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 /* i386 protocol version */
  64 #pragma pack(push, 4)
  65 struct blkif_x86_32_request {
  66         uint8_t        operation;    /* BLKIF_OP_???                         */
  67         uint8_t        nr_segments;  /* number of segments                   */
  68         blkif_vdev_t   handle;       /* only for read/write requests         */
  69         uint64_t       id;           /* private guest value, echoed in resp  */
  70         blkif_sector_t sector_number;/* start sector idx on disk (r/w only)  */
  71         struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
  72 };
  73 struct blkif_x86_32_response {
  74         uint64_t        id;              /* copied from request */
  75         uint8_t         operation;       /* copied from request */
  76         int16_t         status;          /* BLKIF_RSP_???       */
  77 };
  78 #pragma pack(pop)
  79
  80 /* x86_64 protocol version */
  81 struct blkif_x86_64_request {
  82         uint8_t        operation;    /* BLKIF_OP_???                         */
  83         uint8_t        nr_segments;  /* number of segments                   */
  84         blkif_vdev_t   handle;       /* only for read/write requests         */
  85         uint64_t       __attribute__((__aligned__(8))) id;
  86         blkif_sector_t sector_number;/* start sector idx on disk (r/w only)  */
  87         struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
  88 };
  89 struct blkif_x86_64_response {
  90         uint64_t       __attribute__((__aligned__(8))) id;
  91         uint8_t         operation;       /* copied from request */
  92         int16_t         status;          /* BLKIF_RSP_???       */
  93 };
  94
  95 DEFINE_RING_TYPES(blkif_common, struct blkif_common_request,
  96                   struct blkif_common_response);
  97 DEFINE_RING_TYPES(blkif_x86_32, struct blkif_x86_32_request,
  98                   struct blkif_x86_32_response);
  99 DEFINE_RING_TYPES(blkif_x86_64, struct blkif_x86_64_request,
 100                   struct blkif_x86_64_response);
 101
 102 union blkif_back_rings {
 103         struct blkif_back_ring        native;
 104         struct blkif_common_back_ring common;
 105         struct blkif_x86_32_back_ring x86_32;
 106         struct blkif_x86_64_back_ring x86_64;
 107 };
 108
 109 enum blkif_protocol {
 110         BLKIF_PROTOCOL_NATIVE = 1,
 111         BLKIF_PROTOCOL_X86_32 = 2,
 112         BLKIF_PROTOCOL_X86_64 = 3,
 113 };
 114
 115 struct xen_vbd {
 116         /* What the domain refers to this vbd as. */
 117         blkif_vdev_t            handle;
 118         /* Non-zero -> read-only */
 119         unsigned char           readonly;
 120         /* VDISK_xxx */
 121         unsigned char           type;
 122         /* phys device that this vbd maps to. */
 123         u32                     pdevice;
 124         struct block_device     *bdev;
 125         /* Cached size parameter. */
 126         sector_t                size;
 127         bool                    flush_support;
 128 };
 129
 130 struct backend_info;
 131
 132 struct xen_blkif {
 133         /* Unique identifier for this interface. */
 134         domid_t                 domid;
 135         unsigned int            handle;
 136         /* Physical parameters of the comms window. */
 137         unsigned int            irq;
 138         /* Comms information. */
 139         enum blkif_protocol     blk_protocol;
 140         union blkif_back_rings  blk_rings;
 141         struct vm_struct        *blk_ring_area;
 142         /* The VBD attached to this interface. */
 143         struct xen_vbd          vbd;
 144         /* Back pointer to the backend_info. */
 145         struct backend_info     *be;
 146         /* Private fields. */
 147         spinlock_t              blk_ring_lock;
 148         atomic_t                refcnt;
 149
 150         wait_queue_head_t       wq;
 151         /* One thread per one blkif. */
 152         struct task_struct      *xenblkd;
 153         unsigned int            waiting_reqs;
 154
 155         /* statistics */
 156         unsigned long           st_print;
 157         int                     st_rd_req;
 158         int                     st_wr_req;
 159         int                     st_oo_req;
 160         int                     st_f_req;
 161         int                     st_rd_sect;
 162         int                     st_wr_sect;
 163
 164         wait_queue_head_t       waiting_to_free;
 165
 166         grant_handle_t          shmem_handle;
 167         grant_ref_t             shmem_ref;
 168 };
 169
 170
 171 #define vbd_sz(_v)      ((_v)->bdev->bd_part ? \
 172                          (_v)->bdev->bd_part->nr_sects : \
 173                           get_capacity((_v)->bdev->bd_disk))
 174
 175 #define xen_blkif_get(_b) (atomic_inc(&(_b)->refcnt))
 176 #define xen_blkif_put(_b)                               \
 177         do {                                            \
 178                 if (atomic_dec_and_test(&(_b)->refcnt)) \
 179                         wake_up(&(_b)->waiting_to_free);\
 180         } while (0)
 181
 182 struct phys_req {
 183         unsigned short          dev;
 184         unsigned short          nr_sects;
 185         struct block_device     *bdev;
 186         blkif_sector_t          sector_number;
 187 };
 188 int xen_blkif_interface_init(void);
 189
 190 int xen_blkif_xenbus_init(void);
 191
 192 irqreturn_t xen_blkif_be_int(int irq, void *dev_id);
 193 int xen_blkif_schedule(void *arg);
 194
 195 int xen_blkbk_flush_diskcache(struct xenbus_transaction xbt,
 196                               struct backend_info *be, int state);
 197
 198 struct xenbus_device *xen_blkbk_xenbus(struct backend_info *be);
 199
 200 static inline void blkif_get_x86_32_req(struct blkif_request *dst,
 201                                         struct blkif_x86_32_request *src)
 202 {
 203         int i, n = BLKIF_MAX_SEGMENTS_PER_REQUEST;
 204         dst->operation = src->operation;
 205         dst->nr_segments = src->nr_segments;
 206         dst->handle = src->handle;
 207         dst->id = src->id;
 208         dst->u.rw.sector_number = src->sector_number;
 209         barrier();
 210         if (n > dst->nr_segments)
 211                 n = dst->nr_segments;
 212         for (i = 0; i < n; i++)
 213                 dst->u.rw.seg[i] = src->seg[i];
 214 }
 215
 216 static inline void blkif_get_x86_64_req(struct blkif_request *dst,
 217                                         struct blkif_x86_64_request *src)
 218 {
 219         int i, n = BLKIF_MAX_SEGMENTS_PER_REQUEST;
 220         dst->operation = src->operation;
 221         dst->nr_segments = src->nr_segments;
 222         dst->handle = src->handle;
 223         dst->id = src->id;
 224         dst->u.rw.sector_number = src->sector_number;
 225         barrier();
 226         if (n > dst->nr_segments)
 227                 n = dst->nr_segments;
 228         for (i = 0; i < n; i++)
 229                 dst->u.rw.seg[i] = src->seg[i];
 230 }
 231
 232 #endif /* __XEN_BLKIF__BACKEND__COMMON_H__ */