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 <linux/rbtree.h>
  38 #include <asm/setup.h>
  39 #include <asm/pgalloc.h>
  40 #include <asm/hypervisor.h>
  41 #include <xen/grant_table.h>
  42 #include <xen/xenbus.h>
  43 #include <xen/interface/io/ring.h>
  44 #include <xen/interface/io/blkif.h>
  45 #include <xen/interface/io/protocols.h>
  46
  47 #define DRV_PFX "xen-blkback:"
  48 #define DPRINTK(fmt, args...)                           \
  49         pr_debug(DRV_PFX "(%s:%d) " fmt ".\n",          \
  50                  __func__, __LINE__, ##args)
  51
  52
  53 /* Not a real protocol.  Used to generate ring structs which contain
  54  * the elements common to all protocols only.  This way we get a
  55  * compiler-checkable way to use common struct elements, so we can
  56  * avoid using switch(protocol) in a number of places.  */
  57 struct blkif_common_request {
  58         char dummy;
  59 };
  60 struct blkif_common_response {
  61         char dummy;
  62 };
  63
  64 struct blkif_x86_32_request_rw {
  65         uint8_t        nr_segments;  /* number of segments                   */
  66         blkif_vdev_t   handle;       /* only for read/write requests         */
  67         uint64_t       id;           /* private guest value, echoed in resp  */
  68         blkif_sector_t sector_number;/* start sector idx on disk (r/w only)  */
  69         struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
  70 } __attribute__((__packed__));
  71
  72 struct blkif_x86_32_request_discard {
  73         uint8_t        flag;         /* BLKIF_DISCARD_SECURE or zero         */
  74         blkif_vdev_t   _pad1;        /* was "handle" for read/write requests */
  75         uint64_t       id;           /* private guest value, echoed in resp  */
  76         blkif_sector_t sector_number;/* start sector idx on disk (r/w only)  */
  77         uint64_t       nr_sectors;
  78 } __attribute__((__packed__));
  79
  80 struct blkif_x86_32_request_other {
  81         uint8_t        _pad1;
  82         blkif_vdev_t   _pad2;
  83         uint64_t       id;           /* private guest value, echoed in resp  */
  84 } __attribute__((__packed__));
  85
  86 struct blkif_x86_32_request {
  87         uint8_t        operation;    /* BLKIF_OP_???                         */
  88         union {
  89                 struct blkif_x86_32_request_rw rw;
  90                 struct blkif_x86_32_request_discard discard;
  91                 struct blkif_x86_32_request_other other;
  92         } u;
  93 } __attribute__((__packed__));
  94
  95 /* i386 protocol version */
  96 #pragma pack(push, 4)
  97 struct blkif_x86_32_response {
  98         uint64_t        id;              /* copied from request */
  99         uint8_t         operation;       /* copied from request */
 100         int16_t         status;          /* BLKIF_RSP_???       */
 101 };
 102 #pragma pack(pop)
 103 /* x86_64 protocol version */
 104
 105 struct blkif_x86_64_request_rw {
 106         uint8_t        nr_segments;  /* number of segments                   */
 107         blkif_vdev_t   handle;       /* only for read/write requests         */
 108         uint32_t       _pad1;        /* offsetof(blkif_reqest..,u.rw.id)==8  */
 109         uint64_t       id;
 110         blkif_sector_t sector_number;/* start sector idx on disk (r/w only)  */
 111         struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
 112 } __attribute__((__packed__));
 113
 114 struct blkif_x86_64_request_discard {
 115         uint8_t        flag;         /* BLKIF_DISCARD_SECURE or zero         */
 116         blkif_vdev_t   _pad1;        /* was "handle" for read/write requests */
 117         uint32_t       _pad2;        /* offsetof(blkif_..,u.discard.id)==8   */
 118         uint64_t       id;
 119         blkif_sector_t sector_number;/* start sector idx on disk (r/w only)  */
 120         uint64_t       nr_sectors;
 121 } __attribute__((__packed__));
 122
 123 struct blkif_x86_64_request_other {
 124         uint8_t        _pad1;
 125         blkif_vdev_t   _pad2;
 126         uint32_t       _pad3;        /* offsetof(blkif_..,u.discard.id)==8   */
 127         uint64_t       id;           /* private guest value, echoed in resp  */
 128 } __attribute__((__packed__));
 129
 130 struct blkif_x86_64_request {
 131         uint8_t        operation;    /* BLKIF_OP_???                         */
