kernel/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 /*
  48  * This is the maximum number of segments that would be allowed in indirect
  49  * requests. This value will also be passed to the frontend.
  50  */
  51 #define MAX_INDIRECT_SEGMENTS 256
  52
  53 #define SEGS_PER_INDIRECT_FRAME \
  54         (PAGE_SIZE/sizeof(struct blkif_request_segment))
  55 #define MAX_INDIRECT_PAGES \
  56         ((MAX_INDIRECT_SEGMENTS + SEGS_PER_INDIRECT_FRAME - 1)/SEGS_PER_INDIRECT_FRAME)
  57 #define INDIRECT_PAGES(_segs) \
  58         ((_segs + SEGS_PER_INDIRECT_FRAME - 1)/SEGS_PER_INDIRECT_FRAME)
  59
  60 /* Not a real protocol.  Used to generate ring structs which contain
  61  * the elements common to all protocols only.  This way we get a
  62  * compiler-checkable way to use common struct elements, so we can
  63  * avoid using switch(protocol) in a number of places.  */
  64 struct blkif_common_request {
  65         char dummy;
  66 };
  67 struct blkif_common_response {
  68         char dummy;
  69 };
  70
  71 struct blkif_x86_32_request_rw {
  72         uint8_t        nr_segments;  /* number of segments                   */
  73         blkif_vdev_t   handle;       /* only 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         struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
  77 } __attribute__((__packed__));
  78
  79 struct blkif_x86_32_request_discard {
  80         uint8_t        flag;         /* BLKIF_DISCARD_SECURE or zero         */
  81         blkif_vdev_t   _pad1;        /* was "handle" for read/write requests */
  82         uint64_t       id;           /* private guest value, echoed in resp  */
  83         blkif_sector_t sector_number;/* start sector idx on disk (r/w only)  */
  84         uint64_t       nr_sectors;
  85 } __attribute__((__packed__));
  86
  87 struct blkif_x86_32_request_other {
  88         uint8_t        _pad1;
  89         blkif_vdev_t   _pad2;
  90         uint64_t       id;           /* private guest value, echoed in resp  */
  91 } __attribute__((__packed__));
  92
  93 struct blkif_x86_32_request_indirect {
  94         uint8_t        indirect_op;
  95         uint16_t       nr_segments;
  96         uint64_t       id;
  97         blkif_sector_t sector_number;
  98         blkif_vdev_t   handle;
  99         uint16_t       _pad1;
 100         grant_ref_t    indirect_grefs[BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST];
 101         /*
 102          * The maximum number of indirect segments (and pages) that will
 103          * be used is determined by MAX_INDIRECT_SEGMENTS, this value
 104          * is also exported to the guest (via xenstore
 105          * feature-max-indirect-segments entry), so the frontend knows how
 106          * many indirect segments the backend supports.
 107          */
 108         uint64_t       _pad2;        /* make it 64 byte aligned */
 109 } __attribute__((__packed__));
 110
 111 struct blkif_x86_32_request {
 112         uint8_t        operation;    /* BLKIF_OP_???                         */
 113         union {
 114                 struct blkif_x86_32_request_rw rw;
 115                 struct blkif_x86_32_request_discard discard;
 116                 struct blkif_x86_32_request_other other;
 117                 struct blkif_x86_32_request_indirect indirect;
 118         } u;
 119 } __attribute__((__packed__));
 120
 121 /* i386 protocol version */
 122 #pragma pack(push, 4)
 123 struct blkif_x86_32_response {
 124         uint64_t        id;              /* copied from request */
 125         uint8_t         operation;       /* copied from request */
 126         int16_t         status;          /* BLKIF_RSP_???       */
 127 };
 128 #pragma pack(pop)
 129 /* x86_64 protocol version */
 130
 131 struct blkif_x86_64_request_rw {
