Merge tag 'block-pull-request' of https://gitlab.com/stefanha/qemu into staging
[qemu.git] / linux-headers / linux / userfaultfd.h
1 /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
2 /*
3 * include/linux/userfaultfd.h
4 *
5 * Copyright (C) 2007 Davide Libenzi <davidel@xmailserver.org>
6 * Copyright (C) 2015 Red Hat, Inc.
7 *
8 */
9
10 #ifndef _LINUX_USERFAULTFD_H
11 #define _LINUX_USERFAULTFD_H
12
13 #include <linux/types.h>
14
15 /*
16 * If the UFFDIO_API is upgraded someday, the UFFDIO_UNREGISTER and
17 * UFFDIO_WAKE ioctls should be defined as _IOW and not as _IOR. In
18 * userfaultfd.h we assumed the kernel was reading (instead _IOC_READ
19 * means the userland is reading).
20 */
21 #define UFFD_API ((__u64)0xAA)
22 #define UFFD_API_FEATURES (UFFD_FEATURE_PAGEFAULT_FLAG_WP | \
23 UFFD_FEATURE_EVENT_FORK | \
24 UFFD_FEATURE_EVENT_REMAP | \
25 UFFD_FEATURE_EVENT_REMOVE | \
26 UFFD_FEATURE_EVENT_UNMAP | \
27 UFFD_FEATURE_MISSING_HUGETLBFS | \
28 UFFD_FEATURE_MISSING_SHMEM | \
29 UFFD_FEATURE_SIGBUS | \
30 UFFD_FEATURE_THREAD_ID)
31 #define UFFD_API_IOCTLS \
32 ((__u64)1 << _UFFDIO_REGISTER | \
33 (__u64)1 << _UFFDIO_UNREGISTER | \
34 (__u64)1 << _UFFDIO_API)
35 #define UFFD_API_RANGE_IOCTLS \
36 ((__u64)1 << _UFFDIO_WAKE | \
37 (__u64)1 << _UFFDIO_COPY | \
38 (__u64)1 << _UFFDIO_ZEROPAGE | \
39 (__u64)1 << _UFFDIO_WRITEPROTECT)
40 #define UFFD_API_RANGE_IOCTLS_BASIC \
41 ((__u64)1 << _UFFDIO_WAKE | \
42 (__u64)1 << _UFFDIO_COPY)
43
44 /*
45 * Valid ioctl command number range with this API is from 0x00 to
46 * 0x3F. UFFDIO_API is the fixed number, everything else can be
47 * changed by implementing a different UFFD_API. If sticking to the
48 * same UFFD_API more ioctl can be added and userland will be aware of
49 * which ioctl the running kernel implements through the ioctl command
50 * bitmask written by the UFFDIO_API.
51 */
52 #define _UFFDIO_REGISTER (0x00)
53 #define _UFFDIO_UNREGISTER (0x01)
54 #define _UFFDIO_WAKE (0x02)
55 #define _UFFDIO_COPY (0x03)
56 #define _UFFDIO_ZEROPAGE (0x04)
57 #define _UFFDIO_WRITEPROTECT (0x06)
58 #define _UFFDIO_API (0x3F)
59
60 /* userfaultfd ioctl ids */
61 #define UFFDIO 0xAA
62 #define UFFDIO_API _IOWR(UFFDIO, _UFFDIO_API, \
63 struct uffdio_api)
64 #define UFFDIO_REGISTER _IOWR(UFFDIO, _UFFDIO_REGISTER, \
65 struct uffdio_register)
66 #define UFFDIO_UNREGISTER _IOR(UFFDIO, _UFFDIO_UNREGISTER, \
67 struct uffdio_range)
68 #define UFFDIO_WAKE _IOR(UFFDIO, _UFFDIO_WAKE, \
69 struct uffdio_range)
70 #define UFFDIO_COPY _IOWR(UFFDIO, _UFFDIO_COPY, \
71 struct uffdio_copy)
72 #define UFFDIO_ZEROPAGE _IOWR(UFFDIO, _UFFDIO_ZEROPAGE, \
73 struct uffdio_zeropage)
74 #define UFFDIO_WRITEPROTECT _IOWR(UFFDIO, _UFFDIO_WRITEPROTECT, \
75 struct uffdio_writeprotect)
76
77 /* read() structure */
78 struct uffd_msg {
79 __u8 event;