 132         union {
 133                 struct blkif_x86_64_request_rw rw;
 134                 struct blkif_x86_64_request_discard discard;
 135                 struct blkif_x86_64_request_other other;
 136         } u;
 137 } __attribute__((__packed__));
 138
 139 struct blkif_x86_64_response {
 140         uint64_t       __attribute__((__aligned__(8))) id;
 141         uint8_t         operation;       /* copied from request */
 142         int16_t         status;          /* BLKIF_RSP_???       */
 143 };
 144
 145 DEFINE_RING_TYPES(blkif_common, struct blkif_common_request,
 146                   struct blkif_common_response);
 147 DEFINE_RING_TYPES(blkif_x86_32, struct blkif_x86_32_request,
 148                   struct blkif_x86_32_response);
 149 DEFINE_RING_TYPES(blkif_x86_64, struct blkif_x86_64_request,
 150                   struct blkif_x86_64_response);
 151
 152 union blkif_back_rings {
 153         struct blkif_back_ring        native;
 154         struct blkif_common_back_ring common;
 155         struct blkif_x86_32_back_ring x86_32;
 156         struct blkif_x86_64_back_ring x86_64;
 157 };
 158
 159 enum blkif_protocol {
 160         BLKIF_PROTOCOL_NATIVE = 1,
 161         BLKIF_PROTOCOL_X86_32 = 2,
 162         BLKIF_PROTOCOL_X86_64 = 3,
 163 };
 164
 165 struct xen_vbd {
 166         /* What the domain refers to this vbd as. */
 167         blkif_vdev_t            handle;
 168         /* Non-zero -> read-only */
 169         unsigned char           readonly;
 170         /* VDISK_xxx */
 171         unsigned char           type;
 172         /* phys device that this vbd maps to. */
 173         u32                     pdevice;
 174         struct block_device     *bdev;
 175         /* Cached size parameter. */
 176         sector_t                size;
 177         unsigned int            flush_support:1;
 178         unsigned int            discard_secure:1;
 179         unsigned int            feature_gnt_persistent:1;
 180         unsigned int            overflow_max_grants:1;
 181 };
 182
 183 struct backend_info;
 184
 185
 186 struct persistent_gnt {
 187         struct page *page;
 188         grant_ref_t gnt;
 189         grant_handle_t handle;
 190         struct rb_node node;
 191 };
 192
 193 struct xen_blkif {
 194         /* Unique identifier for this interface. */
 195         domid_t                 domid;
 196         unsigned int            handle;
 197         /* Physical parameters of the comms window. */
 198         unsigned int            irq;
 199         /* Comms information. */
 200         enum blkif_protocol     blk_protocol;
 201         union blkif_back_rings  blk_rings;
 202         void                    *blk_ring;
 203         /* The VBD attached to this interface. */
 204         struct xen_vbd          vbd;
 205         /* Back pointer to the backend_info. */
 206         struct backend_info     *be;
 207         /* Private fields. */
 208         spinlock_t              blk_ring_lock;
 209         atomic_t                refcnt;
 210
 211         wait_queue_head_t       wq;
 212         /* for barrier (drain) requests */
 213         struct completion       drain_complete;
 214         atomic_t                drain;
 215         /* One thread per one blkif. */
 216         struct task_struct      *xenblkd;
 217         unsigned int            waiting_reqs;
 218
 219         /* tree to store persistent grants */
 220         struct rb_root          persistent_gnts;
 221         unsigned int            persistent_gnt_c;
 222
 223         /* statistics */
 224         unsigned long           st_print;
 225         unsigned long long                      st_rd_req;
 226         unsigned long long                      st_wr_req;
 227         unsigned long long                      st_oo_req;
 228         unsigned long long                      st_f_req;
 229         unsigned long long                      st_ds_req;
 230         unsigned long long                      st_rd_sect;
 231         unsigned long long                      st_wr_sect;
 232
 233         wait_queue_head_t       waiting_to_free;
 234 };
 235
 236
 237 #define vbd_sz(_v)      ((_v)->bdev->bd_part ? \
 238                          (_v)->bdev->bd_part->nr_sects : \
 239                           get_capacity((_v)->bdev->bd_disk))
 240
 241 #define xen_blkif_get(_b) (atomic_inc(&(_b)->refcnt))
