uapi/linux/virtio_blk.h

0001 #ifndef _LINUX_VIRTIO_BLK_H
0002 #define _LINUX_VIRTIO_BLK_H
0003 /* This header is BSD licensed so anyone can use the definitions to implement
0004  * compatible drivers/servers.
0005  *
0006  * Redistribution and use in source and binary forms, with or without
0007  * modification, are permitted provided that the following conditions
0008  * are met:
0009  * 1. Redistributions of source code must retain the above copyright
0010  *    notice, this list of conditions and the following disclaimer.
0011  * 2. Redistributions in binary form must reproduce the above copyright
0012  *    notice, this list of conditions and the following disclaimer in the
0013  *    documentation and/or other materials provided with the distribution.
0014  * 3. Neither the name of IBM nor the names of its contributors
0015  *    may be used to endorse or promote products derived from this software
0016  *    without specific prior written permission.
0017  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS IS'' AND
0018  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
0019  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
0020  * ARE DISCLAIMED.  IN NO EVENT SHALL IBM OR CONTRIBUTORS BE LIABLE
0021  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
0022  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
0023  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
0024  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
0025  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
0026  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
0027  * SUCH DAMAGE. */
0028 #include <linux/types.h>
0029 #include <linux/virtio_ids.h>
0030 #include <linux/virtio_config.h>
0031 #include <linux/virtio_types.h>
0032
0033 /* Feature bits */
0034 #define VIRTIO_BLK_F_SIZE_MAX   1   /* Indicates maximum segment size */
0035 #define VIRTIO_BLK_F_SEG_MAX    2   /* Indicates maximum # of segments */
0036 #define VIRTIO_BLK_F_GEOMETRY   4   /* Legacy geometry available  */
0037 #define VIRTIO_BLK_F_RO     5   /* Disk is read-only */
0038 #define VIRTIO_BLK_F_BLK_SIZE   6   /* Block size of disk is available*/
0039 #define VIRTIO_BLK_F_TOPOLOGY   10  /* Topology information is available */
0040 #define VIRTIO_BLK_F_MQ     12  /* support more than one vq */
0041 #define VIRTIO_BLK_F_DISCARD    13  /* DISCARD is supported */
0042 #define VIRTIO_BLK_F_WRITE_ZEROES   14  /* WRITE ZEROES is supported */
0043
0044 /* Legacy feature bits */
0045 #ifndef VIRTIO_BLK_NO_LEGACY
0046 #define VIRTIO_BLK_F_BARRIER    0   /* Does host support barriers? */
0047 #define VIRTIO_BLK_F_SCSI   7   /* Supports scsi command passthru */
0048 #define VIRTIO_BLK_F_FLUSH  9   /* Flush command supported */
0049 #define VIRTIO_BLK_F_CONFIG_WCE 11  /* Writeback mode available in config */
0050 #ifndef __KERNEL__
0051 /* Old (deprecated) name for VIRTIO_BLK_F_FLUSH. */
0052 #define VIRTIO_BLK_F_WCE VIRTIO_BLK_F_FLUSH
0053 #endif
0054 #endif /* !VIRTIO_BLK_NO_LEGACY */
0055
0056 #define VIRTIO_BLK_ID_BYTES 20  /* ID string length */
0057
0058 struct virtio_blk_config {
0059     /* The capacity (in 512-byte sectors). */
0060     __virtio64 capacity;
0061     /* The maximum segment size (if VIRTIO_BLK_F_SIZE_MAX) */
0062     __virtio32 size_max;
0063     /* The maximum number of segments (if VIRTIO_BLK_F_SEG_MAX) */
0064     __virtio32 seg_max;
0065     /* geometry of the device (if VIRTIO_BLK_F_GEOMETRY) */
0066     struct virtio_blk_geometry {
0067         __virtio16 cylinders;
0068         __u8 heads;
0069         __u8 sectors;
0070     } geometry;
0071
0072     /* block size of device (if VIRTIO_BLK_F_BLK_SIZE) */
0073     __virtio32 blk_size;
0074
0075     /* the next 4 entries are guarded by VIRTIO_BLK_F_TOPOLOGY  */
0076     /* exponent for physical block per logical block. */
0077     __u8 physical_block_exp;
0078     /* alignment offset in logical blocks. */
0079     __u8 alignment_offset;
0080     /* minimum I/O size without performance penalty in logical blocks. */
0081     __virtio16 min_io_size;
0082     /* optimal sustained I/O size in logical blocks. */
0083     __virtio32 opt_io_size;
0084
0085     /* writeback mode (if VIRTIO_BLK_F_CONFIG_WCE) */
0086     __u8 wce;
0087     __u8 unused;
0088
0089     /* number of vqs, only available when VIRTIO_BLK_F_MQ is set */
0090     __virtio16 num_queues;
0091
0092     /* the next 3 entries are guarded by VIRTIO_BLK_F_DISCARD */
0093     /*
0094      * The maximum discard sectors (in 512-byte sectors) for
0095      * one segment.
