dma-helpers.c

   1 /*
   2  * DMA helper functions
   3  *
   4  * Copyright (c) 2009 Red Hat
   5  *
   6  * This work is licensed under the terms of the GNU General Public License
   7  * (GNU GPL), version 2 or later.
   8  */
   9
  10 #include "dma.h"
  11 #include "block_int.h"
  12 #include "cache-utils.h"
  13
  14 static AIOPool dma_aio_pool;
  15
  16 void qemu_sglist_init(QEMUSGList *qsg, int alloc_hint)
  17 {
  18     qsg->sg = qemu_malloc(alloc_hint * sizeof(ScatterGatherEntry));
  19     qsg->nsg = 0;
  20     qsg->nalloc = alloc_hint;
  21     qsg->size = 0;
  22 }
  23
  24 void qemu_sglist_add(QEMUSGList *qsg, target_phys_addr_t base,
  25                      target_phys_addr_t len)
  26 {
  27     if (qsg->nsg == qsg->nalloc) {
  28         qsg->nalloc = 2 * qsg->nalloc + 1;
  29         qsg->sg = qemu_realloc(qsg->sg, qsg->nalloc * sizeof(ScatterGatherEntry));
  30     }
  31     qsg->sg[qsg->nsg].base = base;
  32     qsg->sg[qsg->nsg].len = len;
  33     qsg->size += len;
  34     ++qsg->nsg;
  35 }
  36
  37 void qemu_sglist_destroy(QEMUSGList *qsg)
  38 {
  39     qemu_free(qsg->sg);
  40 }
  41
  42 typedef struct {
  43     BlockDriverAIOCB common;
  44     BlockDriverState *bs;
  45     BlockDriverAIOCB *acb;
  46     QEMUSGList *sg;
  47     uint64_t sector_num;
  48     int is_write;
  49     int sg_cur_index;
  50     target_phys_addr_t sg_cur_byte;
  51     QEMUIOVector iov;
  52     QEMUBH *bh;
  53 } DMAAIOCB;
  54
  55 static void dma_bdrv_cb(void *opaque, int ret);
  56
  57 static void reschedule_dma(void *opaque)
  58 {
  59     DMAAIOCB *dbs = (DMAAIOCB *)opaque;
  60
  61     qemu_bh_delete(dbs->bh);
  62     dbs->bh = NULL;
  63     dma_bdrv_cb(opaque, 0);
  64 }
  65
  66 static void continue_after_map_failure(void *opaque)
  67 {
  68     DMAAIOCB *dbs = (DMAAIOCB *)opaque;
  69
  70     dbs->bh = qemu_bh_new(reschedule_dma, dbs);
  71     qemu_bh_schedule(dbs->bh);
  72 }
  73
  74 static void dma_bdrv_unmap(DMAAIOCB *dbs)
  75 {
  76     int i;
  77
  78     for (i = 0; i < dbs->iov.niov; ++i) {
  79         cpu_physical_memory_unmap(dbs->iov.iov[i].iov_base,
  80                                   dbs->iov.iov[i].iov_len, !dbs->is_write,
  81                                   dbs->iov.iov[i].iov_len);
  82     }
  83 }
  84
  85 static void dma_bdrv_cb(void *opaque, int ret)
  86 {
  87     DMAAIOCB *dbs = (DMAAIOCB *)opaque;
  88     target_phys_addr_t cur_addr, cur_len;
  89     void *mem;
  90
  91     dbs->acb = NULL;
  92     dbs->sector_num += dbs->iov.size / 512;
  93     dma_bdrv_unmap(dbs);
  94     qemu_iovec_reset(&dbs->iov);
  95
  96     if (dbs->sg_cur_index == dbs->sg->nsg || ret < 0) {
  97         dbs->common.cb(dbs->common.opaque, ret);
  98         qemu_iovec_destroy(&dbs->iov);
  99         qemu_aio_release(dbs);
 100         return;
 101     }
 102
 103     while (dbs->sg_cur_index < dbs->sg->nsg) {
 104         cur_addr = dbs->sg->sg[dbs->sg_cur_index].base + dbs->sg_cur_byte;
 105         cur_len = dbs->sg->sg[dbs->sg_cur_index].len - dbs->sg_cur_byte;
