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 "trace.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, dma_addr_t base, dma_addr_t len)
  22 {
  23     if (qsg->nsg == qsg->nalloc) {
  24         qsg->nalloc = 2 * qsg->nalloc + 1;
  25         qsg->sg = g_realloc(qsg->sg, qsg->nalloc * sizeof(ScatterGatherEntry));
  26     }
  27     qsg->sg[qsg->nsg].base = base;
  28     qsg->sg[qsg->nsg].len = len;
  29     qsg->size += len;
  30     ++qsg->nsg;
  31 }
  32
  33 void qemu_sglist_destroy(QEMUSGList *qsg)
  34 {
  35     g_free(qsg->sg);
  36 }
  37
  38 typedef struct {
  39     BlockDriverAIOCB common;
  40     BlockDriverState *bs;
  41     BlockDriverAIOCB *acb;
  42     QEMUSGList *sg;
  43     uint64_t sector_num;
  44     DMADirection dir;
  45     bool in_cancel;
  46     int sg_cur_index;
  47     dma_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(dbs, 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,
  79                                   dbs->dir != DMA_DIRECTION_TO_DEVICE,
  80                                   dbs->iov.iov[i].iov_len);
  81     }
  82     qemu_iovec_reset(&dbs->iov);
  83 }
  84
  85 static void dma_complete(DMAAIOCB *dbs, int ret)
  86 {
  87     trace_dma_complete(dbs, ret, dbs->common.cb);
  88
  89     dma_bdrv_unmap(dbs);
  90     if (dbs->common.cb) {
  91         dbs->common.cb(dbs->common.opaque, ret);
  92     }
  93     qemu_iovec_destroy(&dbs->iov);
  94     if (dbs->bh) {
  95         qemu_bh_delete(dbs->bh);
  96         dbs->bh = NULL;
  97     }
  98     if (!dbs->in_cancel) {
  99         /* Requests may complete while dma_aio_cancel is in progress.  In
 100          * this case, the AIOCB should not be released because it is still
 101          * referenced by dma_aio_cancel.  */
 102         qemu_aio_release(dbs);
 103     }
 104 }
 105
 106 static void dma_bdrv_cb(void *opaque, int ret)
 107 {
 108     DMAAIOCB *dbs = (DMAAIOCB *)opaque;
 109     target_phys_addr_t cur_addr, cur_len;
 110     void *mem;
 111
 112     trace_dma_bdrv_cb(dbs, ret);
 113
 114     dbs->acb = NULL;
 115     dbs->sector_num += dbs->iov.size / 512;
 116     dma_bdrv_unmap(dbs);
 117
 118     if (dbs->sg_cur_index == dbs->sg->nsg || ret < 0) {
 119         dma_complete(dbs, ret);
 120         return;
 121     }
 122
 123     while (dbs->sg_cur_index < dbs->sg->nsg) {
 124         cur_addr = dbs->sg->sg[dbs->sg_cur_index].base + dbs->sg_cur_byte;
 125         cur_len = dbs->sg->sg[dbs->sg_cur_index].len - dbs->sg_cur_byte;
 126         mem = cpu_physical_memory_map(cur_addr, &cur_len,
 127                                       dbs->dir != DMA_DIRECTION_TO_DEVICE);
 128         if (!mem)
 129             break;
 130         qemu_iovec_add(&dbs->iov, mem, cur_len);
 131         dbs->sg_cur_byte += cur_len;
 132         if (dbs->sg_cur_byte == dbs->sg->sg[dbs->sg_cur_index].len) {
 133             dbs->sg_cur_byte = 0;
 134             ++dbs->sg_cur_index;
 135         }
 136     }
 137
 138     if (dbs->iov.size == 0) {
 139         trace_dma_map_wait(dbs);
 140         cpu_register_map_client(dbs, continue_after_map_failure);
 141         return;
 142     }
 143
 144     dbs->acb = dbs->io_func(dbs->bs, dbs->sector_num, &dbs->iov,
