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 /* i386 protocol version */
  64 #pragma pack(push, 4)
  65
  66 struct blkif_x86_32_request_rw {
  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 };
  70
  71 struct blkif_x86_32_request_discard {
  72         blkif_sector_t sector_number;/* start sector idx on disk (r/w only)  */
  73         uint64_t nr_sectors;
  74 };
  75
  76 struct blkif_x86_32_request {
  77         uint8_t        operation;    /* BLKIF_OP_???                         */
  78         uint8_t        nr_segments;  /* number of segments                   */
  79         blkif_vdev_t   handle;       /* only for read/write requests         */
  80         uint64_t       id;           /* private guest value, echoed in resp  */
  81         union {
  82                 struct blkif_x86_32_request_rw rw;
  83                 struct blkif_x86_32_request_discard discard;
  84         } u;
  85 };
  86 struct blkif_x86_32_response {
  87         uint64_t        id;              /* copied from request */
  88         uint8_t         operation;       /* copied from request */
  89         int16_t         status;          /* BLKIF_RSP_???       */
  90 };
  91 #pragma pack(pop)
  92
  93 /* x86_64 protocol version */
  94
  95 struct blkif_x86_64_request_rw {
  96         blkif_sector_t sector_number;/* start sector idx on disk (r/w only)  */
  97         struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
  98 };
  99
 100 struct blkif_x86_64_request_discard {
 101         blkif_sector_t sector_number;/* start sector idx on disk (r/w only)  */
 102         uint64_t nr_sectors;
 103 };
 104
 105 struct blkif_x86_64_request {
 106         uint8_t        operation;    /* BLKIF_OP_???                         */
 107         uint8_t        nr_segments;  /* number of segments                   */
 108         blkif_vdev_t   handle;       /* only for read/write requests         */
 109         uint64_t       __attribute__((__aligned__(8))) id;
 110         union {
 111                 struct blkif_x86_64_request_rw rw;
 112                 struct blkif_x86_64_request_discard discard;
 113         } u;
 114 };
 115 struct blkif_x86_64_response {
 116         uint64_t       __attribute__((__aligned__(8))) id;
 117         uint8_t         operation;       /* copied from request */
 118         int16_t         status;          /* BLKIF_RSP_???       */
 119 };
 120
 121 DEFINE_RING_TYPES(blkif_common, struct blkif_common_request,
 122                   struct blkif_common_response);
 123 DEFINE_RING_TYPES(blkif_x86_32, struct blkif_x86_32_request,
 124                   struct blkif_x86_32_response);
 125 DEFINE_RING_TYPES(blkif_x86_64, struct blkif_x86_64_request,
 126                   struct blkif_x86_64_response);
 127
 128 union blkif_back_rings {
 129         struct blkif_back_ring        native;
 130         struct blkif_common_back_ring common;
 131         struct blkif_x86_32_back_ring x86_32;
 132         struct blkif_x86_64_back_ring x86_64;
 133 };
 134
 135 enum blkif_protocol {
 136         BLKIF_PROTOCOL_NATIVE = 1,
 137         BLKIF_PROTOCOL_X86_32 = 2,
 138         BLKIF_PROTOCOL_X86_64 = 3,
 139 };
 140
 141 enum blkif_backend_type {
 142         BLKIF_BACKEND_PHY  = 1,
 143         BLKIF_BACKEND_FILE = 2,
 144 };
 145
 146 struct xen_vbd {
 147         /* What the domain refers to this vbd as. */
 148         blkif_vdev_t            handle;
 149         /* Non-zero -> read-only */
 150         unsigned char           readonly;
 151         /* VDISK_xxx */
 152         unsigned char           type;
 153         /* phys device that this vbd maps to. */
 154         u32                     pdevice;
 155         struct block_device     *bdev;
 156         /* Cached size parameter. */
 157         sector_t                size;
 158         bool                    flush_support;
 159 };
 160
 161 struct backend_info;
 162
 163 struct xen_blkif {
 164         /* Unique identifier for this interface. */
 165         domid_t                 domid;
 166         unsigned int            handle;
 167         /* Physical parameters of the comms window. */
 168         unsigned int            irq;
 169         /* Comms information. */
 170         enum blkif_protocol     blk_protocol;
 171         enum blkif_backend_type blk_backend_type;
 172         union blkif_back_rings  blk_rings;
 173         void                    *blk_ring;
 174         /* The VBD attached to this interface. */
 175         struct xen_vbd          vbd;
 176         /* Back pointer to the backend_info. */
 177         struct backend_info     *be;
 178         /* Private fields. */