 106         mem = cpu_physical_memory_map(cur_addr, &cur_len, !dbs->is_write);
 107         if (!mem)
 108             break;
 109         qemu_iovec_add(&dbs->iov, mem, cur_len);
 110         dbs->sg_cur_byte += cur_len;
 111         if (dbs->sg_cur_byte == dbs->sg->sg[dbs->sg_cur_index].len) {
 112             dbs->sg_cur_byte = 0;
 113             ++dbs->sg_cur_index;
 114         }
 115     }
 116
 117     if (dbs->iov.size == 0) {
 118         cpu_register_map_client(dbs, continue_after_map_failure);
 119         return;
 120     }
 121
 122     if (dbs->is_write) {
 123         dbs->acb = bdrv_aio_writev(dbs->bs, dbs->sector_num, &dbs->iov,
 124                                    dbs->iov.size / 512, dma_bdrv_cb, dbs);
 125     } else {
 126         dbs->acb = bdrv_aio_readv(dbs->bs, dbs->sector_num, &dbs->iov,
 127                                   dbs->iov.size / 512, dma_bdrv_cb, dbs);
 128     }
 129     if (!dbs->acb) {
 130         dma_bdrv_unmap(dbs);
 131         qemu_iovec_destroy(&dbs->iov);
 132         return;
 133     }
 134 }
 135
 136 static BlockDriverAIOCB *dma_bdrv_io(
 137     BlockDriverState *bs, QEMUSGList *sg, uint64_t sector_num,
 138     BlockDriverCompletionFunc *cb, void *opaque,
 139     int is_write)
 140 {
 141     int i;
 142     QEMUIOVector *qiov;
 143     DMAAIOCB *dbs =  qemu_aio_get_pool(&dma_aio_pool, bs, cb, opaque);
 144
 145     dbs->acb = NULL;
 146     dbs->bs = bs;
 147     dbs->sg = sg;
 148     dbs->sector_num = sector_num;
 149     dbs->sg_cur_index = 0;
 150     dbs->sg_cur_byte = 0;
 151     dbs->is_write = is_write;
 152     dbs->bh = NULL;
 153     qemu_iovec_init(&dbs->iov, sg->nsg);
 154     dma_bdrv_cb(dbs, 0);
 155
 156     if (!is_write) {
 157         qiov = &dbs->iov;
 158         for (i = 0; i < qiov->niov; ++i) {
 159            qemu_sync_idcache((unsigned long)qiov->iov[i].iov_base,
 160                  (unsigned long)(qiov->iov[i].iov_base + qiov->iov[i].iov_len));
 161         }
 162     }
 163
 164     if (!dbs->acb) {
 165         qemu_aio_release(dbs);
 166         return NULL;
 167     }
 168     return &dbs->common;
 169 }
 170
 171
 172 BlockDriverAIOCB *dma_bdrv_read(BlockDriverState *bs,
 173                                 QEMUSGList *sg, uint64_t sector,
 174                                 void (*cb)(void *opaque, int ret), void *opaque)
 175 {
 176     return dma_bdrv_io(bs, sg, sector, cb, opaque, 0);
 177 }
 178
 179 BlockDriverAIOCB *dma_bdrv_write(BlockDriverState *bs,
 180                                  QEMUSGList *sg, uint64_t sector,
 181                                  void (*cb)(void *opaque, int ret), void *opaque)
 182 {
 183     return dma_bdrv_io(bs, sg, sector, cb, opaque, 1);
 184 }
 185
 186 static void dma_aio_cancel(BlockDriverAIOCB *acb)
 187 {
 188     DMAAIOCB *dbs = container_of(acb, DMAAIOCB, common);
 189
 190     if (dbs->acb) {
 191         bdrv_aio_cancel(dbs->acb);
 192     }
 193 }
 194
 195 void dma_helper_init(void)
 196 {
 197     aio_pool_init(&dma_aio_pool, sizeof(DMAAIOCB), dma_aio_cancel);
 198 }