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Introduce block dma helpers (Avi Kivity) 

These helpers perform read/write requests on entire scatter/gather lists,
relieving the device emulation code from mapping and unmapping physical
memory, and from looping when map resources are exhausted.

Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>


git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6524 c046a42c-6fe2-441c-8c8c-71466251a162
This commit is contained in:
aliguori 2009-02-05 21:23:58 +00:00
parent be959463af
commit 59a703ebaa
2 changed files with 126 additions and 1 deletions
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119
dma-helpers.c
View File

@ -8,7 +8,7 @@
*/
#include "dma.h"
#include "block_int.h"
void qemu_sglist_init(QEMUSGList *qsg, int alloc_hint)
{
@ -36,3 +36,120 @@ void qemu_sglist_destroy(QEMUSGList *qsg)
qemu_free(qsg->sg);
}
typedef struct {
BlockDriverState *bs;
BlockDriverAIOCB *acb;
QEMUSGList *sg;
uint64_t sector_num;
int is_write;
int sg_cur_index;
target_phys_addr_t sg_cur_byte;
QEMUIOVector iov;
QEMUBH *bh;
} DMABlockState;
static void dma_bdrv_cb(void *opaque, int ret);
static void reschedule_dma(void *opaque)
{
DMABlockState *dbs = (DMABlockState *)opaque;
qemu_bh_delete(dbs->bh);
dbs->bh = NULL;
dma_bdrv_cb(opaque, 0);
}
static void continue_after_map_failure(void *opaque)
{
DMABlockState *dbs = (DMABlockState *)opaque;
dbs->bh = qemu_bh_new(reschedule_dma, dbs);
qemu_bh_schedule(dbs->bh);
}
static void dma_bdrv_cb(void *opaque, int ret)
{
DMABlockState *dbs = (DMABlockState *)opaque;
target_phys_addr_t cur_addr, cur_len;
void *mem;
int i;
dbs->sector_num += dbs->iov.size / 512;
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->is_write,
dbs->iov.iov[i].iov_len);
}
qemu_iovec_reset(&dbs->iov);
if (dbs->sg_cur_index == dbs->sg->nsg || ret < 0) {
dbs->acb->cb(dbs->acb->opaque, ret);
qemu_iovec_destroy(&dbs->iov);
qemu_aio_release(dbs->acb);
qemu_free(dbs);
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->is_write);
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;
}
if (dbs->is_write) {
bdrv_aio_writev(dbs->bs, dbs->sector_num, &dbs->iov,
dbs->iov.size / 512, dma_bdrv_cb, dbs);
} else {
bdrv_aio_readv(dbs->bs, dbs->sector_num, &dbs->iov,
dbs->iov.size / 512, dma_bdrv_cb, dbs);
}
}
static BlockDriverAIOCB *dma_bdrv_io(
BlockDriverState *bs, QEMUSGList *sg, uint64_t sector_num,
BlockDriverCompletionFunc *cb, void *opaque,
int is_write)
{
DMABlockState *dbs = qemu_malloc(sizeof(*dbs));
dbs->bs = bs;
dbs->acb = qemu_aio_get(bs, cb, opaque);
dbs->sg = sg;
dbs->sector_num = sector_num;
dbs->sg_cur_index = 0;
dbs->sg_cur_byte = 0;
dbs->is_write = is_write;
dbs->bh = NULL;
qemu_iovec_init(&dbs->iov, sg->nsg);
dma_bdrv_cb(dbs, 0);
return dbs->acb;
}
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, cb, opaque, 0);
}
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, cb, opaque, 1);
}

8
dma.h
View File

@ -12,6 +12,7 @@
#include <stdio.h>
#include "cpu.h"
#include "block.h"
typedef struct {
target_phys_addr_t base;
@ -30,4 +31,11 @@ void qemu_sglist_add(QEMUSGList *qsg, target_phys_addr_t base,
target_phys_addr_t len);
void qemu_sglist_destroy(QEMUSGList *qsg);
BlockDriverAIOCB *dma_bdrv_read(BlockDriverState *bs,
QEMUSGList *sg, uint64_t sector,
BlockDriverCompletionFunc *cb, void *opaque);
BlockDriverAIOCB *dma_bdrv_write(BlockDriverState *bs,
QEMUSGList *sg, uint64_t sector,
BlockDriverCompletionFunc *cb, void *opaque);
#endif