[mirror_ubuntu-hirsute-kernel.git] / include / xen / interface / io / blkif.h

/******************************************************************************
 * blkif.h
 *
 * Unified block-device I/O interface for Xen guest OSes.
 *
 * Copyright (c) 2003-2004, Keir Fraser
 */

#ifndef __XEN_PUBLIC_IO_BLKIF_H__
#define __XEN_PUBLIC_IO_BLKIF_H__

#include <xen/interface/io/ring.h>
#include <xen/interface/grant_table.h>

/*
 * Front->back notifications: When enqueuing a new request, sending a
 * notification can be made conditional on req_event (i.e., the generic
 * hold-off mechanism provided by the ring macros). Backends must set
 * req_event appropriately (e.g., using RING_FINAL_CHECK_FOR_REQUESTS()).
 *
 * Back->front notifications: When enqueuing a new response, sending a
 * notification can be made conditional on rsp_event (i.e., the generic
 * hold-off mechanism provided by the ring macros). Frontends must set
 * rsp_event appropriately (e.g., using RING_FINAL_CHECK_FOR_RESPONSES()).
 */

typedef uint16_t blkif_vdev_t;
typedef uint64_t blkif_sector_t;

/*
 * REQUEST CODES.
 */
#define BLKIF_OP_READ              0
#define BLKIF_OP_WRITE             1
/*
 * Recognised only if "feature-barrier" is present in backend xenbus info.
 * The "feature_barrier" node contains a boolean indicating whether barrier
 * requests are likely to succeed or fail. Either way, a barrier request
 * may fail at any time with BLKIF_RSP_EOPNOTSUPP if it is unsupported by
 * the underlying block-device hardware. The boolean simply indicates whether
 * or not it is worthwhile for the frontend to attempt barrier requests.
 * If a backend does not recognise BLKIF_OP_WRITE_BARRIER, it should *not*
 * create the "feature-barrier" node!
 */
#define BLKIF_OP_WRITE_BARRIER     2

/*
 * Recognised if "feature-flush-cache" is present in backend xenbus
 * info.  A flush will ask the underlying storage hardware to flush its
 * non-volatile caches as appropriate.  The "feature-flush-cache" node
 * contains a boolean indicating whether flush requests are likely to
 * succeed or fail. Either way, a flush request may fail at any time
 * with BLKIF_RSP_EOPNOTSUPP if it is unsupported by the underlying
 * block-device hardware. The boolean simply indicates whether or not it
 * is worthwhile for the frontend to attempt flushes.  If a backend does
 * not recognise BLKIF_OP_WRITE_FLUSH_CACHE, it should *not* create the
 * "feature-flush-cache" node!
 */
#define BLKIF_OP_FLUSH_DISKCACHE   3

/*
 * Recognised only if "feature-discard" is present in backend xenbus info.
 * The "feature-discard" node contains a boolean indicating whether trim
 * (ATA) or unmap (SCSI) - conviently called discard requests are likely
 * to succeed or fail. Either way, a discard request
 * may fail at any time with BLKIF_RSP_EOPNOTSUPP if it is unsupported by
 * the underlying block-device hardware. The boolean simply indicates whether
 * or not it is worthwhile for the frontend to attempt discard requests.
 * If a backend does not recognise BLKIF_OP_DISCARD, it should *not*
 * create the "feature-discard" node!
 *
 * Discard operation is a request for the underlying block device to mark
 * extents to be erased. However, discard does not guarantee that the blocks
 * will be erased from the device - it is just a hint to the device
 * controller that these blocks are no longer in use. What the device
 * controller does with that information is left to the controller.
 * Discard operations are passed with sector_number as the
 * sector index to begin discard operations at and nr_sectors as the number of
 * sectors to be discarded. The specified sectors should be discarded if the
 * underlying block device supports trim (ATA) or unmap (SCSI) operations,
 * or a BLKIF_RSP_EOPNOTSUPP  should be returned.
 * More information about trim/unmap operations at:
 * http://t13.org/Documents/UploadedDocuments/docs2008/
 *     e07154r6-Data_Set_Management_Proposal_for_ATA-ACS2.doc
 * http://www.seagate.com/staticfiles/support/disc/manuals/
 *     Interface%20manuals/100293068c.pdf
 * The backend can optionally provide three extra XenBus attributes to
 * further optimize the discard functionality:
 * 'discard-aligment' - Devices that support discard functionality may
 * internally allocate space in units that are bigger than the exported
 * logical block size. The discard-alignment parameter indicates how many bytes
 * the beginning of the partition is offset from the internal allocation unit's
 * natural alignment.
 * 'discard-granularity'  - Devices that support discard functionality may
 * internally allocate space using units that are bigger than the logical block
 * size. The discard-granularity parameter indicates the size of the internal
 * allocation unit in bytes if reported by the device. Otherwise the
 * discard-granularity will be set to match the device's physical block size.
 * 'discard-secure' - All copies of the discarded sectors (potentially created
 * by garbage collection) must also be erased.  To use this feature, the flag
 * BLKIF_DISCARD_SECURE must be set in the blkif_request_trim.
 */
#define BLKIF_OP_DISCARD           5

