virtio_blk.h

/* SPDX-License-Identifier: BSD-3-Clause */
/*
 * Copyright (C) 2018, Tuomas Tynkkynen <tuomas.tynkkynen@iki.fi>
 * Copyright (C) 2018, Bin Meng <bmeng.cn@gmail.com>
 *
 * From Linux kernel include/uapi/linux/virtio_blk.h
 */

#ifndef _LINUX_VIRTIO_BLK_H
#define _LINUX_VIRTIO_BLK_H

/* Feature bits */
#define VIRTIO_BLK_F_SIZE_MAX	1	/* Indicates maximum segment size */
#define VIRTIO_BLK_F_SEG_MAX	2	/* Indicates maximum # of segments */
#define VIRTIO_BLK_F_GEOMETRY	4	/* Legacy geometry available */
#define VIRTIO_BLK_F_RO		5	/* Disk is read-only */
#define VIRTIO_BLK_F_BLK_SIZE	6	/* Block size of disk is available */
#define VIRTIO_BLK_F_TOPOLOGY	10	/* Topology information is available */
#define VIRTIO_BLK_F_MQ		12	/* Support more than one vq */

/* Legacy feature bits */
#ifndef VIRTIO_BLK_NO_LEGACY
#define VIRTIO_BLK_F_BARRIER	0	/* Does host support barriers? */
#define VIRTIO_BLK_F_SCSI	7	/* Supports scsi command passthru */
#define VIRTIO_BLK_F_FLUSH	9	/* Flush command supported */
#define VIRTIO_BLK_F_CONFIG_WCE	11	/* Writeback mode available in config */
#ifndef __KERNEL__
/* Old (deprecated) name for VIRTIO_BLK_F_FLUSH */
#define VIRTIO_BLK_F_WCE	VIRTIO_BLK_F_FLUSH
#endif
#endif /* !VIRTIO_BLK_NO_LEGACY */

#define VIRTIO_BLK_ID_BYTES	20	/* ID string length */

struct __packed virtio_blk_config {
	/* The capacity (in 512-byte sectors) */
	__u64 capacity;
	/* The maximum segment size (if VIRTIO_BLK_F_SIZE_MAX) */
	__u32 size_max;
	/* The maximum number of segments (if VIRTIO_BLK_F_SEG_MAX) */
	__u32 seg_max;
	/* geometry of the device (if VIRTIO_BLK_F_GEOMETRY) */
	struct virtio_blk_geometry {
		__u16 cylinders;
		__u8 heads;
		__u8 sectors;
	} geometry;

	/* block size of device (if VIRTIO_BLK_F_BLK_SIZE) */
	__u32 blk_size;

	/* the next 4 entries are guarded by VIRTIO_BLK_F_TOPOLOGY */
	/* exponent for physical block per logical block */
	__u8 physical_block_exp;
	/* alignment offset in logical blocks */
	__u8 alignment_offset;
	/* minimum I/O size without performance penalty in logical blocks */
	__u16 min_io_size;
	/* optimal sustained I/O size in logical blocks */
	__u32 opt_io_size;

	/* writeback mode (if VIRTIO_BLK_F_CONFIG_WCE) */
	__u8 wce;
	__u8 unused;

	/* number of vqs, only available when VIRTIO_BLK_F_MQ is set */
	__u16 num_queues;
};

/*
 * Command types
 *
 * Usage is a bit tricky as some bits are used as flags and some are not.
 *
 * Rules:
 *   VIRTIO_BLK_T_OUT may be combined with VIRTIO_BLK_T_SCSI_CMD or
 *   VIRTIO_BLK_T_BARRIER. VIRTIO_BLK_T_FLUSH is a command of its own
 *   and may not be combined with any of the other flags.
 */

/* These two define direction */
#define VIRTIO_BLK_T_IN		0
#define VIRTIO_BLK_T_OUT	1

#ifndef VIRTIO_BLK_NO_LEGACY
/* This bit says it's a scsi command, not an actual read or write */
#define VIRTIO_BLK_T_SCSI_CMD	2
#endif /* VIRTIO_BLK_NO_LEGACY */

/* Cache flush command */
#define VIRTIO_BLK_T_FLUSH	4

/* Get device ID command */
#define VIRTIO_BLK_T_GET_ID	8

#ifndef VIRTIO_BLK_NO_LEGACY
/* Barrier before this op */
#define VIRTIO_BLK_T_BARRIER	0x80000000
#endif /* !VIRTIO_BLK_NO_LEGACY */

/*
 * This comes first in the read scatter-gather list.
 * For legacy virtio, if VIRTIO_F_ANY_LAYOUT is not negotiated,
 * this is the first element of the read scatter-gather list.
 */
struct virtio_blk_outhdr {
	/* VIRTIO_BLK_T* */
	__virtio32 type;
	/* io priority */
	__virtio32 ioprio;
	/* Sector (ie. 512 byte offset) */
	__virtio64 sector;
};

#ifndef VIRTIO_BLK_NO_LEGACY
struct virtio_scsi_inhdr {
	__virtio32 errors;
	__virtio32 data_len;
	__virtio32 sense_len;
	__virtio32 residual;
};
#endif /* !VIRTIO_BLK_NO_LEGACY */

/* And this is the final byte of the write scatter-gather list */
#define VIRTIO_BLK_S_OK		0
#define VIRTIO_BLK_S_IOERR	1
#define VIRTIO_BLK_S_UNSUPP	2

#endif /* _LINUX_VIRTIO_BLK_H */