blkif.h revision 231836
1181624Skmacy/****************************************************************************** 2181624Skmacy * blkif.h 3231743Sgibbs * 4181624Skmacy * Unified block-device I/O interface for Xen guest OSes. 5231743Sgibbs * 6181624Skmacy * Permission is hereby granted, free of charge, to any person obtaining a copy 7181624Skmacy * of this software and associated documentation files (the "Software"), to 8181624Skmacy * deal in the Software without restriction, including without limitation the 9181624Skmacy * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or 10181624Skmacy * sell copies of the Software, and to permit persons to whom the Software is 11181624Skmacy * furnished to do so, subject to the following conditions: 12181624Skmacy * 13181624Skmacy * The above copyright notice and this permission notice shall be included in 14181624Skmacy * all copies or substantial portions of the Software. 15181624Skmacy * 16181624Skmacy * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 17181624Skmacy * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 18181624Skmacy * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 19181624Skmacy * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 20181624Skmacy * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 21181624Skmacy * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 22181624Skmacy * DEALINGS IN THE SOFTWARE. 23181624Skmacy * 24181624Skmacy * Copyright (c) 2003-2004, Keir Fraser 25231743Sgibbs * Copyright (c) 2012, Spectra Logic Corporation 26181624Skmacy */ 27181624Skmacy 28181624Skmacy#ifndef __XEN_PUBLIC_IO_BLKIF_H__ 29181624Skmacy#define __XEN_PUBLIC_IO_BLKIF_H__ 30181624Skmacy 31181624Skmacy#include <xen/interface/io/ring.h> 32181624Skmacy#include <xen/interface/grant_table.h> 33181624Skmacy 34181624Skmacy/* 35181624Skmacy * Front->back notifications: When enqueuing a new request, sending a 36181624Skmacy * notification can be made conditional on req_event (i.e., the generic 37181624Skmacy * hold-off mechanism provided by the ring macros). Backends must set 38181624Skmacy * req_event appropriately (e.g., using RING_FINAL_CHECK_FOR_REQUESTS()). 39231743Sgibbs * 40181624Skmacy * Back->front notifications: When enqueuing a new response, sending a 41181624Skmacy * notification can be made conditional on rsp_event (i.e., the generic 42181624Skmacy * hold-off mechanism provided by the ring macros). Frontends must set 43181624Skmacy * rsp_event appropriately (e.g., using RING_FINAL_CHECK_FOR_RESPONSES()). 44181624Skmacy */ 45181624Skmacy 46181624Skmacy#ifndef blkif_vdev_t 47181624Skmacy#define blkif_vdev_t uint16_t 48181624Skmacy#endif 49181624Skmacy#define blkif_sector_t uint64_t 50181624Skmacy 51181624Skmacy/* 52231743Sgibbs * Feature and Parameter Negotiation 53231743Sgibbs * ================================= 54231743Sgibbs * The two halves of a Xen block driver utilize nodes within the XenStore to 55231743Sgibbs * communicate capabilities and to negotiate operating parameters. This 56231743Sgibbs * section enumerates these nodes which reside in the respective front and 57231743Sgibbs * backend portions of the XenStore, following the XenBus convention. 58231743Sgibbs * 59231743Sgibbs * All data in the XenStore is stored as strings. Nodes specifying numeric 60231743Sgibbs * values are encoded in decimal. Integer value ranges listed below are 61231743Sgibbs * expressed as fixed sized integer types capable of storing the conversion 62231743Sgibbs * of a properly formated node string, without loss of information. 