diff options
| -rw-r--r-- | hw/ide/pci.c | 60 |
1 files changed, 32 insertions, 28 deletions
diff --git a/hw/ide/pci.c b/hw/ide/pci.c index 3722b774b2..404f045a98 100644 --- a/hw/ide/pci.c +++ b/hw/ide/pci.c @@ -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, |