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 "qemu/osdep.h"
  11 #include "sysemu/block-backend.h"
  12 #include "sysemu/dma.h"
  13 #include "trace-root.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     AioContext *ctx;
  74     BlockAIOCB *acb;
  75     QEMUSGList *sg;
  76     uint32_t align;
  77     uint64_t offset;
  78     DMADirection dir;
  79     int sg_cur_index;
  80     dma_addr_t sg_cur_byte;
  81     QEMUIOVector iov;
  82     QEMUBH *bh;
  83     DMAIOFunc *io_func;
  84     void *io_func_opaque;
  85 } DMAAIOCB;
  86
  87 static void dma_blk_cb(void *opaque, int ret);
  88
  89 static void reschedule_dma(void *opaque)
  90 {
  91     DMAAIOCB *dbs = (DMAAIOCB *)opaque;
  92
  93     assert(!dbs->acb && dbs->bh);
  94     qemu_bh_delete(dbs->bh);
  95     dbs->bh = NULL;
  96     dma_blk_cb(dbs, 0);
  97 }
  98
  99 static void dma_blk_unmap(DMAAIOCB *dbs)
 100 {
 101     int i;
 102
 103     for (i = 0; i < dbs->iov.niov; ++i) {
 104         dma_memory_unmap(dbs->sg->as, dbs->iov.iov[i].iov_base,
 105                          dbs->iov.iov[i].iov_len, dbs->dir,
 106                          dbs->iov.iov[i].iov_len);
 107     }
 108     qemu_iovec_reset(&dbs->iov);
 109 }
 110
 111 static void dma_complete(DMAAIOCB *dbs, int ret)
 112 {
 113     trace_dma_complete(dbs, ret, dbs->common.cb);
 114
 115     assert(!dbs->acb && !dbs->bh);
 116     dma_blk_unmap(dbs);
 117     if (dbs->common.cb) {
 118         dbs->common.cb(dbs->common.opaque, ret);
 119     }
 120     qemu_iovec_destroy(&dbs->iov);
 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->offset += dbs->iov.size;
 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(dbs->ctx, reschedule_dma, dbs);
 158         cpu_register_map_client(dbs->bh);
 159         return;
 160     }
 161
 162     if (!QEMU_IS_ALIGNED(dbs->iov.size, dbs->align)) {
 163         qemu_iovec_discard_back(&dbs->iov,
 164                                 QEMU_ALIGN_DOWN(dbs->iov.size, dbs->align));
 165     }
 166
 167     aio_context_acquire(dbs->ctx);
 168     dbs->acb = dbs->io_func(dbs->offset, &dbs->iov,
 169                             dma_blk_cb, dbs, dbs->io_func_opaque);
 170     aio_context_release(dbs->ctx);
 171     assert(dbs->acb);
 172 }
 173
 174 static void dma_aio_cancel(BlockAIOCB *acb)
 175 {
 176     DMAAIOCB *dbs = container_of(acb, DMAAIOCB, common);
 177
 178     trace_dma_aio_cancel(dbs);
 179
 180     assert(!(dbs->acb && dbs->bh));
 181     if (dbs->acb) {
 182         /* This will invoke dma_blk_cb.  */
 183         blk_aio_cancel_async(dbs->acb);
 184         return;
 185     }
 186
 187     if (dbs->bh) {
 188         cpu_unregister_map_client(dbs->bh);
 189         qemu_bh_delete(dbs->bh);
 190         dbs->bh = NULL;
 191     }
 192     if (dbs->common.cb) {
 193         dbs->common.cb(dbs->common.opaque, -ECANCELED);
 194     }
 195 }
 196
 197 static AioContext *dma_get_aio_context(BlockAIOCB *acb)
 198 {
 199     DMAAIOCB *dbs = container_of(acb, DMAAIOCB, common);
 200
 201     return dbs->ctx;
 202 }
 203
 204 static const AIOCBInfo dma_aiocb_info = {
 205     .aiocb_size         = sizeof(DMAAIOCB),
 206     .cancel_async       = dma_aio_cancel,
 207     .get_aio_context    = dma_get_aio_context,
 208 };
 209
 210 BlockAIOCB *dma_blk_io(AioContext *ctx,
 211     QEMUSGList *sg, uint64_t offset, uint32_t align,
 212     DMAIOFunc *io_func, void *io_func_opaque,