63231743Sgibbs * 64231743Sgibbs * Any specified default value is in effect if the corresponding XenBus node 65231743Sgibbs * is not present in the XenStore. 66231743Sgibbs * 67231743Sgibbs * XenStore nodes in sections marked "PRIVATE" are solely for use by the 68231743Sgibbs * driver side whose XenBus tree contains them. 69231743Sgibbs * 70231743Sgibbs * See the XenBus state transition diagram below for details on when XenBus 71231743Sgibbs * nodes must be published and when they can be queried. 72231743Sgibbs * 73231743Sgibbs ***************************************************************************** 74231743Sgibbs * Backend XenBus Nodes 75231743Sgibbs ***************************************************************************** 76231743Sgibbs * 77231743Sgibbs *------------------ Backend Device Identification (PRIVATE) ------------------ 78231743Sgibbs * 79231743Sgibbs * mode 80231743Sgibbs * Values: "r" (read only), "w" (writable) 81231743Sgibbs * 82231743Sgibbs * The read or write access permissions to the backing store to be 83231743Sgibbs * granted to the frontend. 84231743Sgibbs * 85231743Sgibbs * params 86231743Sgibbs * Values: string 87231743Sgibbs * 88231743Sgibbs * A free formatted string providing sufficient information for the 89231743Sgibbs * backend driver to open the backing device. (e.g. the path to the 90231743Sgibbs * file or block device representing the backing store.) 91231743Sgibbs * 92231743Sgibbs * type 93231743Sgibbs * Values: "file", "phy", "tap" 94231743Sgibbs * 95231743Sgibbs * The type of the backing device/object. 96231743Sgibbs * 97231743Sgibbs *--------------------------------- Features --------------------------------- 98231743Sgibbs * 99231743Sgibbs * feature-barrier 100231743Sgibbs * Values: 0/1 (boolean) 101231743Sgibbs * Default Value: 0 102231743Sgibbs * 103231743Sgibbs * A value of "1" indicates that the backend can process requests 104231743Sgibbs * containing the BLKIF_OP_WRITE_BARRIER request opcode. Requests 105231743Sgibbs * of this type may still be returned at any time with the 106231743Sgibbs * BLKIF_RSP_EOPNOTSUPP result code. 107231743Sgibbs * 108231743Sgibbs * feature-flush-cache 109231743Sgibbs * Values: 0/1 (boolean) 110231743Sgibbs * Default Value: 0 111231743Sgibbs * 112231743Sgibbs * A value of "1" indicates that the backend can process requests 113231743Sgibbs * containing the BLKIF_OP_FLUSH_DISKCACHE request opcode. Requests 114231743Sgibbs * of this type may still be returned at any time with the 115231743Sgibbs * BLKIF_RSP_EOPNOTSUPP result code. 116231743Sgibbs * 117231743Sgibbs * feature-discard 118231743Sgibbs * Values: 0/1 (boolean) 119231743Sgibbs * Default Value: 0 120231743Sgibbs * 121231743Sgibbs * A value of "1" indicates that the backend can process requests 122231743Sgibbs * containing the BLKIF_OP_DISCARD request opcode. Requests 123231743Sgibbs * of this type may still be returned at any time with the 124231743Sgibbs * BLKIF_RSP_EOPNOTSUPP result code. 125231743Sgibbs * 126231743Sgibbs *----------------------- Request Transport Parameters ------------------------ 127231743Sgibbs * 128231743Sgibbs * max-ring-page-order 129231743Sgibbs * Values: <uint32_t> 130231743Sgibbs * Default Value: 0 131231743Sgibbs * Notes: 1, 3 132231743Sgibbs * 133231743Sgibbs * The maximum supported size of the request ring buffer in units of 134231743Sgibbs * lb(machine pages). (e.g. 0 == 1 page, 1 = 2 pages, 2 == 4 pages, 135231743Sgibbs * etc.). 136231743Sgibbs * 137231743Sgibbs * max-ring-pages 138231743Sgibbs * Values: <uint32_t> 139231743Sgibbs * Default Value: 1 140231743Sgibbs * Notes: 2, 3 141231743Sgibbs * 142231743Sgibbs * The maximum supported size of the request ring buffer in units of 143231743Sgibbs * machine pages. The value must be a power of 2. 