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