softmmu/dma-helpers.c

   1 /*
   2  * DMA helper functions
   3  *
   4  * Copyright (c) 2009,2020 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/trace-root.h"
  14 #include "qemu/thread.h"
  15 #include "qemu/main-loop.h"
  16 #include "sysemu/cpu-timers.h"
  17 #include "qemu/range.h"
  18
  19 /* #define DEBUG_IOMMU */
  20
  21 MemTxResult dma_memory_set(AddressSpace *as, dma_addr_t addr,
  22                            uint8_t c, dma_addr_t len)
  23 {
  24     dma_barrier(as, DMA_DIRECTION_FROM_DEVICE);
  25
  26 #define FILLBUF_SIZE 512
  27     uint8_t fillbuf[FILLBUF_SIZE];
  28     int l;
  29     MemTxResult error = MEMTX_OK;
  30
  31     memset(fillbuf, c, FILLBUF_SIZE);
  32     while (len > 0) {
  33         l = len < FILLBUF_SIZE ? len : FILLBUF_SIZE;
  34         error |= address_space_write(as, addr, MEMTXATTRS_UNSPECIFIED,
  35                                      fillbuf, l);
  36         len -= l;
  37         addr += l;
  38     }
  39
  40     return error;
  41 }
  42
  43 void qemu_sglist_init(QEMUSGList *qsg, DeviceState *dev, int alloc_hint,
  44                       AddressSpace *as)
  45 {
  46     qsg->sg = g_malloc(alloc_hint * sizeof(ScatterGatherEntry));
  47     qsg->nsg = 0;
  48     qsg->nalloc = alloc_hint;
  49     qsg->size = 0;
  50     qsg->as = as;
  51     qsg->dev = dev;
  52     object_ref(OBJECT(dev));
  53 }
  54
  55 void qemu_sglist_add(QEMUSGList *qsg, dma_addr_t base, dma_addr_t len)
  56 {
  57     if (qsg->nsg == qsg->nalloc) {
  58         qsg->nalloc = 2 * qsg->nalloc + 1;
  59         qsg->sg = g_realloc(qsg->sg, qsg->nalloc * sizeof(ScatterGatherEntry));
  60     }
  61     qsg->sg[qsg->nsg].base = base;
  62     qsg->sg[qsg->nsg].len = len;
  63     qsg->size += len;
  64     ++qsg->nsg;
  65 }
  66
  67 void qemu_sglist_destroy(QEMUSGList *qsg)
  68 {
  69     object_unref(OBJECT(qsg->dev));
  70     g_free(qsg->sg);
  71     memset(qsg, 0, sizeof(*qsg));
  72 }
  73
  74 typedef struct {
  75     BlockAIOCB common;
  76     AioContext *ctx;
  77     BlockAIOCB *acb;
  78     QEMUSGList *sg;
  79     uint32_t align;
  80     uint64_t offset;
  81     DMADirection dir;
  82     int sg_cur_index;
  83     dma_addr_t sg_cur_byte;
  84     QEMUIOVector iov;
  85     QEMUBH *bh;
  86     DMAIOFunc *io_func;
  87     void *io_func_opaque;
  88 } DMAAIOCB;
  89
  90 static void dma_blk_cb(void *opaque, int ret);
  91
  92 static void reschedule_dma(void *opaque)
  93 {
  94     DMAAIOCB *dbs = (DMAAIOCB *)opaque;
  95
  96     assert(!dbs->acb && dbs->bh);
  97     qemu_bh_delete(dbs->bh);
  98     dbs->bh = NULL;
  99     dma_blk_cb(dbs, 0);
 100 }
 101
 102 static void dma_blk_unmap(DMAAIOCB *dbs)
 103 {
 104     int i;
 105
 106     for (i = 0; i < dbs->iov.niov; ++i) {
 107         dma_memory_unmap(dbs->sg->as, dbs->iov.iov[i].iov_base,
 108                          dbs->iov.iov[i].iov_len, dbs->dir,
 109                          dbs->iov.iov[i].iov_len);
 110     }
 111     qemu_iovec_reset(&dbs->iov);
 112 }
 113
 114 static void dma_complete(DMAAIOCB *dbs, int ret)
 115 {
 116     trace_dma_complete(dbs, ret, dbs->common.cb);
 117
 118     assert(!dbs->acb && !dbs->bh);
 119     dma_blk_unmap(dbs);
 120     if (dbs->common.cb) {
 121         dbs->common.cb(dbs->common.opaque, ret);
 122     }
 123     qemu_iovec_destroy(&dbs->iov);
 124     qemu_aio_unref(dbs);
 125 }
 126
 127 static void dma_blk_cb(void *opaque, int ret)
 128 {
 129     DMAAIOCB *dbs = (DMAAIOCB *)opaque;
 130     dma_addr_t cur_addr, cur_len;
 131     void *mem;
 132