144231743Sgibbs * 145231743Sgibbs * max-requests <uint32_t> 146231743Sgibbs * Default Value: BLKIF_MAX_RING_REQUESTS(PAGE_SIZE) 147231743Sgibbs * Maximum Value: BLKIF_MAX_RING_REQUESTS(PAGE_SIZE * max-ring-pages) 148231743Sgibbs * 149231743Sgibbs * The maximum number of concurrent, logical requests that will be 150231743Sgibbs * issued by the backend. 151231743Sgibbs * 152231743Sgibbs * Note: A logical request may span multiple ring entries. 153231743Sgibbs * 154231743Sgibbs * max-request-segments 155231743Sgibbs * Values: <uint8_t> 156231743Sgibbs * Default Value: BLKIF_MAX_SEGMENTS_PER_HEADER_BLOCK 157231743Sgibbs * Maximum Value: BLKIF_MAX_SEGMENTS_PER_REQUEST 158231743Sgibbs * 159231743Sgibbs * The maximum value of blkif_request.nr_segments supported by 160231743Sgibbs * the backend. 161231743Sgibbs * 162231743Sgibbs * max-request-size 163231743Sgibbs * Values: <uint32_t> 164231743Sgibbs * Default Value: BLKIF_MAX_SEGMENTS_PER_HEADER_BLOCK * PAGE_SIZE 165231743Sgibbs * Maximum Value: BLKIF_MAX_SEGMENTS_PER_REQUEST * PAGE_SIZE 166231743Sgibbs * 167231743Sgibbs * The maximum amount of data, in bytes, that can be referenced by a 168231743Sgibbs * request type that accesses frontend memory (currently BLKIF_OP_READ, 169231743Sgibbs * BLKIF_OP_WRITE, or BLKIF_OP_WRITE_BARRIER). 170231743Sgibbs * 171231743Sgibbs *------------------------- Backend Device Properties ------------------------- 172231743Sgibbs * 173231743Sgibbs * discard-aligment 174231743Sgibbs * Values: <uint32_t> 175231743Sgibbs * Default Value: 0 176231743Sgibbs * Notes: 4, 5 177231743Sgibbs * 178231743Sgibbs * The offset, in bytes from the beginning of the virtual block device, 179231743Sgibbs * to the first, addressable, discard extent on the underlying device. 180231743Sgibbs * 181231743Sgibbs * discard-granularity 182231743Sgibbs * Values: <uint32_t> 183231743Sgibbs * Default Value: <"sector-size"> 184231743Sgibbs * Notes: 4 185231743Sgibbs * 186231743Sgibbs * The size, in bytes, of the individually addressable discard extents 187231743Sgibbs * of the underlying device. 188231743Sgibbs * 189231743Sgibbs * discard-secure 190231743Sgibbs * Values: 0/1 (boolean) 191231743Sgibbs * Default Value: 0 192231743Sgibbs * 193231743Sgibbs * A value of "1" indicates that the backend can process BLKIF_OP_DISCARD 194231743Sgibbs * requests with the BLKIF_DISCARD_SECURE flag set. 195231743Sgibbs * 196231743Sgibbs * info 197231743Sgibbs * Values: <uint32_t> (bitmap) 198231743Sgibbs * 199231743Sgibbs * A collection of bit flags describing attributes of the backing 200231743Sgibbs * device. The VDISK_* macros define the meaning of each bit 201231743Sgibbs * location. 202231743Sgibbs * 203231743Sgibbs * sector-size 204231743Sgibbs * Values: <uint32_t> 205231743Sgibbs * 206231743Sgibbs * The native sector size, in bytes, of the backend device. 207231743Sgibbs * 208231743Sgibbs * sectors 209231743Sgibbs * Values: <uint64_t> 210231743Sgibbs * 211231743Sgibbs * The size of the backend device, expressed in units of its native 212231743Sgibbs * sector size ("sector-size"). 213231743Sgibbs * 214231743Sgibbs ***************************************************************************** 215231743Sgibbs * Frontend XenBus Nodes 216231743Sgibbs ***************************************************************************** 217231743Sgibbs * 218231743Sgibbs *----------------------- Request Transport Parameters ----------------------- 219231743Sgibbs * 220231743Sgibbs * event-channel 221231743Sgibbs * Values: <uint32_t> 222231743Sgibbs * 223231743Sgibbs * The identifier of the Xen event channel used to signal activity 224231743Sgibbs * in the ring buffer. 