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