2cc8a524af
If the hypervisor advertises support for the DISCARD command then the guest can perform TRIM commands, freeing space on the backing store. If VIRTIO_BLK_F_DISCARD is enabled, advertise DISKFLAG_CANDELETE Tested with FreeBSD guests on bhyve and KVM Reviewed by: jhb Tested by: freqlabs MFC after: 1 month Relnotes: yes Sponsored by: Klara Inc. Differential Revision: https://reviews.freebsd.org/D21708
174 lines
5.7 KiB
C
174 lines
5.7 KiB
C
/*-
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* SPDX-License-Identifier: BSD-3-Clause
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*
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* This header is BSD licensed so anyone can use the definitions to implement
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* compatible drivers/servers.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of IBM nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL IBM OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#ifndef _VIRTIO_BLK_H
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#define _VIRTIO_BLK_H
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#define VTBLK_BSIZE 512
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/* Feature bits */
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#define VIRTIO_BLK_F_BARRIER 0x0001 /* Does host support barriers? */
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#define VIRTIO_BLK_F_SIZE_MAX 0x0002 /* Indicates maximum segment size */
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#define VIRTIO_BLK_F_SEG_MAX 0x0004 /* Indicates maximum # of segments */
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#define VIRTIO_BLK_F_GEOMETRY 0x0010 /* Legacy geometry available */
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#define VIRTIO_BLK_F_RO 0x0020 /* Disk is read-only */
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#define VIRTIO_BLK_F_BLK_SIZE 0x0040 /* Block size of disk is available*/
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#define VIRTIO_BLK_F_SCSI 0x0080 /* Supports scsi command passthru */
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#define VIRTIO_BLK_F_FLUSH 0x0200 /* Flush command supported */
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#define VIRTIO_BLK_F_WCE 0x0200 /* Legacy alias for FLUSH */
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#define VIRTIO_BLK_F_TOPOLOGY 0x0400 /* Topology information is available */
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#define VIRTIO_BLK_F_CONFIG_WCE 0x0800 /* Writeback mode available in config */
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#define VIRTIO_BLK_F_MQ 0x1000 /* Support more than one vq */
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#define VIRTIO_BLK_F_DISCARD 0x2000 /* Trim blocks */
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#define VIRTIO_BLK_F_WRITE_ZEROES 0x4000 /* Write zeros */
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#define VIRTIO_BLK_ID_BYTES 20 /* ID string length */
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struct virtio_blk_config {
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/* The capacity (in 512-byte sectors). */
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uint64_t capacity;
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/* The maximum segment size (if VIRTIO_BLK_F_SIZE_MAX) */
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uint32_t size_max;
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/* The maximum number of segments (if VIRTIO_BLK_F_SEG_MAX) */
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uint32_t seg_max;
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/* Geometry of the device (if VIRTIO_BLK_F_GEOMETRY) */
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struct virtio_blk_geometry {
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uint16_t cylinders;
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uint8_t heads;
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uint8_t sectors;
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} geometry;
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/* Block size of device (if VIRTIO_BLK_F_BLK_SIZE) */
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uint32_t blk_size;
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/* Topology of the device (if VIRTIO_BLK_F_TOPOLOGY) */
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struct virtio_blk_topology {
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/* Exponent for physical block per logical block. */
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uint8_t physical_block_exp;
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/* Alignment offset in logical blocks. */
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uint8_t alignment_offset;
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/* Minimum I/O size without performance penalty in logical
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* blocks. */
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uint16_t min_io_size;
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/* Optimal sustained I/O size in logical blocks. */
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uint32_t opt_io_size;
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} topology;
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/* Writeback mode (if VIRTIO_BLK_F_CONFIG_WCE) */
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uint8_t wce;
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uint8_t unused;
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/* Number of vqs, only available when VIRTIO_BLK_F_MQ is set */
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uint16_t num_queues;
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uint32_t max_discard_sectors;
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uint32_t max_discard_seg;
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uint32_t discard_sector_alignment;
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uint32_t max_write_zeroes_sectors;
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uint32_t max_write_zeroes_seg;
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uint8_t write_zeroes_may_unmap;
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uint8_t unused1[3];
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} __packed;
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/*
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* Command types
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*
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* Usage is a bit tricky as some bits are used as flags and some are not.
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*
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* Rules:
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* VIRTIO_BLK_T_OUT may be combined with VIRTIO_BLK_T_SCSI_CMD or
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* VIRTIO_BLK_T_BARRIER. VIRTIO_BLK_T_FLUSH is a command of its own
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* and may not be combined with any of the other flags.
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*/
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/* These two define direction. */
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#define VIRTIO_BLK_T_IN 0
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#define VIRTIO_BLK_T_OUT 1
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/* This bit says it's a scsi command, not an actual read or write. */
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#define VIRTIO_BLK_T_SCSI_CMD 2
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#define VIRTIO_BLK_T_SCSI_CMD_OUT 3
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/* Cache flush command */
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#define VIRTIO_BLK_T_FLUSH 4
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#define VIRTIO_BLK_T_FLUSH_OUT 5
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/* Get device ID command */
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#define VIRTIO_BLK_T_GET_ID 8
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/* Discard command */
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#define VIRTIO_BLK_T_DISCARD 11
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/* Write zeros command */
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#define VIRTIO_BLK_T_WRITE_ZEROES 13
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/* Barrier before this op. */
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#define VIRTIO_BLK_T_BARRIER 0x80000000
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/* ID string length */
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#define VIRTIO_BLK_ID_BYTES 20
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/* Unmap this range (only valid for write zeroes command) */
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#define VIRTIO_BLK_WRITE_ZEROES_FLAG_UNMAP 0x00000001
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/* This is the first element of the read scatter-gather list. */
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struct virtio_blk_outhdr {
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/* VIRTIO_BLK_T* */
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uint32_t type;
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/* io priority. */
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uint32_t ioprio;
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/* Sector (ie. 512 byte offset) */
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uint64_t sector;
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};
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struct virtio_blk_discard_write_zeroes {
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uint64_t sector;
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uint32_t num_sectors;
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struct {
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uint32_t unmap:1;
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uint32_t reserved:31;
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} flags;
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};
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struct virtio_scsi_inhdr {
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uint32_t errors;
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uint32_t data_len;
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uint32_t sense_len;
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uint32_t residual;
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};
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/* And this is the final byte of the write scatter-gather list. */
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#define VIRTIO_BLK_S_OK 0
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#define VIRTIO_BLK_S_IOERR 1
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#define VIRTIO_BLK_S_UNSUPP 2
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#endif /* _VIRTIO_BLK_H */
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