On Wed, May 30, 2018 at 08:43:22PM -0400, John Snow wrote:
> AHCI presently signals completion prior to the PxCI register being
> cleared to indicate completion. If a guest driver attempts to issue
> a new command in its IRQ handler, it might be surprised to learn there
> is still a command pending.
>
> In the case of Windows 10's boot driver, it will actually poll the IRQ
> register hoping to find out when the command is done running -- which
> will never happen, as there isn't a command running.
>
> Fix this: clear PxCI in ahci_cmd_done and not in the asynchronous BH.
> Because it now runs synchronously, we don't need to check if the command
> is actually done by spying on the ATA registers. We know it's done.
>
> Signed-off-by: John Snow <js...@redhat.com>
> ---
> hw/ide/ahci.c | 13 ++++++-------
> 1 file changed, 6 insertions(+), 7 deletions(-)
>
> diff --git a/hw/ide/ahci.c b/hw/ide/ahci.c
> index b7a6f68790..a9558e45e7 100644
> --- a/hw/ide/ahci.c
> +++ b/hw/ide/ahci.c
> @@ -532,13 +532,6 @@ static void ahci_check_cmd_bh(void *opaque)
> qemu_bh_delete(ad->check_bh);
> ad->check_bh = NULL;
>
> - if ((ad->busy_slot != -1) &&
> - !(ad->port.ifs[0].status & (BUSY_STAT|DRQ_STAT))) {
> - /* no longer busy */
> - ad->port_regs.cmd_issue &= ~(1 << ad->busy_slot);
> - ad->busy_slot = -1;
> - }
> -
> check_cmd(ad->hba, ad->port_no);
> }
>
> @@ -1425,6 +1418,12 @@ static void ahci_cmd_done(IDEDMA *dma)
>
> trace_ahci_cmd_done(ad->hba, ad->port_no);
>
> + /* no longer busy */
> + if (ad->busy_slot != -1) {
> + ad->port_regs.cmd_issue &= ~(1 << ad->busy_slot);
> + ad->busy_slot = -1;
> + }
> +
> /* update d2h status */
> ahci_write_fis_d2h(ad);
>
> --
> 2.14.3
>
>
Reviewed-by: Jeff Cody <jc...@redhat.com>
