drivers/block/xen-blkback/common.h

   1 /*
   2  * This program is free software; you can redistribute it and/or
   3  * modify it under the terms of the GNU General Public License version 2
   4  * as published by the Free Software Foundation; or, when distributed
   5  * separately from the Linux kernel or incorporated into other
   6  * software packages, subject to the following license:
   7  *
   8  * Permission is hereby granted, free of charge, to any person obtaining a copy
   9  * of this source file (the "Software"), to deal in the Software without
  10  * restriction, including without limitation the rights to use, copy, modify,
  11  * merge, publish, distribute, sublicense, and/or sell copies of the Software,
  12  * and to permit persons to whom the Software is furnished to do so, subject to
  13  * the following conditions:
  14  *
  15  * The above copyright notice and this permission notice shall be included in
  16  * all copies or substantial portions of the Software.
  17  *
  18  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  19  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  20  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  21  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  22  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  23  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  24  * IN THE SOFTWARE.
  25  */
  26
  27 #ifndef __XEN_BLKIF__BACKEND__COMMON_H__
  28 #define __XEN_BLKIF__BACKEND__COMMON_H__
  29
  30 #include <linux/module.h>
  31 #include <linux/interrupt.h>
  32 #include <linux/slab.h>
  33 #include <linux/blkdev.h>
  34 #include <linux/vmalloc.h>
  35 #include <linux/wait.h>
  36 #include <linux/io.h>
  37 #include <asm/setup.h>
  38 #include <asm/pgalloc.h>
  39 #include <asm/hypervisor.h>
  40 #include <xen/grant_table.h>
  41 #include <xen/xenbus.h>
  42 #include <xen/interface/io/ring.h>
  43 #include <xen/interface/io/blkif.h>
  44 #include <xen/interface/io/protocols.h>
  45
  46 #define DRV_PFX "xen-blkback:"
  47 #define DPRINTK(fmt, args...)                           \
  48         pr_debug(DRV_PFX "(%s:%d) " fmt ".\n",          \
  49                  __func__, __LINE__, ##args)
  50
  51
  52 /* Not a real protocol.  Used to generate ring structs which contain
  53  * the elements common to all protocols only.  This way we get a
  54  * compiler-checkable way to use common struct elements, so we can
  55  * avoid using switch(protocol) in a number of places.  */
  56 struct blkif_common_request {
  57         char dummy;
  58 };
  59 struct blkif_common_response {
  60         char dummy;
  61 };
  62
  63 struct blkif_x86_32_request_rw {
  64         uint8_t        nr_segments;  /* number of segments                   */
  65         blkif_vdev_t   handle;       /* only for read/write requests         */
  66         uint64_t       id;           /* private guest value, echoed in resp  */
  67         blkif_sector_t sector_number;/* start sector idx on disk (r/w only)  */
  68         struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
  69 } __attribute__((__packed__));
  70
  71 struct blkif_x86_32_request_discard {
  72         uint8_t        flag;         /* BLKIF_DISCARD_SECURE or zero         */
  73         blkif_vdev_t   _pad1;        /* was "handle" for read/write requests */
  74         uint64_t       id;           /* private guest value, echoed in resp  */
  75         blkif_sector_t sector_number;/* start sector idx on disk (r/w only)  */
  76         uint64_t       nr_sectors;
  77 } __attribute__((__packed__));
  78
  79 struct blkif_x86_32_request {
  80         uint8_t        operation;    /* BLKIF_OP_???                         */
  81         union {
  82                 struct blkif_x86_32_request_rw rw;
  83                 struct blkif_x86_32_request_discard discard;
  84         } u;
  85 } __attribute__((__packed__));
  86
  87 /* i386 protocol version */
  88 #pragma pack(push, 4)
  89 struct blkif_x86_32_response {
  90         uint64_t        id;              /* copied from request */
  91         uint8_t         operation;       /* copied from request */
  92         int16_t         status;          /* BLKIF_RSP_???       */
  93 };
  94 #pragma pack(pop)
  95 /* x86_64 protocol version */
  96
  97 struct blkif_x86_64_request_rw {