225231743Sgibbs * 226231743Sgibbs * ring-ref 227231743Sgibbs * Values: <uint32_t> 228231743Sgibbs * Notes: 6 229231743Sgibbs * 230231743Sgibbs * The Xen grant reference granting permission for the backend to map 231231743Sgibbs * the sole page in a single page sized ring buffer. 232231743Sgibbs * 233231743Sgibbs * ring-ref%u 234231743Sgibbs * Values: <uint32_t> 235231743Sgibbs * Notes: 6 236231743Sgibbs * 237231743Sgibbs * For a frontend providing a multi-page ring, a "num-ring-pages" sized 238231743Sgibbs * list of nodes, each containing a Xen grant reference granting 239231743Sgibbs * permission for the backend to map the page of the ring located 240231743Sgibbs * at page index "%u". Page indexes are zero based. 241231743Sgibbs * 242231743Sgibbs * protocol 243231743Sgibbs * Values: string (XEN_IO_PROTO_ABI_*) 244231743Sgibbs * Default Value: XEN_IO_PROTO_ABI_NATIVE 245231743Sgibbs * 246231743Sgibbs * The machine ABI rules governing the format of all ring request and 247231743Sgibbs * response structures. 248231743Sgibbs * 249231743Sgibbs * ring-page-order 250231743Sgibbs * Values: <uint32_t> 251231743Sgibbs * Default Value: 0 252231743Sgibbs * Maximum Value: MAX(ffs(max-ring-pages) - 1, max-ring-page-order) 253231743Sgibbs * Notes: 1, 3 254231743Sgibbs * 255231743Sgibbs * The size of the frontend allocated request ring buffer in units 256231743Sgibbs * of lb(machine pages). (e.g. 0 == 1 page, 1 = 2 pages, 2 == 4 pages, 257231743Sgibbs * etc.). 258231743Sgibbs * 259231743Sgibbs * num-ring-pages 260231743Sgibbs * Values: <uint32_t> 261231743Sgibbs * Default Value: 1 262231743Sgibbs * Maximum Value: MAX(max-ring-pages,(0x1 << max-ring-page-order)) 263231743Sgibbs * Notes: 2, 3 264231743Sgibbs * 265231743Sgibbs * The size of the frontend allocated request ring buffer in units of 266231743Sgibbs * machine pages. The value must be a power of 2. 267231743Sgibbs * 268231743Sgibbs * max-requests 269231743Sgibbs * Values: <uint32_t> 270231743Sgibbs * Default Value: BLKIF_MAX_RING_REQUESTS(PAGE_SIZE) 271231836Sgibbs * Maximum Value: BLKIF_MAX_RING_REQUESTS(PAGE_SIZE * max-ring-pages) 272231743Sgibbs * 273231743Sgibbs * The maximum number of concurrent, logical requests that will be 274231743Sgibbs * issued by the frontend. 275231743Sgibbs * 276231743Sgibbs * Note: A logical request may span multiple ring entries. 277231743Sgibbs * 278231743Sgibbs * max-request-segments 279231743Sgibbs * Values: <uint8_t> 280231743Sgibbs * Default Value: BLKIF_MAX_SEGMENTS_PER_HEADER_BLOCK 281231743Sgibbs * Maximum Value: MIN(255, backend/max-request-segments) 282231743Sgibbs * 283231743Sgibbs * The maximum value the frontend will set in the 284231743Sgibbs * blkif_request.nr_segments field. 285231743Sgibbs * 286231743Sgibbs * max-request-size 287231743Sgibbs * Values: <uint32_t> 288231743Sgibbs * Default Value: BLKIF_MAX_SEGMENTS_PER_HEADER_BLOCK * PAGE_SIZE 289231743Sgibbs * Maximum Value: max-request-segments * PAGE_SIZE 290231743Sgibbs * 291231743Sgibbs * The maximum amount of data, in bytes, that can be referenced by 292231743Sgibbs * a request type that accesses frontend memory (currently BLKIF_OP_READ, 293231743Sgibbs * BLKIF_OP_WRITE, or BLKIF_OP_WRITE_BARRIER). 294231743Sgibbs * 295231743Sgibbs *------------------------- Virtual Device Properties ------------------------- 296231743Sgibbs * 297231743Sgibbs * device-type 298231743Sgibbs * Values: "disk", "cdrom", "floppy", etc. 299231743Sgibbs * 300231743Sgibbs * virtual-device 301231743Sgibbs * Values: <uint32_t> 302231743Sgibbs * 303231743Sgibbs * A value indicating the physical device to virtualize within the 304231743Sgibbs * frontend's domain. (e.g. "The first ATA disk", "The third SCSI 305231743Sgibbs * disk", etc.) 306231743Sgibbs * 307231743Sgibbs * See docs/misc/vbd-interface.txt for details on the format of this 308231743Sgibbs * value. 