 132         uint8_t        nr_segments;  /* number of segments                   */
 133         blkif_vdev_t   handle;       /* only for read/write requests         */
 134         uint32_t       _pad1;        /* offsetof(blkif_reqest..,u.rw.id)==8  */
 135         uint64_t       id;
 136         blkif_sector_t sector_number;/* start sector idx on disk (r/w only)  */
 137         struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
 138 } __attribute__((__packed__));
 139
 140 struct blkif_x86_64_request_discard {
 141         uint8_t        flag;         /* BLKIF_DISCARD_SECURE or zero         */
 142         blkif_vdev_t   _pad1;        /* was "handle" for read/write requests */
 143         uint32_t       _pad2;        /* offsetof(blkif_..,u.discard.id)==8   */
 144         uint64_t       id;
 145         blkif_sector_t sector_number;/* start sector idx on disk (r/w only)  */
 146         uint64_t       nr_sectors;
 147 } __attribute__((__packed__));
 148
 149 struct blkif_x86_64_request_other {
 150         uint8_t        _pad1;
 151         blkif_vdev_t   _pad2;
 152         uint32_t       _pad3;        /* offsetof(blkif_..,u.discard.id)==8   */
 153         uint64_t       id;           /* private guest value, echoed in resp  */
 154 } __attribute__((__packed__));
 155
 156 struct blkif_x86_64_request_indirect {
 157         uint8_t        indirect_op;
 158         uint16_t       nr_segments;
 159         uint32_t       _pad1;        /* offsetof(blkif_..,u.indirect.id)==8   */
 160         uint64_t       id;
 161         blkif_sector_t sector_number;
 162         blkif_vdev_t   handle;
 163         uint16_t       _pad2;
 164         grant_ref_t    indirect_grefs[BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST];
 165         /*
 166          * The maximum number of indirect segments (and pages) that will
 167          * be used is determined by MAX_INDIRECT_SEGMENTS, this value
 168          * is also exported to the guest (via xenstore
 169          * feature-max-indirect-segments entry), so the frontend knows how
 170          * many indirect segments the backend supports.
 171          */
 172         uint32_t       _pad3;        /* make it 64 byte aligned */
 173 } __attribute__((__packed__));
 174
 175 struct blkif_x86_64_request {
 176         uint8_t        operation;    /* BLKIF_OP_???                         */
 177         union {
 178                 struct blkif_x86_64_request_rw rw;
 179                 struct blkif_x86_64_request_discard discard;
 180                 struct blkif_x86_64_request_other other;
 181                 struct blkif_x86_64_request_indirect indirect;
 182         } u;
 183 } __attribute__((__packed__));
 184
 185 struct blkif_x86_64_response {
 186         uint64_t       __attribute__((__aligned__(8))) id;
 187         uint8_t         operation;       /* copied from request */
 188         int16_t         status;          /* BLKIF_RSP_???       */
 189 };
 190
 191 DEFINE_RING_TYPES(blkif_common, struct blkif_common_request,
 192                   struct blkif_common_response);
 193 DEFINE_RING_TYPES(blkif_x86_32, struct blkif_x86_32_request,
 194                   struct blkif_x86_32_response);
 195 DEFINE_RING_TYPES(blkif_x86_64, struct blkif_x86_64_request,
 196                   struct blkif_x86_64_response);
 197
 198 union blkif_back_rings {
 199         struct blkif_back_ring        native;
 200         struct blkif_common_back_ring common;
 201         struct blkif_x86_32_back_ring x86_32;
 202         struct blkif_x86_64_back_ring x86_64;
 203 };
 204
 205 enum blkif_protocol {
 206         BLKIF_PROTOCOL_NATIVE = 1,
 207         BLKIF_PROTOCOL_X86_32 = 2,
 208         BLKIF_PROTOCOL_X86_64 = 3,
 209 };
 210
 211 /*
 212  * Default protocol if the frontend doesn't specify one.
