OvmfPkg/XenBusDxe: Add Event Channel Notify.

This first function is used to notify the other side that there is
something to do. The other side is another Xen domain.

Change in V4:
- Replace the license by the commonly used file header text.

Change in V3:
- Return error code from hypercall instead of ASSERT for
  XenEventChannelNotify
- moving event_channel.h to this patch.

Change in V2:
- file header
- coding style
- adding comment to functions
- Licenses

License: This patch adds event_channel.h which is under MIT licence.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Acked-by: Jordan Justen <jordan.l.justen@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@16265 6f19259b-4bc3-4df7-8a09-765794883524

1 files changed, 118 insertions, 0 deletions

diff --git a/OvmfPkg/Include/IndustryStandard/Xen/event_channel.h b/OvmfPkg/Include/IndustryStandard/Xen/event_channel.h
new file mode 100644
index 0000000000..6377ce7b1a
--- /dev/null
+++ b/OvmfPkg/Include/IndustryStandard/Xen/event_channel.h
@@ -0,0 +1,118 @@
+/******************************************************************************

+ * event_channel.h

+ *

+ * Event channels between domains.

+ *

+ * Permission is hereby granted, free of charge, to any person obtaining a copy

+ * of this software and associated documentation files (the "Software"), to

+ * deal in the Software without restriction, including without limitation the

+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or

+ * sell copies of the Software, and to permit persons to whom the Software is

+ * furnished to do so, subject to the following conditions:

+ *

+ * The above copyright notice and this permission notice shall be included in

+ * all copies or substantial portions of the Software.

+ *

+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING

+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER

+ * DEALINGS IN THE SOFTWARE.

+ *

+ * Copyright (c) 2003-2004, K A Fraser.

+ */

+

+#ifndef __XEN_PUBLIC_EVENT_CHANNEL_H__

+#define __XEN_PUBLIC_EVENT_CHANNEL_H__

+

+#include "xen.h"

+

+/*

+ * `incontents 150 evtchn Event Channels

+ *

+ * Event channels are the basic primitive provided by Xen for event

+ * notifications. An event is the Xen equivalent of a hardware

+ * interrupt. They essentially store one bit of information, the event

+ * of interest is signalled by transitioning this bit from 0 to 1.

+ *

+ * Notifications are received by a guest via an upcall from Xen,

+ * indicating when an event arrives (setting the bit). Further

+ * notifications are masked until the bit is cleared again (therefore,

+ * guests must check the value of the bit after re-enabling event

+ * delivery to ensure no missed notifications).

+ *

+ * Event notifications can be masked by setting a flag; this is

+ * equivalent to disabling interrupts and can be used to ensure

+ * atomicity of certain operations in the guest kernel.

+ *

+ * Event channels are represented by the evtchn_* fields in

+ * struct shared_info and struct vcpu_info.

+ */

+

+/*

+ * ` enum neg_errnoval

+ * ` HYPERVISOR_event_channel_op(enum event_channel_op cmd, VOID *args)

+ * `

+ * @cmd  == EVTCHNOP_* (event-channel operation).

+ * @args == struct evtchn_* Operation-specific extra arguments (NULL if none).

+ */

+

+/* ` enum event_channel_op { // EVTCHNOP_* => struct evtchn_* */

+#define EVTCHNOP_close            3

+#define EVTCHNOP_send             4

+#define EVTCHNOP_alloc_unbound    6

+/* ` } */

+

+typedef UINT32 evtchn_port_t;

+DEFINE_XEN_GUEST_HANDLE(evtchn_port_t);

+

+/*

+ * EVTCHNOP_alloc_unbound: Allocate a port in domain <dom> and mark as

+ * accepting interdomain bindings from domain <remote_dom>. A fresh port

+ * is allocated in <dom> and returned as <port>.

+ * NOTES:

+ *  1. If the caller is unprivileged then <dom> must be DOMID_SELF.

+ *  2. <rdom> may be DOMID_SELF, allowing loopback connections.

+ */

+struct evtchn_alloc_unbound {

+    /* IN parameters */

+    domid_t dom, remote_dom;

+    /* OUT parameters */

+    evtchn_port_t port;

+};

+typedef struct evtchn_alloc_unbound evtchn_alloc_unbound_t;

+

+/*

+ * EVTCHNOP_close: Close a local event channel <port>. If the channel is

+ * interdomain then the remote end is placed in the unbound state

+ * (EVTCHNSTAT_unbound), awaiting a new connection.

+ */

+struct evtchn_close {

+    /* IN parameters. */

+    evtchn_port_t port;

+};

+typedef struct evtchn_close evtchn_close_t;

+

+/*

+ * EVTCHNOP_send: Send an event to the remote end of the channel whose local

+ * endpoint is <port>.

+ */

+struct evtchn_send {

+    /* IN parameters. */

+    evtchn_port_t port;

+};

+typedef struct evtchn_send evtchn_send_t;

+

+#endif /* __XEN_PUBLIC_EVENT_CHANNEL_H__ */

+

+/*

+ * Local variables:

+ * mode: C

+ * c-file-style: "BSD"

+ * c-basic-offset: 4

+ * tab-width: 4

+ * indent-tabs-mode: nil

+ * End:

+ */