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 "sysemu/block-backend.h"
  11 #include "sysemu/dma.h"
  12 #include "trace.h"
  13 #include "qemu/thread.h"
  14 #include "qemu/main-loop.h"
  15
  16 /* #define DEBUG_IOMMU */
  17
  18 int dma_memory_set(AddressSpace *as, dma_addr_t addr, uint8_t c, dma_addr_t len)
  19 {
  20     dma_barrier(as, DMA_DIRECTION_FROM_DEVICE);
  21
  22 #define FILLBUF_SIZE 512
  23     uint8_t fillbuf[FILLBUF_SIZE];
  24     int l;
  25     bool error = false;
  26
  27     memset(fillbuf, c, FILLBUF_SIZE);
  28     while (len > 0) {
  29         l = len < FILLBUF_SIZE ? len : FILLBUF_SIZE;
  30         error |= address_space_rw(as, addr, MEMTXATTRS_UNSPECIFIED,
  31                                   fillbuf, l, true);
  32         len -= l;
  33         addr += l;
  34     }
  35
  36     return error;
  37 }
  38
  39 void qemu_sglist_init(QEMUSGList *qsg, DeviceState *dev, int alloc_hint,
  40                       AddressSpace *as)
  41 {
  42     qsg->sg = g_malloc(alloc_hint * sizeof(ScatterGatherEntry));
  43     qsg->nsg = 0;
  44     qsg->nalloc = alloc_hint;
  45     qsg->size = 0;
  46     qsg->as = as;
  47     qsg->dev = dev;
  48     object_ref(OBJECT(dev));
  49 }
  50
  51 void qemu_sglist_add(QEMUSGList *qsg, dma_addr_t base, dma_addr_t len)
  52 {
  53     if (qsg->nsg == qsg->nalloc) {
  54         qsg->nalloc = 2 * qsg->nalloc + 1;
  55         qsg->sg = g_realloc(qsg->sg, qsg->nalloc * sizeof(ScatterGatherEntry));
  56     }
  57     qsg->sg[qsg->nsg].base = base;
  58     qsg->sg[qsg->nsg].len = len;
  59     qsg->size += len;
  60     ++qsg->nsg;
  61 }
  62
  63 void qemu_sglist_destroy(QEMUSGList *qsg)
  64 {
  65     object_unref(OBJECT(qsg->dev));
  66     g_free(qsg->sg);
  67     memset(qsg, 0, sizeof(*qsg));
  68 }
  69
  70 typedef struct {
  71     BlockAIOCB common;
  72     BlockBackend *blk;
  73     BlockAIOCB *acb;
  74     QEMUSGList *sg;
  75     uint64_t sector_num;
  76     DMADirection dir;
  77     int sg_cur_index;
  78     dma_addr_t sg_cur_byte;
  79     QEMUIOVector iov;
  80     QEMUBH *bh;
  81     DMAIOFunc *io_func;
  82 } DMAAIOCB;
  83
  84 static void dma_blk_cb(void *opaque, int ret);
  85
  86 static void reschedule_dma(void *opaque)
  87 {
  88     DMAAIOCB *dbs = (DMAAIOCB *)opaque;
  89
  90     qemu_bh_delete(dbs->bh);
  91     dbs->bh = NULL;
  92     dma_blk_cb(dbs, 0);
  93 }
  94
  95 static void dma_blk_unmap(DMAAIOCB *dbs)
  96 {
  97     int i;
  98
  99     for (i = 0; i < dbs->iov.niov; ++i) {
 100         dma_memory_unmap(dbs->sg->as, dbs->iov.iov[i].iov_base,
 101                          dbs->iov.iov[i].iov_len, dbs->dir,
 102                          dbs->iov.iov[i].iov_len);
 103     }
 104     qemu_iovec_reset(&dbs->iov);
 105 }
 106
 107 static void dma_complete(DMAAIOCB *dbs, int ret)
 108 {
 109     trace_dma_complete(dbs, ret, dbs->common.cb);
 110
 111     dma_blk_unmap(dbs);
 112     if (dbs->common.cb) {
 113         dbs->common.cb(dbs->common.opaque, ret);
 114     }
 115     qemu_iovec_destroy(&dbs->iov);
 116     if (dbs->bh) {
 117         qemu_bh_delete(dbs->bh);
 118         dbs->bh = NULL;
 119     }
 120     qemu_aio_unref(dbs);
 121 }
 122
 123 static void dma_blk_cb(void *opaque, int ret)
 124 {
 125     DMAAIOCB *dbs = (DMAAIOCB *)opaque;
 126     dma_addr_t cur_addr, cur_len;
 127     void *mem;
 128
 129     trace_dma_blk_cb(dbs, ret);
 130
 131     dbs->acb = NULL;
 132     dbs->sector_num += dbs->iov.size / 512;
 133
 134     if (dbs->sg_cur_index == dbs->sg->nsg || ret < 0) {
 135         dma_complete(dbs, ret);
 136         return;
 137     }
 138     dma_blk_unmap(dbs);
 139
 140     while (dbs->sg_cur_index < dbs->sg->nsg) {
 141         cur_addr = dbs->sg->sg[dbs->sg_cur_index].base + dbs->sg_cur_byte;
 142         cur_len = dbs->sg->sg[dbs->sg_cur_index].len - dbs->sg_cur_byte;
 143         mem = dma_memory_map(dbs->sg->as, cur_addr, &cur_len, dbs->dir);
 144         if (!mem)
 145             break;