309231743Sgibbs * 310231743Sgibbs * Notes 311231743Sgibbs * ----- 312231743Sgibbs * (1) Multi-page ring buffer scheme first developed in the Citrix XenServer 313231743Sgibbs * PV drivers. 314231743Sgibbs * (2) Multi-page ring buffer scheme first used in some RedHat distributions 315231743Sgibbs * including a distribution deployed on certain nodes of the Amazon 316231743Sgibbs * EC2 cluster. 317231743Sgibbs * (3) Support for multi-page ring buffers was implemented independently, 318231743Sgibbs * in slightly different forms, by both Citrix and RedHat/Amazon. 319231743Sgibbs * For full interoperability, block front and backends should publish 320231743Sgibbs * identical ring parameters, adjusted for unit differences, to the 321231743Sgibbs * XenStore nodes used in both schemes. 322231743Sgibbs * (4) Devices that support discard functionality may internally allocate 323231743Sgibbs * space (discardable extents) in units that are larger than the 324231743Sgibbs * exported logical block size. 325231743Sgibbs * (5) The discard-alignment parameter allows a physical device to be 326231743Sgibbs * partitioned into virtual devices that do not necessarily begin or 327231743Sgibbs * end on a discardable extent boundary. 328231743Sgibbs * (6) When there is only a single page allocated to the request ring, 329231743Sgibbs * 'ring-ref' is used to communicate the grant reference for this 330231743Sgibbs * page to the backend. When using a multi-page ring, the 'ring-ref' 331231743Sgibbs * node is not created. Instead 'ring-ref0' - 'ring-refN' are used. 332231743Sgibbs */ 333231743Sgibbs 334231743Sgibbs/* 335231743Sgibbs * STATE DIAGRAMS 336231743Sgibbs * 337231743Sgibbs ***************************************************************************** 338231743Sgibbs * Startup * 339231743Sgibbs ***************************************************************************** 340231743Sgibbs * 341231743Sgibbs * Tool stack creates front and back nodes with state XenbusStateInitialising. 342231743Sgibbs * 343231743Sgibbs * Front Back 344231743Sgibbs * ================================= ===================================== 345231743Sgibbs * XenbusStateInitialising XenbusStateInitialising 346231743Sgibbs * o Query virtual device o Query backend device identification 347231743Sgibbs * properties. data. 348231743Sgibbs * o Setup OS device instance. o Open and validate backend device. 349231743Sgibbs * o Publish backend features and 350231743Sgibbs * transport parameters. 351231743Sgibbs * | 352231743Sgibbs * | 353231743Sgibbs * V 354231743Sgibbs * XenbusStateInitWait 355231743Sgibbs * 356231743Sgibbs * o Query backend features and 357231743Sgibbs * transport parameters. 358231743Sgibbs * o Allocate and initialize the 359231743Sgibbs * request ring. 360231743Sgibbs * o Publish transport parameters 361231743Sgibbs * that will be in effect during 362231743Sgibbs * this connection. 363231743Sgibbs * | 364231743Sgibbs * | 365231743Sgibbs * V 366231743Sgibbs * XenbusStateInitialised 367231743Sgibbs * 368231743Sgibbs * o Query frontend transport parameters. 369231743Sgibbs * o Connect to the request ring and 370231743Sgibbs * event channel. 371231743Sgibbs * o Publish backend device properties. 372231743Sgibbs * | 373231743Sgibbs * | 374231743Sgibbs * V 375231743Sgibbs * XenbusStateConnected 376231743Sgibbs * 377231743Sgibbs * o Query backend device properties. 