 242 #define xen_blkif_put(_b)                               \
 243         do {                                            \
 244                 if (atomic_dec_and_test(&(_b)->refcnt)) \
 245                         wake_up(&(_b)->waiting_to_free);\
 246         } while (0)
 247
 248 struct phys_req {
 249         unsigned short          dev;
 250         blkif_sector_t          nr_sects;
 251         struct block_device     *bdev;
 252         blkif_sector_t          sector_number;
 253 };
 254 int xen_blkif_interface_init(void);
 255
 256 int xen_blkif_xenbus_init(void);
 257
 258 irqreturn_t xen_blkif_be_int(int irq, void *dev_id);
 259 int xen_blkif_schedule(void *arg);
 260
 261 int xen_blkbk_flush_diskcache(struct xenbus_transaction xbt,
 262                               struct backend_info *be, int state);
 263
 264 int xen_blkbk_barrier(struct xenbus_transaction xbt,
 265                       struct backend_info *be, int state);
 266 struct xenbus_device *xen_blkbk_xenbus(struct backend_info *be);
 267
 268 static inline void blkif_get_x86_32_req(struct blkif_request *dst,
 269                                         struct blkif_x86_32_request *src)
 270 {
 271         int i, n = BLKIF_MAX_SEGMENTS_PER_REQUEST;
 272         dst->operation = src->operation;
 273         switch (src->operation) {
 274         case BLKIF_OP_READ:
 275         case BLKIF_OP_WRITE:
 276         case BLKIF_OP_WRITE_BARRIER:
 277         case BLKIF_OP_FLUSH_DISKCACHE:
 278                 dst->u.rw.nr_segments = src->u.rw.nr_segments;
 279                 dst->u.rw.handle = src->u.rw.handle;
 280                 dst->u.rw.id = src->u.rw.id;
 281                 dst->u.rw.sector_number = src->u.rw.sector_number;
 282                 barrier();
 283                 if (n > dst->u.rw.nr_segments)
 284                         n = dst->u.rw.nr_segments;
 285                 for (i = 0; i < n; i++)
 286                         dst->u.rw.seg[i] = src->u.rw.seg[i];
 287                 break;
 288         case BLKIF_OP_DISCARD:
 289                 dst->u.discard.flag = src->u.discard.flag;
 290                 dst->u.discard.id = src->u.discard.id;
 291                 dst->u.discard.sector_number = src->u.discard.sector_number;
 292                 dst->u.discard.nr_sectors = src->u.discard.nr_sectors;
 293                 break;
 294         default:
 295                 /*
 296                  * Don't know how to translate this op. Only get the
 297                  * ID so failure can be reported to the frontend.
 298                  */
 299                 dst->u.other.id = src->u.other.id;
 300                 break;
 301         }
 302 }
 303
 304 static inline void blkif_get_x86_64_req(struct blkif_request *dst,
 305                                         struct blkif_x86_64_request *src)
 306 {
 307         int i, n = BLKIF_MAX_SEGMENTS_PER_REQUEST;
 308         dst->operation = src->operation;
 309         switch (src->operation) {
 310         case BLKIF_OP_READ:
 311         case BLKIF_OP_WRITE:
 312         case BLKIF_OP_WRITE_BARRIER:
 313         case BLKIF_OP_FLUSH_DISKCACHE:
 314                 dst->u.rw.nr_segments = src->u.rw.nr_segments;
 315                 dst->u.rw.handle = src->u.rw.handle;
 316                 dst->u.rw.id = src->u.rw.id;
 317                 dst->u.rw.sector_number = src->u.rw.sector_number;
 318                 barrier();
 319                 if (n > dst->u.rw.nr_segments)
 320                         n = dst->u.rw.nr_segments;
 321                 for (i = 0; i < n; i++)
 322                         dst->u.rw.seg[i] = src->u.rw.seg[i];
 323                 break;
 324         case BLKIF_OP_DISCARD:
 325                 dst->u.discard.flag = src->u.discard.flag;
 326                 dst->u.discard.id = src->u.discard.id;
 327                 dst->u.discard.sector_number = src->u.discard.sector_number;
 328                 dst->u.discard.nr_sectors = src->u.discard.nr_sectors;
 329                 break;
 330         default:
 331                 /*
 332                  * Don't know how to translate this op. Only get the
 333                  * ID so failure can be reported to the frontend.
 334                  */
 335                 dst->u.other.id = src->u.other.id;
 336                 break;
 337         }
 338 }
 339
 340 #endif /* __XEN_BLKIF__BACKEND__COMMON_H__ */