1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
|
/*
* Copyright 2013 Red Hat Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* 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.
*
* Authors: Jérôme Glisse <jglisse@redhat.com>
*/
/*
* Refer to include/linux/hmm.h for information about heterogeneous memory
* management or HMM for short.
*/
#include <linux/mm.h>
#include <linux/hmm.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/mmu_notifier.h>
#ifdef CONFIG_HMM
static const struct mmu_notifier_ops hmm_mmu_notifier_ops;
/*
* struct hmm - HMM per mm struct
*
* @mm: mm struct this HMM struct is bound to
* @sequence: we track updates to the CPU page table with a sequence number
* @mirrors: list of mirrors for this mm
* @mmu_notifier: mmu notifier to track updates to CPU page table
* @mirrors_sem: read/write semaphore protecting the mirrors list
*/
struct hmm {
struct mm_struct *mm;
atomic_t sequence;
struct list_head mirrors;
struct mmu_notifier mmu_notifier;
struct rw_semaphore mirrors_sem;
};
/*
* hmm_register - register HMM against an mm (HMM internal)
*
* @mm: mm struct to attach to
*
* This is not intended to be used directly by device drivers. It allocates an
* HMM struct if mm does not have one, and initializes it.
*/
static struct hmm *hmm_register(struct mm_struct *mm)
{
struct hmm *hmm = READ_ONCE(mm->hmm);
bool cleanup = false;
/*
* The hmm struct can only be freed once the mm_struct goes away,
* hence we should always have pre-allocated an new hmm struct
* above.
*/
if (hmm)
return hmm;
hmm = kmalloc(sizeof(*hmm), GFP_KERNEL);
if (!hmm)
return NULL;
INIT_LIST_HEAD(&hmm->mirrors);
init_rwsem(&hmm->mirrors_sem);
atomic_set(&hmm->sequence, 0);
hmm->mmu_notifier.ops = NULL;
hmm->mm = mm;
/*
* We should only get here if hold the mmap_sem in write mode ie on
* registration of first mirror through hmm_mirror_register()
*/
hmm->mmu_notifier.ops = &hmm_mmu_notifier_ops;
if (__mmu_notifier_register(&hmm->mmu_notifier, mm)) {
kfree(hmm);
return NULL;
}
spin_lock(&mm->page_table_lock);
if (!mm->hmm)
mm->hmm = hmm;
else
cleanup = true;
spin_unlock(&mm->page_table_lock);
if (cleanup) {
mmu_notifier_unregister(&hmm->mmu_notifier, mm);
kfree(hmm);
}
return mm->hmm;
}
void hmm_mm_destroy(struct mm_struct *mm)
{
kfree(mm->hmm);
}
#endif /* CONFIG_HMM */
#if IS_ENABLED(CONFIG_HMM_MIRROR)
static void hmm_invalidate_range(struct hmm *hmm,
enum hmm_update_type action,
unsigned long start,
unsigned long end)
{
struct hmm_mirror *mirror;
down_read(&hmm->mirrors_sem);
list_for_each_entry(mirror, &hmm->mirrors, list)
mirror->ops->sync_cpu_device_pagetables(mirror, action,
start, end);
up_read(&hmm->mirrors_sem);
}
static void hmm_invalidate_range_start(struct mmu_notifier *mn,
struct mm_struct *mm,
unsigned long start,
unsigned long end)
{
struct hmm *hmm = mm->hmm;
VM_BUG_ON(!hmm);
atomic_inc(&hmm->sequence);
}
static void hmm_invalidate_range_end(struct mmu_notifier *mn,
struct mm_struct *mm,
unsigned long start,
unsigned long end)
{
struct hmm *hmm = mm->hmm;
VM_BUG_ON(!hmm);
hmm_invalidate_range(mm->hmm, HMM_UPDATE_INVALIDATE, start, end);
}
static const struct mmu_notifier_ops hmm_mmu_notifier_ops = {
.invalidate_range_start = hmm_invalidate_range_start,
.invalidate_range_end = hmm_invalidate_range_end,
};
/*
* hmm_mirror_register() - register a mirror against an mm
*
* @mirror: new mirror struct to register
* @mm: mm to register against
*
* To start mirroring a process address space, the device driver must register
* an HMM mirror struct.
*
* THE mm->mmap_sem MUST BE HELD IN WRITE MODE !
*/
int hmm_mirror_register(struct hmm_mirror *mirror, struct mm_struct *mm)
{
/* Sanity check */
if (!mm || !mirror || !mirror->ops)
return -EINVAL;
mirror->hmm = hmm_register(mm);
if (!mirror->hmm)
return -ENOMEM;
down_write(&mirror->hmm->mirrors_sem);
list_add(&mirror->list, &mirror->hmm->mirrors);
up_write(&mirror->hmm->mirrors_sem);
return 0;
}
EXPORT_SYMBOL(hmm_mirror_register);
/*
* hmm_mirror_unregister() - unregister a mirror
*
* @mirror: new mirror struct to register
*
* Stop mirroring a process address space, and cleanup.
*/
void hmm_mirror_unregister(struct hmm_mirror *mirror)
{
struct hmm *hmm = mirror->hmm;
down_write(&hmm->mirrors_sem);
list_del(&mirror->list);
up_write(&hmm->mirrors_sem);
}
EXPORT_SYMBOL(hmm_mirror_unregister);
#endif /* IS_ENABLED(CONFIG_HMM_MIRROR) */
|
