diff options
Diffstat (limited to 'include/xen/interface/io/blkif.h')
| -rw-r--r-- | include/xen/interface/io/blkif.h | 79 |
1 files changed, 68 insertions, 11 deletions
diff --git a/include/xen/interface/io/blkif.h b/include/xen/interface/io/blkif.h index ee338bfde18..c33e1c489eb 100644 --- a/include/xen/interface/io/blkif.h +++ b/include/xen/interface/io/blkif.h @@ -9,8 +9,8 @@ #ifndef __XEN_PUBLIC_IO_BLKIF_H__ #define __XEN_PUBLIC_IO_BLKIF_H__ -#include "ring.h" -#include "../grant_table.h" +#include <xen/interface/io/ring.h> +#include <xen/interface/grant_table.h> /* * Front->back notifications: When enqueuing a new request, sending a @@ -86,7 +86,7 @@ typedef uint64_t blkif_sector_t; * 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 + * 'discard-alignment' - 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 @@ -103,33 +103,61 @@ typedef uint64_t blkif_sector_t; #define BLKIF_OP_DISCARD 5 /* + * Recognized if "feature-max-indirect-segments" in present in the backend + * xenbus info. The "feature-max-indirect-segments" node contains the maximum + * number of segments allowed by the backend per request. If the node is + * present, the frontend might use blkif_request_indirect structs in order to + * issue requests with more than BLKIF_MAX_SEGMENTS_PER_REQUEST (11). The + * maximum number of indirect segments is fixed by the backend, but the + * frontend can issue requests with any number of indirect segments as long as + * it's less than the number provided by the backend. The indirect_grefs field + * in blkif_request_indirect should be filled by the frontend with the + * grant references of the pages that are holding the indirect segments. + * These pages are filled with an array of blkif_request_segment that hold the + * information about the segments. The number of indirect pages to use is + * determined by the number of segments an indirect request contains. Every + * indirect page can contain a maximum of + * (PAGE_SIZE / sizeof(struct blkif_request_segment)) segments, so to + * calculate the number of indirect pages to use we have to do + * ceil(indirect_segments / (PAGE_SIZE / sizeof(struct blkif_request_segment))). + * + * If a backend does not recognize BLKIF_OP_INDIRECT, it should *not* + * create the "feature-max-indirect-segments" node! + */ +#define BLKIF_OP_INDIRECT 6 + +/* * 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 +#define BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST 8 + +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; +}; + struct blkif_request_rw { uint8_t nr_segments; /* number of segments */ blkif_vdev_t handle; /* only for read/write requests */ -#ifdef CONFIG_X86_64 +#ifndef CONFIG_X86_32 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]; + struct blkif_request_segment 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 +#ifndef CONFIG_X86_32 uint32_t _pad2; /* offsetof(blkif_req..,u.discard.id)==8*/ #endif uint64_t id; /* private guest value, echoed in resp */ @@ -138,11 +166,40 @@ struct blkif_request_discard { uint8_t _pad3; } __attribute__((__packed__)); +struct blkif_request_other { + uint8_t _pad1; + blkif_vdev_t _pad2; /* only for read/write requests */ +#ifndef CONFIG_X86_32 + 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_indirect { + uint8_t indirect_op; + uint16_t nr_segments; +#ifndef CONFIG_X86_32 + uint32_t _pad1; /* offsetof(blkif_...,u.indirect.id) == 8 */ +#endif + uint64_t id; + blkif_sector_t sector_number; + blkif_vdev_t handle; + uint16_t _pad2; + grant_ref_t indirect_grefs[BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST]; +#ifndef CONFIG_X86_32 + uint32_t _pad3; /* make it 64 byte aligned */ +#else + uint64_t _pad3; /* make it 64 byte aligned */ +#endif +} __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; + struct blkif_request_indirect indirect; } u; } __attribute__((__packed__)); |