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