378231743Sgibbs * o Finalize OS virtual device 379231743Sgibbs * instance. 380231743Sgibbs * | 381231743Sgibbs * | 382231743Sgibbs * V 383231743Sgibbs * XenbusStateConnected 384231743Sgibbs * 385231743Sgibbs * Note: Drivers that do not support any optional features, or the negotiation 386231743Sgibbs * of transport parameters, can skip certain states in the state machine: 387231743Sgibbs * 388231743Sgibbs * o A frontend may transition to XenbusStateInitialised without 389231743Sgibbs * waiting for the backend to enter XenbusStateInitWait. In this 390231743Sgibbs * case, default transport parameters are in effect and any 391231743Sgibbs * transport parameters published by the frontend must contain 392231743Sgibbs * their default values. 393231743Sgibbs * 394231743Sgibbs * o A backend may transition to XenbusStateInitialised, bypassing 395231743Sgibbs * XenbusStateInitWait, without waiting for the frontend to first 396231743Sgibbs * enter the XenbusStateInitialised state. In this case, default 397231743Sgibbs * transport parameters are in effect and any transport parameters 398231743Sgibbs * published by the backend must contain their default values. 399231743Sgibbs * 400231743Sgibbs * Drivers that support optional features and/or transport parameter 401231743Sgibbs * negotiation must tolerate these additional state transition paths. 402231743Sgibbs * In general this means performing the work of any skipped state 403231743Sgibbs * transition, if it has not already been performed, in addition to the 404231743Sgibbs * work associated with entry into the current state. 405231743Sgibbs */ 406231743Sgibbs 407231743Sgibbs/* 408181624Skmacy * REQUEST CODES. 409181624Skmacy */ 410181624Skmacy#define BLKIF_OP_READ 0 411181624Skmacy#define BLKIF_OP_WRITE 1 412181624Skmacy/* 413231743Sgibbs * All writes issued prior to a request with the BLKIF_OP_WRITE_BARRIER 414231743Sgibbs * operation code ("barrier request") must be completed prior to the 415231743Sgibbs * execution of the barrier request. All writes issued after the barrier 416231743Sgibbs * request must not execute until after the completion of the barrier request. 417231743Sgibbs * 418231743Sgibbs * Optional. See "feature-barrier" XenBus node documentation above. 419181624Skmacy */ 420181624Skmacy#define BLKIF_OP_WRITE_BARRIER 2 421183375Skmacy/* 422231743Sgibbs * Commit any uncommitted contents of the backing device's volatile cache 423231743Sgibbs * to stable storage. 424231743Sgibbs * 425231743Sgibbs * Optional. See "feature-flush-cache" XenBus node documentation above. 426183375Skmacy */ 427183375Skmacy#define BLKIF_OP_FLUSH_DISKCACHE 3 428231743Sgibbs/* 429231743Sgibbs * Used in SLES sources for device specific command packet 430231743Sgibbs * contained within the request. Reserved for that purpose. 431231743Sgibbs */ 432231743Sgibbs#define BLKIF_OP_RESERVED_1 4 433231743Sgibbs/* 434231743Sgibbs * Indicate to the backend device that a region of storage is no longer in 435231743Sgibbs * use, and may be discarded at any time without impact to the client. If 436231743Sgibbs * the BLKIF_DISCARD_SECURE flag is set on the request, all copies of the 437231743Sgibbs * discarded region on the device must be rendered unrecoverable before the 438231743Sgibbs * command returns. 439231743Sgibbs * 440231743Sgibbs * This operation is analogous to performing a trim (ATA) or unamp (SCSI), 441231743Sgibbs * command on a native device. 