hw/block/xen_blkif.h

   1 #ifndef __XEN_BLKIF_H__
   2 #define __XEN_BLKIF_H__
   3
   4 #include <xen/io/ring.h>
   5 #include <xen/io/blkif.h>
   6 #include <xen/io/protocols.h>
   7
   8 /*
   9  * Not a real protocol.  Used to generate ring structs which contain
  10  * the elements common to all protocols only.  This way we get a
  11  * compiler-checkable way to use common struct elements, so we can
  12  * avoid using switch(protocol) in a number of places.
  13  */
  14 struct blkif_common_request {
  15     char dummy;
  16 };
  17 struct blkif_common_response {
  18     char dummy;
  19 };
  20
  21 /* i386 protocol version */
  22 #pragma pack(push, 4)
  23 struct blkif_x86_32_request {
  24     uint8_t        operation;        /* BLKIF_OP_???                         */
  25     uint8_t        nr_segments;      /* number of segments                   */
  26     blkif_vdev_t   handle;           /* only for read/write requests         */
  27     uint64_t       id;               /* private guest value, echoed in resp  */
  28     blkif_sector_t sector_number;    /* start sector idx on disk (r/w only)  */
  29     struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
  30 };
  31 struct blkif_x86_32_request_discard {
  32     uint8_t        operation;        /* BLKIF_OP_DISCARD                     */
  33     uint8_t        flag;             /* nr_segments in request struct        */
  34     blkif_vdev_t   handle;           /* only for read/write requests         */
  35     uint64_t       id;               /* private guest value, echoed in resp  */
  36     blkif_sector_t sector_number;    /* start sector idx on disk (r/w only)  */
  37     uint64_t       nr_sectors;       /* # of contiguous sectors to discard   */
  38 };
  39 struct blkif_x86_32_response {
  40     uint64_t        id;              /* copied from request */
  41     uint8_t         operation;       /* copied from request */
  42     int16_t         status;          /* BLKIF_RSP_???       */
  43 };
  44 typedef struct blkif_x86_32_request blkif_x86_32_request_t;
  45 typedef struct blkif_x86_32_response blkif_x86_32_response_t;
  46 #pragma pack(pop)
  47
  48 /* x86_64 protocol version */
  49 struct blkif_x86_64_request {
  50     uint8_t        operation;        /* BLKIF_OP_???                         */
  51     uint8_t        nr_segments;      /* number of segments                   */
  52     blkif_vdev_t   handle;           /* only for read/write requests         */
  53     uint64_t       __attribute__((__aligned__(8))) id;
  54     blkif_sector_t sector_number;    /* start sector idx on disk (r/w only)  */
  55     struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
  56 };
  57 struct blkif_x86_64_request_discard {
  58     uint8_t        operation;        /* BLKIF_OP_DISCARD                     */
  59     uint8_t        flag;             /* nr_segments in request struct        */
  60     blkif_vdev_t   handle;           /* only for read/write requests         */
  61     uint64_t       __attribute__((__aligned__(8))) id;
  62     blkif_sector_t sector_number;    /* start sector idx on disk (r/w only)  */
  63     uint64_t       nr_sectors;       /* # of contiguous sectors to discard   */
  64 };
  65 struct blkif_x86_64_response {
  66     uint64_t       __attribute__((__aligned__(8))) id;
  67     uint8_t         operation;       /* copied from request */
  68     int16_t         status;          /* BLKIF_RSP_???       */
  69 };
  70 typedef struct blkif_x86_64_request blkif_x86_64_request_t;
  71 typedef struct blkif_x86_64_response blkif_x86_64_response_t;
  72
  73 DEFINE_RING_TYPES(blkif_common, struct blkif_common_request,
  74                   struct blkif_common_response);
  75 DEFINE_RING_TYPES(blkif_x86_32, struct blkif_x86_32_request,
  76                   struct blkif_x86_32_response);
  77 DEFINE_RING_TYPES(blkif_x86_64, struct blkif_x86_64_request,
  78                   struct blkif_x86_64_response);
  79
  80 union blkif_back_rings {
  81     blkif_back_ring_t        native;
  82     blkif_common_back_ring_t common;
  83     blkif_x86_32_back_ring_t x86_32_part;
  84     blkif_x86_64_back_ring_t x86_64_part;
  85 };
  86 typedef union blkif_back_rings blkif_back_rings_t;
  87
  88 enum blkif_protocol {
  89     BLKIF_PROTOCOL_NATIVE = 1,
  90     BLKIF_PROTOCOL_X86_32 = 2,
  91     BLKIF_PROTOCOL_X86_64 = 3,
  92 };
  93
  94 static inline void blkif_get_x86_32_req(blkif_request_t *dst,
  95                                         blkif_x86_32_request_t *src)
  96 {
  97     int i, n = BLKIF_MAX_SEGMENTS_PER_REQUEST;
  98
  99     dst->operation = src->operation;
 100     dst->nr_segments = src->nr_segments;
 101     dst->handle = src->handle;
 102     dst->id = src->id;
 103     dst->sector_number = src->sector_number;
 104     /* Prevent the compiler from using src->... instead. */
 105     barrier();
 106     if (dst->operation == BLKIF_OP_DISCARD) {
 107         struct blkif_x86_32_request_discard *s = (void *)src;
 108         struct blkif_request_discard *d = (void *)dst;
 109         d->nr_sectors = s->nr_sectors;
 110         return;
 111     }
 112     if (n > dst->nr_segments) {
 113         n = dst->nr_segments;
 114     }
 115     for (i = 0; i < n; i++) {
 116         dst->seg[i] = src->seg[i];
 117     }
 118 }
 119
 120 static inline void blkif_get_x86_64_req(blkif_request_t *dst,
 121                                         blkif_x86_64_request_t *src)
 122 {
 123     int i, n = BLKIF_MAX_SEGMENTS_PER_REQUEST;
 124
 125     dst->operation = src->operation;
 126     dst->nr_segments = src->nr_segments;
 127     dst->handle = src->handle;
 128     dst->id = src->id;
 129     dst->sector_number = src->sector_number;
 130     /* Prevent the compiler from using src->... instead. */
 131     barrier();
 132     if (dst->operation == BLKIF_OP_DISCARD) {
 133         struct blkif_x86_64_request_discard *s = (void *)src;
 134         struct blkif_request_discard *d = (void *)dst;
 135         d->nr_sectors = s->nr_sectors;
 136         return;
 137     }
 138     if (n > dst->nr_segments) {
 139         n = dst->nr_segments;
 140     }
 141     for (i = 0; i < n; i++) {
 142         dst->seg[i] = src->seg[i];
 143     }
 144 }
 145
 146 #endif /* __XEN_BLKIF_H__ */