drivers/xen/blktap/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
   9 #include "common.h"
  10 #include <xen/evtchn.h>
  11
  12 static kmem_cache_t *blkif_cachep;
  13
  14 blkif_t *alloc_blkif(domid_t domid)
  15 {
  16         blkif_t *blkif;
  17
  18         blkif = kmem_cache_alloc(blkif_cachep, GFP_KERNEL);
  19         if (!blkif)
  20                 return ERR_PTR(-ENOMEM);
  21
  22         memset(blkif, 0, sizeof(*blkif));
  23         blkif->domid = domid;
  24         blkif->status = DISCONNECTED;
  25         spin_lock_init(&blkif->blk_ring_lock);
  26         atomic_set(&blkif->refcnt, 1);
  27
  28         return blkif;
  29 }
  30
  31 static int map_frontend_page(blkif_t *blkif, unsigned long shared_page)
  32 {
  33         struct gnttab_map_grant_ref op;
  34         int ret;
  35
  36         op.host_addr = (unsigned long)blkif->blk_ring_area->addr;
  37         op.flags     = GNTMAP_host_map;
  38         op.ref       = shared_page;
  39         op.dom       = blkif->domid;
  40
  41         lock_vm_area(blkif->blk_ring_area);
  42         ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, &op, 1);
  43         unlock_vm_area(blkif->blk_ring_area);
  44         BUG_ON(ret);
  45
  46         if (op.status) {
  47                 DPRINTK(" Grant table operation failure !\n");
  48                 return op.status;
  49         }
  50
  51         blkif->shmem_ref    = shared_page;
  52         blkif->shmem_handle = op.handle;
  53
  54         return 0;
  55 }
  56
  57 static void unmap_frontend_page(blkif_t *blkif)
  58 {
  59         struct gnttab_unmap_grant_ref op;
  60         int ret;
  61
  62         op.host_addr    = (unsigned long)blkif->blk_ring_area->addr;
  63         op.handle       = blkif->shmem_handle;
  64         op.dev_bus_addr = 0;
  65
  66         lock_vm_area(blkif->blk_ring_area);
  67         ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, &op, 1);
  68         unlock_vm_area(blkif->blk_ring_area);
  69         BUG_ON(ret);
  70 }
  71
  72 int blkif_map(blkif_t *blkif, unsigned long shared_page, unsigned int evtchn)
  73 {
  74         blkif_sring_t *sring;
  75         int err;
  76         evtchn_op_t op = {
  77                 .cmd = EVTCHNOP_bind_interdomain,
  78                 .u.bind_interdomain.remote_dom  = blkif->domid,
  79                 .u.bind_interdomain.remote_port = evtchn };
  80
  81         if ((blkif->blk_ring_area = alloc_vm_area(PAGE_SIZE)) == NULL)
  82                 return -ENOMEM;
  83
  84         err = map_frontend_page(blkif, shared_page);
  85         if (err) {
  86                 free_vm_area(blkif->blk_ring_area);
  87                 return err;
  88         }
  89
  90         err = HYPERVISOR_event_channel_op(&op);
  91         if (err) {
  92                 unmap_frontend_page(blkif);
  93                 free_vm_area(blkif->blk_ring_area);
  94                 return err;
  95         }
  96
  97         blkif->evtchn = op.u.bind_interdomain.local_port;
  98
  99         sring = (blkif_sring_t *)blkif->blk_ring_area->addr;
 100         BACK_RING_INIT(&blkif->blk_ring, sring, PAGE_SIZE);
 101
 102         blkif->irq = bind_evtchn_to_irqhandler(
 103                 blkif->evtchn, blkif_be_int, 0, "blkif-backend", blkif);
 104
 105         blkif->status = CONNECTED;
 106
 107         return 0;
 108 }
 109
 110 static void free_blkif(void *arg)
 111 {
 112         blkif_t *blkif = (blkif_t *)arg;
 113
 114         if (blkif->irq)
 115                 unbind_from_irqhandler(blkif->irq, blkif);
 116
 117         if (blkif->blk_ring.sring) {
 118                 unmap_frontend_page(blkif);
 119                 free_vm_area(blkif->blk_ring_area);
 120                 blkif->blk_ring.sring = NULL;
 121         }
 122
 123         kmem_cache_free(blkif_cachep, blkif);
 124 }
 125
 126 void free_blkif_callback(blkif_t *blkif)
 127 {
 128         INIT_WORK(&blkif->free_work, free_blkif, (void *)blkif);
 129         schedule_work(&blkif->free_work);
 130 }
 131
 132 void __init blkif_interface_init(void)
 133 {
 134         blkif_cachep = kmem_cache_create(
 135                 "blkif_cache", sizeof(blkif_t), 0, 0, NULL, NULL);
 136 }
 137
 138 /*
 139  * Local variables:
 140  *  c-file-style: "linux"
 141  *  indent-tabs-mode: t
 142  *  c-indent-level: 8
 143  *  c-basic-offset: 8
 144  *  tab-width: 8
 145  * End:
 146  */