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/range.h"
  14 #include "qemu/thread.h"
  15 #include "qemu/main-loop.h"
  16
  17 /* #define DEBUG_IOMMU */
  18
  19 int dma_memory_set(AddressSpace *as, dma_addr_t addr, uint8_t c, dma_addr_t len)
  20 {
  21     dma_barrier(as, DMA_DIRECTION_FROM_DEVICE);
  22
  23 #define FILLBUF_SIZE 512
  24     uint8_t fillbuf[FILLBUF_SIZE];
  25     int l;
  26     bool error = false;
  27
  28     memset(fillbuf, c, FILLBUF_SIZE);
  29     while (len > 0) {
  30         l = len < FILLBUF_SIZE ? len : FILLBUF_SIZE;
  31         error |= address_space_rw(as, addr, MEMTXATTRS_UNSPECIFIED,
  32                                   fillbuf, l, true);
  33         len -= l;
  34         addr += l;
  35     }
  36
  37     return error;
  38 }
  39
  40 void qemu_sglist_init(QEMUSGList *qsg, DeviceState *dev, int alloc_hint,
  41                       AddressSpace *as)
  42 {
  43     qsg->sg = g_malloc(alloc_hint * sizeof(ScatterGatherEntry));
  44     qsg->nsg = 0;
  45     qsg->nalloc = alloc_hint;
  46     qsg->size = 0;
  47     qsg->as = as;
  48     qsg->dev = dev;
  49     object_ref(OBJECT(dev));
  50 }
  51
  52 void qemu_sglist_add(QEMUSGList *qsg, dma_addr_t base, dma_addr_t len)
  53 {
  54     if (qsg->nsg == qsg->nalloc) {
  55         qsg->nalloc = 2 * qsg->nalloc + 1;
  56         qsg->sg = g_realloc(qsg->sg, qsg->nalloc * sizeof(ScatterGatherEntry));
  57     }
  58     qsg->sg[qsg->nsg].base = base;
  59     qsg->sg[qsg->nsg].len = len;
  60     qsg->size += len;
  61     ++qsg->nsg;
  62 }
  63
  64 void qemu_sglist_destroy(QEMUSGList *qsg)
  65 {
  66     object_unref(OBJECT(qsg->dev));
  67     g_free(qsg->sg);
  68     memset(qsg, 0, sizeof(*qsg));
  69 }
  70
  71 typedef struct {
  72     BlockAIOCB common;
  73     BlockBackend *blk;
  74     BlockAIOCB *acb;
  75     QEMUSGList *sg;
  76     uint64_t sector_num;
  77     DMADirection dir;
  78     int sg_cur_index;
  79     dma_addr_t sg_cur_byte;
  80     QEMUIOVector iov;
  81     QEMUBH *bh;
  82     DMAIOFunc *io_func;
  83 } DMAAIOCB;
  84
  85 static void dma_blk_cb(void *opaque, int ret);
  86
  87 static void reschedule_dma(void *opaque)
  88 {
  89     DMAAIOCB *dbs = (DMAAIOCB *)opaque;
  90
  91     qemu_bh_delete(dbs->bh);
  92     dbs->bh = NULL;
  93     dma_blk_cb(dbs, 0);
  94 }
  95
  96 static void dma_blk_unmap(DMAAIOCB *dbs)
  97 {
  98     int i;
  99
 100     for (i = 0; i < dbs->iov.niov; ++i) {
 101         dma_memory_unmap(dbs->sg->as, dbs->iov.iov[i].iov_base,
 102                          dbs->iov.iov[i].iov_len, dbs->dir,
 103                          dbs->iov.iov[i].iov_len);
 104     }
 105     qemu_iovec_reset(&dbs->iov);
 106 }
 107
 108 static void dma_complete(DMAAIOCB *dbs, int ret)
 109 {
 110     trace_dma_complete(dbs, ret, dbs->common.cb);
 111
 112     dma_blk_unmap(dbs);
 113     if (dbs->common.cb) {
 114         dbs->common.cb(dbs->common.opaque, ret);
 115     }
 116     qemu_iovec_destroy(&dbs->iov);
 117     if (dbs->bh) {
 118         qemu_bh_delete(dbs->bh);
 119         dbs->bh = NULL;
 120     }
 121     qemu_aio_unref(dbs);
 122 }
 123
 124 static void dma_blk_cb(void *opaque, int ret)
 125 {
 126     DMAAIOCB *dbs = (DMAAIOCB *)opaque;
 127     dma_addr_t cur_addr, cur_len;
 128     void *mem;
 129
 130     trace_dma_blk_cb(dbs, ret);
 131
 132     dbs->acb = NULL;
 133     dbs->sector_num += dbs->iov.size / 512;
 134
 135     if (dbs->sg_cur_index == dbs->sg->nsg || ret < 0) {
 136         dma_complete(dbs, ret);
 137         return;
 138     }
 139     dma_blk_unmap(dbs);
 140
 141     while (dbs->sg_cur_index < dbs->sg->nsg) {
 142         cur_addr = dbs->sg->sg[dbs->sg_cur_index].base + dbs->sg_cur_byte;
 143         cur_len = dbs->sg->sg[dbs->sg_cur_index].len - dbs->sg_cur_byte;
 144         mem = dma_memory_map(dbs->sg->as, cur_addr, &cur_len, dbs->dir);
 145         if (!mem)
 146             break;
 147         qemu_iovec_add(&dbs->iov, mem, cur_len);