/*
 * Maximum scatter/gather segments per request.
 * This is carefully chosen so that sizeof(struct blkif_ring) <= PAGE_SIZE.
 * NB. This could be 12 if the ring indexes weren't stored in the same page.
 */
#define BLKIF_MAX_SEGMENTS_PER_REQUEST 11

struct blkif_request_rw {
	uint8_t        nr_segments;  /* number of segments                   */
	blkif_vdev_t   handle;       /* only for read/write requests         */
#ifdef CONFIG_X86_64
	uint32_t       _pad1;	     /* offsetof(blkif_request,u.rw.id) == 8 */
#endif
	uint64_t       id;           /* private guest value, echoed in resp  */
	blkif_sector_t sector_number;/* start sector idx on disk (r/w only)  */
	struct blkif_request_segment {
		grant_ref_t gref;        /* reference to I/O buffer frame        */
		/* @first_sect: first sector in frame to transfer (inclusive).   */
		/* @last_sect: last sector in frame to transfer (inclusive).     */
		uint8_t     first_sect, last_sect;
	} seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
} __attribute__((__packed__));

struct blkif_request_discard {
	uint8_t        flag;         /* BLKIF_DISCARD_SECURE or zero.        */
#define BLKIF_DISCARD_SECURE (1<<0)  /* ignored if discard-secure=0          */
	blkif_vdev_t   _pad1;        /* only for read/write requests         */
#ifdef CONFIG_X86_64
	uint32_t       _pad2;        /* offsetof(blkif_req..,u.discard.id)==8*/
#endif
	uint64_t       id;           /* private guest value, echoed in resp  */
	blkif_sector_t sector_number;
	uint64_t       nr_sectors;
	uint8_t        _pad3;
} __attribute__((__packed__));

struct blkif_request_other {
	uint8_t      _pad1;
	blkif_vdev_t _pad2;        /* only for read/write requests         */
#ifdef CONFIG_X86_64
	uint32_t     _pad3;        /* offsetof(blkif_req..,u.other.id)==8*/
#endif
	uint64_t     id;           /* private guest value, echoed in resp  */
} __attribute__((__packed__));

struct blkif_request {
	uint8_t        operation;    /* BLKIF_OP_???                         */
	union {
		struct blkif_request_rw rw;
		struct blkif_request_discard discard;
		struct blkif_request_other other;
	} u;
} __attribute__((__packed__));

struct blkif_response {
	uint64_t        id;              /* copied from request */
	uint8_t         operation;       /* copied from request */
	int16_t         status;          /* BLKIF_RSP_???       */
};

/*
 * STATUS RETURN CODES.
 */
 /* Operation not supported (only happens on barrier writes). */
#define BLKIF_RSP_EOPNOTSUPP  -2
 /* Operation failed for some unspecified reason (-EIO). */
#define BLKIF_RSP_ERROR       -1
 /* Operation completed successfully. */
#define BLKIF_RSP_OKAY         0

/*
 * Generate blkif ring structures and types.
 */

DEFINE_RING_TYPES(blkif, struct blkif_request, struct blkif_response);