0096      */
0097     __virtio32 max_discard_sectors;
0098     /*
0099      * The maximum number of discard segments in a
0100      * discard command.
0101      */
0102     __virtio32 max_discard_seg;
0103     /* Discard commands must be aligned to this number of sectors. */
0104     __virtio32 discard_sector_alignment;
0105
0106     /* the next 3 entries are guarded by VIRTIO_BLK_F_WRITE_ZEROES */
0107     /*
0108      * The maximum number of write zeroes sectors (in 512-byte sectors) in
0109      * one segment.
0110      */
0111     __virtio32 max_write_zeroes_sectors;
0112     /*
0113      * The maximum number of segments in a write zeroes
0114      * command.
0115      */
0116     __virtio32 max_write_zeroes_seg;
0117     /*
0118      * Set if a VIRTIO_BLK_T_WRITE_ZEROES request may result in the
0119      * deallocation of one or more of the sectors.
0120      */
0121     __u8 write_zeroes_may_unmap;
0122
0123     __u8 unused1[3];
0124 } __attribute__((packed));
0125
0126 /*
0127  * Command types
0128  *
0129  * Usage is a bit tricky as some bits are used as flags and some are not.
0130  *
0131  * Rules:
0132  *   VIRTIO_BLK_T_OUT may be combined with VIRTIO_BLK_T_SCSI_CMD or
0133  *   VIRTIO_BLK_T_BARRIER.  VIRTIO_BLK_T_FLUSH is a command of its own
0134  *   and may not be combined with any of the other flags.
0135  */
0136
0137 /* These two define direction. */
0138 #define VIRTIO_BLK_T_IN     0
0139 #define VIRTIO_BLK_T_OUT    1
0140
0141 #ifndef VIRTIO_BLK_NO_LEGACY
0142 /* This bit says it's a scsi command, not an actual read or write. */
0143 #define VIRTIO_BLK_T_SCSI_CMD   2
0144 #endif /* VIRTIO_BLK_NO_LEGACY */
0145
0146 /* Cache flush command */
0147 #define VIRTIO_BLK_T_FLUSH  4
0148
0149 /* Get device ID command */
0150 #define VIRTIO_BLK_T_GET_ID    8
0151
0152 /* Discard command */
0153 #define VIRTIO_BLK_T_DISCARD    11
0154
0155 /* Write zeroes command */
0156 #define VIRTIO_BLK_T_WRITE_ZEROES   13
0157
0158 #ifndef VIRTIO_BLK_NO_LEGACY
0159 /* Barrier before this op. */
0160 #define VIRTIO_BLK_T_BARRIER    0x80000000
0161 #endif /* !VIRTIO_BLK_NO_LEGACY */
0162
0163 /*
0164  * This comes first in the read scatter-gather list.
0165  * For legacy virtio, if VIRTIO_F_ANY_LAYOUT is not negotiated,
0166  * this is the first element of the read scatter-gather list.
0167  */
0168 struct virtio_blk_outhdr {
0169     /* VIRTIO_BLK_T* */
0170     __virtio32 type;
0171     /* io priority. */
0172     __virtio32 ioprio;
0173     /* Sector (ie. 512 byte offset) */
0174     __virtio64 sector;
0175 };
0176
0177 /* Unmap this range (only valid for write zeroes command) */
0178 #define VIRTIO_BLK_WRITE_ZEROES_FLAG_UNMAP  0x00000001
0179
0180 /* Discard/write zeroes range for each request. */
0181 struct virtio_blk_discard_write_zeroes {
0182     /* discard/write zeroes start sector */
0183     __le64 sector;
0184     /* number of discard/write zeroes sectors */
0185     __le32 num_sectors;
0186     /* flags for this range */
0187     __le32 flags;
0188 };
0189
0190 #ifndef VIRTIO_BLK_NO_LEGACY
0191 struct virtio_scsi_inhdr {
0192     __virtio32 errors;
0193     __virtio32 data_len;
0194     __virtio32 sense_len;
0195     __virtio32 residual;
0196 };
0197 #endif /* !VIRTIO_BLK_NO_LEGACY */
0198
0199 /* And this is the final byte of the write scatter-gather list. */
0200 #define VIRTIO_BLK_S_OK     0
0201 #define VIRTIO_BLK_S_IOERR  1
0202 #define VIRTIO_BLK_S_UNSUPP 2
0203 #endif /* _LINUX_VIRTIO_BLK_H */