 148         dbs->sg_cur_byte += cur_len;
 149         if (dbs->sg_cur_byte == dbs->sg->sg[dbs->sg_cur_index].len) {
 150             dbs->sg_cur_byte = 0;
 151             ++dbs->sg_cur_index;
 152         }
 153     }
 154
 155     if (dbs->iov.size == 0) {
 156         trace_dma_map_wait(dbs);
 157         dbs->bh = aio_bh_new(blk_get_aio_context(dbs->blk),
 158                              reschedule_dma, dbs);
 159         cpu_register_map_client(dbs->bh);
 160         return;
 161     }
 162
 163     if (dbs->iov.size & ~BDRV_SECTOR_MASK) {
 164         qemu_iovec_discard_back(&dbs->iov, dbs->iov.size & ~BDRV_SECTOR_MASK);
 165     }
 166
 167     dbs->acb = dbs->io_func(dbs->blk, dbs->sector_num, &dbs->iov,
 168                             dbs->iov.size / 512, dma_blk_cb, dbs);
 169     assert(dbs->acb);
 170 }
 171
 172 static void dma_aio_cancel(BlockAIOCB *acb)
 173 {
 174     DMAAIOCB *dbs = container_of(acb, DMAAIOCB, common);
 175
 176     trace_dma_aio_cancel(dbs);
 177
 178     if (dbs->acb) {
 179         blk_aio_cancel_async(dbs->acb);
 180     }
 181     if (dbs->bh) {
 182         cpu_unregister_map_client(dbs->bh);
 183         qemu_bh_delete(dbs->bh);
 184         dbs->bh = NULL;
 185     }
 186 }
 187
 188
 189 static const AIOCBInfo dma_aiocb_info = {
 190     .aiocb_size         = sizeof(DMAAIOCB),
 191     .cancel_async       = dma_aio_cancel,
 192 };
 193
 194 BlockAIOCB *dma_blk_io(
 195     BlockBackend *blk, QEMUSGList *sg, uint64_t sector_num,
 196     DMAIOFunc *io_func, BlockCompletionFunc *cb,
 197     void *opaque, DMADirection dir)
 198 {
 199     DMAAIOCB *dbs = blk_aio_get(&dma_aiocb_info, blk, cb, opaque);
 200
 201     trace_dma_blk_io(dbs, blk, sector_num, (dir == DMA_DIRECTION_TO_DEVICE));
 202
 203     dbs->acb = NULL;
 204     dbs->blk = blk;
 205     dbs->sg = sg;
 206     dbs->sector_num = sector_num;
 207     dbs->sg_cur_index = 0;
 208     dbs->sg_cur_byte = 0;
 209     dbs->dir = dir;
 210     dbs->io_func = io_func;
 211     dbs->bh = NULL;
 212     qemu_iovec_init(&dbs->iov, sg->nsg);
 213     dma_blk_cb(dbs, 0);
 214     return &dbs->common;
 215 }
 216
 217
 218 BlockAIOCB *dma_blk_read(BlockBackend *blk,
 219                          QEMUSGList *sg, uint64_t sector,
 220                          void (*cb)(void *opaque, int ret), void *opaque)
 221 {
 222     return dma_blk_io(blk, sg, sector, blk_aio_readv, cb, opaque,
 223                       DMA_DIRECTION_FROM_DEVICE);
 224 }
 225
 226 BlockAIOCB *dma_blk_write(BlockBackend *blk,
 227                           QEMUSGList *sg, uint64_t sector,
 228                           void (*cb)(void *opaque, int ret), void *opaque)
 229 {
 230     return dma_blk_io(blk, sg, sector, blk_aio_writev, cb, opaque,
 231                       DMA_DIRECTION_TO_DEVICE);
 232 }
 233
 234
 235 static uint64_t dma_buf_rw(uint8_t *ptr, int32_t len, QEMUSGList *sg,
 236                            DMADirection dir)
 237 {
 238     uint64_t resid;
 239     int sg_cur_index;
 240
 241     resid = sg->size;
 242     sg_cur_index = 0;
 243     len = MIN(len, resid);
 244     while (len > 0) {
 245         ScatterGatherEntry entry = sg->sg[sg_cur_index++];
 246         int32_t xfer = MIN(len, entry.len);
 247         dma_memory_rw(sg->as, entry.base, ptr, xfer, dir);
 248         ptr += xfer;
 249         len -= xfer;
 250         resid -= xfer;
 251     }
 252
 253     return resid;
 254 }
 255
 256 uint64_t dma_buf_read(uint8_t *ptr, int32_t len, QEMUSGList *sg)
 257 {
 258     return dma_buf_rw(ptr, len, sg, DMA_DIRECTION_FROM_DEVICE);
 259 }
 260
 261 uint64_t dma_buf_write(uint8_t *ptr, int32_t len, QEMUSGList *sg)
 262 {
 263     return dma_buf_rw(ptr, len, sg, DMA_DIRECTION_TO_DEVICE);
 264 }
 265
 266 void dma_acct_start(BlockBackend *blk, BlockAcctCookie *cookie,
 267                     QEMUSGList *sg, enum BlockAcctType type)
 268 {
 269     block_acct_start(blk_get_stats(blk), cookie, sg->size, type);
 270 }