1/* $NetBSD: blkif.h,v 1.7 2008/05/04 19:56:29 cegger Exp $ */ 2/****************************************************************************** 3 * blkif.h 4 * 5 * Unified block-device I/O interface for Xen guest OSes. 6 * 7 * Permission is hereby granted, free of charge, to any person obtaining a copy 8 * of this software and associated documentation files (the "Software"), to 9 * deal in the Software without restriction, including without limitation the 10 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or 11 * sell copies of the Software, and to permit persons to whom the Software is 12 * furnished to do so, subject to the following conditions: 13 * 14 * The above copyright notice and this permission notice shall be included in 15 * all copies or substantial portions of the Software. 16 * 17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 20 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 21 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 22 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 23 * DEALINGS IN THE SOFTWARE. 24 * 25 * Copyright (c) 2003-2004, Keir Fraser 26 */ 27 28#ifndef __XEN_PUBLIC_IO_BLKIF_H__ 29#define __XEN_PUBLIC_IO_BLKIF_H__ 30 31#include "ring.h" 32#include "../grant_table.h" 33 34/* 35 * Front->back notifications: When enqueuing a new request, sending a 36 * notification can be made conditional on req_event (i.e., the generic 37 * hold-off mechanism provided by the ring macros). Backends must set 38 * req_event appropriately (e.g., using RING_FINAL_CHECK_FOR_REQUESTS()). 39 * 40 * Back->front notifications: When enqueuing a new response, sending a 41 * notification can be made conditional on rsp_event (i.e., the generic 42 * hold-off mechanism provided by the ring macros). Frontends must set 43 * rsp_event appropriately (e.g., using RING_FINAL_CHECK_FOR_RESPONSES()). 44 */ 45 46#ifndef blkif_vdev_t 47#define blkif_vdev_t uint16_t 48#endif 49#define blkif_sector_t uint64_t 50 51/* 52 * REQUEST CODES. 53 */ 54#define BLKIF_OP_READ 0 55#define BLKIF_OP_WRITE 1 56/* 57 * Recognised only if "feature-barrier" is present in backend xenbus info. 58 * The "feature-barrier" node contains a boolean indicating whether barrier 59 * requests are likely to succeed or fail. Either way, a barrier request 60 * may fail at any time with BLKIF_RSP_EOPNOTSUPP if it is unsupported by 61 * the underlying block-device hardware. The boolean simply indicates whether 62 * or not it is worthwhile for the frontend to attempt barrier requests. 63 * If a backend does not recognise BLKIF_OP_WRITE_BARRIER, it should *not* 64 * create the "feature-barrier" node! 65 */ 66#define BLKIF_OP_WRITE_BARRIER 2 67/* 68 * Recognised if "feature-flush-cache" is present in backend xenbus 69 * info. A flush will ask the underlying storage hardware to flush its 70 * non-volatile caches as appropriate. The "feature-flush-cache" node 71 * contains a boolean indicating whether flush requests are likely to 72 * succeed or fail. Either way, a flush request may fail at any time 73 * with BLKIF_RSP_EOPNOTSUPP if it is unsupported by the underlying 74 * block-device hardware. The boolean simply indicates whether or not it 75 * is worthwhile for the frontend to attempt flushes. If a backend does 76 * not recognise BLKIF_OP_WRITE_FLUSH_CACHE, it should *not* create the 77 * "feature-flush-cache" node! 78 */ 79#define BLKIF_OP_FLUSH_DISKCACHE 3 80 81/* 82 * Maximum scatter/gather segments per request. 