 145                             dbs->iov.size / 512, dma_bdrv_cb, dbs);
 146     assert(dbs->acb);
 147 }
 148
 149 static void dma_aio_cancel(BlockDriverAIOCB *acb)
 150 {
 151     DMAAIOCB *dbs = container_of(acb, DMAAIOCB, common);
 152
 153     trace_dma_aio_cancel(dbs);
 154
 155     if (dbs->acb) {
 156         BlockDriverAIOCB *acb = dbs->acb;
 157         dbs->acb = NULL;
 158         dbs->in_cancel = true;
 159         bdrv_aio_cancel(acb);
 160         dbs->in_cancel = false;
 161     }
 162     dbs->common.cb = NULL;
 163     dma_complete(dbs, 0);
 164 }
 165
 166 static AIOPool dma_aio_pool = {
 167     .aiocb_size         = sizeof(DMAAIOCB),
 168     .cancel             = dma_aio_cancel,
 169 };
 170
 171 BlockDriverAIOCB *dma_bdrv_io(
 172     BlockDriverState *bs, QEMUSGList *sg, uint64_t sector_num,
 173     DMAIOFunc *io_func, BlockDriverCompletionFunc *cb,
 174     void *opaque, DMADirection dir)
 175 {
 176     DMAAIOCB *dbs = qemu_aio_get(&dma_aio_pool, bs, cb, opaque);
 177
 178     trace_dma_bdrv_io(dbs, bs, sector_num, (dir == DMA_DIRECTION_TO_DEVICE));
 179
 180     dbs->acb = NULL;
 181     dbs->bs = bs;
 182     dbs->sg = sg;
 183     dbs->sector_num = sector_num;
 184     dbs->sg_cur_index = 0;
 185     dbs->sg_cur_byte = 0;
 186     dbs->dir = dir;
 187     dbs->io_func = io_func;
 188     dbs->bh = NULL;
 189     qemu_iovec_init(&dbs->iov, sg->nsg);
 190     dma_bdrv_cb(dbs, 0);
 191     return &dbs->common;
 192 }
 193
 194
 195 BlockDriverAIOCB *dma_bdrv_read(BlockDriverState *bs,
 196                                 QEMUSGList *sg, uint64_t sector,
 197                                 void (*cb)(void *opaque, int ret), void *opaque)
 198 {
 199     return dma_bdrv_io(bs, sg, sector, bdrv_aio_readv, cb, opaque,
 200                        DMA_DIRECTION_FROM_DEVICE);
 201 }
 202
 203 BlockDriverAIOCB *dma_bdrv_write(BlockDriverState *bs,
 204                                  QEMUSGList *sg, uint64_t sector,
 205                                  void (*cb)(void *opaque, int ret), void *opaque)
 206 {
 207     return dma_bdrv_io(bs, sg, sector, bdrv_aio_writev, cb, opaque,
 208                        DMA_DIRECTION_TO_DEVICE);
 209 }
 210
 211
 212 static uint64_t dma_buf_rw(uint8_t *ptr, int32_t len, QEMUSGList *sg, bool to_dev)
 213 {
 214     uint64_t resid;
 215     int sg_cur_index;
 216
 217     resid = sg->size;
 218     sg_cur_index = 0;
 219     len = MIN(len, resid);
 220     while (len > 0) {
 221         ScatterGatherEntry entry = sg->sg[sg_cur_index++];
 222         int32_t xfer = MIN(len, entry.len);
 223         cpu_physical_memory_rw(entry.base, ptr, xfer, !to_dev);
 224         ptr += xfer;
 225         len -= xfer;
 226         resid -= xfer;
 227     }
 228
 229     return resid;
 230 }
 231
 232 uint64_t dma_buf_read(uint8_t *ptr, int32_t len, QEMUSGList *sg)
 233 {
 234     return dma_buf_rw(ptr, len, sg, 0);
 235 }
 236
 237 uint64_t dma_buf_write(uint8_t *ptr, int32_t len, QEMUSGList *sg)
 238 {
 239     return dma_buf_rw(ptr, len, sg, 1);
 240 }
 241
 242 void dma_acct_start(BlockDriverState *bs, BlockAcctCookie *cookie,
 243                     QEMUSGList *sg, enum BlockAcctType type)
 244 {
 245     bdrv_acct_start(bs, cookie, sg->size, type);
 246 }