80
81 __u8 reserved1;
82 __u16 reserved2;
83 __u32 reserved3;
84
85 union {
86 struct {
87 __u64 flags;
88 __u64 address;
89 union {
90 __u32 ptid;
91 } feat;
92 } pagefault;
93
94 struct {
95 __u32 ufd;
96 } fork;
97
98 struct {
99 __u64 from;
100 __u64 to;
101 __u64 len;
102 } remap;
103
104 struct {
105 __u64 start;
106 __u64 end;
107 } remove;
108
109 struct {
110 /* unused reserved fields */
111 __u64 reserved1;
112 __u64 reserved2;
113 __u64 reserved3;
114 } reserved;
115 } arg;
116 } __attribute__((packed));
117
118 /*
119 * Start at 0x12 and not at 0 to be more strict against bugs.
120 */
121 #define UFFD_EVENT_PAGEFAULT 0x12
122 #define UFFD_EVENT_FORK 0x13
123 #define UFFD_EVENT_REMAP 0x14
124 #define UFFD_EVENT_REMOVE 0x15
125 #define UFFD_EVENT_UNMAP 0x16
126
127 /* flags for UFFD_EVENT_PAGEFAULT */
128 #define UFFD_PAGEFAULT_FLAG_WRITE (1<<0) /* If this was a write fault */
129 #define UFFD_PAGEFAULT_FLAG_WP (1<<1) /* If reason is VM_UFFD_WP */
130
131 struct uffdio_api {
132 /* userland asks for an API number and the features to enable */
133 __u64 api;
134 /*
135 * Kernel answers below with the all available features for
136 * the API, this notifies userland of which events and/or
137 * which flags for each event are enabled in the current
138 * kernel.
139 *
140 * Note: UFFD_EVENT_PAGEFAULT and UFFD_PAGEFAULT_FLAG_WRITE
141 * are to be considered implicitly always enabled in all kernels as
142 * long as the uffdio_api.api requested matches UFFD_API.
143 *
144 * UFFD_FEATURE_MISSING_HUGETLBFS means an UFFDIO_REGISTER
145 * with UFFDIO_REGISTER_MODE_MISSING mode will succeed on
146 * hugetlbfs virtual memory ranges. Adding or not adding
147 * UFFD_FEATURE_MISSING_HUGETLBFS to uffdio_api.features has
148 * no real functional effect after UFFDIO_API returns, but
149 * it's only useful for an initial feature set probe at
150 * UFFDIO_API time. There are two ways to use it:
151 *
152 * 1) by adding UFFD_FEATURE_MISSING_HUGETLBFS to the
153 * uffdio_api.features before calling UFFDIO_API, an error
154 * will be returned by UFFDIO_API on a kernel without
155 * hugetlbfs missing support
156 *
157 * 2) the UFFD_FEATURE_MISSING_HUGETLBFS can not be added in
158 * uffdio_api.features and instead it will be set by the
159 * kernel in the uffdio_api.features if the kernel supports
160 * it, so userland can later check if the feature flag is
161 * present in uffdio_api.features after UFFDIO_API
162 * succeeded.
163 *
164 * UFFD_FEATURE_MISSING_SHMEM works the same as
165 * UFFD_FEATURE_MISSING_HUGETLBFS, but it applies to shmem
166 * (i.e. tmpfs and other shmem based APIs).
167 *
168 * UFFD_FEATURE_SIGBUS feature means no page-fault
169 * (UFFD_EVENT_PAGEFAULT) event will be delivered, instead
170 * a SIGBUS signal will be sent to the faulting process.