#define VDISK_CDROM        0x1
#define VDISK_REMOVABLE    0x2
#define VDISK_READONLY     0x4

/* Xen-defined major numbers for virtual disks, they look strangely
 * familiar */
#define XEN_IDE0_MAJOR	3
#define XEN_IDE1_MAJOR	22
#define XEN_SCSI_DISK0_MAJOR	8
#define XEN_SCSI_DISK1_MAJOR	65
#define XEN_SCSI_DISK2_MAJOR	66
#define XEN_SCSI_DISK3_MAJOR	67
#define XEN_SCSI_DISK4_MAJOR	68
#define XEN_SCSI_DISK5_MAJOR	69
#define XEN_SCSI_DISK6_MAJOR	70
#define XEN_SCSI_DISK7_MAJOR	71
#define XEN_SCSI_DISK8_MAJOR	128
#define XEN_SCSI_DISK9_MAJOR	129
#define XEN_SCSI_DISK10_MAJOR	130
#define XEN_SCSI_DISK11_MAJOR	131
#define XEN_SCSI_DISK12_MAJOR	132
#define XEN_SCSI_DISK13_MAJOR	133
#define XEN_SCSI_DISK14_MAJOR	134
#define XEN_SCSI_DISK15_MAJOR	135

#endif /* __XEN_PUBLIC_IO_BLKIF_H__ */
Commit	Line	Data
a42089dd JF	1	/******************************************************************************
	2	* blkif.h
	3	*
	4	* Unified block-device I/O interface for Xen guest OSes.
	5	*
	6	* Copyright (c) 2003-2004, Keir Fraser
	7	*/
	8
	9	#ifndef __XEN_PUBLIC_IO_BLKIF_H__
	10	#define __XEN_PUBLIC_IO_BLKIF_H__
	11
a1ce3928 DH	12	#include <xen/interface/io/ring.h>
a1ce3928 DH	13	#include <xen/interface/grant_table.h>
a42089dd JF	14
	15	/*
	16	* Front->back notifications: When enqueuing a new request, sending a
	17	* notification can be made conditional on req_event (i.e., the generic
	18	* hold-off mechanism provided by the ring macros). Backends must set
	19	* req_event appropriately (e.g., using RING_FINAL_CHECK_FOR_REQUESTS()).
	20	*
	21	* Back->front notifications: When enqueuing a new response, sending a
	22	* notification can be made conditional on rsp_event (i.e., the generic
	23	* hold-off mechanism provided by the ring macros). Frontends must set
	24	* rsp_event appropriately (e.g., using RING_FINAL_CHECK_FOR_RESPONSES()).
	25	*/
	26
	27	typedef uint16_t blkif_vdev_t;
	28	typedef uint64_t blkif_sector_t;
	29
	30	/*
	31	* REQUEST CODES.
	32	*/
	33	#define BLKIF_OP_READ 0
	34	#define BLKIF_OP_WRITE 1
	35	/*
	36	* Recognised only if "feature-barrier" is present in backend xenbus info.
	37	* The "feature_barrier" node contains a boolean indicating whether barrier
	38	* requests are likely to succeed or fail. Either way, a barrier request
	39	* may fail at any time with BLKIF_RSP_EOPNOTSUPP if it is unsupported by
	40	* the underlying block-device hardware. The boolean simply indicates whether
	41	* or not it is worthwhile for the frontend to attempt barrier requests.
	42	* If a backend does not recognise BLKIF_OP_WRITE_BARRIER, it should not
	43	* create the "feature-barrier" node!
	44	*/
	45	#define BLKIF_OP_WRITE_BARRIER 2
	46
6dcfb751 KRW	47	/*
	48	* Recognised if "feature-flush-cache" is present in backend xenbus
	49	* info. A flush will ask the underlying storage hardware to flush its
	50	* non-volatile caches as appropriate. The "feature-flush-cache" node
	51	* contains a boolean indicating whether flush requests are likely to
	52	* succeed or fail. Either way, a flush request may fail at any time
	53	* with BLKIF_RSP_EOPNOTSUPP if it is unsupported by the underlying
	54	* block-device hardware. The boolean simply indicates whether or not it
	55	* is worthwhile for the frontend to attempt flushes. If a backend does
	56	* not recognise BLKIF_OP_WRITE_FLUSH_CACHE, it should not create the
	57	* "feature-flush-cache" node!
	58	*/
