1/******************************************************************************
2 * event_channel.h
3 *
4 * Event channels between domains.
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a copy
7 * of this software and associated documentation files (the "Software"), to
8 * deal in the Software without restriction, including without limitation the
9 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
10 * sell copies of the Software, and to permit persons to whom the Software is
11 * furnished to do so, subject to the following conditions:
12 *
13 * The above copyright notice and this permission notice shall be included in
14 * all copies or substantial portions of the Software.
15 *
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
19 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
21 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
22 * DEALINGS IN THE SOFTWARE.
23 *
24 * Copyright (c) 2003-2004, K A Fraser.
25 */
26
27#ifndef __XEN_PUBLIC_EVENT_CHANNEL_H__
28#define __XEN_PUBLIC_EVENT_CHANNEL_H__
29
30#include "xen.h"
31
32/*
33 * `incontents 150 evtchn Event Channels
34 *
35 * Event channels are the basic primitive provided by Xen for event
36 * notifications. An event is the Xen equivalent of a hardware
37 * interrupt. They essentially store one bit of information, the event
38 * of interest is signalled by transitioning this bit from 0 to 1.
39 *
40 * Notifications are received by a guest via an upcall from Xen,
41 * indicating when an event arrives (setting the bit). Further
42 * notifications are masked until the bit is cleared again (therefore,
43 * guests must check the value of the bit after re-enabling event
44 * delivery to ensure no missed notifications).
45 *
46 * Event notifications can be masked by setting a flag; this is
47 * equivalent to disabling interrupts and can be used to ensure
48 * atomicity of certain operations in the guest kernel.
49 *
50 * Event channels are represented by the evtchn_* fields in
51 * struct shared_info and struct vcpu_info.
52 */
53
54/*
55 * ` enum neg_errnoval
56 * ` HYPERVISOR_event_channel_op(enum event_channel_op cmd, VOID *args)
57 * `
58 * @cmd  == EVTCHNOP_* (event-channel operation).
59 * @args == struct evtchn_* Operation-specific extra arguments (NULL if none).
60 */
61
62/* ` enum event_channel_op { // EVTCHNOP_* => struct evtchn_* */
63#define EVTCHNOP_close            3
64#define EVTCHNOP_send             4
65#define EVTCHNOP_alloc_unbound    6
66/* ` } */
67
68typedef UINT32 evtchn_port_t;
69DEFINE_XEN_GUEST_HANDLE(evtchn_port_t);
70
71/*
72 * EVTCHNOP_alloc_unbound: Allocate a port in domain <dom> and mark as
73 * accepting interdomain bindings from domain <remote_dom>. A fresh port
74 * is allocated in <dom> and returned as <port>.
75 * NOTES:
76 *  1. If the caller is unprivileged then <dom> must be DOMID_SELF.
77 *  2. <rdom> may be DOMID_SELF, allowing loopback connections.
78 */
79struct evtchn_alloc_unbound {
80    /* IN parameters */
81    domid_t dom, remote_dom;
82    /* OUT parameters */
83    evtchn_port_t port;
84};
85typedef struct evtchn_alloc_unbound evtchn_alloc_unbound_t;
86
87/*
88 * EVTCHNOP_close: Close a local event channel <port>. If the channel is
89 * interdomain then the remote end is placed in the unbound state
90 * (EVTCHNSTAT_unbound), awaiting a new connection.
91 */
92struct evtchn_close {
93    /* IN parameters. */
94    evtchn_port_t port;
95};
96typedef struct evtchn_close evtchn_close_t;
97
98/*
99 * EVTCHNOP_send: Send an event to the remote end of the channel whose local
100 * endpoint is <port>.
101 */
102struct evtchn_send {
103    /* IN parameters. */
104    evtchn_port_t port;
105};
106typedef struct evtchn_send evtchn_send_t;
107
108#endif /* __XEN_PUBLIC_EVENT_CHANNEL_H__ */
109
110/*
111 * Local variables:
112 * mode: C
113 * c-file-style: "BSD"
114 * c-basic-offset: 4
115 * tab-width: 4
116 * indent-tabs-mode: nil
117 * End:
118 */
119