83 * This is carefully chosen so that sizeof(blkif_ring_t) <= PAGE_SIZE. 84 * NB. This could be 12 if the ring indexes weren't stored in the same page. 85 */ 86#define BLKIF_MAX_SEGMENTS_PER_REQUEST 11 87 88struct blkif_request_segment { 89 grant_ref_t gref; /* reference to I/O buffer frame */ 90 /* @first_sect: first sector in frame to transfer (inclusive). */ 91 /* @last_sect: last sector in frame to transfer (inclusive). */ 92 uint8_t first_sect, last_sect; 93}; 94 95/* native-type requests/responses (always used in frontends ) */ 96 97struct blkif_request { 98 uint8_t operation; /* BLKIF_OP_??? */ 99 uint8_t nr_segments; /* number of segments */ 100 blkif_vdev_t handle; /* only for read/write requests */ 101 uint64_t id; /* private guest value, echoed in resp */ 102 blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */ 103 struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 104}; 105typedef struct blkif_request blkif_request_t; 106 107struct blkif_response { 108 uint64_t id; /* copied from request */ 109 uint8_t operation; /* copied from request */ 110 int16_t status; /* BLKIF_RSP_??? */ 111}; 112typedef struct blkif_response blkif_response_t; 113 114/* i386 requests/responses */ 115struct blkif_x86_32_request { 116 uint8_t operation; /* BLKIF_OP_??? */ 117 uint8_t nr_segments; /* number of segments */ 118 blkif_vdev_t handle; /* only for read/write requests */ 119 uint64_t id; /* private guest value, echoed in resp */ 120 blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */ 121 struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 122} __packed; 123typedef struct blkif_x86_32_request blkif_x86_32_request_t; 124 125struct blkif_x86_32_response { 126 uint64_t id; /* copied from request */ 127 uint8_t operation; /* copied from request */ 128 uint8_t _pad; 129 int16_t status; /* BLKIF_RSP_??? */ 130} __packed; 131typedef struct blkif_x86_32_response blkif_x86_32_response_t; 132 133/* amd64-type requests/responses (always used in frontends ) */ 134 135struct blkif_x86_64_request { 136 uint8_t operation; /* BLKIF_OP_??? */ 137 uint8_t nr_segments; /* number of segments */ 138 blkif_vdev_t handle; /* only for read/write requests */ 139 uint64_t __attribute__((__aligned__(8))) id;/* private guest value, echoed in resp */ 140 blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */ 141 struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 142}; 143typedef struct blkif_x86_64_request blkif_x86_64_request_t; 144 145struct blkif_x86_64_response { 146 uint64_t __attribute__((__aligned__(8))) id; /* copied from request */ 147 uint8_t operation; /* copied from request */ 148 int16_t status; /* BLKIF_RSP_??? */ 149}; 150typedef struct blkif_x86_64_response blkif_x86_64_response_t; 151 152/* 153 * STATUS RETURN CODES. 154 */ 155 /* Operation not supported (only happens on barrier writes). */ 156#define BLKIF_RSP_EOPNOTSUPP -2 157 /* Operation failed for some unspecified reason (-EIO). */ 158#define BLKIF_RSP_ERROR -1 159 /* Operation completed successfully. */ 160#define BLKIF_RSP_OKAY 0 161 162/* 163 * Generate blkif ring structures and types. 164 */ 165 166DEFINE_RING_TYPES(blkif, struct blkif_request, struct blkif_response); 167DEFINE_RING_TYPES(blkif_x86_32, struct blkif_x86_32_request, struct blkif_x86_32_response); 168DEFINE_RING_TYPES(blkif_x86_64, struct blkif_x86_64_request, struct blkif_x86_64_response); 169 170union blkif_back_ring_proto { 171 blkif_back_ring_t ring_n; /* native/common members */ 172 blkif_x86_32_back_ring_t ring_32; 173 blkif_x86_64_back_ring_t ring_64; 174}; 175typedef union blkif_back_ring_proto blkif_back_ring_proto_t; 176 177#define VDISK_CDROM 0x1 178#define VDISK_REMOVABLE 0x2 179#define VDISK_READONLY 0x4 180 181#endif /* __XEN_PUBLIC_IO_BLKIF_H__ */ 182 183/* 184 * Local variables: 185 * mode: C 186 * c-set-style: "BSD" 187 * c-basic-offset: 4 188 * tab-width: 4 189 * indent-tabs-mode: nil 190 * End: 191 */ 192