Merge remote-tracking branch 'remotes/mcayland/tags/qemu-openbios-20220115' into...
[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_REGISTER_MODES (UFFDIO_REGISTER_MODE_MISSING | \
23 UFFDIO_REGISTER_MODE_WP | \
24 UFFDIO_REGISTER_MODE_MINOR)
25 #define UFFD_API_FEATURES (UFFD_FEATURE_PAGEFAULT_FLAG_WP | \
26 UFFD_FEATURE_EVENT_FORK | \
27 UFFD_FEATURE_EVENT_REMAP | \
28 UFFD_FEATURE_EVENT_REMOVE | \
29 UFFD_FEATURE_EVENT_UNMAP | \
30 UFFD_FEATURE_MISSING_HUGETLBFS | \
31 UFFD_FEATURE_MISSING_SHMEM | \
32 UFFD_FEATURE_SIGBUS | \
33 UFFD_FEATURE_THREAD_ID | \
34 UFFD_FEATURE_MINOR_HUGETLBFS | \
35 UFFD_FEATURE_MINOR_SHMEM)
36 #define UFFD_API_IOCTLS \
37 ((__u64)1 << _UFFDIO_REGISTER | \
38 (__u64)1 << _UFFDIO_UNREGISTER | \
39 (__u64)1 << _UFFDIO_API)
40 #define UFFD_API_RANGE_IOCTLS \
41 ((__u64)1 << _UFFDIO_WAKE | \
42 (__u64)1 << _UFFDIO_COPY | \
43 (__u64)1 << _UFFDIO_ZEROPAGE | \
44 (__u64)1 << _UFFDIO_WRITEPROTECT | \
45 (__u64)1 << _UFFDIO_CONTINUE)
46 #define UFFD_API_RANGE_IOCTLS_BASIC \
47 ((__u64)1 << _UFFDIO_WAKE | \
48 (__u64)1 << _UFFDIO_COPY | \
49 (__u64)1 << _UFFDIO_CONTINUE)
50
51 /*
52 * Valid ioctl command number range with this API is from 0x00 to
53 * 0x3F. UFFDIO_API is the fixed number, everything else can be
54 * changed by implementing a different UFFD_API. If sticking to the
55 * same UFFD_API more ioctl can be added and userland will be aware of
56 * which ioctl the running kernel implements through the ioctl command
57 * bitmask written by the UFFDIO_API.
58 */
59 #define _UFFDIO_REGISTER (0x00)
60 #define _UFFDIO_UNREGISTER (0x01)
61 #define _UFFDIO_WAKE (0x02)
62 #define _UFFDIO_COPY (0x03)
63 #define _UFFDIO_ZEROPAGE (0x04)
64 #define _UFFDIO_WRITEPROTECT (0x06)
65 #define _UFFDIO_CONTINUE (0x07)
66 #define _UFFDIO_API (0x3F)
67
68 /* userfaultfd ioctl ids */
69 #define UFFDIO 0xAA
70 #define UFFDIO_API _IOWR(UFFDIO, _UFFDIO_API, \
71 struct uffdio_api)
72 #define UFFDIO_REGISTER _IOWR(UFFDIO, _UFFDIO_REGISTER, \
73 struct uffdio_register)
74 #define UFFDIO_UNREGISTER _IOR(UFFDIO, _UFFDIO_UNREGISTER, \
75 struct uffdio_range)
76 #define UFFDIO_WAKE _IOR(UFFDIO, _UFFDIO_WAKE, \
77 struct uffdio_range)
78 #define UFFDIO_COPY _IOWR(UFFDIO, _UFFDIO_COPY, \
79 struct uffdio_copy)
80 #define UFFDIO_ZEROPAGE _IOWR(UFFDIO, _UFFDIO_ZEROPAGE, \
81 struct uffdio_zeropage)
82 #define UFFDIO_WRITEPROTECT _IOWR(UFFDIO, _UFFDIO_WRITEPROTECT, \
83 struct uffdio_writeprotect)
84 #define UFFDIO_CONTINUE _IOWR(UFFDIO, _UFFDIO_CONTINUE, \
85 struct uffdio_continue)
86
87 /* read() structure */
88 struct uffd_msg {
89 __u8 event;
90
91 __u8 reserved1;
92 __u16 reserved2;
93 __u32 reserved3;
94
95 union {
96 struct {
97 __u64 flags;
98 __u64 address;
99 union {
100 __u32 ptid;
101 } feat;
102 } pagefault;
103
104 struct {
105 __u32 ufd;
106 } fork;
107
108 struct {
109 __u64 from;
110 __u64 to;
111 __u64 len;
112 } remap;
113
114 struct {
115 __u64 start;
116 __u64 end;
117 } remove;
118
119 struct {
120 /* unused reserved fields */
121 __u64 reserved1;
122 __u64 reserved2;
123 __u64 reserved3;
124 } reserved;
125 } arg;
126 } __attribute__((packed));
127
128 /*
129 * Start at 0x12 and not at 0 to be more strict against bugs.
