drivers/xen/blkback/interface.c

   1 /******************************************************************************
   2  * arch/xen/drivers/blkif/backend/interface.c
   3  *
   4  * Block-device interface management.
   5  *
   6  * Copyright (c) 2004, Keir Fraser
   7  *
   8  * This program is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU General Public License version 2
  10  * as published by the Free Software Foundation; or, when distributed
  11  * separately from the Linux kernel or incorporated into other
  12  * software packages, subject to the following license:
  13  *
  14  * Permission is hereby granted, free of charge, to any person obtaining a copy
  15  * of this source file (the "Software"), to deal in the Software without
  16  * restriction, including without limitation the rights to use, copy, modify,
  17  * merge, publish, distribute, sublicense, and/or sell copies of the Software,
  18  * and to permit persons to whom the Software is furnished to do so, subject to
  19  * the following conditions:
  20  *
  21  * The above copyright notice and this permission notice shall be included in
  22  * all copies or substantial portions of the Software.
  23  *
  24  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  25  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  26  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  27  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  28  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  29  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  30  * IN THE SOFTWARE.
  31  */
  32
  33 #include "common.h"
  34 #include <xen/evtchn.h>
  35 #include <linux/kthread.h>
  36 #include <linux/delay.h>
  37
  38 static struct kmem_cache *blkif_cachep;
  39
  40 blkif_t *blkif_alloc(domid_t domid)
  41 {
  42         blkif_t *blkif;
  43
  44         blkif = kmem_cache_alloc(blkif_cachep, GFP_KERNEL|__GFP_ZERO);
  45         if (!blkif)
  46                 return ERR_PTR(-ENOMEM);
  47
  48         blkif->domid = domid;
  49         spin_lock_init(&blkif->blk_ring_lock);
  50         atomic_set(&blkif->refcnt, 1);
  51         init_waitqueue_head(&blkif->wq);
  52         blkif->st_print = jiffies;
  53         init_waitqueue_head(&blkif->waiting_to_free);
  54
  55         return blkif;
  56 }
  57
  58 static int map_frontend_page(blkif_t *blkif, unsigned long shared_page)
  59 {
  60         struct gnttab_map_grant_ref op;
  61
  62         gnttab_set_map_op(&op, (unsigned long)blkif->blk_ring_area->addr,
  63                           GNTMAP_host_map, shared_page, blkif->domid);
  64
  65     do {
  66             if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1))
  67                     BUG();
  68         msleep(100);
  69     } while(op.status == GNTST_eagain);
  70
  71         if (op.status) {
  72                 DPRINTK(" Grant table operation failure !\n");
  73                 return op.status;
  74         }
  75
  76         blkif->shmem_ref = shared_page;
  77         blkif->shmem_handle = op.handle;
  78
  79         return 0;
  80 }
  81
  82 static void unmap_frontend_page(blkif_t *blkif)
  83 {
  84         struct gnttab_unmap_grant_ref op;
  85
  86         gnttab_set_unmap_op(&op, (unsigned long)blkif->blk_ring_area->addr,
  87                             GNTMAP_host_map, blkif->shmem_handle);
  88
  89         if (HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, &op, 1))
  90                 BUG();
  91 }
  92
  93 int blkif_map(blkif_t *blkif, unsigned long shared_page, unsigned int evtchn)
  94 {
  95         int err;
  96
  97         /* Already connected through? */
  98         if (blkif->irq)
  99                 return 0;
 100
 101         if ( (blkif->blk_ring_area = alloc_vm_area(PAGE_SIZE)) == NULL )
 102                 return -ENOMEM;
 103
 104         err = map_frontend_page(blkif, shared_page);
 105         if (err) {
 106                 free_vm_area(blkif->blk_ring_area);
 107                 return err;
 108         }
 109
 110         switch (blkif->blk_protocol) {
 111         case BLKIF_PROTOCOL_NATIVE:
 112         {
 113                 blkif_sring_t *sring;
 114                 sring = (blkif_sring_t *)blkif->blk_ring_area->addr;
 115                 BACK_RING_INIT(&blkif->blk_rings.native, sring, PAGE_SIZE);
 116                 break;
 117         }
 118         case BLKIF_PROTOCOL_X86_32:
 119         {
 120                 blkif_x86_32_sring_t *sring_x86_32;
 121                 sring_x86_32 = (blkif_x86_32_sring_t *)blkif->blk_ring_area->addr;
 122                 BACK_RING_INIT(&blkif->blk_rings.x86_32, sring_x86_32, PAGE_SIZE);
 123                 break;
 124         }
 125         case BLKIF_PROTOCOL_X86_64:
 126         {
 127                 blkif_x86_64_sring_t *sring_x86_64;
 128                 sring_x86_64 = (blkif_x86_64_sring_t *)blkif->blk_ring_area->addr;
 129                 BACK_RING_INIT(&blkif->blk_rings.x86_64, sring_x86_64, PAGE_SIZE);
 130                 break;
 131         }
 132         default:
 133                 BUG();
 134         }
 135
 136         err = bind_interdomain_evtchn_to_irqhandler(
 137                 blkif->domid, evtchn, blkif_be_int, 0, "blkif-backend", blkif);
 138         if (err < 0)
 139         {
 140                 unmap_frontend_page(blkif);
 141                 free_vm_area(blkif->blk_ring_area);
 142                 blkif->blk_rings.common.sring = NULL;
 143                 return err;
 144         }
 145         blkif->irq = err;
 146
 147         return 0;
 148 }
 149
 150 void blkif_disconnect(blkif_t *blkif)
 151 {
 152         if (blkif->xenblkd) {
 153                 kthread_stop(blkif->xenblkd);
 154                 blkif->xenblkd = NULL;
 155         }
 156
 157         atomic_dec(&blkif->refcnt);
 158         wait_event(blkif->waiting_to_free, atomic_read(&blkif->refcnt) == 0);
 159         atomic_inc(&blkif->refcnt);
 160
 161         if (blkif->irq) {
 162                 unbind_from_irqhandler(blkif->irq, blkif);
 163                 blkif->irq = 0;
 164         }
 165
 166         if (blkif->blk_rings.common.sring) {
 167                 unmap_frontend_page(blkif);
 168                 free_vm_area(blkif->blk_ring_area);
 169                 blkif->blk_rings.common.sring = NULL;
 170         }
 171 }
 172
 173 void blkif_free(blkif_t *blkif)
 174 {
 175         if (!atomic_dec_and_test(&blkif->refcnt))
 176                 BUG();
 177         kmem_cache_free(blkif_cachep, blkif);
 178 }
 179
 180 void __init blkif_interface_init(void)
 181 {
 182         blkif_cachep = kmem_cache_create("blkif_cache", sizeof(blkif_t),
 183                                          0, 0, NULL);
 184 }