On Fri, 4 May 2018 13:02:36 +0200 Pierre Morel <pmorel@xxxxxxxxxxxxxxxxxx> wrote: > On 04/05/2018 03:19, Dong Jia Shi wrote: > > * Pierre Morel <pmorel@xxxxxxxxxxxxxxxxxx> [2018-05-03 16:26:29 +0200]: > > > >> On 02/05/2018 09:46, Dong Jia Shi wrote: > >>> * Cornelia Huck <cohuck@xxxxxxxxxx> [2018-04-30 17:33:05 +0200]: > >>> > >>>> On Thu, 26 Apr 2018 15:48:06 +0800 > >>>> Dong Jia Shi <bjsdjshi@xxxxxxxxxxxxxxxxxx> wrote: > >>>> > >>>>> * Dong Jia Shi <bjsdjshi@xxxxxxxxxxxxxxxxxx> [2018-04-26 15:30:54 +0800]: > >>>>> > >>>>> [...] > >>>>> > >>>>>>> @@ -179,7 +160,7 @@ static int fsm_irq(struct vfio_ccw_private *private, > >>>>>>> if (private->io_trigger) > >>>>>>> eventfd_signal(private->io_trigger, 1); > >>>>>>> > >>>>>>> - return private->state; > >>>>>>> + return VFIO_CCW_STATE_IDLE; > >>>>>> This is not right. For example, if we are in STANDBY state (subch driver > >>>>>> is probed, but mdev device is not created), we can not jump to IDLE > >>>>>> state. > >>>>> I see my problem, for STANDBY state, we should introduce another event > >>>>> callback for VFIO_CCW_EVENT_INTERRUPT. It doesn't make sense to call > >>>>> fsm_irq() which tries to signal userspace with interrupt notification > >>>>> when mdev is not created yet... So we'd need a separated fix for this > >>>>> issue too. > >>>> But how do we even get into that situation when we don't have an mdev > >>>> yet? > >>>> > >>> We cann't... So let's assign fsm_nop() as the interrupt callback for > >>> STANDBY state? > >>> > >> :) Isn't it exactly what my patch series handle? > > As far as I see, that's not true. ;) > > > > After this series applied, > > vfio_ccw_jumptable[VFIO_CCW_STATE_STANDBY][VFIO_CCW_EVENT_INTERRUPT] is > > still fsm_irq(). > > > > > What I mean is, this code tries to handle design problems > without changing too much of the original code at first. > > The problem here is not that the fsm_irq function is called on interrupt, > if we have an interrupt it must be signaled to user land. > The problem is that this state is entered at the wrong moment. > > STANDBY should be entered, during the mdev_open when we realize the QEMU > device, > and not during the probe, in which we should stay in NOT_OPER until we > get the QEMU device. > > The probe() and mdev_open() function should be modified, not the state > table. So, the takeaway is that we should handle starting via the init callbacks and not via the state machine?
