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/version.h>
  31 #include <linux/module.h>
  32 #include <linux/interrupt.h>
  33 #include <linux/slab.h>
  34 #include <linux/blkdev.h>
  35 #include <linux/vmalloc.h>
  36 #include <linux/wait.h>
  37 #include <linux/io.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 /* i386 protocol version */
  65 #pragma pack(push, 4)
  66 struct blkif_x86_32_request {
  67         uint8_t        operation;    /* BLKIF_OP_???                         */
  68         uint8_t        nr_segments;  /* number of segments                   */
  69         blkif_vdev_t   handle;       /* only for read/write requests         */
  70         uint64_t       id;           /* private guest value, echoed in resp  */
  71         blkif_sector_t sector_number;/* start sector idx on disk (r/w only)  */
  72         struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
  73 };
  74 struct blkif_x86_32_response {
  75         uint64_t        id;              /* copied from request */
  76         uint8_t         operation;       /* copied from request */
  77         int16_t         status;          /* BLKIF_RSP_???       */
  78 };
  79 #pragma pack(pop)
  80
  81 /* x86_64 protocol version */
  82 struct blkif_x86_64_request {
  83         uint8_t        operation;    /* BLKIF_OP_???                         */
  84         uint8_t        nr_segments;  /* number of segments                   */
  85         blkif_vdev_t   handle;       /* only for read/write requests         */
  86         uint64_t       __attribute__((__aligned__(8))) id;
  87         blkif_sector_t sector_number;/* start sector idx on disk (r/w only)  */
  88         struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
  89 };
  90 struct blkif_x86_64_response {
  91         uint64_t       __attribute__((__aligned__(8))) id;
  92         uint8_t         operation;       /* copied from request */
  93         int16_t         status;          /* BLKIF_RSP_???       */
  94 };
  95
  96 DEFINE_RING_TYPES(blkif_common, struct blkif_common_request,
  97                   struct blkif_common_response);
  98 DEFINE_RING_TYPES(blkif_x86_32, struct blkif_x86_32_request,
  99                   struct blkif_x86_32_response);
 100 DEFINE_RING_TYPES(blkif_x86_64, struct blkif_x86_64_request,
 101                   struct blkif_x86_64_response);
 102
 103 union blkif_back_rings {
 104         struct blkif_back_ring        native;
 105         struct blkif_common_back_ring common;
 106         struct blkif_x86_32_back_ring x86_32;
 107         struct blkif_x86_64_back_ring x86_64;
 108 };
 109
 110 enum blkif_protocol {
 111         BLKIF_PROTOCOL_NATIVE = 1,
 112         BLKIF_PROTOCOL_X86_32 = 2,
 113         BLKIF_PROTOCOL_X86_64 = 3,
 114 };
 115
 116 struct xen_vbd {
 117         /* What the domain refers to this vbd as. */
 118         blkif_vdev_t            handle;
 119         /* Non-zero -> read-only */
 120         unsigned char           readonly;
 121         /* VDISK_xxx */
 122         unsigned char           type;
 123         /* phys device that this vbd maps to. */
 124         u32                     pdevice;
 125         struct block_device     *bdev;
 126         /* Cached size parameter. */
 127         sector_t                size;
 128         bool                    flush_support;
 129 };
 130
 131 struct backend_info;
 132
 133 struct xen_blkif {
 134         /* Unique identifier for this interface. */
 135         domid_t                 domid;
 136         unsigned int            handle;
 137         /* Physical parameters of the comms window. */
 138         unsigned int            irq;
 139         /* Comms information. */
 140         enum blkif_protocol     blk_protocol;
 141         union blkif_back_rings  blk_rings;
 142         void                    *blk_ring;
 143         /* The VBD attached to this interface. */
 144         struct xen_vbd          vbd;
 145         /* Back pointer to the backend_info. */
 146         struct backend_info     *be;
 147         /* Private fields. */
 148         spinlock_t              blk_ring_lock;
 149         atomic_t                refcnt;
 150
 151         wait_queue_head_t       wq;
 152         /* One thread per one blkif. */
 153         struct task_struct      *xenblkd;
 154         unsigned int            waiting_reqs;
 155
 156         /* statistics */
 157         unsigned long           st_print;
 158         int                     st_rd_req;
 159         int                     st_wr_req;
 160         int                     st_oo_req;
 161         int                     st_f_req;
 162         int                     st_rd_sect;
 163         int                     st_wr_sect;
 164
 165         wait_queue_head_t       waiting_to_free;
 166 };
 167
 168
 169 #define vbd_sz(_v)      ((_v)->bdev->bd_part ? \
 170                          (_v)->bdev->bd_part->nr_sects : \
 171                           get_capacity((_v)->bdev->bd_disk))
 172
 173 #define xen_blkif_get(_b) (atomic_inc(&(_b)->refcnt))
 174 #define xen_blkif_put(_b)                               \
 175         do {                                            \
 176                 if (atomic_dec_and_test(&(_b)->refcnt)) \
 177                         wake_up(&(_b)->waiting_to_free);\
 178         } while (0)
 179
 180 struct phys_req {
 181         unsigned short          dev;
 182         unsigned short          nr_sects;
 183         struct block_device     *bdev;
 184         blkif_sector_t          sector_number;
 185 };
 186 int xen_blkif_interface_init(void);
 187
 188 int xen_blkif_xenbus_init(void);
 189
 190 irqreturn_t xen_blkif_be_int(int irq, void *dev_id);
 191 int xen_blkif_schedule(void *arg);
 192
 193 int xen_blkbk_flush_diskcache(struct xenbus_transaction xbt,
 194                               struct backend_info *be, int state);
 195
 196 struct xenbus_device *xen_blkbk_xenbus(struct backend_info *be);
 197
 198 static inline void blkif_get_x86_32_req(struct blkif_request *dst,
 199                                         struct blkif_x86_32_request *src)
 200 {
 201         int i, n = BLKIF_MAX_SEGMENTS_PER_REQUEST;
 202         dst->operation = src->operation;
 203         dst->nr_segments = src->nr_segments;
 204         dst->handle = src->handle;
 205         dst->id = src->id;
 206         dst->u.rw.sector_number = src->sector_number;
 207         barrier();
 208         if (n > dst->nr_segments)
 209                 n = dst->nr_segments;
 210         for (i = 0; i < n; i++)
 211                 dst->u.rw.seg[i] = src->seg[i];
 212 }
 213
 214 static inline void blkif_get_x86_64_req(struct blkif_request *dst,
 215                                         struct blkif_x86_64_request *src)
 216 {
 217         int i, n = BLKIF_MAX_SEGMENTS_PER_REQUEST;
 218         dst->operation = src->operation;
 219         dst->nr_segments = src->nr_segments;
 220         dst->handle = src->handle;
 221         dst->id = src->id;
 222         dst->u.rw.sector_number = src->sector_number;
 223         barrier();
 224         if (n > dst->nr_segments)
 225                 n = dst->nr_segments;
 226         for (i = 0; i < n; i++)
 227                 dst->u.rw.seg[i] = src->seg[i];
 228 }
 229
 230 #endif /* __XEN_BLKIF__BACKEND__COMMON_H__ */