  98         uint8_t        nr_segments;  /* number of segments                   */
  99         blkif_vdev_t   handle;       /* only for read/write requests         */
 100         uint32_t       _pad1;        /* offsetof(blkif_reqest..,u.rw.id)==8  */
 101         uint64_t       id;
 102         blkif_sector_t sector_number;/* start sector idx on disk (r/w only)  */
 103         struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
 104 } __attribute__((__packed__));
 105
 106 struct blkif_x86_64_request_discard {
 107         uint8_t        flag;         /* BLKIF_DISCARD_SECURE or zero         */
 108         blkif_vdev_t   _pad1;        /* was "handle" for read/write requests */
 109         uint32_t       _pad2;        /* offsetof(blkif_..,u.discard.id)==8   */
 110         uint64_t       id;
 111         blkif_sector_t sector_number;/* start sector idx on disk (r/w only)  */
 112         uint64_t       nr_sectors;
 113 } __attribute__((__packed__));
 114
 115 struct blkif_x86_64_request {
 116         uint8_t        operation;    /* BLKIF_OP_???                         */
 117         union {
 118                 struct blkif_x86_64_request_rw rw;
 119                 struct blkif_x86_64_request_discard discard;
 120         } u;
 121 } __attribute__((__packed__));
 122
 123 struct blkif_x86_64_response {
 124         uint64_t       __attribute__((__aligned__(8))) id;
 125         uint8_t         operation;       /* copied from request */
 126         int16_t         status;          /* BLKIF_RSP_???       */
 127 };
 128
 129 DEFINE_RING_TYPES(blkif_common, struct blkif_common_request,
 130                   struct blkif_common_response);
 131 DEFINE_RING_TYPES(blkif_x86_32, struct blkif_x86_32_request,
 132                   struct blkif_x86_32_response);
 133 DEFINE_RING_TYPES(blkif_x86_64, struct blkif_x86_64_request,
 134                   struct blkif_x86_64_response);
 135
 136 union blkif_back_rings {
 137         struct blkif_back_ring        native;
 138         struct blkif_common_back_ring common;
 139         struct blkif_x86_32_back_ring x86_32;
 140         struct blkif_x86_64_back_ring x86_64;
 141 };
 142
 143 enum blkif_protocol {
 144         BLKIF_PROTOCOL_NATIVE = 1,
 145         BLKIF_PROTOCOL_X86_32 = 2,
 146         BLKIF_PROTOCOL_X86_64 = 3,
 147 };
 148
 149 enum blkif_backend_type {
 150         BLKIF_BACKEND_PHY  = 1,
 151         BLKIF_BACKEND_FILE = 2,
 152 };
 153
 154 struct xen_vbd {
 155         /* What the domain refers to this vbd as. */
 156         blkif_vdev_t            handle;
 157         /* Non-zero -> read-only */
 158         unsigned char           readonly;
 159         /* VDISK_xxx */
 160         unsigned char           type;
 161         /* phys device that this vbd maps to. */
 162         u32                     pdevice;
 163         struct block_device     *bdev;
 164         /* Cached size parameter. */
 165         sector_t                size;
 166         bool                    flush_support;
 167         bool                    discard_secure;
 168 };
 169
 170 struct backend_info;
 171
 172 struct xen_blkif {
 173         /* Unique identifier for this interface. */
 174         domid_t                 domid;
 175         unsigned int            handle;
 176         /* Physical parameters of the comms window. */
 177         unsigned int            irq;
 178         /* Comms information. */
 179         enum blkif_protocol     blk_protocol;
 180         enum blkif_backend_type blk_backend_type;
 181         union blkif_back_rings  blk_rings;
 182         void                    *blk_ring;
 183         /* The VBD attached to this interface. */
 184         struct xen_vbd          vbd;
 185         /* Back pointer to the backend_info. */
 186         struct backend_info     *be;
 187         /* Private fields. */
 188         spinlock_t              blk_ring_lock;
 189         atomic_t                refcnt;
 190
 191         wait_queue_head_t       wq;
 192         /* for barrier (drain) requests */
 193         struct completion       drain_complete;
 194         atomic_t                drain;
 195         /* One thread per one blkif. */
 196         struct task_struct      *xenblkd;
 197         unsigned int            waiting_reqs;
 198
 199         /* statistics */
 200         unsigned long           st_print;
 201         int                     st_rd_req;
