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_response {
  32     uint64_t        id;              /* copied from request */
  33     uint8_t         operation;       /* copied from request */
  34     int16_t         status;          /* BLKIF_RSP_???       */
  35 };
  36 typedef struct blkif_x86_32_request blkif_x86_32_request_t;
  37 typedef struct blkif_x86_32_response blkif_x86_32_response_t;
  38 #pragma pack(pop)
  39
  40 /* x86_64 protocol version */
  41 struct blkif_x86_64_request {
  42     uint8_t        operation;        /* BLKIF_OP_???                         */
  43     uint8_t        nr_segments;      /* number of segments                   */
  44     blkif_vdev_t   handle;           /* only for read/write requests         */
  45     uint64_t       __attribute__((__aligned__(8))) id;
  46     blkif_sector_t sector_number;    /* start sector idx on disk (r/w only)  */
  47     struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
  48 };
  49 struct blkif_x86_64_response {
  50     uint64_t       __attribute__((__aligned__(8))) id;
  51     uint8_t         operation;       /* copied from request */
  52     int16_t         status;          /* BLKIF_RSP_???       */
  53 };
  54 typedef struct blkif_x86_64_request blkif_x86_64_request_t;
  55 typedef struct blkif_x86_64_response blkif_x86_64_response_t;
  56
  57 DEFINE_RING_TYPES(blkif_common, struct blkif_common_request,
  58                   struct blkif_common_response);
  59 DEFINE_RING_TYPES(blkif_x86_32, struct blkif_x86_32_request,
  60                   struct blkif_x86_32_response);
  61 DEFINE_RING_TYPES(blkif_x86_64, struct blkif_x86_64_request,
  62                   struct blkif_x86_64_response);
  63
  64 union blkif_back_rings {
  65     blkif_back_ring_t        native;
  66     blkif_common_back_ring_t common;
  67     blkif_x86_32_back_ring_t x86_32_part;
  68     blkif_x86_64_back_ring_t x86_64_part;
  69 };
  70 typedef union blkif_back_rings blkif_back_rings_t;
  71
  72 enum blkif_protocol {
  73     BLKIF_PROTOCOL_NATIVE = 1,
  74     BLKIF_PROTOCOL_X86_32 = 2,
  75     BLKIF_PROTOCOL_X86_64 = 3,
  76 };
  77
  78 static inline void blkif_get_x86_32_req(blkif_request_t *dst,
  79                                         blkif_x86_32_request_t *src)
  80 {
  81     int i, n = BLKIF_MAX_SEGMENTS_PER_REQUEST;
  82
  83     dst->operation = src->operation;
  84     dst->nr_segments = src->nr_segments;
  85     dst->handle = src->handle;
  86     dst->id = src->id;
  87     dst->sector_number = src->sector_number;
  88     /* Prevent the compiler from using src->... instead. */
  89     barrier();
  90     if (dst->operation == BLKIF_OP_DISCARD) {
  91         struct blkif_request_discard *s = (void *)src;
  92         struct blkif_request_discard *d = (void *)dst;
  93         d->nr_sectors = s->nr_sectors;
  94         return;
  95     }
  96     if (n > dst->nr_segments) {
  97         n = dst->nr_segments;
  98     }
  99     for (i = 0; i < n; i++) {
 100         dst->seg[i] = src->seg[i];
 101     }
 102 }
 103
 104 static inline void blkif_get_x86_64_req(blkif_request_t *dst,
 105                                         blkif_x86_64_request_t *src)
 106 {
 107     int i, n = BLKIF_MAX_SEGMENTS_PER_REQUEST;
 108
 109     dst->operation = src->operation;
 110     dst->nr_segments = src->nr_segments;
 111     dst->handle = src->handle;
 112     dst->id = src->id;
 113     dst->sector_number = src->sector_number;
 114     /* Prevent the compiler from using src->... instead. */
 115     barrier();
 116     if (dst->operation == BLKIF_OP_DISCARD) {
 117         struct blkif_request_discard *s = (void *)src;
 118         struct blkif_request_discard *d = (void *)dst;
 119         d->nr_sectors = s->nr_sectors;
 120         return;
 121     }
 122     if (n > dst->nr_segments) {
 123         n = dst->nr_segments;
 124     }
 125     for (i = 0; i < n; i++) {
 126         dst->seg[i] = src->seg[i];
 127     }
 128 }
 129
 130 #endif /* __XEN_BLKIF_H__ */