OvmfPkg/IndustryStandard/Xen: replace MIT license text with SPDX ID

[mirror_edk2.git] / OvmfPkg / Include / IndustryStandard / Xen / event_channel.h

/******************************************************************************\r
 * event_channel.h\r
 *\r
 * Event channels between domains.\r
 *\r
 * SPDX-License-Identifier: MIT\r
 *\r
 * Copyright (c) 2003-2004, K A Fraser.\r
 */\r
\r
#ifndef __XEN_PUBLIC_EVENT_CHANNEL_H__\r
#define __XEN_PUBLIC_EVENT_CHANNEL_H__\r
\r
#include "xen.h"\r
\r
/*\r
 * `incontents 150 evtchn Event Channels\r
 *\r
 * Event channels are the basic primitive provided by Xen for event\r
 * notifications. An event is the Xen equivalent of a hardware\r
 * interrupt. They essentially store one bit of information, the event\r
 * of interest is signalled by transitioning this bit from 0 to 1.\r
 *\r
 * Notifications are received by a guest via an upcall from Xen,\r
 * indicating when an event arrives (setting the bit). Further\r
 * notifications are masked until the bit is cleared again (therefore,\r
 * guests must check the value of the bit after re-enabling event\r
 * delivery to ensure no missed notifications).\r
 *\r
 * Event notifications can be masked by setting a flag; this is\r
 * equivalent to disabling interrupts and can be used to ensure\r
 * atomicity of certain operations in the guest kernel.\r
 *\r
 * Event channels are represented by the evtchn_* fields in\r
 * struct shared_info and struct vcpu_info.\r
 */\r
\r
/*\r
 * ` enum neg_errnoval\r
 * ` HYPERVISOR_event_channel_op(enum event_channel_op cmd, VOID *args)\r
 * `\r
 * @cmd  == EVTCHNOP_* (event-channel operation).\r
 * @args == struct evtchn_* Operation-specific extra arguments (NULL if none).\r
 */\r
\r
/* ` enum event_channel_op { // EVTCHNOP_* => struct evtchn_* */\r
#define EVTCHNOP_close            3\r
#define EVTCHNOP_send             4\r
#define EVTCHNOP_alloc_unbound    6\r
/* ` } */\r
\r
typedef UINT32 evtchn_port_t;\r
DEFINE_XEN_GUEST_HANDLE(evtchn_port_t);\r
\r
/*\r
 * EVTCHNOP_alloc_unbound: Allocate a port in domain <dom> and mark as\r
 * accepting interdomain bindings from domain <remote_dom>. A fresh port\r
 * is allocated in <dom> and returned as <port>.\r
 * NOTES:\r
 *  1. If the caller is unprivileged then <dom> must be DOMID_SELF.\r
 *  2. <rdom> may be DOMID_SELF, allowing loopback connections.\r
 */\r
struct evtchn_alloc_unbound {\r
    /* IN parameters */\r
    domid_t dom, remote_dom;\r
    /* OUT parameters */\r
    evtchn_port_t port;\r
};\r
typedef struct evtchn_alloc_unbound evtchn_alloc_unbound_t;\r
\r
/*\r
 * EVTCHNOP_close: Close a local event channel <port>. If the channel is\r
 * interdomain then the remote end is placed in the unbound state\r
 * (EVTCHNSTAT_unbound), awaiting a new connection.\r
 */\r
struct evtchn_close {\r
    /* IN parameters. */\r
    evtchn_port_t port;\r
};\r
typedef struct evtchn_close evtchn_close_t;\r
\r
/*\r
 * EVTCHNOP_send: Send an event to the remote end of the channel whose local\r
 * endpoint is <port>.\r
 */\r
struct evtchn_send {\r
    /* IN parameters. */\r
    evtchn_port_t port;\r
};\r
typedef struct evtchn_send evtchn_send_t;\r
\r
#endif /* __XEN_PUBLIC_EVENT_CHANNEL_H__ */\r
\r
/*\r
 * Local variables:\r
 * mode: C\r
 * c-file-style: "BSD"\r
 * c-basic-offset: 4\r
 * tab-width: 4\r
 * indent-tabs-mode: nil\r
 * End:\r
 */\r