130 */
131 #define UFFD_EVENT_PAGEFAULT 0x12
132 #define UFFD_EVENT_FORK 0x13
133 #define UFFD_EVENT_REMAP 0x14
134 #define UFFD_EVENT_REMOVE 0x15
135 #define UFFD_EVENT_UNMAP 0x16
136
137 /* flags for UFFD_EVENT_PAGEFAULT */
138 #define UFFD_PAGEFAULT_FLAG_WRITE (1<<0) /* If this was a write fault */
139 #define UFFD_PAGEFAULT_FLAG_WP (1<<1) /* If reason is VM_UFFD_WP */
140 #define UFFD_PAGEFAULT_FLAG_MINOR (1<<2) /* If reason is VM_UFFD_MINOR */
141
142 struct uffdio_api {
143 /* userland asks for an API number and the features to enable */
144 __u64 api;
145 /*
146 * Kernel answers below with the all available features for
147 * the API, this notifies userland of which events and/or
148 * which flags for each event are enabled in the current
149 * kernel.
150 *
151 * Note: UFFD_EVENT_PAGEFAULT and UFFD_PAGEFAULT_FLAG_WRITE
152 * are to be considered implicitly always enabled in all kernels as
153 * long as the uffdio_api.api requested matches UFFD_API.
154 *
155 * UFFD_FEATURE_MISSING_HUGETLBFS means an UFFDIO_REGISTER
156 * with UFFDIO_REGISTER_MODE_MISSING mode will succeed on
157 * hugetlbfs virtual memory ranges. Adding or not adding
158 * UFFD_FEATURE_MISSING_HUGETLBFS to uffdio_api.features has
159 * no real functional effect after UFFDIO_API returns, but
160 * it's only useful for an initial feature set probe at
161 * UFFDIO_API time. There are two ways to use it:
162 *
163 * 1) by adding UFFD_FEATURE_MISSING_HUGETLBFS to the
164 * uffdio_api.features before calling UFFDIO_API, an error
165 * will be returned by UFFDIO_API on a kernel without
166 * hugetlbfs missing support
167 *
168 * 2) the UFFD_FEATURE_MISSING_HUGETLBFS can not be added in
169 * uffdio_api.features and instead it will be set by the
170 * kernel in the uffdio_api.features if the kernel supports
171 * it, so userland can later check if the feature flag is
172 * present in uffdio_api.features after UFFDIO_API
173 * succeeded.
174 *
175 * UFFD_FEATURE_MISSING_SHMEM works the same as
176 * UFFD_FEATURE_MISSING_HUGETLBFS, but it applies to shmem
177 * (i.e. tmpfs and other shmem based APIs).
178 *
179 * UFFD_FEATURE_SIGBUS feature means no page-fault
180 * (UFFD_EVENT_PAGEFAULT) event will be delivered, instead
181 * a SIGBUS signal will be sent to the faulting process.
182 *
183 * UFFD_FEATURE_THREAD_ID pid of the page faulted task_struct will
184 * be returned, if feature is not requested 0 will be returned.
185 *
186 * UFFD_FEATURE_MINOR_HUGETLBFS indicates that minor faults
187 * can be intercepted (via REGISTER_MODE_MINOR) for
188 * hugetlbfs-backed pages.
189 *
190 * UFFD_FEATURE_MINOR_SHMEM indicates the same support as
191 * UFFD_FEATURE_MINOR_HUGETLBFS, but for shmem-backed pages instead.
