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virtio_blk.h 5.0 KB

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  1. /* This header is BSD licensed so anyone can use the definitions to implement
  2. * compatible drivers/servers.
  3. *
  4. * Redistribution and use in source and binary forms, with or without
  5. * modification, are permitted provided that the following conditions
  6. * are met:
  7. * 1. Redistributions of source code must retain the above copyright
  8. * notice, this list of conditions and the following disclaimer.
  9. * 2. Redistributions in binary form must reproduce the above copyright
  10. * notice, this list of conditions and the following disclaimer in the
  11. * documentation and/or other materials provided with the distribution.
  12. * 3. Neither the name of IBM nor the names of its contributors
  13. * may be used to endorse or promote products derived from this software
  14. * without specific prior written permission.
  15. * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS IS'' AND
  16. * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  17. * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  18. * ARE DISCLAIMED. IN NO EVENT SHALL IBM OR CONTRIBUTORS BE LIABLE
  19. * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  20. * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  21. * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  22. * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  23. * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  24. * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  25. * SUCH DAMAGE. */
  26. /* Feature bits */
  27. #define VIRTIO_BLK_F_SIZE_MAX 1 /* Indicates maximum segment size */
  28. #define VIRTIO_BLK_F_SEG_MAX 2 /* Indicates maximum # of segments */
  29. #define VIRTIO_BLK_F_GEOMETRY 4 /* Legacy geometry available */
  30. #define VIRTIO_BLK_F_RO 5 /* Disk is read-only */
  31. #define VIRTIO_BLK_F_BLK_SIZE 6 /* Block size of disk is available*/
  32. #define VIRTIO_BLK_F_TOPOLOGY 10 /* Topology information is available */
  33. #define VIRTIO_BLK_F_MQ 12 /* support more than one vq */
  34. /* Legacy feature bits */
  35. #ifndef VIRTIO_BLK_NO_LEGACY
  36. #define VIRTIO_BLK_F_BARRIER 0 /* Does host support barriers? */
  37. #define VIRTIO_BLK_F_SCSI 7 /* Supports scsi command passthru */
  38. #define VIRTIO_BLK_F_FLUSH 9 /* Flush command supported */
  39. #define VIRTIO_BLK_F_CONFIG_WCE 11 /* Writeback mode available in config */
  40. #ifndef __KERNEL__
  41. /* Old (deprecated) name for VIRTIO_BLK_F_FLUSH. */
  42. #define VIRTIO_BLK_F_WCE VIRTIO_BLK_F_FLUSH
  43. #endif
  44. #endif /* !VIRTIO_BLK_NO_LEGACY */
  45. #define VIRTIO_BLK_ID_BYTES 20 /* ID string length */
  46. struct virtio_blk_config {
  47. /* The capacity (in 512-byte sectors). */
  48. uint64_t capacity;
  49. /* The maximum segment size (if VIRTIO_BLK_F_SIZE_MAX) */
  50. uint32_t size_max;
  51. /* The maximum number of segments (if VIRTIO_BLK_F_SEG_MAX) */
  52. uint32_t seg_max;
  53. /* geometry of the device (if VIRTIO_BLK_F_GEOMETRY) */
  54. struct virtio_blk_geometry {
  55. uint16_t cylinders;
  56. uint8_t heads;
  57. uint8_t sectors;
  58. } geometry;
  59. /* block size of device (if VIRTIO_BLK_F_BLK_SIZE) */
  60. uint32_t blk_size;
  61. /* the next 4 entries are guarded by VIRTIO_BLK_F_TOPOLOGY */
  62. /* exponent for physical block per logical block. */
  63. uint8_t physical_block_exp;
  64. /* alignment offset in logical blocks. */
  65. uint8_t alignment_offset;
  66. /* minimum I/O size without performance penalty in logical blocks. */
  67. uint16_t min_io_size;
  68. /* optimal sustained I/O size in logical blocks. */
  69. uint32_t opt_io_size;
  70. /* writeback mode (if VIRTIO_BLK_F_CONFIG_WCE) */
  71. uint8_t wce;
  72. uint8_t unused;
  73. /* number of vqs, only available when VIRTIO_BLK_F_MQ is set */
  74. uint16_t num_queues;
  75. } __attribute__((packed));
  76. /*
  77. * Command types
  78. *
  79. * Usage is a bit tricky as some bits are used as flags and some are not.
  80. *
  81. * Rules:
  82. * VIRTIO_BLK_T_OUT may be combined with VIRTIO_BLK_T_SCSI_CMD or
  83. * VIRTIO_BLK_T_BARRIER. VIRTIO_BLK_T_FLUSH is a command of its own
  84. * and may not be combined with any of the other flags.
  85. */
  86. /* These two define direction. */
  87. #define VIRTIO_BLK_T_IN 0
  88. #define VIRTIO_BLK_T_OUT 1
  89. #ifndef VIRTIO_BLK_NO_LEGACY
  90. /* This bit says it's a scsi command, not an actual read or write. */
  91. #define VIRTIO_BLK_T_SCSI_CMD 2
  92. #endif /* VIRTIO_BLK_NO_LEGACY */
  93. /* Cache flush command */
  94. #define VIRTIO_BLK_T_FLUSH 4
  95. /* Get device ID command */
  96. #define VIRTIO_BLK_T_GET_ID 8
  97. #ifndef VIRTIO_BLK_NO_LEGACY
  98. /* Barrier before this op. */
  99. #define VIRTIO_BLK_T_BARRIER 0x80000000
  100. #endif /* !VIRTIO_BLK_NO_LEGACY */
  101. /*
  102. * This comes first in the read scatter-gather list.
  103. * For legacy virtio, if VIRTIO_F_ANY_LAYOUT is not negotiated,
  104. * this is the first element of the read scatter-gather list.
  105. */
  106. struct virtio_blk_outhdr {
  107. /* VIRTIO_BLK_T* */
  108. uint32_t type;
  109. /* io priority. */
  110. uint32_t ioprio;
  111. /* Sector (ie. 512 byte offset) */
  112. uint64_t sector;
  113. };
  114. #ifndef VIRTIO_BLK_NO_LEGACY
  115. struct virtio_scsi_inhdr {
  116. uint32_t errors;
  117. uint32_t data_len;
  118. uint32_t sense_len;
  119. uint32_t residual;
  120. };
  121. #endif /* !VIRTIO_BLK_NO_LEGACY */
  122. /* And this is the final byte of the write scatter-gather list. */
  123. #define VIRTIO_BLK_S_OK 0
  124. #define VIRTIO_BLK_S_IOERR 1
  125. #define VIRTIO_BLK_S_UNSUPP 2