 213  */
 214 #ifdef CONFIG_X86
 215 #  define BLKIF_PROTOCOL_DEFAULT BLKIF_PROTOCOL_X86_32
 216 #else
 217 #  define BLKIF_PROTOCOL_DEFAULT BLKIF_PROTOCOL_NATIVE
 218 #endif
 219
 220 struct xen_vbd {
 221         /* What the domain refers to this vbd as. */
 222         blkif_vdev_t            handle;
 223         /* Non-zero -> read-only */
 224         unsigned char           readonly;
 225         /* VDISK_xxx */
 226         unsigned char           type;
 227         /* phys device that this vbd maps to. */
 228         u32                     pdevice;
 229         struct block_device     *bdev;
 230         /* Cached size parameter. */
 231         sector_t                size;
 232         unsigned int            flush_support:1;
 233         unsigned int            discard_secure:1;
 234         unsigned int            feature_gnt_persistent:1;
 235         unsigned int            overflow_max_grants:1;
 236 };
 237
 238 struct backend_info;
 239
 240 /* Number of available flags */
 241 #define PERSISTENT_GNT_FLAGS_SIZE       2
 242 /* This persistent grant is currently in use */
 243 #define PERSISTENT_GNT_ACTIVE           0
 244 /*
 245  * This persistent grant has been used, this flag is set when we remove the
 246  * PERSISTENT_GNT_ACTIVE, to know that this grant has been used recently.
 247  */
 248 #define PERSISTENT_GNT_WAS_ACTIVE       1
 249
 250 /* Number of requests that we can fit in a ring */
 251 #define XEN_BLKIF_REQS                  32
 252
 253 struct persistent_gnt {
 254         struct page *page;
 255         grant_ref_t gnt;
 256         grant_handle_t handle;
 257         DECLARE_BITMAP(flags, PERSISTENT_GNT_FLAGS_SIZE);
 258         struct rb_node node;
 259         struct list_head remove_node;
 260 };
 261
 262 struct xen_blkif {
 263         /* Unique identifier for this interface. */
 264         domid_t                 domid;
 265         unsigned int            handle;
 266         /* Physical parameters of the comms window. */
 267         unsigned int            irq;
 268         /* Comms information. */
 269         enum blkif_protocol     blk_protocol;
 270         union blkif_back_rings  blk_rings;
 271         void                    *blk_ring;
 272         /* The VBD attached to this interface. */
 273         struct xen_vbd          vbd;
 274         /* Back pointer to the backend_info. */
 275         struct backend_info     *be;
 276         /* Private fields. */
 277         spinlock_t              blk_ring_lock;
 278         atomic_t                refcnt;
 279
 280         wait_queue_head_t       wq;
 281         /* for barrier (drain) requests */
 282         struct completion       drain_complete;
 283         atomic_t                drain;
 284         atomic_t                inflight;
 285         /* One thread per one blkif. */
 286         struct task_struct      *xenblkd;
 287         unsigned int            waiting_reqs;
 288
 289         /* tree to store persistent grants */
 290         struct rb_root          persistent_gnts;
 291         unsigned int            persistent_gnt_c;
 292         atomic_t                persistent_gnt_in_use;
 293         unsigned long           next_lru;
 294
 295         /* used by the kworker that offload work from the persistent purge */
 296         struct list_head        persistent_purge_list;
 297         struct work_struct      persistent_purge_work;
 298
 299         /* buffer of free pages to map grant refs */
 300         spinlock_t              free_pages_lock;
 301         int                     free_pages_num;
 302         struct list_head        free_pages;
 303
 304         /* List of all 'pending_req' available */
 305         struct list_head        pending_free;
 306         /* And its spinlock. */
 307         spinlock_t              pending_free_lock;
 308         wait_queue_head_t       pending_free_wq;
 309
 310         /* statistics */
 311         unsigned long           st_print;
 312         unsigned long long                      st_rd_req;
 313         unsigned long long                      st_wr_req;
 314         unsigned long long                      st_oo_req;
 315         unsigned long long                      st_f_req;
 316         unsigned long long                      st_ds_req;
 317         unsigned long long                      st_rd_sect;
 318         unsigned long long                      st_wr_sect;
 319
 320         struct work_struct      free_work;
 321         /* Thread shutdown wait queue. */
 322         wait_queue_head_t       shutdown_wq;
 323 };
 324
 325 struct seg_buf {
 326         unsigned long offset;
 327         unsigned int nsec;
 328 };
 329
 330 struct grant_page {
 331         struct page             *page;
 332         struct persistent_gnt   *persistent_gnt;
 333         grant_handle_t          handle;
 334         grant_ref_t             gref;
 335 };
 336
 337 /*
 338  * Each outstanding request that we've passed to the lower device layers has a
 339  * 'pending_req' allocated to it. Each buffer_head that completes decrements
 340  * the pendcnt towards zero. When it hits zero, the specified domain has a
 341  * response queued for it, with the saved 'id' passed back.