442231743Sgibbs * 443231743Sgibbs * More information about trim/unmap operations can be found at: 444231743Sgibbs * http://t13.org/Documents/UploadedDocuments/docs2008/ 445231743Sgibbs * e07154r6-Data_Set_Management_Proposal_for_ATA-ACS2.doc 446231743Sgibbs * http://www.seagate.com/staticfiles/support/disc/manuals/ 447231743Sgibbs * Interface%20manuals/100293068c.pdf 448231743Sgibbs * 449231743Sgibbs * Optional. See "feature-discard", "discard-alignment", 450231743Sgibbs * "discard-granularity", and "discard-secure" in the XenBus node 451231743Sgibbs * documentation above. 452231743Sgibbs */ 453231743Sgibbs#define BLKIF_OP_DISCARD 5 454181624Skmacy 455181624Skmacy/* 456214077Sgibbs * Maximum scatter/gather segments associated with a request header block. 457231743Sgibbs * This is carefully chosen so that sizeof(blkif_ring_t) <= PAGE_SIZE. 458231743Sgibbs * NB. This could be 12 if the ring indexes weren't stored in the same page. 459181624Skmacy */ 460214077Sgibbs#define BLKIF_MAX_SEGMENTS_PER_HEADER_BLOCK 11 461181624Skmacy 462214077Sgibbs/* 463214077Sgibbs * Maximum scatter/gather segments associated with a segment block. 464214077Sgibbs */ 465214077Sgibbs#define BLKIF_MAX_SEGMENTS_PER_SEGMENT_BLOCK 14 466214077Sgibbs 467214077Sgibbs/* 468214077Sgibbs * Maximum scatter/gather segments per request (header + segment blocks). 469214077Sgibbs */ 470214077Sgibbs#define BLKIF_MAX_SEGMENTS_PER_REQUEST 255 471214077Sgibbs 472231743Sgibbs/* 473231743Sgibbs * NB. first_sect and last_sect in blkif_request_segment, as well as 474231743Sgibbs * sector_number in blkif_request, are always expressed in 512-byte units. 475231743Sgibbs * However they must be properly aligned to the real sector size of the 476231743Sgibbs * physical disk, which is reported in the "sector-size" node in the backend 477231743Sgibbs * xenbus info. Also the xenbus "sectors" node is expressed in 512-byte units. 478231743Sgibbs */ 479181624Skmacystruct blkif_request_segment { 480181624Skmacy grant_ref_t gref; /* reference to I/O buffer frame */ 481181624Skmacy /* @first_sect: first sector in frame to transfer (inclusive). */ 482181624Skmacy /* @last_sect: last sector in frame to transfer (inclusive). */ 483181624Skmacy uint8_t first_sect, last_sect; 484181624Skmacy}; 485214077Sgibbstypedef struct blkif_request_segment blkif_request_segment_t; 486181624Skmacy 487231743Sgibbs/* 488231743Sgibbs * Starting ring element for any I/O request. 489231743Sgibbs * 490231743Sgibbs * One or more segment blocks can be inserted into the request ring 491231743Sgibbs * just after a blkif_request_t, allowing requests to operate on 492231743Sgibbs * up to BLKIF_MAX_SEGMENTS_PER_REQUEST. 493231743Sgibbs * 494231743Sgibbs * BLKIF_SEGS_TO_BLOCKS() can be used on blkif_requst.nr_segments 495231743Sgibbs * to determine the number of contiguous ring entries associated 496231743Sgibbs * with this request. 497231743Sgibbs * 498231743Sgibbs * Note: Due to the way Xen request rings operate, the producer and 499231743Sgibbs * consumer indices of the ring must be incremented by the 500231743Sgibbs * BLKIF_SEGS_TO_BLOCKS() value of the associated request. 501231743Sgibbs * (e.g. a response to a 3 ring entry request must also consume 502231743Sgibbs * 3 entries in the ring, even though only the first ring entry 503231743Sgibbs * in the response has any data.) 504231743Sgibbs */ 505181624Skmacystruct blkif_request { 506181624Skmacy uint8_t operation; /* BLKIF_OP_??? */ 507181624Skmacy uint8_t nr_segments; /* number of segments */ 508181624Skmacy blkif_vdev_t handle; /* only for read/write requests */ 509181624Skmacy uint64_t id; /* private guest value, echoed in resp */ 510181624Skmacy blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */ 511231743Sgibbs blkif_request_segment_t