 213     BlockCompletionFunc *cb,
 214     void *opaque, DMADirection dir)
 215 {
 216     DMAAIOCB *dbs = qemu_aio_get(&dma_aiocb_info, NULL, cb, opaque);
 217
 218     trace_dma_blk_io(dbs, io_func_opaque, offset, (dir == DMA_DIRECTION_TO_DEVICE));
 219
 220     dbs->acb = NULL;
 221     dbs->sg = sg;
 222     dbs->ctx = ctx;
 223     dbs->offset = offset;
 224     dbs->align = align;
 225     dbs->sg_cur_index = 0;
 226     dbs->sg_cur_byte = 0;
 227     dbs->dir = dir;
 228     dbs->io_func = io_func;
 229     dbs->io_func_opaque = io_func_opaque;
 230     dbs->bh = NULL;
 231     qemu_iovec_init(&dbs->iov, sg->nsg);
 232     dma_blk_cb(dbs, 0);
 233     return &dbs->common;
 234 }
 235
 236
 237 static
 238 BlockAIOCB *dma_blk_read_io_func(int64_t offset, QEMUIOVector *iov,
 239                                  BlockCompletionFunc *cb, void *cb_opaque,
 240                                  void *opaque)
 241 {
 242     BlockBackend *blk = opaque;
 243     return blk_aio_preadv(blk, offset, iov, 0, cb, cb_opaque);
 244 }
 245
 246 BlockAIOCB *dma_blk_read(BlockBackend *blk,
 247                          QEMUSGList *sg, uint64_t offset, uint32_t align,
 248                          void (*cb)(void *opaque, int ret), void *opaque)
 249 {
 250     return dma_blk_io(blk_get_aio_context(blk), sg, offset, align,
 251                       dma_blk_read_io_func, blk, cb, opaque,
 252                       DMA_DIRECTION_FROM_DEVICE);
 253 }
 254
 255 static
 256 BlockAIOCB *dma_blk_write_io_func(int64_t offset, QEMUIOVector *iov,
 257                                   BlockCompletionFunc *cb, void *cb_opaque,
 258                                   void *opaque)
 259 {
 260     BlockBackend *blk = opaque;
 261     return blk_aio_pwritev(blk, offset, iov, 0, cb, cb_opaque);
 262 }
 263
 264 BlockAIOCB *dma_blk_write(BlockBackend *blk,
 265                           QEMUSGList *sg, uint64_t offset, uint32_t align,
 266                           void (*cb)(void *opaque, int ret), void *opaque)
 267 {
 268     return dma_blk_io(blk_get_aio_context(blk), sg, offset, align,
 269                       dma_blk_write_io_func, blk, cb, opaque,
 270                       DMA_DIRECTION_TO_DEVICE);
 271 }
 272
 273
 274 static uint64_t dma_buf_rw(uint8_t *ptr, int32_t len, QEMUSGList *sg,
 275                            DMADirection dir)
 276 {
 277     uint64_t resid;
 278     int sg_cur_index;
 279
 280     resid = sg->size;
 281     sg_cur_index = 0;
 282     len = MIN(len, resid);
 283     while (len > 0) {
 284         ScatterGatherEntry entry = sg->sg[sg_cur_index++];
 285         int32_t xfer = MIN(len, entry.len);
 286         dma_memory_rw(sg->as, entry.base, ptr, xfer, dir);
 287         ptr += xfer;
 288         len -= xfer;
 289         resid -= xfer;
 290     }
 291
 292     return resid;
 293 }
 294
 295 uint64_t dma_buf_read(uint8_t *ptr, int32_t len, QEMUSGList *sg)
 296 {
 297     return dma_buf_rw(ptr, len, sg, DMA_DIRECTION_FROM_DEVICE);
 298 }
 299
 300 uint64_t dma_buf_write(uint8_t *ptr, int32_t len, QEMUSGList *sg)
 301 {
 302     return dma_buf_rw(ptr, len, sg, DMA_DIRECTION_TO_DEVICE);
 303 }
 304
 305 void dma_acct_start(BlockBackend *blk, BlockAcctCookie *cookie,
 306                     QEMUSGList *sg, enum BlockAcctType type)
 307 {
 308     block_acct_start(blk_get_stats(blk), cookie, sg->size, type);
 309 }