	59	#define BLKIF_OP_FLUSH_DISKCACHE 3
32a8d26c LD	60
	61	/*
	62	* Recognised only if "feature-discard" is present in backend xenbus info.
	63	* The "feature-discard" node contains a boolean indicating whether trim
	64	* (ATA) or unmap (SCSI) - conviently called discard requests are likely
	65	* to succeed or fail. Either way, a discard request
	66	* may fail at any time with BLKIF_RSP_EOPNOTSUPP if it is unsupported by
	67	* the underlying block-device hardware. The boolean simply indicates whether
	68	* or not it is worthwhile for the frontend to attempt discard requests.
	69	* If a backend does not recognise BLKIF_OP_DISCARD, it should not
	70	* create the "feature-discard" node!
	71	*
	72	* Discard operation is a request for the underlying block device to mark
	73	* extents to be erased. However, discard does not guarantee that the blocks
	74	* will be erased from the device - it is just a hint to the device
	75	* controller that these blocks are no longer in use. What the device
	76	* controller does with that information is left to the controller.
	77	* Discard operations are passed with sector_number as the
	78	* sector index to begin discard operations at and nr_sectors as the number of
	79	* sectors to be discarded. The specified sectors should be discarded if the
	80	* underlying block device supports trim (ATA) or unmap (SCSI) operations,
	81	* or a BLKIF_RSP_EOPNOTSUPP should be returned.
	82	* More information about trim/unmap operations at:
	83	* http://t13.org/Documents/UploadedDocuments/docs2008/
	84	* e07154r6-Data_Set_Management_Proposal_for_ATA-ACS2.doc
	85	* http://www.seagate.com/staticfiles/support/disc/manuals/
	86	* Interface%20manuals/100293068c.pdf
5ea42986 KRW	87	* The backend can optionally provide three extra XenBus attributes to
	88	* further optimize the discard functionality:
	89	* 'discard-aligment' - Devices that support discard functionality may
	90	* internally allocate space in units that are bigger than the exported
	91	* logical block size. The discard-alignment parameter indicates how many bytes
	92	* the beginning of the partition is offset from the internal allocation unit's
	93	* natural alignment.
	94	* 'discard-granularity' - Devices that support discard functionality may
	95	* internally allocate space using units that are bigger than the logical block
	96	* size. The discard-granularity parameter indicates the size of the internal
	97	* allocation unit in bytes if reported by the device. Otherwise the
	98	* discard-granularity will be set to match the device's physical block size.
	99	* 'discard-secure' - All copies of the discarded sectors (potentially created
	100	* by garbage collection) must also be erased. To use this feature, the flag
	101	* BLKIF_DISCARD_SECURE must be set in the blkif_request_trim.
32a8d26c LD	102	*/
	103	#define BLKIF_OP_DISCARD 5
	104
a42089dd JF	105	/*
	106	* Maximum scatter/gather segments per request.
	107	* This is carefully chosen so that sizeof(struct blkif_ring) <= PAGE_SIZE.
	108	* NB. This could be 12 if the ring indexes weren't stored in the same page.
	109	*/
	110	#define BLKIF_MAX_SEGMENTS_PER_REQUEST 11
	111
51de6952	112	struct blkif_request_rw {
97e36834 KRW	113	uint8_t nr_segments; /* number of segments */
	114	blkif_vdev_t handle; /* only for read/write requests */
	115	#ifdef CONFIG_X86_64
	116	uint32_t _pad1; /* offsetof(blkif_request,u.rw.id) == 8 */
