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 continue_after_map_failure(void *opaque)
  97 {
  98     DMAAIOCB *dbs = (DMAAIOCB *)opaque;
  99
 100     dbs->bh = qemu_bh_new(reschedule_dma, dbs);
 101     qemu_bh_schedule(dbs->bh);
 102 }
 103
 104 static void dma_blk_unmap(DMAAIOCB *dbs)
 105 {
 106     int i;
 107
 108     for (i = 0; i < dbs->iov.niov; ++i) {
 109         dma_memory_unmap(dbs->sg->as, dbs->iov.iov[i].iov_base,
 110                          dbs->iov.iov[i].iov_len, dbs->dir,
 111                          dbs->iov.iov[i].iov_len);
 112     }
 113     qemu_iovec_reset(&dbs->iov);
 114 }
 115
 116 static void dma_complete(DMAAIOCB *dbs, int ret)
 117 {
 118     trace_dma_complete(dbs, ret, dbs->common.cb);
 119
 120     dma_blk_unmap(dbs);
 121     if (dbs->common.cb) {
 122         dbs->common.cb(dbs->common.opaque, ret);
 123     }
 124     qemu_iovec_destroy(&dbs->iov);
 125     if (dbs->bh) {
 126         qemu_bh_delete(dbs->bh);
 127         dbs->bh = NULL;
 128     }
 129     qemu_aio_unref(dbs);
 130 }
 131
 132 static void dma_blk_cb(void *opaque, int ret)
 133 {
 134     DMAAIOCB *dbs = (DMAAIOCB *)opaque;
 135     dma_addr_t cur_addr, cur_len;
 136     void *mem;
 137
 138     trace_dma_blk_cb(dbs, ret);
 139
 140     dbs->acb = NULL;
 141     dbs->sector_num += dbs->iov.size / 512;
 142
 143     if (dbs->sg_cur_index == dbs->sg->nsg || ret < 0) {
 144         dma_complete(dbs, ret);
 145         return;
 146     }
 147     dma_blk_unmap(dbs);
 148
 149     while (dbs->sg_cur_index < dbs->sg->nsg) {
 150         cur_addr = dbs->sg->sg[dbs->sg_cur_index].base + dbs->sg_cur_byte;
 151         cur_len = dbs->sg->sg[dbs->sg_cur_index].len - dbs->sg_cur_byte;
 152         mem = dma_memory_map(dbs->sg->as, cur_addr, &cur_len, dbs->dir);
 153         if (!mem)
 154             break;
 155         qemu_iovec_add(&dbs->iov, mem, cur_len);
 156         dbs->sg_cur_byte += cur_len;
 157         if (dbs->sg_cur_byte == dbs->sg->sg[dbs->sg_cur_index].len) {
 158             dbs->sg_cur_byte = 0;
 159             ++dbs->sg_cur_index;
 160         }
 161     }
 162
 163     if (dbs->iov.size == 0) {
 164         trace_dma_map_wait(dbs);
 165         cpu_register_map_client(dbs, continue_after_map_failure);
 166         return;
 167     }
 168
 169     if (dbs->iov.size & ~BDRV_SECTOR_MASK) {
 170         qemu_iovec_discard_back(&dbs->iov, dbs->iov.size & ~BDRV_SECTOR_MASK);
 171     }
 172
 173     dbs->acb = dbs->io_func(dbs->blk, dbs->sector_num, &dbs->iov,
 174                             dbs->iov.size / 512, dma_blk_cb, dbs);
 175     assert(dbs->acb);
 176 }
 177
 178 static void dma_aio_cancel(BlockAIOCB *acb)
 179 {
 180     DMAAIOCB *dbs = container_of(acb, DMAAIOCB, common);
 181
 182     trace_dma_aio_cancel(dbs);
 183
 184     if (dbs->acb) {
 185         blk_aio_cancel_async(dbs->acb);
 186     }
 187 }
 188
 189
 190 static const AIOCBInfo dma_aiocb_info = {
 191     .aiocb_size         = sizeof(DMAAIOCB),
 192     .cancel_async       = dma_aio_cancel,
 193 };
 194
 195 BlockAIOCB *dma_blk_io(
 196     BlockBackend *blk, QEMUSGList *sg, uint64_t sector_num,
 197     DMAIOFunc *io_func, BlockCompletionFunc *cb,
 198     void *opaque, DMADirection dir)
 199 {
 200     DMAAIOCB *dbs = blk_aio_get(&dma_aiocb_info, blk, cb, opaque);
 201
 202     trace_dma_blk_io(dbs, blk, sector_num, (dir == DMA_DIRECTION_TO_DEVICE));
 203
 204     dbs->acb = NULL;
 205     dbs->blk = blk;
 206     dbs->sg = sg;
 207     dbs->sector_num = sector_num;
 208     dbs->sg_cur_index = 0;
 209     dbs->sg_cur_byte = 0;
 210     dbs->dir = dir;
 211     dbs->io_func = io_func;
 212     dbs->bh = NULL;
 213     qemu_iovec_init(&dbs->iov, sg->nsg);
 214     dma_blk_cb(dbs, 0);
 215     return &dbs->common;
 216 }
 217
 218
 219 BlockAIOCB *dma_blk_read(BlockBackend *blk,
 220                          QEMUSGList *sg, uint64_t sector,
 221                          void (*cb)(void *opaque, int ret), void *opaque)
 222 {
 223     return dma_blk_io(blk, sg, sector, blk_aio_readv, cb, opaque,
 224                       DMA_DIRECTION_FROM_DEVICE);
 225 }
 226
 227 BlockAIOCB *dma_blk_write(BlockBackend *blk,
 228                           QEMUSGList *sg, uint64_t sector,
 229                           void (*cb)(void *opaque, int ret), void *opaque)
 230 {
 231     return dma_blk_io(blk, sg, sector, blk_aio_writev, cb, opaque,
 232                       DMA_DIRECTION_TO_DEVICE);
 233 }
 234
 235
 236 static uint64_t dma_buf_rw(uint8_t *ptr, int32_t len, QEMUSGList *sg,
 237                            DMADirection dir)
 238 {
 239     uint64_t resid;
 240     int sg_cur_index;
 241
 242     resid = sg->size;
 243     sg_cur_index = 0;
 244     len = MIN(len, resid);
 245     while (len > 0) {
 246         ScatterGatherEntry entry = sg->sg[sg_cur_index++];
 247         int32_t xfer = MIN(len, entry.len);
 248         dma_memory_rw(sg->as, entry.base, ptr, xfer, dir);
 249         ptr += xfer;
 250         len -= xfer;
 251         resid -= xfer;
 252     }
 253
 254     return resid;
 255 }
 256
 257 uint64_t dma_buf_read(uint8_t *ptr, int32_t len, QEMUSGList *sg)
 258 {
 259     return dma_buf_rw(ptr, len, sg, DMA_DIRECTION_FROM_DEVICE);
 260 }
 261
 262 uint64_t dma_buf_write(uint8_t *ptr, int32_t len, QEMUSGList *sg)
 263 {
 264     return dma_buf_rw(ptr, len, sg, DMA_DIRECTION_TO_DEVICE);
 265 }
 266
 267 void dma_acct_start(BlockBackend *blk, BlockAcctCookie *cookie,
 268                     QEMUSGList *sg, enum BlockAcctType type)
 269 {
 270     block_acct_start(blk_get_stats(blk), cookie, sg->size, type);
 271 }