1/** 2 * @file 3 * @section AUTHORS 4 * 5 * Copyright (C) 2010 Rafal Wojtczuk <rafal@invisiblethingslab.com> 6 * 7 * Authors: 8 * Rafal Wojtczuk <rafal@invisiblethingslab.com> 9 * Daniel De Graaf <dgdegra@tycho.nsa.gov> 10 * 11 * @section LICENSE 12 * 13 * This library is free software; you can redistribute it and/or 14 * modify it under the terms of the GNU Lesser General Public 15 * License as published by the Free Software Foundation; either 16 * version 2.1 of the License, or (at your option) any later version. 17 * 18 * This library is distributed in the hope that it will be useful, 19 * but WITHOUT ANY WARRANTY; without even the implied warranty of 20 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 21 * Lesser General Public License for more details. 22 * 23 * You should have received a copy of the GNU Lesser General Public 24 * License along with this library; if not, write to the Free Software 25 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 26 * 27 * @section DESCRIPTION 28 * 29 * Originally borrowed from the Qubes OS Project, http://www.qubes-os.org, 30 * this code has been substantially rewritten to use the gntdev and gntalloc 31 * devices instead of raw MFNs and map_foreign_range. 32 * 33 * This is a library for inter-domain communication. A standard Xen ring 34 * buffer is used, with a datagram-based interface built on top. The grant 35 * reference and event channels are shared in XenStore under a user-specified 36 * path. 37 * 38 * The ring.h macros define an asymmetric interface to a shared data structure 39 * that assumes all rings reside in a single contiguous memory space. This is 40 * not suitable for vchan because the interface to the ring is symmetric except 41 * for the setup. Unlike the producer-consumer rings defined in ring.h, the 42 * size of the rings used in vchan are determined at execution time instead of 43 * compile time, so the macros in ring.h cannot be used to access the rings. 44 */ 45 46#include <stdint.h> 47#include <sys/types.h> 48 49struct ring_shared { 50 uint32_t cons, prod; 51}; 52 53#define VCHAN_NOTIFY_WRITE 0x1 54#define VCHAN_NOTIFY_READ 0x2 55 56/** 57 * vchan_interface: primary shared data structure 58 */ 59struct vchan_interface { 60 /** 61 * Standard consumer/producer interface, one pair per buffer 62 * left is client write, server read 63 * right is client read, server write 64 */ 65 struct ring_shared left, right; 66 /** 67 * size of the rings, which determines their location 68 * 10 - at offset 1024 in ring's page 69 * 11 - at offset 2048 in ring's page 70 * 12+ - uses 2^(N-12) grants to describe the multi-page ring 71 * These should remain constant once the page is shared. 72 * Only one of the two orders can be 10 (or 11). 73 */ 74 uint16_t left_order, right_order; 75 /** 76 * Shutdown detection: 77 * 0: client (or server) has exited 78 * 1: client (or server) is connected 79 * 2: client has not yet connected 80 */ 81 uint8_t cli_live, srv_live; 82 /** 83 * Notification bits: 84 * VCHAN_NOTIFY_WRITE: send notify when data is written 85 * VCHAN_NOTIFY_READ: send notify when data is read (consumed) 86 * cli_notify is used for the client to inform the server of its action 87 */ 88 uint8_t cli_notify, srv_notify; 89 /** 90 * Grant list: ordering is left, right. Must not extend into actual ring 91 * or grow beyond the end of the initial shared page. 92 * These should remain constant once the page is shared, to allow 93 * for possible remapping by a client that restarts. 94 */ 95 uint32_t grants[0]; 96}; 97 98