 342  */
 343 struct pending_req {
 344         struct xen_blkif        *blkif;
 345         u64                     id;
 346         int                     nr_pages;
 347         atomic_t                pendcnt;
 348         unsigned short          operation;
 349         int                     status;
 350         struct list_head        free_list;
 351         struct grant_page       *segments[MAX_INDIRECT_SEGMENTS];
 352         /* Indirect descriptors */
 353         struct grant_page       *indirect_pages[MAX_INDIRECT_PAGES];
 354         struct seg_buf          seg[MAX_INDIRECT_SEGMENTS];
 355         struct bio              *biolist[MAX_INDIRECT_SEGMENTS];
 356         struct gnttab_unmap_grant_ref unmap[MAX_INDIRECT_SEGMENTS];
 357         struct page                   *unmap_pages[MAX_INDIRECT_SEGMENTS];
 358         struct gntab_unmap_queue_data gnttab_unmap_data;
 359 };
 360
 361
 362 #define vbd_sz(_v)      ((_v)->bdev->bd_part ? \
 363                          (_v)->bdev->bd_part->nr_sects : \
 364                           get_capacity((_v)->bdev->bd_disk))
 365
 366 #define xen_blkif_get(_b) (atomic_inc(&(_b)->refcnt))
 367 #define xen_blkif_put(_b)                               \
 368         do {                                            \
 369                 if (atomic_dec_and_test(&(_b)->refcnt)) \
 370                         schedule_work(&(_b)->free_work);\
 371         } while (0)
 372
 373 struct phys_req {
 374         unsigned short          dev;
 375         blkif_sector_t          nr_sects;
 376         struct block_device     *bdev;
 377         blkif_sector_t          sector_number;
 378 };
 379 int xen_blkif_interface_init(void);
 380
 381 int xen_blkif_xenbus_init(void);
 382
 383 irqreturn_t xen_blkif_be_int(int irq, void *dev_id);
 384 int xen_blkif_schedule(void *arg);
 385 int xen_blkif_purge_persistent(void *arg);
 386 void xen_blkbk_free_caches(struct xen_blkif *blkif);
 387
 388 int xen_blkbk_flush_diskcache(struct xenbus_transaction xbt,
 389                               struct backend_info *be, int state);
 390
 391 int xen_blkbk_barrier(struct xenbus_transaction xbt,
 392                       struct backend_info *be, int state);
 393 struct xenbus_device *xen_blkbk_xenbus(struct backend_info *be);
 394 void xen_blkbk_unmap_purged_grants(struct work_struct *work);
 395
 396 static inline void blkif_get_x86_32_req(struct blkif_request *dst,
 397                                         struct blkif_x86_32_request *src)
 398 {
 399         int i, n = BLKIF_MAX_SEGMENTS_PER_REQUEST, j;
 400         dst->operation = src->operation;
 401         switch (src->operation) {
 402         case BLKIF_OP_READ:
 403         case BLKIF_OP_WRITE:
 404         case BLKIF_OP_WRITE_BARRIER:
 405         case BLKIF_OP_FLUSH_DISKCACHE:
 406                 dst->u.rw.nr_segments = src->u.rw.nr_segments;
 407                 dst->u.rw.handle = src->u.rw.handle;
 408                 dst->u.rw.id = src->u.rw.id;
 409                 dst->u.rw.sector_number = src->u.rw.sector_number;
 410                 barrier();
 411                 if (n > dst->u.rw.nr_segments)
 412                         n = dst->u.rw.nr_segments;
 413                 for (i = 0; i < n; i++)
 414                         dst->u.rw.seg[i] = src->u.rw.seg[i];
 415                 break;
 416         case BLKIF_OP_DISCARD:
 417                 dst->u.discard.flag = src->u.discard.flag;
 418                 dst->u.discard.id = src->u.discard.id;
 419                 dst->u.discard.sector_number = src->u.discard.sector_number;