 202         int                     st_wr_req;
 203         int                     st_oo_req;
 204         int                     st_f_req;
 205         int                     st_ds_req;
 206         int                     st_rd_sect;
 207         int                     st_wr_sect;
 208
 209         wait_queue_head_t       waiting_to_free;
 210 };
 211
 212
 213 #define vbd_sz(_v)      ((_v)->bdev->bd_part ? \
 214                          (_v)->bdev->bd_part->nr_sects : \
 215                           get_capacity((_v)->bdev->bd_disk))
 216
 217 #define xen_blkif_get(_b) (atomic_inc(&(_b)->refcnt))
 218 #define xen_blkif_put(_b)                               \
 219         do {                                            \
 220                 if (atomic_dec_and_test(&(_b)->refcnt)) \
 221                         wake_up(&(_b)->waiting_to_free);\
 222         } while (0)
 223
 224 struct phys_req {
 225         unsigned short          dev;
 226         blkif_sector_t          nr_sects;
 227         struct block_device     *bdev;
 228         blkif_sector_t          sector_number;
 229 };
 230 int xen_blkif_interface_init(void);
 231
 232 int xen_blkif_xenbus_init(void);
 233
 234 irqreturn_t xen_blkif_be_int(int irq, void *dev_id);
 235 int xen_blkif_schedule(void *arg);
 236
 237 int xen_blkbk_flush_diskcache(struct xenbus_transaction xbt,
 238                               struct backend_info *be, int state);
 239
 240 int xen_blkbk_barrier(struct xenbus_transaction xbt,
 241                       struct backend_info *be, int state);
 242 struct xenbus_device *xen_blkbk_xenbus(struct backend_info *be);
 243
 244 static inline void blkif_get_x86_32_req(struct blkif_request *dst,
 245                                         struct blkif_x86_32_request *src)
 246 {
 247         int i, n = BLKIF_MAX_SEGMENTS_PER_REQUEST;
 248         dst->operation = src->operation;
 249         switch (src->operation) {
 250         case BLKIF_OP_READ:
 251         case BLKIF_OP_WRITE:
 252         case BLKIF_OP_WRITE_BARRIER:
 253         case BLKIF_OP_FLUSH_DISKCACHE:
 254                 dst->u.rw.nr_segments = src->u.rw.nr_segments;
 255                 dst->u.rw.handle = src->u.rw.handle;
 256                 dst->u.rw.id = src->u.rw.id;
 257                 dst->u.rw.sector_number = src->u.rw.sector_number;
 258                 barrier();
 259                 if (n > dst->u.rw.nr_segments)
 260                         n = dst->u.rw.nr_segments;
 261                 for (i = 0; i < n; i++)
 262                         dst->u.rw.seg[i] = src->u.rw.seg[i];
 263                 break;
 264         case BLKIF_OP_DISCARD:
 265                 dst->u.discard.flag = src->u.discard.flag;
 266                 dst->u.discard.sector_number = src->u.discard.sector_number;
 267                 dst->u.discard.nr_sectors = src->u.discard.nr_sectors;
 268                 break;
 269         default:
 270                 break;
 271         }
 272 }
 273
 274 static inline void blkif_get_x86_64_req(struct blkif_request *dst,
 275                                         struct blkif_x86_64_request *src)
 276 {
 277         int i, n = BLKIF_MAX_SEGMENTS_PER_REQUEST;
 278         dst->operation = src->operation;
 279         switch (src->operation) {
 280         case BLKIF_OP_READ:
 281         case BLKIF_OP_WRITE:
 282         case BLKIF_OP_WRITE_BARRIER:
 283         case BLKIF_OP_FLUSH_DISKCACHE:
 284                 dst->u.rw.nr_segments = src->u.rw.nr_segments;
 285                 dst->u.rw.handle = src->u.rw.handle;
 286                 dst->u.rw.id = src->u.rw.id;
 287                 dst->u.rw.sector_number = src->u.rw.sector_number;
 288                 barrier();
 289                 if (n > dst->u.rw.nr_segments)
 290                         n = dst->u.rw.nr_segments;
 291                 for (i = 0; i < n; i++)
 292                         dst->u.rw.seg[i] = src->u.rw.seg[i];
 293                 break;
 294         case BLKIF_OP_DISCARD:
 295                 dst->u.discard.flag = src->u.discard.flag;
 296                 dst->u.discard.sector_number = src->u.discard.sector_number;
 297                 dst->u.discard.nr_sectors = src->u.discard.nr_sectors;
 298                 break;
 299         default:
 300                 break;
 301         }
 302 }
 303
 304 #endif /* __XEN_BLKIF__BACKEND__COMMON_H__ */