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
  13 void qemu_sglist_init(QEMUSGList *qsg, int alloc_hint)
  14 {
  15     qsg->sg = g_malloc(alloc_hint * sizeof(ScatterGatherEntry));
  16     qsg->nsg = 0;
  17     qsg->nalloc = alloc_hint;
  18     qsg->size = 0;
  19 }
  20
  21 void qemu_sglist_add(QEMUSGList *qsg, target_phys_addr_t base,
  22                      target_phys_addr_t len)
  23 {
  24     if (qsg->nsg == qsg->nalloc) {
  25         qsg->nalloc = 2 * qsg->nalloc + 1;
  26         qsg->sg = g_realloc(qsg->sg, qsg->nalloc * sizeof(ScatterGatherEntry));
  27     }
  28     qsg->sg[qsg->nsg].base = base;
  29     qsg->sg[qsg->nsg].len = len;
  30     qsg->size += len;
  31     ++qsg->nsg;
  32 }
  33
  34 void qemu_sglist_destroy(QEMUSGList *qsg)
  35 {
  36     g_free(qsg->sg);
  37 }
  38
  39 typedef struct {
  40     BlockDriverAIOCB common;
  41     BlockDriverState *bs;
  42     BlockDriverAIOCB *acb;
  43     QEMUSGList *sg;
  44     uint64_t sector_num;
  45     int is_write;
  46     int sg_cur_index;
  47     target_phys_addr_t sg_cur_byte;
  48     QEMUIOVector iov;
  49     QEMUBH *bh;
  50     DMAIOFunc *io_func;
  51 } DMAAIOCB;
  52
  53 static void dma_bdrv_cb(void *opaque, int ret);
  54
  55 static void reschedule_dma(void *opaque)
  56 {
  57     DMAAIOCB *dbs = (DMAAIOCB *)opaque;
  58
  59     qemu_bh_delete(dbs->bh);
  60     dbs->bh = NULL;
  61     dma_bdrv_cb(opaque, 0);
  62 }
  63
  64 static void continue_after_map_failure(void *opaque)
  65 {
  66     DMAAIOCB *dbs = (DMAAIOCB *)opaque;
  67
  68     dbs->bh = qemu_bh_new(reschedule_dma, dbs);
  69     qemu_bh_schedule(dbs->bh);
  70 }
  71
  72 static void dma_bdrv_unmap(DMAAIOCB *dbs)
  73 {
  74     int i;
  75
  76     for (i = 0; i < dbs->iov.niov; ++i) {
  77         cpu_physical_memory_unmap(dbs->iov.iov[i].iov_base,
  78                                   dbs->iov.iov[i].iov_len, !dbs->is_write,
  79                                   dbs->iov.iov[i].iov_len);
  80     }
  81 }
  82
  83 static void dma_bdrv_cb(void *opaque, int ret)
  84 {
  85     DMAAIOCB *dbs = (DMAAIOCB *)opaque;
  86     target_phys_addr_t cur_addr, cur_len;
  87     void *mem;
  88
  89     dbs->acb = NULL;
  90     dbs->sector_num += dbs->iov.size / 512;
  91     dma_bdrv_unmap(dbs);
  92     qemu_iovec_reset(&dbs->iov);
  93
  94     if (dbs->sg_cur_index == dbs->sg->nsg || ret < 0) {
  95         dbs->common.cb(dbs->common.opaque, ret);
  96         qemu_iovec_destroy(&dbs->iov);
  97         qemu_aio_release(dbs);
  98         return;
  99     }
 100
 101     while (dbs->sg_cur_index < dbs->sg->nsg) {
 102         cur_addr = dbs->sg->sg[dbs->sg_cur_index].base + dbs->sg_cur_byte;
 103         cur_len = dbs->sg->sg[dbs->sg_cur_index].len - dbs->sg_cur_byte;
 104         mem = cpu_physical_memory_map(cur_addr, &cur_len, !dbs->is_write);
 105         if (!mem)
 106             break;
 107         qemu_iovec_add(&dbs->iov, mem, cur_len);
 108         dbs->sg_cur_byte += cur_len;
 109         if (dbs->sg_cur_byte == dbs->sg->sg[dbs->sg_cur_index].len) {
 110             dbs->sg_cur_byte = 0;
 111             ++dbs->sg_cur_index;
 112         }
 113     }
 114
 115     if (dbs->iov.size == 0) {
 116         cpu_register_map_client(dbs, continue_after_map_failure);
 117         return;
 118     }
 119
 120     dbs->acb = dbs->io_func(dbs->bs, dbs->sector_num, &dbs->iov,
 121                             dbs->iov.size / 512, dma_bdrv_cb, dbs);
 122     if (!dbs->acb) {
 123         dma_bdrv_unmap(dbs);
 124         qemu_iovec_destroy(&dbs->iov);
 125         return;
 126     }
 127 }
 128
 129 static void dma_aio_cancel(BlockDriverAIOCB *acb)
 130 {
 131     DMAAIOCB *dbs = container_of(acb, DMAAIOCB, common);
 132
 133     if (dbs->acb) {
 134         bdrv_aio_cancel(dbs->acb);
 135     }
 136 }
 137
 138 static AIOPool dma_aio_pool = {
 139     .aiocb_size         = sizeof(DMAAIOCB),
 140     .cancel             = dma_aio_cancel,
 141 };
 142
 143 BlockDriverAIOCB *dma_bdrv_io(
 144     BlockDriverState *bs, QEMUSGList *sg, uint64_t sector_num,
 145     DMAIOFunc *io_func, BlockDriverCompletionFunc *cb,
 146     void *opaque, int is_write)
 147 {
 148     DMAAIOCB *dbs = qemu_aio_get(&dma_aio_pool, bs, cb, opaque);
 149
 150     dbs->acb = NULL;
 151     dbs->bs = bs;
 152     dbs->sg = sg;
 153     dbs->sector_num = sector_num;
 154     dbs->sg_cur_index = 0;
 155     dbs->sg_cur_byte = 0;
 156     dbs->is_write = is_write;
 157     dbs->io_func = io_func;
 158     dbs->bh = NULL;
 159     qemu_iovec_init(&dbs->iov, sg->nsg);
 160     dma_bdrv_cb(dbs, 0);
 161     if (!dbs->acb) {
 162         qemu_aio_release(dbs);
 163         return NULL;
 164     }
 165     return &dbs->common;
 166 }
 167
 168
 169 BlockDriverAIOCB *dma_bdrv_read(BlockDriverState *bs,
 170                                 QEMUSGList *sg, uint64_t sector,
 171                                 void (*cb)(void *opaque, int ret), void *opaque)
 172 {
 173     return dma_bdrv_io(bs, sg, sector, bdrv_aio_readv, cb, opaque, 0);
 174 }
 175
 176 BlockDriverAIOCB *dma_bdrv_write(BlockDriverState *bs,
 177                                  QEMUSGList *sg, uint64_t sector,
 178                                  void (*cb)(void *opaque, int ret), void *opaque)
 179 {
 180     return dma_bdrv_io(bs, sg, sector, bdrv_aio_writev, cb, opaque, 1);
 181 }