OvmfPkg/Include/IndustryStandard/Xen/event_channel.h

   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
  68 typedef UINT32 evtchn_port_t;
  69 DEFINE_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  */
  79 struct evtchn_alloc_unbound {
  80     /* IN parameters */
  81     domid_t dom, remote_dom;
  82     /* OUT parameters */
  83     evtchn_port_t port;
  84 };
  85 typedef 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  */
  92 struct evtchn_close {
  93     /* IN parameters. */
  94     evtchn_port_t port;
  95 };
  96 typedef 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  */
 102 struct evtchn_send {
 103     /* IN parameters. */
 104     evtchn_port_t port;
 105 };
 106 typedef 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  */