 420                 dst->u.discard.nr_sectors = src->u.discard.nr_sectors;
 421                 break;
 422         case BLKIF_OP_INDIRECT:
 423                 dst->u.indirect.indirect_op = src->u.indirect.indirect_op;
 424                 dst->u.indirect.nr_segments = src->u.indirect.nr_segments;
 425                 dst->u.indirect.handle = src->u.indirect.handle;
 426                 dst->u.indirect.id = src->u.indirect.id;
 427                 dst->u.indirect.sector_number = src->u.indirect.sector_number;
 428                 barrier();
 429                 j = min(MAX_INDIRECT_PAGES, INDIRECT_PAGES(dst->u.indirect.nr_segments));
 430                 for (i = 0; i < j; i++)
 431                         dst->u.indirect.indirect_grefs[i] =
 432                                 src->u.indirect.indirect_grefs[i];
 433                 break;
 434         default:
 435                 /*
 436                  * Don't know how to translate this op. Only get the
 437                  * ID so failure can be reported to the frontend.
 438                  */
 439                 dst->u.other.id = src->u.other.id;
 440                 break;
 441         }
 442 }
 443
 444 static inline void blkif_get_x86_64_req(struct blkif_request *dst,
 445                                         struct blkif_x86_64_request *src)
 446 {
 447         int i, n = BLKIF_MAX_SEGMENTS_PER_REQUEST, j;
 448         dst->operation = src->operation;
 449         switch (src->operation) {
 450         case BLKIF_OP_READ:
 451         case BLKIF_OP_WRITE:
 452         case BLKIF_OP_WRITE_BARRIER:
 453         case BLKIF_OP_FLUSH_DISKCACHE:
 454                 dst->u.rw.nr_segments = src->u.rw.nr_segments;
 455                 dst->u.rw.handle = src->u.rw.handle;
 456                 dst->u.rw.id = src->u.rw.id;
 457                 dst->u.rw.sector_number = src->u.rw.sector_number;
 458                 barrier();
 459                 if (n > dst->u.rw.nr_segments)
 460                         n = dst->u.rw.nr_segments;
 461                 for (i = 0; i < n; i++)
 462                         dst->u.rw.seg[i] = src->u.rw.seg[i];
 463                 break;
 464         case BLKIF_OP_DISCARD:
 465                 dst->u.discard.flag = src->u.discard.flag;
 466                 dst->u.discard.id = src->u.discard.id;
 467                 dst->u.discard.sector_number = src->u.discard.sector_number;
 468                 dst->u.discard.nr_sectors = src->u.discard.nr_sectors;
 469                 break;
 470         case BLKIF_OP_INDIRECT:
 471                 dst->u.indirect.indirect_op = src->u.indirect.indirect_op;
 472                 dst->u.indirect.nr_segments = src->u.indirect.nr_segments;
 473                 dst->u.indirect.handle = src->u.indirect.handle;
 474                 dst->u.indirect.id = src->u.indirect.id;
 475                 dst->u.indirect.sector_number = src->u.indirect.sector_number;
 476                 barrier();
 477                 j = min(MAX_INDIRECT_PAGES, INDIRECT_PAGES(dst->u.indirect.nr_segments));
 478                 for (i = 0; i < j; i++)
 479                         dst->u.indirect.indirect_grefs[i] =
 480                                 src->u.indirect.indirect_grefs[i];
 481                 break;
 482         default:
 483                 /*
 484                  * Don't know how to translate this op. Only get the
 485                  * ID so failure can be reported to the frontend.
 486                  */
 487                 dst->u.other.id = src->u.other.id;
 488                 break;
 489         }
 490 }
 491
 492 #endif /* __XEN_BLKIF__BACKEND__COMMON_H__ */