Archipelago » qemu

/*

 * DMA helper functions

 *

 * Copyright (c) 2009 Red Hat

 *

 * This work is licensed under the terms of the GNU General Public License

 * (GNU GPL), version 2 or later.

 */

#include "dma.h"

#include "block_int.h"

void qemu_sglist_init(QEMUSGList *qsg, int alloc_hint)

{

    qsg->sg = g_malloc(alloc_hint * sizeof(ScatterGatherEntry));

    qsg->nsg = 0;

    qsg->nalloc = alloc_hint;

    qsg->size = 0;

}

void qemu_sglist_add(QEMUSGList *qsg, target_phys_addr_t base,

                     target_phys_addr_t len)

{

    if (qsg->nsg == qsg->nalloc) {

        qsg->nalloc = 2 * qsg->nalloc + 1;

        qsg->sg = g_realloc(qsg->sg, qsg->nalloc * sizeof(ScatterGatherEntry));

    }

    qsg->sg[qsg->nsg].base = base;

    qsg->sg[qsg->nsg].len = len;

    qsg->size += len;

    ++qsg->nsg;

}

void qemu_sglist_destroy(QEMUSGList *qsg)

{

    g_free(qsg->sg);

}

typedef struct {

    BlockDriverAIOCB common;

    BlockDriverState *bs;

    BlockDriverAIOCB *acb;

    QEMUSGList *sg;

    uint64_t sector_num;

    bool to_dev;

    bool in_cancel;

    int sg_cur_index;

    target_phys_addr_t sg_cur_byte;

    QEMUIOVector iov;

    QEMUBH *bh;

    DMAIOFunc *io_func;

} DMAAIOCB;

static void dma_bdrv_cb(void *opaque, int ret);

static void reschedule_dma(void *opaque)

{

    DMAAIOCB *dbs = (DMAAIOCB *)opaque;

    qemu_bh_delete(dbs->bh);

    dbs->bh = NULL;

    dma_bdrv_cb(dbs, 0);

}

static void continue_after_map_failure(void *opaque)

{

    DMAAIOCB *dbs = (DMAAIOCB *)opaque;

    dbs->bh = qemu_bh_new(reschedule_dma, dbs);

    qemu_bh_schedule(dbs->bh);

}

static void dma_bdrv_unmap(DMAAIOCB *dbs)

{

    int i;

    for (i = 0; i < dbs->iov.niov; ++i) {

        cpu_physical_memory_unmap(dbs->iov.iov[i].iov_base,

                                  dbs->iov.iov[i].iov_len, !dbs->to_dev,

                                  dbs->iov.iov[i].iov_len);

    }

    qemu_iovec_reset(&dbs->iov);

}

static void dma_complete(DMAAIOCB *dbs, int ret)

{

    dma_bdrv_unmap(dbs);

    if (dbs->common.cb) {

        dbs->common.cb(dbs->common.opaque, ret);

    }

    qemu_iovec_destroy(&dbs->iov);

    if (dbs->bh) {

        qemu_bh_delete(dbs->bh);

        dbs->bh = NULL;

    }

    if (!dbs->in_cancel) {

        /* Requests may complete while dma_aio_cancel is in progress.  In

         * this case, the AIOCB should not be released because it is still

         * referenced by dma_aio_cancel.  */

        qemu_aio_release(dbs);

    }

}

static void dma_bdrv_cb(void *opaque, int ret)

{

    DMAAIOCB *dbs = (DMAAIOCB *)opaque;

    target_phys_addr_t cur_addr, cur_len;

    void *mem;

    dbs->acb = NULL;

    dbs->sector_num += dbs->iov.size / 512;

    dma_bdrv_unmap(dbs);

    if (dbs->sg_cur_index == dbs->sg->nsg || ret < 0) {

        dma_complete(dbs, ret);

        return;

    }

    while (dbs->sg_cur_index < dbs->sg->nsg) {

        cur_addr = dbs->sg->sg[dbs->sg_cur_index].base + dbs->sg_cur_byte;

        cur_len = dbs->sg->sg[dbs->sg_cur_index].len - dbs->sg_cur_byte;

        mem = cpu_physical_memory_map(cur_addr, &cur_len, !dbs->to_dev);

        if (!mem)

            break;

        qemu_iovec_add(&dbs->iov, mem, cur_len);

        dbs->sg_cur_byte += cur_len;

        if (dbs->sg_cur_byte == dbs->sg->sg[dbs->sg_cur_index].len) {

            dbs->sg_cur_byte = 0;

            ++dbs->sg_cur_index;

        }

    }

    if (dbs->iov.size == 0) {

        cpu_register_map_client(dbs, continue_after_map_failure);

        return;

    }

    dbs->acb = dbs->io_func(dbs->bs, dbs->sector_num, &dbs->iov,

                            dbs->iov.size / 512, dma_bdrv_cb, dbs);

    if (!dbs->acb) {

        dma_complete(dbs, -EIO);

    }

}

static void dma_aio_cancel(BlockDriverAIOCB *acb)

{

    DMAAIOCB *dbs = container_of(acb, DMAAIOCB, common);

    if (dbs->acb) {

        BlockDriverAIOCB *acb = dbs->acb;

        dbs->acb = NULL;

        dbs->in_cancel = true;

        bdrv_aio_cancel(acb);

        dbs->in_cancel = false;

    }

    dbs->common.cb = NULL;

    dma_complete(dbs, 0);

}

static AIOPool dma_aio_pool = {

    .aiocb_size         = sizeof(DMAAIOCB),

    .cancel             = dma_aio_cancel,

};

BlockDriverAIOCB *dma_bdrv_io(

    BlockDriverState *bs, QEMUSGList *sg, uint64_t sector_num,

    DMAIOFunc *io_func, BlockDriverCompletionFunc *cb,

    void *opaque, bool to_dev)

{

    DMAAIOCB *dbs = qemu_aio_get(&dma_aio_pool, bs, cb, opaque);

    dbs->acb = NULL;

    dbs->bs = bs;

    dbs->sg = sg;

    dbs->sector_num = sector_num;

    dbs->sg_cur_index = 0;

    dbs->sg_cur_byte = 0;

    dbs->to_dev = to_dev;

    dbs->io_func = io_func;

    dbs->bh = NULL;

    qemu_iovec_init(&dbs->iov, sg->nsg);

    dma_bdrv_cb(dbs, 0);

    return &dbs->common;

}

BlockDriverAIOCB *dma_bdrv_read(BlockDriverState *bs,

                                QEMUSGList *sg, uint64_t sector,

                                void (*cb)(void *opaque, int ret), void *opaque)

{

    return dma_bdrv_io(bs, sg, sector, bdrv_aio_readv, cb, opaque, false);

}

BlockDriverAIOCB *dma_bdrv_write(BlockDriverState *bs,

                                 QEMUSGList *sg, uint64_t sector,

                                 void (*cb)(void *opaque, int ret), void *opaque)

{

    return dma_bdrv_io(bs, sg, sector, bdrv_aio_writev, cb, opaque, true);

}