On Thu, 14 Feb 2019 13:30:59 -0500 Tony Krowiak <akrowiak@xxxxxxxxxxxxx> wrote: > On 2/14/19 12:36 PM, Pierre Morel wrote: > > On 14/02/2019 17:57, Cornelia Huck wrote: > >> On Thu, 14 Feb 2019 16:47:30 +0100 Pierre Morel > >> <pmorel@xxxxxxxxxxxxx> wrote: > >> > >>> On 14/02/2019 15:54, Cornelia Huck wrote: > >>>> On Thu, 14 Feb 2019 14:51:01 +0100 Pierre Morel > >>>> <pmorel@xxxxxxxxxxxxx> wrote: > >>>>> - matrix_dev->device.type = &vfio_ap_dev_type; > >>>>> dev_set_name(&matrix_dev->device, "%s", VFIO_AP_DEV_NAME); > >>>>> matrix_dev->device.parent = root_device; + > >>>>> matrix_dev->device.bus = &matrix_bus; matrix_dev->device.release = > >>>>> vfio_ap_matrix_dev_release; - > >>>>> matrix_dev->device.driver = &vfio_ap_drv.driver; + > >>>>> matrix_dev->vfio_ap_drv = &vfio_ap_drv; > >>>> > >>>> Can't you get that structure through matrix_dev->device.driver > >>>> instead when you need it in the function below? > >>> > >>> Not anymore. We have two different drivers and devices matrix_drv > >>> <-> matrix_dev and vfio_ap_drv <-> ap_devices > >>> > >>> The driver behind the matrix_dev->dev->driver is matrix_drv what is > >>> needed here is vfio_ap_drv. > >> > >> Wait, we had tacked a driver for ap devices unto a matrix device, > >> which is not on the ap bus? > > It's really a bit more complicated than that. Without going into a > lengthy description of the history of AP passthrough support, suffice it > to say that we needed a device to serve as the parent of each mediated > device used to configure a matrix of AP adapter IDs and domain indexes > identifying the devices to which a guest would be granted access. The > AP devices themselves are attached to the AP bus, but the matrix device > is an artificial (virtual?) device whose sole purpose in life is to > serve as an anchor for the mediated devices whose sysfs interfaces are > created and managed by the vfio_ap device driver. The matrix device > itself is created by the vfio_ap device driver - when it is initialized > - for that purpose. In hindsight, maybe there was a better way to > implement this, but neither this patch nor this discussion belongs in > this series. It distracts from discussion of interrupt support which is > the sole purpose of the patch series. The we-need-a-parent part is fine; but whatever we're doing with that driver just looks wrong, so that even the new bus that basically does nothing looks better... > > > > > ...yes -( > > > >> Maybe that's what trips libudev? > > >> (And reading further in the current code, it seems we clear that > >> structure _after_ the matrix device had been setup, so how can that > >> even work? Where am I confused?) > > > > On device_register there were no bus, so the core just do not look for a > > driver and this field was nor tested nor overwritten. Hm... so has the callback in driver_for_each_device() in vfio_ap_verify_queue_reserved() ever been invoked at all? It seems this patch fixes more than just libudev issues... > > > >> > >>> > >>>> > >>>>> > >>>>> ret = device_register(&matrix_dev->device); if (ret) goto > >>>>> matrix_reg_err; > >>>>> > >>>>> + ret = driver_register(&matrix_driver.drv); + if (ret) > >>>>> + goto > >>>>> matrix_drv_err; + > >>>> > >>>> As you already have several structures that can be registered > >>>> exactly once (the root device, the bus, the driver, ...), you can > >>>> already be sure that there's only one device on the bus, can't > >>>> you? > >>> > >>> hum, no I don't think so, no device can register before this module > >>> is loaded, but what does prevent a device to register later from > >>> another module? > >> > >> Not unless you export the interface, I guess. > >> > > > > :) definitively right > > thanks, this will simplify the code in the next version. > > I will take the patch away from this series to get the way to stable as > > Christian requested. Yeah, makes sense.