 133     trace_dma_blk_cb(dbs, ret);
 134
 135     dbs->acb = NULL;
 136     dbs->offset += dbs->iov.size;
 137
 138     if (dbs->sg_cur_index == dbs->sg->nsg || ret < 0) {
 139         dma_complete(dbs, ret);
 140         return;
 141     }
 142     dma_blk_unmap(dbs);
 143
 144     while (dbs->sg_cur_index < dbs->sg->nsg) {
 145         cur_addr = dbs->sg->sg[dbs->sg_cur_index].base + dbs->sg_cur_byte;
 146         cur_len = dbs->sg->sg[dbs->sg_cur_index].len - dbs->sg_cur_byte;
 147         mem = dma_memory_map(dbs->sg->as, cur_addr, &cur_len, dbs->dir);
 148         /*
 149          * Make reads deterministic in icount mode. Windows sometimes issues
 150          * disk read requests with overlapping SGs. It leads
 151          * to non-determinism, because resulting buffer contents may be mixed
 152          * from several sectors. This code splits all SGs into several
 153          * groups. SGs in every group do not overlap.
 154          */
 155         if (mem && icount_enabled() && dbs->dir == DMA_DIRECTION_FROM_DEVICE) {
 156             int i;
 157             for (i = 0 ; i < dbs->iov.niov ; ++i) {
 158                 if (ranges_overlap((intptr_t)dbs->iov.iov[i].iov_base,
 159                                    dbs->iov.iov[i].iov_len, (intptr_t)mem,
 160                                    cur_len)) {
 161                     dma_memory_unmap(dbs->sg->as, mem, cur_len,
 162                                      dbs->dir, cur_len);
 163                     mem = NULL;
 164                     break;
 165                 }
 166             }
 167         }
 168         if (!mem)
 169             break;
 170         qemu_iovec_add(&dbs->iov, mem, cur_len);
 171         dbs->sg_cur_byte += cur_len;
 172         if (dbs->sg_cur_byte == dbs->sg->sg[dbs->sg_cur_index].len) {
 173             dbs->sg_cur_byte = 0;
 174             ++dbs->sg_cur_index;
 175         }
 176     }
 177
 178     if (dbs->iov.size == 0) {
 179         trace_dma_map_wait(dbs);
 180         dbs->bh = aio_bh_new(dbs->ctx, reschedule_dma, dbs);
 181         cpu_register_map_client(dbs->bh);
 182         return;
 183     }
 184
 185     if (!QEMU_IS_ALIGNED(dbs->iov.size, dbs->align)) {
 186         qemu_iovec_discard_back(&dbs->iov,
 187                                 QEMU_ALIGN_DOWN(dbs->iov.size, dbs->align));
 188     }
 189
 190     aio_context_acquire(dbs->ctx);
 191     dbs->acb = dbs->io_func(dbs->offset, &dbs->iov,
 192                             dma_blk_cb, dbs, dbs->io_func_opaque);
 193     aio_context_release(dbs->ctx);
 194     assert(dbs->acb);
 195 }
 196
 197 static void dma_aio_cancel(BlockAIOCB *acb)
 198 {
 199     DMAAIOCB *dbs = container_of(acb, DMAAIOCB, common);
 200
 201     trace_dma_aio_cancel(dbs);
 202
 203     assert(!(dbs->acb && dbs->bh));
 204     if (dbs->acb) {
 205         /* This will invoke dma_blk_cb.  */
 206         blk_aio_cancel_async(dbs->acb);
 207         return;
 208     }
 209
 210     if (dbs->bh) {
 211         cpu_unregister_map_client(dbs->bh);
 212         qemu_bh_delete(dbs->bh);
 213         dbs->bh = NULL;
 214     }
 215     if (dbs->common.cb) {
 216         dbs->common.cb(dbs->common.opaque, -ECANCELED);
 217     }
 218 }
 219
 220 static AioContext *dma_get_aio_context(BlockAIOCB *acb)
 221 {
 222     DMAAIOCB *dbs = container_of(acb, DMAAIOCB, common);
 223
 224     return dbs->ctx;
 225 }
 226
 227 static const AIOCBInfo dma_aiocb_info = {
 228     .aiocb_size         = sizeof(DMAAIOCB),
 229     .cancel_async       = dma_aio_cancel,
 230     .get_aio_context    = dma_get_aio_context,
