
 36		dev_warn(dev, "rejecting DAX region %pR with invalid node: %d\n",
 37			 res, numa_node);
 38		return -EINVAL;
 39	}
 40
 41	/* Hotplug starting at the beginning of the next block: */
 42	kmem_start = ALIGN(res->start, memory_block_size_bytes());
 43
 44	kmem_size = resource_size(res);
 45	/* Adjust the size down to compensate for moving up kmem_start: */
 46	kmem_size -= kmem_start - res->start;
 47	/* Align the size down to cover only complete blocks: */
 48	kmem_size &= ~(memory_block_size_bytes() - 1);
 49	kmem_end = kmem_start + kmem_size;
 50
 51	/* Region is permanently reserved.  Hot-remove not yet implemented. */
 52	new_res = request_mem_region(kmem_start, kmem_size, dev_name(dev));
 53	if (!new_res) {
 54		dev_warn(dev, "could not reserve region [%pa-%pa]\n",
 55			 &kmem_start, &kmem_end);
 56		return -EBUSY;
 57	}
 58
 59	/*
 60	 * Set flags appropriate for System RAM.  Leave ..._BUSY clear
 61	 * so that add_memory() can add a child resource.  Do not
 62	 * inherit flags from the parent since it may set new flags
 63	 * unknown to us that will break add_memory() below.
 64	 */
 65	new_res->flags = IORESOURCE_SYSTEM_RAM;
 66	new_res->name = dev_name(dev);
 67
 68	rc = add_memory(numa_node, new_res->start, resource_size(new_res));
 69	if (rc) {
 70		release_resource(new_res);
 71		kfree(new_res);
 72		return rc;
 73	}
 74	dev_dax->dax_kmem_res = new_res;
 75
 76	return 0;
 77}
 78
 79#ifdef CONFIG_MEMORY_HOTREMOVE
 80static int dev_dax_kmem_remove(struct device *dev)
 81{
 82	struct dev_dax *dev_dax = to_dev_dax(dev);
 83	struct resource *res = dev_dax->dax_kmem_res;
 84	resource_size_t kmem_start = res->start;
 85	resource_size_t kmem_size = resource_size(res);
 86	int rc;
 87
 88	/*
 89	 * We have one shot for removing memory, if some memory blocks were not
 90	 * offline prior to calling this function remove_memory() will fail, and
 91	 * there is no way to hotremove this memory until reboot because device
 92	 * unbind will succeed even if we return failure.
 93	 */
 94	rc = remove_memory(dev_dax->target_node, kmem_start, kmem_size);
 95	if (rc) {
 96		dev_err(dev,
 97			"DAX region %pR cannot be hotremoved until the next reboot\n",
 98			res);
 99		return rc;
100	}
101
102	/* Release and free dax resources */
103	release_resource(res);
104	kfree(res);
105	dev_dax->dax_kmem_res = NULL;
106
107	return 0;
108}
109#else
110static int dev_dax_kmem_remove(struct device *dev)
111{
112	/*
113	 * Without hotremove purposely leak the request_mem_region() for the
114	 * device-dax range and return '0' to ->remove() attempts. The removal
115	 * of the device from the driver always succeeds, but the region is
116	 * permanently pinned as reserved by the unreleased
117	 * request_mem_region().
118	 */
119	return 0;
120}
121#endif /* CONFIG_MEMORY_HOTREMOVE */
122
123static struct dax_device_driver device_dax_kmem_driver = {
124	.drv = {
125		.probe = dev_dax_kmem_probe,
126		.remove = dev_dax_kmem_remove,
127	},
128};
129
130static int __init dax_kmem_init(void)
131{
132	return dax_driver_register(&device_dax_kmem_driver);
133}
134
135static void __exit dax_kmem_exit(void)
136{
137	dax_driver_unregister(&device_dax_kmem_driver);
138}
139
140MODULE_AUTHOR("Intel Corporation");
141MODULE_LICENSE("GPL v2");
142module_init(dax_kmem_init);
143module_exit(dax_kmem_exit);
144MODULE_ALIAS_DAX_DEVICE(0);