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 struct xen_vbd {
 150         /* What the domain refers to this vbd as. */
 151         blkif_vdev_t            handle;
 152         /* Non-zero -> read-only */
 153         unsigned char           readonly;
 154         /* VDISK_xxx */
 155         unsigned char           type;
 156         /* phys device that this vbd maps to. */
 157         u32                     pdevice;
 158         struct block_device     *bdev;
 159         /* Cached size parameter. */
 160         sector_t                size;
 161         bool                    flush_support;
 162         bool                    discard_secure;
 163 };
 164
 165 struct backend_info;
 166
 167 struct xen_blkif {
 168         /* Unique identifier for this interface. */
 169         domid_t                 domid;
 170         unsigned int            handle;
 171         /* Physical parameters of the comms window. */
 172         unsigned int            irq;
 173         /* Comms information. */
 174         enum blkif_protocol     blk_protocol;
 175         union blkif_back_rings  blk_rings;
 176         void                    *blk_ring;
 177         /* The VBD attached to this interface. */
 178         struct xen_vbd          vbd;
 179         /* Back pointer to the backend_info. */
 180         struct backend_info     *be;
 181         /* Private fields. */
 182         spinlock_t              blk_ring_lock;
 183         atomic_t                refcnt;
 184
 185         wait_queue_head_t       wq;
 186         /* for barrier (drain) requests */
 187         struct completion       drain_complete;
 188         atomic_t                drain;
 189         /* One thread per one blkif. */
 190         struct task_struct      *xenblkd;
 191         unsigned int            waiting_reqs;
 192
 193         /* statistics */
 194         unsigned long           st_print;
 195         int                     st_rd_req;
 196         int                     st_wr_req;
 197         int                     st_oo_req;
 198         int                     st_f_req;
 199         int                     st_ds_req;
 200         int                     st_rd_sect;
 201         int                     st_wr_sect;
 202
 203         wait_queue_head_t       waiting_to_free;
 204 };
 205
 206
 207 #define vbd_sz(_v)      ((_v)->bdev->bd_part ? \
 208                          (_v)->bdev->bd_part->nr_sects : \
 209                           get_capacity((_v)->bdev->bd_disk))
 210
 211 #define xen_blkif_get(_b) (atomic_inc(&(_b)->refcnt))
 212 #define xen_blkif_put(_b)                               \
 213         do {                                            \
 214                 if (atomic_dec_and_test(&(_b)->refcnt)) \
 215                         wake_up(&(_b)->waiting_to_free);\
 216         } while (0)
 217
 218 struct phys_req {
 219         unsigned short          dev;
 220         blkif_sector_t          nr_sects;
 221         struct block_device     *bdev;
 222         blkif_sector_t          sector_number;
 223 };
 224 int xen_blkif_interface_init(void);
 225
 226 int xen_blkif_xenbus_init(void);
 227
 228 irqreturn_t xen_blkif_be_int(int irq, void *dev_id);
 229 int xen_blkif_schedule(void *arg);
 230
 231 int xen_blkbk_flush_diskcache(struct xenbus_transaction xbt,
 232                               struct backend_info *be, int state);
 233
 234 int xen_blkbk_barrier(struct xenbus_transaction xbt,
 235                       struct backend_info *be, int state);
 236 struct xenbus_device *xen_blkbk_xenbus(struct backend_info *be);
 237
 238 static inline void blkif_get_x86_32_req(struct blkif_request *dst,
 239                                         struct blkif_x86_32_request *src)
 240 {
 241         int i, n = BLKIF_MAX_SEGMENTS_PER_REQUEST;
 242         dst->operation = src->operation;
 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.nr_segments = src->u.rw.nr_segments;
 249                 dst->u.rw.handle = src->u.rw.handle;
 250                 dst->u.rw.id = src->u.rw.id;
 251                 dst->u.rw.sector_number = src->u.rw.sector_number;
 252                 barrier();
 253                 if (n > dst->u.rw.nr_segments)
 254                         n = dst->u.rw.nr_segments;
 255                 for (i = 0; i < n; i++)
 256                         dst->u.rw.seg[i] = src->u.rw.seg[i];
 257                 break;
 258         case BLKIF_OP_DISCARD:
 259                 dst->u.discard.flag = src->u.discard.flag;
 260                 dst->u.discard.id = src->u.discard.id;
 261                 dst->u.discard.sector_number = src->u.discard.sector_number;
 262                 dst->u.discard.nr_sectors = src->u.discard.nr_sectors;
 263                 break;
 264         default:
 265                 break;
 266         }
 267 }
 268
 269 static inline void blkif_get_x86_64_req(struct blkif_request *dst,
 270                                         struct blkif_x86_64_request *src)
 271 {
 272         int i, n = BLKIF_MAX_SEGMENTS_PER_REQUEST;
 273         dst->operation = src->operation;
 274         switch (src->operation) {
 275         case BLKIF_OP_READ:
 276         case BLKIF_OP_WRITE:
 277         case BLKIF_OP_WRITE_BARRIER:
 278         case BLKIF_OP_FLUSH_DISKCACHE:
 279                 dst->u.rw.nr_segments = src->u.rw.nr_segments;
 280                 dst->u.rw.handle = src->u.rw.handle;
 281                 dst->u.rw.id = src->u.rw.id;
 282                 dst->u.rw.sector_number = src->u.rw.sector_number;
 283                 barrier();
 284                 if (n > dst->u.rw.nr_segments)
 285                         n = dst->u.rw.nr_segments;
 286                 for (i = 0; i < n; i++)
 287                         dst->u.rw.seg[i] = src->u.rw.seg[i];
 288                 break;
 289         case BLKIF_OP_DISCARD:
 290                 dst->u.discard.flag = src->u.discard.flag;
 291                 dst->u.discard.id = src->u.discard.id;
 292                 dst->u.discard.sector_number = src->u.discard.sector_number;
 293                 dst->u.discard.nr_sectors = src->u.discard.nr_sectors;
 294                 break;
 295         default:
 296                 break;
 297         }
 298 }
 299
 300 #endif /* __XEN_BLKIF__BACKEND__COMMON_H__ */