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 | |
17 | int 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 | |
75 | static 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 | |
87 | static 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 | |
94 | static int __init dax_kmem_init(void) |
95 | { |
96 | return dax_driver_register(&device_dax_kmem_driver); |
97 | } |
98 | |
99 | static void __exit dax_kmem_exit(void) |
100 | { |
101 | dax_driver_unregister(&device_dax_kmem_driver); |
102 | } |
103 | |
104 | MODULE_AUTHOR("Intel Corporation" ); |
105 | MODULE_LICENSE("GPL v2" ); |
106 | module_init(dax_kmem_init); |
107 | module_exit(dax_kmem_exit); |
108 | MODULE_ALIAS_DAX_DEVICE(0); |
109 | |