1 /****************************************************************************** 2 * blkif.h 3 * 4 * Unified block-device I/O interface for Xen guest OSes. 5 * 6 * Permission is hereby granted, free of charge, to any person obtaining a copy 7 * of this software and associated documentation files (the "Software"), to 8 * deal in the Software without restriction, including without limitation the 9 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or 10 * sell copies of the Software, and to permit persons to whom the Software is 11 * furnished to do so, subject to the following conditions: 12 * 13 * The above copyright notice and this permission notice shall be included in 14 * all copies or substantial portions of the Software. 15 * 16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 19 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 21 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 22 * DEALINGS IN THE SOFTWARE. 23 * 24 * Copyright (c) 2003-2004, Keir Fraser 25 */ 26 27 #ifndef __XEN_PUBLIC_IO_BLKIF_H__ 28 #define __XEN_PUBLIC_IO_BLKIF_H__ 29 30 #include "ring.h" 31 #include "../grant_table.h" 32 33 /* 34 * Front->back notifications: When enqueuing a new request, sending a 35 * notification can be made conditional on req_event (i.e., the generic 36 * hold-off mechanism provided by the ring macros). Backends must set 37 * req_event appropriately (e.g., using RING_FINAL_CHECK_FOR_REQUESTS()). 38 * 39 * Back->front notifications: When enqueuing a new response, sending a 40 * notification can be made conditional on rsp_event (i.e., the generic 41 * hold-off mechanism provided by the ring macros). Frontends must set 42 * rsp_event appropriately (e.g., using RING_FINAL_CHECK_FOR_RESPONSES()). 43 */ 44 45 #ifndef blkif_vdev_t 46 #define blkif_vdev_t uint16_t 47 #endif 48 #define blkif_sector_t uint64_t 49 50 /* 51 * REQUEST CODES. 52 */ 53 #define BLKIF_OP_READ 0 54 #define BLKIF_OP_WRITE 1 55 /* 56 * Recognised only if "feature-barrier" is present in backend xenbus info. 57 * The "feature_barrier" node contains a boolean indicating whether barrier 58 * requests or disk cache flush requests are likely to succeed or fail. 59 * Either way, a barrier request or a disk cache flush 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/flush 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 #define BLKIF_OP_FLUSH_DISKCACHE 3 68 69 /* 70 * Maximum scatter/gather segments per request. 71 * This is carefully chosen so that sizeof(blkif_ring_t) <= PAGE_SIZE. 72 * NB. This could be 12 if the ring indexes weren't stored in the same page. 73 */ 74 #define BLKIF_MAX_SEGMENTS_PER_REQUEST 11 75 76 struct blkif_request_segment { 77 grant_ref_t gref; /* reference to I/O buffer frame */ 78 /* @first_sect: first sector in frame to transfer (inclusive). */ 79 /* @last_sect: last sector in frame to transfer (inclusive). */ 80 uint8_t first_sect, last_sect; 81 }; 82 83 struct blkif_request { 84 uint8_t operation; /* BLKIF_OP_??? */ 85 uint8_t nr_segments; /* number of segments */ 86 blkif_vdev_t handle; /* only for read/write requests */ 87 uint64_t id; /* private guest value, echoed in resp */ 88 blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */ 89 struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 90 }; 91 typedef struct blkif_request blkif_request_t; 92 93 struct blkif_response { 94 uint64_t id; /* copied from request */ 95 uint8_t operation; /* copied from request */ 96 int16_t status; /* BLKIF_RSP_??? */ 97 }; 98 typedef struct blkif_response blkif_response_t; 99 100 /* 101 * STATUS RETURN CODES. 102 */ 103 /* Operation not supported (only happens on barrier writes). */ 104 #define BLKIF_RSP_EOPNOTSUPP -2 105 /* Operation failed for some unspecified reason (-EIO). */ 106 #define BLKIF_RSP_ERROR -1 107 /* Operation completed successfully. */ 108 #define BLKIF_RSP_OKAY 0 109 110 /* 111 * Generate blkif ring structures and types. 112 */ 113 114 DEFINE_RING_TYPES(blkif, struct blkif_request, struct blkif_response); 115 116 #define VDISK_CDROM 0x1 117 #define VDISK_REMOVABLE 0x2 118 #define VDISK_READONLY 0x4 119 120 #endif /* __XEN_PUBLIC_IO_BLKIF_H__ */ 121 122 /* 123 * Local variables: 124 * mode: C 125 * c-set-style: "BSD" 126 * c-basic-offset: 4 127 * tab-width: 4 128 * indent-tabs-mode: nil 129 * End: 130 */ 131