seg[BLKIF_MAX_SEGMENTS_PER_HEADER_BLOCK]; 512181624Skmacy}; 513181624Skmacytypedef struct blkif_request blkif_request_t; 514181624Skmacy 515231743Sgibbs/* 516231743Sgibbs * A segment block is a ring request structure that contains only 517231743Sgibbs * segment data. 518231743Sgibbs * 519231743Sgibbs * sizeof(struct blkif_segment_block) <= sizeof(struct blkif_request) 520231743Sgibbs */ 521231743Sgibbsstruct blkif_segment_block { 522231743Sgibbs blkif_request_segment_t seg[BLKIF_MAX_SEGMENTS_PER_SEGMENT_BLOCK]; 523231743Sgibbs}; 524231743Sgibbstypedef struct blkif_segment_block blkif_segment_block_t; 525231743Sgibbs 526231743Sgibbs/* 527231743Sgibbs * Cast to this structure when blkif_request.operation == BLKIF_OP_DISCARD 528231743Sgibbs * sizeof(struct blkif_request_discard) <= sizeof(struct blkif_request) 529231743Sgibbs */ 530231743Sgibbsstruct blkif_request_discard { 531231743Sgibbs uint8_t operation; /* BLKIF_OP_DISCARD */ 532231743Sgibbs uint8_t flag; /* BLKIF_DISCARD_SECURE or zero */ 533231743Sgibbs#define BLKIF_DISCARD_SECURE (1<<0) /* ignored if discard-secure=0 */ 534231743Sgibbs blkif_vdev_t handle; /* same as for read/write requests */ 535231743Sgibbs uint64_t id; /* private guest value, echoed in resp */ 536231743Sgibbs blkif_sector_t sector_number;/* start sector idx on disk */ 537231743Sgibbs uint64_t nr_sectors; /* number of contiguous sectors to discard*/ 538231743Sgibbs}; 539231743Sgibbstypedef struct blkif_request_discard blkif_request_discard_t; 540231743Sgibbs 541181624Skmacystruct blkif_response { 542181624Skmacy uint64_t id; /* copied from request */ 543181624Skmacy uint8_t operation; /* copied from request */ 544181624Skmacy int16_t status; /* BLKIF_RSP_??? */ 545181624Skmacy}; 546181624Skmacytypedef struct blkif_response blkif_response_t; 547181624Skmacy 548181624Skmacy/* 549181624Skmacy * STATUS RETURN CODES. 550181624Skmacy */ 551181624Skmacy /* Operation not supported (only happens on barrier writes). */ 552181624Skmacy#define BLKIF_RSP_EOPNOTSUPP -2 553181624Skmacy /* Operation failed for some unspecified reason (-EIO). */ 554181624Skmacy#define BLKIF_RSP_ERROR -1 555181624Skmacy /* Operation completed successfully. */ 556181624Skmacy#define BLKIF_RSP_OKAY 0 557181624Skmacy 558181624Skmacy/* 559181624Skmacy * Generate blkif ring structures and types. 560181624Skmacy */ 561181624SkmacyDEFINE_RING_TYPES(blkif, struct blkif_request, struct blkif_response); 562181624Skmacy 563231743Sgibbs/* 564231743Sgibbs * Index to, and treat as a segment block, an entry in the ring. 565231743Sgibbs */ 566231743Sgibbs#define BLKRING_GET_SEG_BLOCK(_r, _idx) \ 567231743Sgibbs (((blkif_segment_block_t *)RING_GET_REQUEST(_r, _idx))->seg) 568214077Sgibbs 569214077Sgibbs/* 570214077Sgibbs * The number of ring request blocks required to handle an I/O 571214077Sgibbs * request containing _segs segments. 572214077Sgibbs */ 573231743Sgibbs#define BLKIF_SEGS_TO_BLOCKS(_segs) \ 574231743Sgibbs ((((_segs - BLKIF_MAX_SEGMENTS_PER_HEADER_BLOCK) \ 575231743Sgibbs + (BLKIF_MAX_SEGMENTS_PER_SEGMENT_BLOCK - 1)) \ 576231743Sgibbs / BLKIF_MAX_SEGMENTS_PER_SEGMENT_BLOCK) + /*header_block*/1) 577214077Sgibbs 578231743Sgibbs#define VDISK_CDROM 0x1 579231743Sgibbs#define VDISK_REMOVABLE 0x2 580231743Sgibbs#define VDISK_READONLY 0x4 581231743Sgibbs 582181624Skmacy#endif /* __XEN_PUBLIC_IO_BLKIF_H__ */ 583181624Skmacy 584181624Skmacy/* 585181624Skmacy * Local variables: 586181624Skmacy * mode: C 587181624Skmacy * c-set-style: "BSD" 588181624Skmacy * c-basic-offset: 4 589181624Skmacy * tab-width: 4 590181624Skmacy * indent-tabs-mode: nil 591181624Skmacy * End: 592181624Skmacy */ 593