 146         qemu_iovec_add(&dbs->iov, mem, cur_len);
 147         dbs->sg_cur_byte += cur_len;
 148         if (dbs->sg_cur_byte == dbs->sg->sg[dbs->sg_cur_index].len) {
 149             dbs->sg_cur_byte = 0;
 150             ++dbs->sg_cur_index;
 151         }
 152     }
 153
 154     if (dbs->iov.size == 0) {
 155         trace_dma_map_wait(dbs);
 156         dbs->bh = aio_bh_new(blk_get_aio_context(dbs->blk),
 157                              reschedule_dma, dbs);
 158         cpu_register_map_client(dbs->bh);
 159         return;
 160     }
 161
 162     if (dbs->iov.size & ~BDRV_SECTOR_MASK) {
 163         qemu_iovec_discard_back(&dbs->iov, dbs->iov.size & ~BDRV_SECTOR_MASK);
 164     }
 165
 166     dbs->acb = dbs->io_func(dbs->blk, dbs->sector_num, &dbs->iov,
 167                             dbs->iov.size / 512, dma_blk_cb, dbs);
 168     assert(dbs->acb);
 169 }
 170
 171 static void dma_aio_cancel(BlockAIOCB *acb)
 172 {
 173     DMAAIOCB *dbs = container_of(acb, DMAAIOCB, common);
 174
 175     trace_dma_aio_cancel(dbs);
 176
 177     if (dbs->acb) {
 178         blk_aio_cancel_async(dbs->acb);
 179     }
 180     if (dbs->bh) {
 181         cpu_unregister_map_client(dbs->bh);
 182         qemu_bh_delete(dbs->bh);
 183         dbs->bh = NULL;
 184     }
 185 }
 186
 187
 188 static const AIOCBInfo dma_aiocb_info = {
 189     .aiocb_size         = sizeof(DMAAIOCB),
 190     .cancel_async       = dma_aio_cancel,
 191 };
 192
 193 BlockAIOCB *dma_blk_io(
 194     BlockBackend *blk, QEMUSGList *sg, uint64_t sector_num,
 195     DMAIOFunc *io_func, BlockCompletionFunc *cb,
 196     void *opaque, DMADirection dir)
 197 {
 198     DMAAIOCB *dbs = blk_aio_get(&dma_aiocb_info, blk, cb, opaque);
 199
 200     trace_dma_blk_io(dbs, blk, sector_num, (dir == DMA_DIRECTION_TO_DEVICE));
 201
 202     dbs->acb = NULL;
 203     dbs->blk = blk;
 204     dbs->sg = sg;
 205     dbs->sector_num = sector_num;
 206     dbs->sg_cur_index = 0;
 207     dbs->sg_cur_byte = 0;
 208     dbs->dir = dir;
 209     dbs->io_func = io_func;
 210     dbs->bh = NULL;
 211     qemu_iovec_init(&dbs->iov, sg->nsg);
 212     dma_blk_cb(dbs, 0);
 213     return &dbs->common;
 214 }
 215
 216
 217 BlockAIOCB *dma_blk_read(BlockBackend *blk,
 218                          QEMUSGList *sg, uint64_t sector,
 219                          void (*cb)(void *opaque, int ret), void *opaque)
 220 {
 221     return dma_blk_io(blk, sg, sector, blk_aio_readv, cb, opaque,
 222                       DMA_DIRECTION_FROM_DEVICE);
 223 }
 224
 225 BlockAIOCB *dma_blk_write(BlockBackend *blk,
 226                           QEMUSGList *sg, uint64_t sector,
 227                           void (*cb)(void *opaque, int ret), void *opaque)
 228 {
 229     return dma_blk_io(blk, sg, sector, blk_aio_writev, cb, opaque,
 230                       DMA_DIRECTION_TO_DEVICE);
 231 }
 232
 233
 234 static uint64_t dma_buf_rw(uint8_t *ptr, int32_t len, QEMUSGList *sg,
 235                            DMADirection dir)
 236 {
 237     uint64_t resid;
 238     int sg_cur_index;
 239
 240     resid = sg->size;
 241     sg_cur_index = 0;
 242     len = MIN(len, resid);
 243     while (len > 0) {
 244         ScatterGatherEntry entry = sg->sg[sg_cur_index++];
 245         int32_t xfer = MIN(len, entry.len);
 246         dma_memory_rw(sg->as, entry.base, ptr, xfer, dir);
 247         ptr += xfer;
 248         len -= xfer;
 249         resid -= xfer;
 250     }
 251
 252     return resid;
 253 }
 254
 255 uint64_t dma_buf_read(uint8_t *ptr, int32_t len, QEMUSGList *sg)
 256 {
 257     return dma_buf_rw(ptr, len, sg, DMA_DIRECTION_FROM_DEVICE);
 258 }
 259
 260 uint64_t dma_buf_write(uint8_t *ptr, int32_t len, QEMUSGList *sg)
 261 {
 262     return dma_buf_rw(ptr, len, sg, DMA_DIRECTION_TO_DEVICE);
 263 }
 264
 265 void dma_acct_start(BlockBackend *blk, BlockAcctCookie *cookie,
 266                     QEMUSGList *sg, enum BlockAcctType type)
 267 {
 268     block_acct_start(blk_get_stats(blk), cookie, sg->size, type);
 269 }