	117	#endif
	118	uint64_t id; /* private guest value, echoed in resp */
a42089dd JF	119	blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */
	120	struct blkif_request_segment {
	121	grant_ref_t gref; /* reference to I/O buffer frame */
	122	/* @first_sect: first sector in frame to transfer (inclusive). */
	123	/* @last_sect: last sector in frame to transfer (inclusive). */
	124	uint8_t first_sect, last_sect;
	125	} seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
97e36834	126	} __attribute__((__packed__));
a42089dd	127
32a8d26c	128	struct blkif_request_discard {
5ea42986 KRW	129	uint8_t flag; /* BLKIF_DISCARD_SECURE or zero. */
5ea42986 KRW	130	#define BLKIF_DISCARD_SECURE (1<<0) /* ignored if discard-secure=0 */
97e36834 KRW	131	blkif_vdev_t _pad1; /* only for read/write requests */
	132	#ifdef CONFIG_X86_64
	133	uint32_t _pad2; /* offsetof(blkif_req..,u.discard.id)==8*/
	134	#endif
	135	uint64_t id; /* private guest value, echoed in resp */
32a8d26c	136	blkif_sector_t sector_number;
97e36834 KRW	137	uint64_t nr_sectors;
	138	uint8_t _pad3;
	139	} __attribute__((__packed__));
32a8d26c	140
0e367ae4 DV	141	struct blkif_request_other {
	142	uint8_t _pad1;
	143	blkif_vdev_t _pad2; /* only for read/write requests */
	144	#ifdef CONFIG_X86_64
	145	uint32_t _pad3; /* offsetof(blkif_req..,u.other.id)==8*/
	146	#endif
	147	uint64_t id; /* private guest value, echoed in resp */
	148	} __attribute__((__packed__));
	149
51de6952 OS	150	struct blkif_request {
51de6952 OS	151	uint8_t operation; /* BLKIF_OP_??? */
51de6952 OS	152	union {
51de6952 OS	153	struct blkif_request_rw rw;
32a8d26c	154	struct blkif_request_discard discard;
0e367ae4	155	struct blkif_request_other other;
51de6952	156	} u;
97e36834	157	} __attribute__((__packed__));
51de6952	158
a42089dd JF	159	struct blkif_response {
	160	uint64_t id; /* copied from request */
	161	uint8_t operation; /* copied from request */
	162	int16_t status; /* BLKIF_RSP_??? */
	163	};
	164
	165	/*
	166	* STATUS RETURN CODES.
	167	*/
	168	/* Operation not supported (only happens on barrier writes). */
	169	#define BLKIF_RSP_EOPNOTSUPP -2
	170	/* Operation failed for some unspecified reason (-EIO). */
	171	#define BLKIF_RSP_ERROR -1
	172	/* Operation completed successfully. */
	173	#define BLKIF_RSP_OKAY 0
	174
	175	/*
	176	* Generate blkif ring structures and types.
	177	*/
	178
	179	DEFINE_RING_TYPES(blkif, struct blkif_request, struct blkif_response);
	180
	181	#define VDISK_CDROM 0x1
	182	#define VDISK_REMOVABLE 0x2
	183	#define VDISK_READONLY 0x4
	184
c80a4209 SS	185	/* Xen-defined major numbers for virtual disks, they look strangely
	186	* familiar */
	187	#define XEN_IDE0_MAJOR 3
	188	#define XEN_IDE1_MAJOR 22
	189	#define XEN_SCSI_DISK0_MAJOR 8
	190	#define XEN_SCSI_DISK1_MAJOR 65
	191	#define XEN_SCSI_DISK2_MAJOR 66
	192	#define XEN_SCSI_DISK3_MAJOR 67
	193	#define XEN_SCSI_DISK4_MAJOR 68
	194	#define XEN_SCSI_DISK5_MAJOR 69
	195	#define XEN_SCSI_DISK6_MAJOR 70
	196	#define XEN_SCSI_DISK7_MAJOR 71
	197	#define XEN_SCSI_DISK8_MAJOR 128
	198	#define XEN_SCSI_DISK9_MAJOR 129
	199	#define XEN_SCSI_DISK10_MAJOR 130
	200	#define XEN_SCSI_DISK11_MAJOR 131
	201	#define XEN_SCSI_DISK12_MAJOR 132
	202	#define XEN_SCSI_DISK13_MAJOR 133
	203	#define XEN_SCSI_DISK14_MAJOR 134
	204	#define XEN_SCSI_DISK15_MAJOR 135
	205
a42089dd	206	#endif /* __XEN_PUBLIC_IO_BLKIF_H__ */