1 /****************************************************************************** 2 * blkif.h 3 * 4 * Unified block-device I/O interface for Xen guest OSes. 5 * 6 * Copyright (c) 2003-2004, Keir Fraser 7 */ 8 9 #ifndef __XEN_PUBLIC_IO_BLKIF_H__ 10 #define __XEN_PUBLIC_IO_BLKIF_H__ 11 12 #include "ring.h" 13 #include "../grant_table.h" 14 15 /* 16 * Front->back notifications: When enqueuing a new request, sending a 17 * notification can be made conditional on req_event (i.e., the generic 18 * hold-off mechanism provided by the ring macros). Backends must set 19 * req_event appropriately (e.g., using RING_FINAL_CHECK_FOR_REQUESTS()). 20 * 21 * Back->front notifications: When enqueuing a new response, sending a 22 * notification can be made conditional on rsp_event (i.e., the generic 23 * hold-off mechanism provided by the ring macros). Frontends must set 24 * rsp_event appropriately (e.g., using RING_FINAL_CHECK_FOR_RESPONSES()). 25 */ 26 27 typedef uint16_t blkif_vdev_t; 28 typedef uint64_t blkif_sector_t; 29 30 /* 31 * REQUEST CODES. 32 */ 33 #define BLKIF_OP_READ 0 34 #define BLKIF_OP_WRITE 1 35 /* 36 * Recognised only if "feature-barrier" is present in backend xenbus info. 37 * The "feature_barrier" node contains a boolean indicating whether barrier 38 * requests are likely to succeed or fail. Either way, a barrier request 39 * may fail at any time with BLKIF_RSP_EOPNOTSUPP if it is unsupported by 40 * the underlying block-device hardware. The boolean simply indicates whether 41 * or not it is worthwhile for the frontend to attempt barrier requests. 42 * If a backend does not recognise BLKIF_OP_WRITE_BARRIER, it should *not* 43 * create the "feature-barrier" node! 44 */ 45 #define BLKIF_OP_WRITE_BARRIER 2 46 47 /* 48 * Maximum scatter/gather segments per request. 49 * This is carefully chosen so that sizeof(struct blkif_ring) <= PAGE_SIZE. 50 * NB. This could be 12 if the ring indexes weren't stored in the same page. 51 */ 52 #define BLKIF_MAX_SEGMENTS_PER_REQUEST 11 53 54 struct blkif_request_rw { 55 blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */ 56 struct blkif_request_segment { 57 grant_ref_t gref; /* reference to I/O buffer frame */ 58 /* @first_sect: first sector in frame to transfer (inclusive). */ 59 /* @last_sect: last sector in frame to transfer (inclusive). */ 60 uint8_t first_sect, last_sect; 61 } seg[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 62 }; 63 64 struct blkif_request { 65 uint8_t operation; /* BLKIF_OP_??? */ 66 uint8_t nr_segments; /* number of segments */ 67 blkif_vdev_t handle; /* only for read/write requests */ 68 uint64_t id; /* private guest value, echoed in resp */ 69 union { 70 struct blkif_request_rw rw; 71 } u; 72 }; 73 74 struct blkif_response { 75 uint64_t id; /* copied from request */ 76 uint8_t operation; /* copied from request */ 77 int16_t status; /* BLKIF_RSP_??? */ 78 }; 79 80 /* 81 * STATUS RETURN CODES. 82 */ 83 /* Operation not supported (only happens on barrier writes). */ 84 #define BLKIF_RSP_EOPNOTSUPP -2 85 /* Operation failed for some unspecified reason (-EIO). */ 86 #define BLKIF_RSP_ERROR -1 87 /* Operation completed successfully. */ 88 #define BLKIF_RSP_OKAY 0 89 90 /* 91 * Generate blkif ring structures and types. 92 */ 93 94 DEFINE_RING_TYPES(blkif, struct blkif_request, struct blkif_response); 95 96 #define VDISK_CDROM 0x1 97 #define VDISK_REMOVABLE 0x2 98 #define VDISK_READONLY 0x4 99 100 /* Xen-defined major numbers for virtual disks, they look strangely 101 * familiar */ 102 #define XEN_IDE0_MAJOR 3 103 #define XEN_IDE1_MAJOR 22 104 #define XEN_SCSI_DISK0_MAJOR 8 105 #define XEN_SCSI_DISK1_MAJOR 65 106 #define XEN_SCSI_DISK2_MAJOR 66 107 #define XEN_SCSI_DISK3_MAJOR 67 108 #define XEN_SCSI_DISK4_MAJOR 68 109 #define XEN_SCSI_DISK5_MAJOR 69 110 #define XEN_SCSI_DISK6_MAJOR 70 111 #define XEN_SCSI_DISK7_MAJOR 71 112 #define XEN_SCSI_DISK8_MAJOR 128 113 #define XEN_SCSI_DISK9_MAJOR 129 114 #define XEN_SCSI_DISK10_MAJOR 130 115 #define XEN_SCSI_DISK11_MAJOR 131 116 #define XEN_SCSI_DISK12_MAJOR 132 117 #define XEN_SCSI_DISK13_MAJOR 133 118 #define XEN_SCSI_DISK14_MAJOR 134 119 #define XEN_SCSI_DISK15_MAJOR 135 120 121 #endif /* __XEN_PUBLIC_IO_BLKIF_H__ */ 122