On Fri, 8 Sep 2017 17:24:43 +0200 Halil Pasic <pa...@linux.vnet.ibm.com> wrote:
> The architecture says that channel-data check is indicating that > an uncorrected storage (memory) error has been detected in regard > to the data residing in main storage (memory) that is currently > used for an I/O operation. The described detection is done using > the CBC technology. > > The ccw interpretation code is however generating a channel-data check > effectively when the (device specific) ccw_cb returns -EFAULT. In case > of virtio-ccw devices this happens when mapping memory fails, or when a > NULL pointer is encountered. So this behavior is not architecture > conform. > > Furthermore the best fit for these situations (null pointer, mapping a > piece of guest memory fails) from architectural perspective the condition > described as the channel subsystem refers to a location that is not > available, which when encountered shall result in a channel-program > check. > > To fix this, all we have to do is to get rid of the switch case matching > -EFAULT: the default is generating a channel-program check. > > --- > > Was posted as stand alone patch. See: > http://patchwork.ozlabs.org/patch/810995/ > > If you are going to, *please review there*. Countered. *Please review here* (It makes it easier for me.) > > Signed-off-by: Halil Pasic <pa...@linux.vnet.ibm.com> Your s-o-b should go before the triple-dash delimiter. I can fix that up. > --- > hw/s390x/css.c | 9 --------- > 1 file changed, 9 deletions(-) > > diff --git a/hw/s390x/css.c b/hw/s390x/css.c > index 901dc6a0f3..09f6ba0310 100644 > --- a/hw/s390x/css.c > +++ b/hw/s390x/css.c > @@ -980,15 +980,6 @@ static void sch_handle_start_func_virtual(SubchDev *sch) > SCSW_STCTL_ALERT | SCSW_STCTL_STATUS_PEND; > s->cpa = sch->channel_prog + 8; > break; > - case -EFAULT: > - /* memory problem, generate channel data check */ > - s->ctrl &= ~SCSW_ACTL_START_PEND; > - s->cstat = SCSW_CSTAT_DATA_CHECK; > - s->ctrl &= ~SCSW_CTRL_MASK_STCTL; > - s->ctrl |= SCSW_STCTL_PRIMARY | SCSW_STCTL_SECONDARY | > - SCSW_STCTL_ALERT | SCSW_STCTL_STATUS_PEND; > - s->cpa = sch->channel_prog + 8; > - break; > case -EBUSY: > /* subchannel busy, generate deferred cc 1 */ > s->flags &= ~SCSW_FLAGS_MASK_CC; Looks reasonable. Queued.