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ide/atapi: make PIO read requests async

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PIO read requests on the ATAPI interface used to be sync blk requests.
This has two significant drawbacks. First the main loop hangs util an
I/O request is completed and secondly if the I/O request does not
complete (e.g. due to an unresponsive storage) Qemu hangs completely.

Note: Due to possible race conditions requests during an ongoing
elementary transfer are still sync.

Signed-off-by: Peter Lieven <pl@kamp.de>
Reviewed-by: John Snow <jsnow@redhat.com>
Message-id: 1447345846-15624-2-git-send-email-pl@kamp.de
Signed-off-by: John Snow <jsnow@redhat.com>
This commit is contained in:
Peter Lieven 2015-11-17 14:59:52 -05:00 committed by John Snow
parent c27e9014d5
commit 5f81724d80
1 changed files with 82 additions and 13 deletions
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89
hw/ide/atapi.c
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@ -105,20 +105,27 @@ static void cd_data_to_raw(uint8_t *buf, int lba)
memset(buf, 0, 288);
}
static int cd_read_sector(IDEState *s, int lba, uint8_t *buf, int sector_size)
static int
cd_read_sector_sync(IDEState *s)
{
int ret;
block_acct_start(blk_get_stats(s->blk), &s->acct,
4 * BDRV_SECTOR_SIZE, BLOCK_ACCT_READ);
switch(sector_size) {
#ifdef DEBUG_IDE_ATAPI
printf("cd_read_sector_sync: lba=%d\n", s->lba);
#endif
switch (s->cd_sector_size) {
case 2048:
ret = blk_read(s->blk, (int64_t)lba << 2, buf, 4);
ret = blk_read(s->blk, (int64_t)s->lba << 2,
s->io_buffer, 4);
break;
case 2352:
ret = blk_read(s->blk, (int64_t)lba << 2, buf + 16, 4);
ret = blk_read(s->blk, (int64_t)s->lba << 2,
s->io_buffer + 16, 4);
if (ret >= 0) {
cd_data_to_raw(buf, lba);
cd_data_to_raw(s->io_buffer, s->lba);
}
break;
default:
@ -130,11 +137,65 @@ static int cd_read_sector(IDEState *s, int lba, uint8_t *buf, int sector_size)
block_acct_failed(blk_get_stats(s->blk), &s->acct);
} else {
block_acct_done(blk_get_stats(s->blk), &s->acct);
s->lba++;
s->io_buffer_index = 0;
}
return ret;
}
static void cd_read_sector_cb(void *opaque, int ret)
{
IDEState *s = opaque;
block_acct_done(blk_get_stats(s->blk), &s->acct);
#ifdef DEBUG_IDE_ATAPI
printf("cd_read_sector_cb: lba=%d ret=%d\n", s->lba, ret);
#endif
if (ret < 0) {
ide_atapi_io_error(s, ret);
return;
}
if (s->cd_sector_size == 2352) {
cd_data_to_raw(s->io_buffer, s->lba);
}
s->lba++;
s->io_buffer_index = 0;
s->status &= ~BUSY_STAT;
ide_atapi_cmd_reply_end(s);
}
static int cd_read_sector(IDEState *s)
{
if (s->cd_sector_size != 2048 && s->cd_sector_size != 2352) {
return -EINVAL;
}
s->iov.iov_base = (s->cd_sector_size == 2352) ?
s->io_buffer + 16 : s->io_buffer;
s->iov.iov_len = 4 * BDRV_SECTOR_SIZE;
qemu_iovec_init_external(&s->qiov, &s->iov, 1);
#ifdef DEBUG_IDE_ATAPI
printf("cd_read_sector: lba=%d\n", s->lba);
#endif
block_acct_start(blk_get_stats(s->blk), &s->acct,
4 * BDRV_SECTOR_SIZE, BLOCK_ACCT_READ);
blk_aio_readv(s->blk, (int64_t)s->lba << 2, &s->qiov, 4,
cd_read_sector_cb, s);
s->status |= BUSY_STAT;
return 0;
}
void ide_atapi_cmd_ok(IDEState *s)
{
s->error = 0;
@ -196,18 +257,27 @@ void ide_atapi_cmd_reply_end(IDEState *s)
ide_atapi_cmd_ok(s);
ide_set_irq(s->bus);
#ifdef DEBUG_IDE_ATAPI
printf("status=0x%x\n", s->status);
printf("end of transfer, status=0x%x\n", s->status);
#endif
} else {
/* see if a new sector must be read */
if (s->lba != -1 && s->io_buffer_index >= s->cd_sector_size) {
ret = cd_read_sector(s, s->lba, s->io_buffer, s->cd_sector_size);
if (!s->elementary_transfer_size) {
ret = cd_read_sector(s);
if (ret < 0) {
ide_atapi_io_error(s, ret);
}
return;
} else {
/* rebuffering within an elementary transfer is
* only possible with a sync request because we
* end up with a race condition otherwise */
ret = cd_read_sector_sync(s);
if (ret < 0) {
ide_atapi_io_error(s, ret);
return;
}
s->lba++;
s->io_buffer_index = 0;
}
}
if (s->elementary_transfer_size > 0) {
/* there are some data left to transmit in this elementary
@ -287,7 +357,6 @@ static void ide_atapi_cmd_read_pio(IDEState *s, int lba, int nb_sectors,
s->io_buffer_index = sector_size;
s->cd_sector_size = sector_size;
s->status = READY_STAT | SEEK_STAT;
ide_atapi_cmd_reply_end(s);
}