192 */
193 #define UFFD_FEATURE_PAGEFAULT_FLAG_WP (1<<0)
194 #define UFFD_FEATURE_EVENT_FORK (1<<1)
195 #define UFFD_FEATURE_EVENT_REMAP (1<<2)
196 #define UFFD_FEATURE_EVENT_REMOVE (1<<3)
197 #define UFFD_FEATURE_MISSING_HUGETLBFS (1<<4)
198 #define UFFD_FEATURE_MISSING_SHMEM (1<<5)
199 #define UFFD_FEATURE_EVENT_UNMAP (1<<6)
200 #define UFFD_FEATURE_SIGBUS (1<<7)
201 #define UFFD_FEATURE_THREAD_ID (1<<8)
202 #define UFFD_FEATURE_MINOR_HUGETLBFS (1<<9)
203 #define UFFD_FEATURE_MINOR_SHMEM (1<<10)
204 __u64 features;
205
206 __u64 ioctls;
207 };
208
209 struct uffdio_range {
210 __u64 start;
211 __u64 len;
212 };
213
214 struct uffdio_register {
215 struct uffdio_range range;
216 #define UFFDIO_REGISTER_MODE_MISSING ((__u64)1<<0)
217 #define UFFDIO_REGISTER_MODE_WP ((__u64)1<<1)
218 #define UFFDIO_REGISTER_MODE_MINOR ((__u64)1<<2)
219 __u64 mode;
220
221 /*
222 * kernel answers which ioctl commands are available for the
223 * range, keep at the end as the last 8 bytes aren't read.
224 */
225 __u64 ioctls;
226 };
227
228 struct uffdio_copy {
229 __u64 dst;
230 __u64 src;
231 __u64 len;
232 #define UFFDIO_COPY_MODE_DONTWAKE ((__u64)1<<0)
233 /*
234 * UFFDIO_COPY_MODE_WP will map the page write protected on
235 * the fly. UFFDIO_COPY_MODE_WP is available only if the
236 * write protected ioctl is implemented for the range
237 * according to the uffdio_register.ioctls.
238 */
239 #define UFFDIO_COPY_MODE_WP ((__u64)1<<1)
240 __u64 mode;
241
242 /*
243 * "copy" is written by the ioctl and must be at the end: the
244 * copy_from_user will not read the last 8 bytes.
245 */
246 __s64 copy;
247 };
248
249 struct uffdio_zeropage {
250 struct uffdio_range range;
251 #define UFFDIO_ZEROPAGE_MODE_DONTWAKE ((__u64)1<<0)
252 __u64 mode;
253
254 /*
255 * "zeropage" is written by the ioctl and must be at the end:
256 * the copy_from_user will not read the last 8 bytes.
257 */
258 __s64 zeropage;
259 };
260
261 struct uffdio_writeprotect {
262 struct uffdio_range range;
263 /*
264 * UFFDIO_WRITEPROTECT_MODE_WP: set the flag to write protect a range,
265 * unset the flag to undo protection of a range which was previously
266 * write protected.
267 *
268 * UFFDIO_WRITEPROTECT_MODE_DONTWAKE: set the flag to avoid waking up
269 * any wait thread after the operation succeeds.
270 *
271 * NOTE: Write protecting a region (WP=1) is unrelated to page faults,
272 * therefore DONTWAKE flag is meaningless with WP=1. Removing write
273 * protection (WP=0) in response to a page fault wakes the faulting
274 * task unless DONTWAKE is set.
275 */
276 #define UFFDIO_WRITEPROTECT_MODE_WP ((__u64)1<<0)
277 #define UFFDIO_WRITEPROTECT_MODE_DONTWAKE ((__u64)1<<1)
278 __u64 mode;
279 };
280
281 struct uffdio_continue {
282 struct uffdio_range range;
283 #define UFFDIO_CONTINUE_MODE_DONTWAKE ((__u64)1<<0)
284 __u64 mode;
285
286 /*
287 * Fields below here are written by the ioctl and must be at the end:
288 * the copy_from_user will not read past here.
289 */
290 __s64 mapped;
291 };
292
293 /*
294 * Flags for the userfaultfd(2) system call itself.
295 */
296
297 /*
298 * Create a userfaultfd that can handle page faults only in user mode.
299 */
300 #define UFFD_USER_MODE_ONLY 1
301
302 #endif /* _LINUX_USERFAULTFD_H */