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, see <http://www.gnu.org/licenses/>. 25 * 26 * @section DESCRIPTION 27 * 28 * Originally borrowed from the Qubes OS Project, http://www.qubes-os.org, 29 * this code has been substantially rewritten to use the gntdev and gntalloc 30 * devices instead of raw MFNs and map_foreign_range. 31 * 32 * This is a library for inter-domain communication. A standard Xen ring 33 * buffer is used, with a datagram-based interface built on top. The grant 34 * reference and event channels are shared in XenStore under a user-specified 35 * path. 36 * 37 * The ring.h macros define an asymmetric interface to a shared data structure 38 * that assumes all rings reside in a single contiguous memory space. This is 39 * not suitable for vchan because the interface to the ring is symmetric except 40 * for the setup. Unlike the producer-consumer rings defined in ring.h, the 41 * size of the rings used in vchan are determined at execution time instead of 42 * compile time, so the macros in ring.h cannot be used to access the rings. 43 */ 44 45 #include <stdint.h> 46 #include <sys/types.h> 47 48 struct ring_shared { 49 uint32_t cons, prod; 50 }; 51 52 #define VCHAN_NOTIFY_WRITE 0x1 53 #define VCHAN_NOTIFY_READ 0x2 54 55 /** 56 * vchan_interface: primary shared data structure 57 */ 58 struct vchan_interface { 59 /** 60 * Standard consumer/producer interface, one pair per buffer 61 * left is client write, server read 62 * right is client read, server write 63 */ 64 struct ring_shared left, right; 65 /** 66 * size of the rings, which determines their location 67 * 10 - at offset 1024 in ring's page 68 * 11 - at offset 2048 in ring's page 69 * 12+ - uses 2^(N-12) grants to describe the multi-page ring 70 * These should remain constant once the page is shared. 71 * Only one of the two orders can be 10 (or 11). 72 */ 73 uint16_t left_order, right_order; 74 /** 75 * Shutdown detection: 76 * 0: client (or server) has exited 77 * 1: client (or server) is connected 78 * 2: client has not yet connected 79 */ 80 uint8_t cli_live, srv_live; 81 /** 82 * Notification bits: 83 * VCHAN_NOTIFY_WRITE: send notify when data is written 84 * VCHAN_NOTIFY_READ: send notify when data is read (consumed) 85 * cli_notify is used for the client to inform the server of its action 86 */ 87 uint8_t cli_notify, srv_notify; 88 /** 89 * Grant list: ordering is left, right. Must not extend into actual ring 90 * or grow beyond the end of the initial shared page. 91 * These should remain constant once the page is shared, to allow 92 * for possible remapping by a client that restarts. 93 */ 94 uint32_t grants[0]; 95 }; 96 97