171 *
172 * UFFD_FEATURE_THREAD_ID pid of the page faulted task_struct will
173 * be returned, if feature is not requested 0 will be returned.
174 */
175 #define UFFD_FEATURE_PAGEFAULT_FLAG_WP (1<<0)
176 #define UFFD_FEATURE_EVENT_FORK (1<<1)
177 #define UFFD_FEATURE_EVENT_REMAP (1<<2)
178 #define UFFD_FEATURE_EVENT_REMOVE (1<<3)
179 #define UFFD_FEATURE_MISSING_HUGETLBFS (1<<4)
180 #define UFFD_FEATURE_MISSING_SHMEM (1<<5)
181 #define UFFD_FEATURE_EVENT_UNMAP (1<<6)
182 #define UFFD_FEATURE_SIGBUS (1<<7)
183 #define UFFD_FEATURE_THREAD_ID (1<<8)
184 __u64 features;
185
186 __u64 ioctls;
187 };
188
189 struct uffdio_range {
190 __u64 start;
191 __u64 len;
192 };
193
194 struct uffdio_register {
195 struct uffdio_range range;
196 #define UFFDIO_REGISTER_MODE_MISSING ((__u64)1<<0)
197 #define UFFDIO_REGISTER_MODE_WP ((__u64)1<<1)
198 __u64 mode;
199
200 /*
201 * kernel answers which ioctl commands are available for the
202 * range, keep at the end as the last 8 bytes aren't read.
203 */
204 __u64 ioctls;
205 };
206
207 struct uffdio_copy {
208 __u64 dst;
209 __u64 src;
210 __u64 len;
211 #define UFFDIO_COPY_MODE_DONTWAKE ((__u64)1<<0)
212 /*
213 * UFFDIO_COPY_MODE_WP will map the page write protected on
214 * the fly. UFFDIO_COPY_MODE_WP is available only if the
215 * write protected ioctl is implemented for the range
216 * according to the uffdio_register.ioctls.
217 */
218 #define UFFDIO_COPY_MODE_WP ((__u64)1<<1)
219 __u64 mode;
220
221 /*
222 * "copy" is written by the ioctl and must be at the end: the
223 * copy_from_user will not read the last 8 bytes.
224 */
225 __s64 copy;
226 };
227
228 struct uffdio_zeropage {
229 struct uffdio_range range;
230 #define UFFDIO_ZEROPAGE_MODE_DONTWAKE ((__u64)1<<0)
231 __u64 mode;
232
233 /*
234 * "zeropage" is written by the ioctl and must be at the end:
235 * the copy_from_user will not read the last 8 bytes.
236 */
237 __s64 zeropage;
238 };
239
240 struct uffdio_writeprotect {
241 struct uffdio_range range;
242 /*
243 * UFFDIO_WRITEPROTECT_MODE_WP: set the flag to write protect a range,
244 * unset the flag to undo protection of a range which was previously
245 * write protected.
246 *
247 * UFFDIO_WRITEPROTECT_MODE_DONTWAKE: set the flag to avoid waking up
248 * any wait thread after the operation succeeds.
249 *
250 * NOTE: Write protecting a region (WP=1) is unrelated to page faults,
251 * therefore DONTWAKE flag is meaningless with WP=1. Removing write
252 * protection (WP=0) in response to a page fault wakes the faulting
253 * task unless DONTWAKE is set.
254 */
255 #define UFFDIO_WRITEPROTECT_MODE_WP ((__u64)1<<0)
256 #define UFFDIO_WRITEPROTECT_MODE_DONTWAKE ((__u64)1<<1)
257 __u64 mode;
258 };
259
260 /*
261 * Flags for the userfaultfd(2) system call itself.
262 */
263
264 /*
265 * Create a userfaultfd that can handle page faults only in user mode.
266 */
267 #define UFFD_USER_MODE_ONLY 1
268
269 #endif /* _LINUX_USERFAULTFD_H */