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ide: Ignore double DMA transfer starts/stops 

You can only start a DMA transfer if it's not running yet, and you can only
cancel it if it's running.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
This commit is contained in:
Kevin Wolf 2010-11-26 16:44:53 +01:00
parent e3982b3cf6
commit c29947bbb0
1 changed files with 32 additions and 28 deletions
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60
hw/ide/pci.c
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@ -39,38 +39,42 @@ void bmdma_cmd_writeb(void *opaque, uint32_t addr, uint32_t val)
#ifdef DEBUG_IDE
printf("%s: 0x%08x\n", __func__, val);
#endif
if (!(val & BM_CMD_START)) {
/*
* We can't cancel Scatter Gather DMA in the middle of the
* operation or a partial (not full) DMA transfer would reach
* the storage so we wait for completion instead (we beahve
* like if the DMA was completed by the time the guest trying
* to cancel dma with bmdma_cmd_writeb with BM_CMD_START not
* set).
*
* In the future we'll be able to safely cancel the I/O if the
* whole DMA operation will be submitted to disk with a single
* aio operation with preadv/pwritev.
*/
if (bm->aiocb) {
qemu_aio_flush();
/* Ignore writes to SSBM if it keeps the old value */
if ((val & BM_CMD_START) != (bm->cmd & BM_CMD_START)) {
if (!(val & BM_CMD_START)) {
/*
* We can't cancel Scatter Gather DMA in the middle of the
* operation or a partial (not full) DMA transfer would reach
* the storage so we wait for completion instead (we beahve
* like if the DMA was completed by the time the guest trying
* to cancel dma with bmdma_cmd_writeb with BM_CMD_START not
* set).
*
* In the future we'll be able to safely cancel the I/O if the
* whole DMA operation will be submitted to disk with a single
* aio operation with preadv/pwritev.
*/
if (bm->aiocb) {
qemu_aio_flush();
#ifdef DEBUG_IDE
if (bm->aiocb)
printf("ide_dma_cancel: aiocb still pending");
if (bm->status & BM_STATUS_DMAING)
printf("ide_dma_cancel: BM_STATUS_DMAING still pending");
if (bm->aiocb)
printf("ide_dma_cancel: aiocb still pending");
if (bm->status & BM_STATUS_DMAING)
printf("ide_dma_cancel: BM_STATUS_DMAING still pending");
#endif
}
} else {
if (!(bm->status & BM_STATUS_DMAING)) {
bm->status |= BM_STATUS_DMAING;
/* start dma transfer if possible */
if (bm->dma_cb)
bm->dma_cb(bm, 0);
}
}
bm->cmd = val & 0x09;
} else {
if (!(bm->status & BM_STATUS_DMAING)) {
bm->status |= BM_STATUS_DMAING;
/* start dma transfer if possible */
if (bm->dma_cb)
bm->dma_cb(bm, 0);
}
bm->cmd = val & 0x09;
}
bm->cmd = val & 0x09;
}
static void bmdma_addr_read(IORange *ioport, uint64_t addr,