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 {
  81         uint8_t        operation;    /* BLKIF_OP_???                         */
  82         union {
  83                 struct blkif_x86_32_request_rw rw;
  84                 struct blkif_x86_32_request_discard discard;
  85         } u;
  86 } __attribute__((__packed__));
  87
  88 /* i386 protocol version */
  89 #pragma pack(push, 4)
  90 struct blkif_x86_32_response {
  91         uint64_t        id;              /* copied from request */
  92         uint8_t         operation;       /* copied from request */
  93         int16_t         status;          /* BLKIF_RSP_???       */
  94 };
  95 #pragma pack(pop)
  96 /* x86_64 protocol version */
  97
  98 struct blkif_x86_64_request_rw {
  99         uint8_t        nr_segments;  /* number of segments                   */
 100         blkif_vdev_t   handle;       /* only for read/write requests         */
 101         uint32_t       _pad1;        /* offsetof(blkif_reqest..,u.rw.id)==8  */
 102         uint64_t       id;
 103         blkif_sector_t sector_number;/* start sector idx on disk (r/w only)  */
 104         struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
 105 } __attribute__((__packed__));
 106
 107 struct blkif_x86_64_request_discard {
 108         uint8_t        flag;         /* BLKIF_DISCARD_SECURE or zero         */
 109         blkif_vdev_t   _pad1;        /* was "handle" for read/write requests */
 110         uint32_t       _pad2;        /* offsetof(blkif_..,u.discard.id)==8   */
 111         uint64_t       id;
 112         blkif_sector_t sector_number;/* start sector idx on disk (r/w only)  */
 113         uint64_t       nr_sectors;
 114 } __attribute__((__packed__));
 115
 116 struct blkif_x86_64_request {
 117         uint8_t        operation;    /* BLKIF_OP_???                         */
 118         union {
 119                 struct blkif_x86_64_request_rw rw;
 120                 struct blkif_x86_64_request_discard discard;
 121         } u;
 122 } __attribute__((__packed__));
 123
 124 struct blkif_x86_64_response {
 125         uint64_t       __attribute__((__aligned__(8))) id;
 126         uint8_t         operation;       /* copied from request */
 127         int16_t         status;          /* BLKIF_RSP_???       */
 128 };
 129
 130 DEFINE_RING_TYPES(blkif_common, struct blkif_common_request,
 131                   struct blkif_common_response);
 132 DEFINE_RING_TYPES(blkif_x86_32, struct blkif_x86_32_request,
 133                   struct blkif_x86_32_response);
 134 DEFINE_RING_TYPES(blkif_x86_64, struct blkif_x86_64_request,
 135                   struct blkif_x86_64_response);
 136
 137 union blkif_back_rings {
 138         struct blkif_back_ring        native;
 139         struct blkif_common_back_ring common;
 140         struct blkif_x86_32_back_ring x86_32;
 141         struct blkif_x86_64_back_ring x86_64;
 142 };
 143
 144 enum blkif_protocol {
 145         BLKIF_PROTOCOL_NATIVE = 1,
 146         BLKIF_PROTOCOL_X86_32 = 2,
 147         BLKIF_PROTOCOL_X86_64 = 3,
 148 };
 149
 150 struct xen_vbd {
 151         /* What the domain refers to this vbd as. */
 152         blkif_vdev_t            handle;
 153         /* Non-zero -> read-only */
 154         unsigned char           readonly;
 155         /* VDISK_xxx */
 156         unsigned char           type;
 157         /* phys device that this vbd maps to. */
 158         u32                     pdevice;
 159         struct block_device     *bdev;
 160         /* Cached size parameter. */
 161         sector_t                size;
 162         bool                    flush_support;
 163         bool                    discard_secure;
 164
 165         unsigned int            feature_gnt_persistent:1;
 166         unsigned int            overflow_max_grants:1;
 167 };
 168
 169 struct backend_info;
 170
 171
 172 struct persistent_gnt {
 173         struct page *page;
 174         grant_ref_t gnt;
 175         grant_handle_t handle;
 176         uint64_t dev_bus_addr;
 177         struct rb_node node;
 178 };
 179
 180 struct xen_blkif {
 181         /* Unique identifier for this interface. */
 182         domid_t                 domid;
 183         unsigned int            handle;
 184         /* Physical parameters of the comms window. */
 185         unsigned int            irq;
 186         /* Comms information. */
 187         enum blkif_protocol     blk_protocol;
 188         union blkif_back_rings  blk_rings;
 189         void                    *blk_ring;
 190         /* The VBD attached to this interface. */
 191         struct xen_vbd          vbd;
 192         /* Back pointer to the backend_info. */
 193         struct backend_info     *be;
 194         /* Private fields. */
 195         spinlock_t              blk_ring_lock;
 196         atomic_t                refcnt;
 197
 198         wait_queue_head_t       wq;
 199         /* for barrier (drain) requests */
 200         struct completion       drain_complete;
 201         atomic_t                drain;
 202         /* One thread per one blkif. */
 203         struct task_struct      *xenblkd;
 204         unsigned int            waiting_reqs;
 205
 206         /* tree to store persistent grants */
 207         struct rb_root          persistent_gnts;
 208         unsigned int            persistent_gnt_c;
 209
 210         /* statistics */
 211         unsigned long           st_print;
 212         int                     st_rd_req;
 213         int                     st_wr_req;
 214         int                     st_oo_req;
 215         int                     st_f_req;
 216         int                     st_ds_req;
 217         int                     st_rd_sect;
 218         int                     st_wr_sect;
 219
 220         wait_queue_head_t       waiting_to_free;
 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                 break;
 283         }
 284 }
 285
 286 static inline void blkif_get_x86_64_req(struct blkif_request *dst,
 287                                         struct blkif_x86_64_request *src)
 288 {
 289         int i, n = BLKIF_MAX_SEGMENTS_PER_REQUEST;
 290         dst->operation = src->operation;
 291         switch (src->operation) {
 292         case BLKIF_OP_READ:
 293         case BLKIF_OP_WRITE:
 294         case BLKIF_OP_WRITE_BARRIER:
 295         case BLKIF_OP_FLUSH_DISKCACHE:
 296                 dst->u.rw.nr_segments = src->u.rw.nr_segments;
 297                 dst->u.rw.handle = src->u.rw.handle;
 298                 dst->u.rw.id = src->u.rw.id;
 299                 dst->u.rw.sector_number = src->u.rw.sector_number;
 300                 barrier();
 301                 if (n > dst->u.rw.nr_segments)
 302                         n = dst->u.rw.nr_segments;
 303                 for (i = 0; i < n; i++)
 304                         dst->u.rw.seg[i] = src->u.rw.seg[i];
 305                 break;
 306         case BLKIF_OP_DISCARD:
 307                 dst->u.discard.flag = src->u.discard.flag;
 308                 dst->u.discard.id = src->u.discard.id;
 309                 dst->u.discard.sector_number = src->u.discard.sector_number;
 310                 dst->u.discard.nr_sectors = src->u.discard.nr_sectors;
 311                 break;
 312         default:
 313                 break;
 314         }
 315 }
 316
 317 #endif /* __XEN_BLKIF__BACKEND__COMMON_H__ */