On Mon, Jul 05, 2021 at 10:18:59AM +0000, Shameerali Kolothum Thodi wrote: > > > > -----Original Message----- > > From: Max Gurtovoy [mailto:mgurtovoy@xxxxxxxxxx] > > Sent: 05 July 2021 10:42 > > To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@xxxxxxxxxx>; > > Leon Romanovsky <leon@xxxxxxxxxx> > > Cc: kvm@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > > linux-crypto@xxxxxxxxxxxxxxx; alex.williamson@xxxxxxxxxx; jgg@xxxxxxxxxx; > > Linuxarm <linuxarm@xxxxxxxxxx>; liulongfang <liulongfang@xxxxxxxxxx>; > > Zengtao (B) <prime.zeng@xxxxxxxxxxxxx>; yuzenghui > > <yuzenghui@xxxxxxxxxx>; Jonathan Cameron > > <jonathan.cameron@xxxxxxxxxx>; Wangzhou (B) <wangzhou1@xxxxxxxxxxxxx> > > Subject: Re: [RFC v2 1/4] hisi-acc-vfio-pci: add new vfio_pci driver for HiSilicon > > ACC devices > > > > > > On 7/5/2021 11:47 AM, Shameerali Kolothum Thodi wrote: > > > > > >> -----Original Message----- > > >> From: Leon Romanovsky [mailto:leon@xxxxxxxxxx] > > >> Sent: 04 July 2021 08:04 > > >> To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@xxxxxxxxxx> > > >> Cc: kvm@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > > >> linux-crypto@xxxxxxxxxxxxxxx; alex.williamson@xxxxxxxxxx; > > jgg@xxxxxxxxxx; > > >> mgurtovoy@xxxxxxxxxx; Linuxarm <linuxarm@xxxxxxxxxx>; liulongfang > > >> <liulongfang@xxxxxxxxxx>; Zengtao (B) <prime.zeng@xxxxxxxxxxxxx>; > > >> yuzenghui <yuzenghui@xxxxxxxxxx>; Jonathan Cameron > > >> <jonathan.cameron@xxxxxxxxxx>; Wangzhou (B) > > <wangzhou1@xxxxxxxxxxxxx> > > >> Subject: Re: [RFC v2 1/4] hisi-acc-vfio-pci: add new vfio_pci driver for > > HiSilicon > > >> ACC devices > > >> > > >> On Fri, Jul 02, 2021 at 10:58:46AM +0100, Shameer Kolothum wrote: > > >>> Add a vendor-specific vfio_pci driver for HiSilicon ACC devices. > > >>> This will be extended in follow-up patches to add support for > > >>> vfio live migration feature. > > >>> > > >>> Signed-off-by: Shameer Kolothum > > >> <shameerali.kolothum.thodi@xxxxxxxxxx> > > >>> --- > > >>> drivers/vfio/pci/Kconfig | 9 +++ > > >>> drivers/vfio/pci/Makefile | 2 + > > >>> drivers/vfio/pci/hisi_acc_vfio_pci.c | 100 > > +++++++++++++++++++++++++++ > > >>> 3 files changed, 111 insertions(+) > > >>> create mode 100644 drivers/vfio/pci/hisi_acc_vfio_pci.c > > >> <...> > > >> > > >>> +static const struct vfio_device_ops hisi_acc_vfio_pci_ops = { > > >>> + .name = "hisi-acc-vfio-pci", > > >>> + .open = hisi_acc_vfio_pci_open, > > >>> + .release = vfio_pci_core_release, > > >>> + .ioctl = vfio_pci_core_ioctl, > > >>> + .read = vfio_pci_core_read, > > >>> + .write = vfio_pci_core_write, > > >>> + .mmap = vfio_pci_core_mmap, > > >>> + .request = vfio_pci_core_request, > > >>> + .match = vfio_pci_core_match, > > >>> + .reflck_attach = vfio_pci_core_reflck_attach, > > >> I don't remember what was proposed in vfio-pci-core conversion patches, > > >> but would expect that default behaviour is to fallback to vfio_pci_core_* > > API > > >> if ".release/.ioctl/e.t.c" are not redefined. > > > Yes, that would be nice, but don't think it does that in latest(v4). > > > > > > Hi Max, > > > Could we please consider fall back to the core defaults, may be check and > > assign defaults > > > in vfio_pci_core_register_device() ? > > > > I don't see why we should do this. > > > > vfio_pci_core.ko is just a library driver. It shouldn't decide for the > > vendor driver ops. > > > > If a vendor driver would like to use its helper functions - great. > > > > If it wants to override it - great. > > > > If it wants to leave some op as NULL - it can do it also. > > Based on the documentation of the vfio_device_ops callbacks, > It looks like we already have a precedence in the case of reflck_attach > callback where it uses the vfio core default one, if it is not implemented. The reflck_attach pattern is pretty common pattern in the kernel to provide fallback. > > Also I would imagine that in majority use cases the vendor drivers will be > defaulting to core functions. Right, this is whole idea of having core functionality in one place, if vendor wants/needs, he will overwrite. > > I think, in any case, it would be good to update the Documentation based on > which way we end up doing this. The request to update Documentation can be seen as an example of choosing not-good API decisions. Expectation to see all drivers to use same callbacks with same vfio-core function calls sounds strange to me. Thanks > > Thanks, > Shameer > > > > > > > > > > > > Thanks, > > > Shameer