 231 };
 232
 233 BlockAIOCB *dma_blk_io(AioContext *ctx,
 234     QEMUSGList *sg, uint64_t offset, uint32_t align,
 235     DMAIOFunc *io_func, void *io_func_opaque,
 236     BlockCompletionFunc *cb,
 237     void *opaque, DMADirection dir)
 238 {
 239     DMAAIOCB *dbs = qemu_aio_get(&dma_aiocb_info, NULL, cb, opaque);
 240
 241     trace_dma_blk_io(dbs, io_func_opaque, offset, (dir == DMA_DIRECTION_TO_DEVICE));
 242
 243     dbs->acb = NULL;
 244     dbs->sg = sg;
 245     dbs->ctx = ctx;
 246     dbs->offset = offset;
 247     dbs->align = align;
 248     dbs->sg_cur_index = 0;
 249     dbs->sg_cur_byte = 0;
 250     dbs->dir = dir;
 251     dbs->io_func = io_func;
 252     dbs->io_func_opaque = io_func_opaque;
 253     dbs->bh = NULL;
 254     qemu_iovec_init(&dbs->iov, sg->nsg);
 255     dma_blk_cb(dbs, 0);
 256     return &dbs->common;
 257 }
 258
 259
 260 static
 261 BlockAIOCB *dma_blk_read_io_func(int64_t offset, QEMUIOVector *iov,
 262                                  BlockCompletionFunc *cb, void *cb_opaque,
 263                                  void *opaque)
 264 {
 265     BlockBackend *blk = opaque;
 266     return blk_aio_preadv(blk, offset, iov, 0, cb, cb_opaque);
 267 }
 268
 269 BlockAIOCB *dma_blk_read(BlockBackend *blk,
 270                          QEMUSGList *sg, uint64_t offset, uint32_t align,
 271                          void (*cb)(void *opaque, int ret), void *opaque)
 272 {
 273     return dma_blk_io(blk_get_aio_context(blk), sg, offset, align,
 274                       dma_blk_read_io_func, blk, cb, opaque,
 275                       DMA_DIRECTION_FROM_DEVICE);
 276 }
 277
 278 static
 279 BlockAIOCB *dma_blk_write_io_func(int64_t offset, QEMUIOVector *iov,
 280                                   BlockCompletionFunc *cb, void *cb_opaque,
 281                                   void *opaque)
 282 {
 283     BlockBackend *blk = opaque;
 284     return blk_aio_pwritev(blk, offset, iov, 0, cb, cb_opaque);
 285 }
 286
 287 BlockAIOCB *dma_blk_write(BlockBackend *blk,
 288                           QEMUSGList *sg, uint64_t offset, uint32_t align,
 289                           void (*cb)(void *opaque, int ret), void *opaque)
 290 {
 291     return dma_blk_io(blk_get_aio_context(blk), sg, offset, align,
 292                       dma_blk_write_io_func, blk, cb, opaque,
 293                       DMA_DIRECTION_TO_DEVICE);
 294 }
 295
 296
 297 static uint64_t dma_buf_rw(uint8_t *ptr, int32_t len, QEMUSGList *sg,
 298                            DMADirection dir)
 299 {
 300     uint64_t resid;
 301     int sg_cur_index;
 302
 303     resid = sg->size;
 304     sg_cur_index = 0;
 305     len = MIN(len, resid);
 306     while (len > 0) {
 307         ScatterGatherEntry entry = sg->sg[sg_cur_index++];
 308         int32_t xfer = MIN(len, entry.len);
 309         dma_memory_rw(sg->as, entry.base, ptr, xfer, dir);
 310         ptr += xfer;
 311         len -= xfer;
 312         resid -= xfer;
 313     }
 314
 315     return resid;
 316 }
 317
 318 uint64_t dma_buf_read(uint8_t *ptr, int32_t len, QEMUSGList *sg)
 319 {
 320     return dma_buf_rw(ptr, len, sg, DMA_DIRECTION_FROM_DEVICE);
 321 }
 322
 323 uint64_t dma_buf_write(uint8_t *ptr, int32_t len, QEMUSGList *sg)
 324 {
 325     return dma_buf_rw(ptr, len, sg, DMA_DIRECTION_TO_DEVICE);
 326 }
 327
 328 void dma_acct_start(BlockBackend *blk, BlockAcctCookie *cookie,
 329                     QEMUSGList *sg, enum BlockAcctType type)
 330 {
 331     block_acct_start(blk_get_stats(blk), cookie, sg->size, type);
 332 }