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 return rc;
71
72 return 0;
73}
74
75static int dev_dax_kmem_remove(struct device *dev)
76{
77 /*
78 * Purposely leak the request_mem_region() for the device-dax
79 * range and return '0' to ->remove() attempts. The removal of
80 * the device from the driver always succeeds, but the region
81 * is permanently pinned as reserved by the unreleased
82 * request_mem_region().
83 */
84 return 0;
85}
86
87static struct dax_device_driver device_dax_kmem_driver = {
88 .drv = {
89 .probe = dev_dax_kmem_probe,
90 .remove = dev_dax_kmem_remove,
91 },
92};
93
94static int __init dax_kmem_init(void)
95{
96 return dax_driver_register(&device_dax_kmem_driver);
97}
98
99static void __exit dax_kmem_exit(void)
100{
101 dax_driver_unregister(&device_dax_kmem_driver);
102}
103
104MODULE_AUTHOR("Intel Corporation");
105MODULE_LICENSE("GPL v2");
106module_init(dax_kmem_init);
107module_exit(dax_kmem_exit);
108MODULE_ALIAS_DAX_DEVICE(0);
109