1/*
2 * Permission to use, copy, modify, and/or distribute this software for any
3 * purpose with or without fee is hereby granted, provided that the above
4 * copyright notice and this permission notice appear in all copies.
5 *
6 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
7 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
8 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
9 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
10 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
11 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
12 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
13 *
14 * Copyright (C) 2019 Intel Corporation
15 */
16#ifndef _UAPI_LINUX_UM_TIMETRAVEL_H
17#define _UAPI_LINUX_UM_TIMETRAVEL_H
18#include <linux/types.h>
19
20/**
21 * struct um_timetravel_msg - UM time travel message
22 *
23 * This is the basic message type, going in both directions.
24 *
25 * This is the message passed between the host (user-mode Linux instance)
26 * and the calendar (the application on the other side of the socket) in
27 * order to implement common scheduling.
28 *
29 * Whenever UML has an event it will request runtime for it from the
30 * calendar, and then wait for its turn until it can run, etc. Note
31 * that it will only ever request the single next runtime, i.e. multiple
32 * REQUEST messages override each other.
33 */
34struct um_timetravel_msg {
35 /**
36 * @op: operation value from &enum um_timetravel_ops
37 */
38 __u32 op;
39
40 /**
41 * @seq: sequence number for the message - shall be reflected in
42 * the ACK response, and should be checked while processing
43 * the response to see if it matches
44 */
45 __u32 seq;
46
47 /**
48 * @time: time in nanoseconds
49 */
50 __u64 time;
51};
52
53/**
54 * enum um_timetravel_ops - Operation codes
55 */
56enum um_timetravel_ops {
57 /**
58 * @UM_TIMETRAVEL_ACK: response (ACK) to any previous message,
59 * this usually doesn't carry any data in the 'time' field
60 * unless otherwise specified below
61 */
62 UM_TIMETRAVEL_ACK = 0,
63
64 /**
65 * @UM_TIMETRAVEL_START: initialize the connection, the time
66 * field contains an (arbitrary) ID to possibly be able
67 * to distinguish the connections.
68 */
69 UM_TIMETRAVEL_START = 1,
70
71 /**
72 * @UM_TIMETRAVEL_REQUEST: request to run at the given time
73 * (host -> calendar)
74 */
75 UM_TIMETRAVEL_REQUEST = 2,
76
77 /**
78 * @UM_TIMETRAVEL_WAIT: Indicate waiting for the previously requested
79 * runtime, new requests may be made while waiting (e.g. due to
80 * interrupts); the time field is ignored. The calendar must process
81 * this message and later send a %UM_TIMETRAVEL_RUN message when
82 * the host can run again.
83 * (host -> calendar)
84 */
85 UM_TIMETRAVEL_WAIT = 3,
86
87 /**
88 * @UM_TIMETRAVEL_GET: return the current time from the calendar in the
89 * ACK message, the time in the request message is ignored
90 * (host -> calendar)
91 */
92 UM_TIMETRAVEL_GET = 4,
93
94 /**
95 * @UM_TIMETRAVEL_UPDATE: time update to the calendar, must be sent e.g.
96 * before kicking an interrupt to another calendar
97 * (host -> calendar)
98 */
99 UM_TIMETRAVEL_UPDATE = 5,
100
101 /**
102 * @UM_TIMETRAVEL_RUN: run time request granted, current time is in
103 * the time field
104 * (calendar -> host)
105 */
106 UM_TIMETRAVEL_RUN = 6,
107
108 /**
109 * @UM_TIMETRAVEL_FREE_UNTIL: Enable free-running until the given time,
110 * this is a message from the calendar telling the host that it can
111 * freely do its own scheduling for anything before the indicated
112 * time.
113 * Note that if a calendar sends this message once, the host may
114 * assume that it will also do so in the future, if it implements
115 * wraparound semantics for the time field.
116 * (calendar -> host)
117 */
118 UM_TIMETRAVEL_FREE_UNTIL = 7,
119
120 /**
121 * @UM_TIMETRAVEL_GET_TOD: Return time of day, typically used once at
122 * boot by the virtual machines to get a synchronized time from
123 * the simulation.
124 */
125 UM_TIMETRAVEL_GET_TOD = 8,
126};
127
128#endif /* _UAPI_LINUX_UM_TIMETRAVEL_H */
129

source code of linux/include/uapi/linux/um_timetravel.h