 179         spinlock_t              blk_ring_lock;
 180         atomic_t                refcnt;
 181
 182         wait_queue_head_t       wq;
 183         /* for barrier (drain) requests */
 184         struct completion       drain_complete;
 185         atomic_t                drain;
 186         /* One thread per one blkif. */
 187         struct task_struct      *xenblkd;
 188         unsigned int            waiting_reqs;
 189
 190         /* statistics */
 191         unsigned long           st_print;
 192         int                     st_rd_req;
 193         int                     st_wr_req;
 194         int                     st_oo_req;
 195         int                     st_f_req;
 196         int                     st_ds_req;
 197         int                     st_rd_sect;
 198         int                     st_wr_sect;
 199
 200         wait_queue_head_t       waiting_to_free;
 201 };
 202
 203
 204 #define vbd_sz(_v)      ((_v)->bdev->bd_part ? \
 205                          (_v)->bdev->bd_part->nr_sects : \
 206                           get_capacity((_v)->bdev->bd_disk))
 207
 208 #define xen_blkif_get(_b) (atomic_inc(&(_b)->refcnt))
 209 #define xen_blkif_put(_b)                               \
 210         do {                                            \
 211                 if (atomic_dec_and_test(&(_b)->refcnt)) \
 212                         wake_up(&(_b)->waiting_to_free);\
 213         } while (0)
 214
 215 struct phys_req {
 216         unsigned short          dev;
 217         blkif_sector_t          nr_sects;
 218         struct block_device     *bdev;
 219         blkif_sector_t          sector_number;
 220 };
 221 int xen_blkif_interface_init(void);
 222
 223 int xen_blkif_xenbus_init(void);
 224
 225 irqreturn_t xen_blkif_be_int(int irq, void *dev_id);
 226 int xen_blkif_schedule(void *arg);
 227
 228 int xen_blkbk_flush_diskcache(struct xenbus_transaction xbt,
 229                               struct backend_info *be, int state);
 230
 231 int xen_blkbk_barrier(struct xenbus_transaction xbt,
 232                       struct backend_info *be, int state);
 233 struct xenbus_device *xen_blkbk_xenbus(struct backend_info *be);
 234
 235 static inline void blkif_get_x86_32_req(struct blkif_request *dst,
 236                                         struct blkif_x86_32_request *src)
 237 {
 238         int i, n = BLKIF_MAX_SEGMENTS_PER_REQUEST;
 239         dst->operation = src->operation;
 240         dst->nr_segments = src->nr_segments;
 241         dst->handle = src->handle;
 242         dst->id = src->id;
 243         switch (src->operation) {
 244         case BLKIF_OP_READ:
 245         case BLKIF_OP_WRITE:
 246         case BLKIF_OP_WRITE_BARRIER:
 247         case BLKIF_OP_FLUSH_DISKCACHE:
 248                 dst->u.rw.sector_number = src->u.rw.sector_number;
 249                 barrier();
 250                 if (n > dst->nr_segments)
 251                         n = dst->nr_segments;
 252                 for (i = 0; i < n; i++)
 253                         dst->u.rw.seg[i] = src->u.rw.seg[i];
 254                 break;
 255         case BLKIF_OP_DISCARD:
 256                 dst->u.discard.sector_number = src->u.discard.sector_number;
 257                 dst->u.discard.nr_sectors = src->u.discard.nr_sectors;
 258                 break;
 259         default:
 260                 break;
 261         }
 262 }
 263
 264 static inline void blkif_get_x86_64_req(struct blkif_request *dst,
 265                                         struct blkif_x86_64_request *src)
 266 {
 267         int i, n = BLKIF_MAX_SEGMENTS_PER_REQUEST;
 268         dst->operation = src->operation;
 269         dst->nr_segments = src->nr_segments;
 270         dst->handle = src->handle;
 271         dst->id = src->id;
 272         switch (src->operation) {
 273         case BLKIF_OP_READ:
 274         case BLKIF_OP_WRITE:
 275         case BLKIF_OP_WRITE_BARRIER:
 276         case BLKIF_OP_FLUSH_DISKCACHE:
 277                 dst->u.rw.sector_number = src->u.rw.sector_number;
 278                 barrier();
 279                 if (n > dst->nr_segments)
 280                         n = dst->nr_segments;
 281                 for (i = 0; i < n; i++)
 282                         dst->u.rw.seg[i] = src->u.rw.seg[i];
 283                 break;
 284         case BLKIF_OP_DISCARD:
 285                 dst->u.discard.sector_number = src->u.discard.sector_number;
 286                 dst->u.discard.nr_sectors = src->u.discard.nr_sectors;
 287                 break;
 288         default:
 289                 break;
 290         }
 291 }
 292
 293 #endif /* __XEN_BLKIF__BACKEND__COMMON_H__ */