drivers/block/xen-blkback/interface.c

   1 /******************************************************************************
   2  * Block-device interface management.
   3  *
   4  * Copyright (c) 2004, Keir Fraser
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License version 2
   8  * as published by the Free Software Foundation; or, when distributed
   9  * separately from the Linux kernel or incorporated into other
  10  * software packages, subject to the following license:
  11  *
  12  * Permission is hereby granted, free of charge, to any person obtaining a copy
  13  * of this source file (the "Software"), to deal in the Software without
  14  * restriction, including without limitation the rights to use, copy, modify,
  15  * merge, publish, distribute, sublicense, and/or sell copies of the Software,
  16  * and to permit persons to whom the Software is furnished to do so, subject to
  17  * the following conditions:
  18  *
  19  * The above copyright notice and this permission notice shall be included in
  20  * all copies or substantial portions of the Software.
  21  *
  22  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  23  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  24  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  25  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  26  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  27  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  28  * IN THE SOFTWARE.
  29  */
  30
  31 #include "common.h"
  32 #include <xen/events.h>
  33 #include <xen/grant_table.h>
  34 #include <linux/kthread.h>
  35
  36 static struct kmem_cache *blkif_cachep;
  37
  38 struct blkif_st *blkif_alloc(domid_t domid)
  39 {
  40         struct blkif_st *blkif;
  41
  42         blkif = kmem_cache_alloc(blkif_cachep, GFP_KERNEL);
  43         if (!blkif)
  44                 return ERR_PTR(-ENOMEM);
  45
  46         memset(blkif, 0, sizeof(*blkif));
  47         blkif->domid = domid;
  48         spin_lock_init(&blkif->blk_ring_lock);
  49         atomic_set(&blkif->refcnt, 1);
  50         init_waitqueue_head(&blkif->wq);
  51         blkif->st_print = jiffies;
  52         init_waitqueue_head(&blkif->waiting_to_free);
  53
  54         return blkif;
  55 }
  56
  57 static int map_frontend_page(struct blkif_st *blkif, unsigned long shared_page)
  58 {
  59         struct gnttab_map_grant_ref op;
  60
  61         gnttab_set_map_op(&op, (unsigned long)blkif->blk_ring_area->addr,
  62                           GNTMAP_host_map, shared_page, blkif->domid);
  63
  64         if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1))
  65                 BUG();
  66
  67         if (op.status) {
  68                 DPRINTK(" Grant table operation failure !\n");
  69                 return op.status;
  70         }
  71
  72         blkif->shmem_ref = shared_page;
  73         blkif->shmem_handle = op.handle;
  74
  75         return 0;
  76 }
  77
  78 static void unmap_frontend_page(struct blkif_st *blkif)
  79 {
  80         struct gnttab_unmap_grant_ref op;
  81
  82         gnttab_set_unmap_op(&op, (unsigned long)blkif->blk_ring_area->addr,
  83                             GNTMAP_host_map, blkif->shmem_handle);
  84
  85         if (HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, &op, 1))
  86                 BUG();
  87 }
  88
  89 int blkif_map(struct blkif_st *blkif, unsigned long shared_page,
  90               unsigned int evtchn)
  91 {
  92         int err;
  93
  94         /* Already connected through? */
  95         if (blkif->irq)
  96                 return 0;
  97
  98         blkif->blk_ring_area = alloc_vm_area(PAGE_SIZE);
  99         if (!blkif->blk_ring_area)
 100                 return -ENOMEM;
 101
 102         err = map_frontend_page(blkif, shared_page);
 103         if (err) {
 104                 free_vm_area(blkif->blk_ring_area);
 105                 return err;
 106         }
 107
 108         switch (blkif->blk_protocol) {
 109         case BLKIF_PROTOCOL_NATIVE:
 110         {
 111                 struct blkif_sring *sring;
 112                 sring = (struct blkif_sring *)blkif->blk_ring_area->addr;
 113                 BACK_RING_INIT(&blkif->blk_rings.native, sring, PAGE_SIZE);
 114                 break;
 115         }
 116         case BLKIF_PROTOCOL_X86_32:
 117         {
 118                 struct blkif_x86_32_sring *sring_x86_32;
 119                 sring_x86_32 = (struct blkif_x86_32_sring *)blkif->blk_ring_area->addr;
 120                 BACK_RING_INIT(&blkif->blk_rings.x86_32, sring_x86_32, PAGE_SIZE);
 121                 break;
 122         }
 123         case BLKIF_PROTOCOL_X86_64:
 124         {
 125                 struct blkif_x86_64_sring *sring_x86_64;
 126                 sring_x86_64 = (struct blkif_x86_64_sring *)blkif->blk_ring_area->addr;
 127                 BACK_RING_INIT(&blkif->blk_rings.x86_64, sring_x86_64, PAGE_SIZE);
 128                 break;
 129         }
 130         default:
 131                 BUG();
 132         }
 133
 134         err = bind_interdomain_evtchn_to_irqhandler(
 135                 blkif->domid, evtchn, blkif_be_int, 0, "blkif-backend", blkif);
 136         if (err < 0) {
 137                 unmap_frontend_page(blkif);
 138                 free_vm_area(blkif->blk_ring_area);
 139                 blkif->blk_rings.common.sring = NULL;
 140                 return err;
 141         }
 142         blkif->irq = err;
 143
 144         return 0;
 145 }
 146
 147 void blkif_disconnect(struct blkif_st *blkif)
 148 {
 149         if (blkif->xenblkd) {
 150                 kthread_stop(blkif->xenblkd);
 151                 blkif->xenblkd = NULL;
 152         }
 153
 154         atomic_dec(&blkif->refcnt);
 155         wait_event(blkif->waiting_to_free, atomic_read(&blkif->refcnt) == 0);
 156         atomic_inc(&blkif->refcnt);
 157
 158         if (blkif->irq) {
 159                 unbind_from_irqhandler(blkif->irq, blkif);
 160                 blkif->irq = 0;
 161         }
 162
 163         if (blkif->blk_rings.common.sring) {
 164                 unmap_frontend_page(blkif);
 165                 free_vm_area(blkif->blk_ring_area);
 166                 blkif->blk_rings.common.sring = NULL;
 167         }
 168 }
 169
 170 void blkif_free(struct blkif_st *blkif)
 171 {
 172         if (!atomic_dec_and_test(&blkif->refcnt))
 173                 BUG();
 174         kmem_cache_free(blkif_cachep, blkif);
 175 }
 176
 177 int __init blkif_interface_init(void)
 178 {
 179         blkif_cachep = kmem_cache_create("blkif_cache", sizeof(struct blkif_st),
 180                                          0, 0, NULL);
 181         if (!blkif_cachep)
 182                 return -ENOMEM;
 183
 184         return 0;
 185 }