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 * Permission is hereby granted, free of charge, to any person obtaining a copy 14 * of this software and associated documentation files (the "Software"), to 15 * deal in the Software without restriction, including without limitation the 16 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or 17 * sell copies of the Software, and to permit persons to whom the Software is 18 * furnished to do so, subject to the following conditions: 19 * 20 * The above copyright notice and this permission notice shall be included in 21 * all copies or substantial portions of the Software. 22 * 23 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 24 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 25 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 26 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 27 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 28 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 29 * DEALINGS IN THE SOFTWARE. 30 * 31 * @section DESCRIPTION 32 * 33 * Originally borrowed from the Qubes OS Project, http://www.qubes-os.org, 34 * this code has been substantially rewritten to use the gntdev and gntalloc 35 * devices instead of raw MFNs and map_foreign_range. 36 * 37 * This is a library for inter-domain communication. A standard Xen ring 38 * buffer is used, with a datagram-based interface built on top. The grant 39 * reference and event channels are shared in XenStore under a user-specified 40 * path. 41 * 42 * The ring.h macros define an asymmetric interface to a shared data structure 43 * that assumes all rings reside in a single contiguous memory space. This is 44 * not suitable for vchan because the interface to the ring is symmetric except 45 * for the setup. Unlike the producer-consumer rings defined in ring.h, the 46 * size of the rings used in vchan are determined at execution time instead of 47 * compile time, so the macros in ring.h cannot be used to access the rings. 48 */ 49 50 #include <stdint.h> 51 #include <sys/types.h> 52 53 struct ring_shared { 54 uint32_t cons, prod; 55 }; 56 57 #define VCHAN_NOTIFY_WRITE 0x1 58 #define VCHAN_NOTIFY_READ 0x2 59 60 /** 61 * vchan_interface: primary shared data structure 62 */ 63 struct vchan_interface { 64 /** 65 * Standard consumer/producer interface, one pair per buffer 66 * left is client write, server read 67 * right is client read, server write 68 */ 69 struct ring_shared left, right; 70 /** 71 * size of the rings, which determines their location 72 * 10 - at offset 1024 in ring's page 73 * 11 - at offset 2048 in ring's page 74 * 12+ - uses 2^(N-12) grants to describe the multi-page ring 75 * These should remain constant once the page is shared. 76 * Only one of the two orders can be 10 (or 11). 77 */ 78 uint16_t left_order, right_order; 79 /** 80 * Shutdown detection: 81 * 0: client (or server) has exited 82 * 1: client (or server) is connected 83 * 2: client has not yet connected 84 */ 85 uint8_t cli_live, srv_live; 86 /** 87 * Notification bits: 88 * VCHAN_NOTIFY_WRITE: send notify when data is written 89 * VCHAN_NOTIFY_READ: send notify when data is read (consumed) 90 * cli_notify is used for the client to inform the server of its action 91 */ 92 uint8_t cli_notify, srv_notify; 93 /** 94 * Grant list: ordering is left, right. Must not extend into actual ring 95 * or grow beyond the end of the initial shared page. 96 * These should remain constant once the page is shared, to allow 97 * for possible remapping by a client that restarts. 98 */ 99 uint32_t grants[0]; 100 }; 101 102