On Wed, Oct 11, 2023 at 10:44:49AM +0300, Yishai Hadas wrote: > On 10/10/2023 23:42, Michael S. Tsirkin wrote: > > On Tue, Oct 10, 2023 at 07:09:08PM +0300, Yishai Hadas wrote: > > > > > Assuming that we'll put each command inside virtio as the generic layer, we > > > > > won't be able to call/use this API internally to get the PF as of cyclic > > > > > dependencies between the modules, link will fail. > > I just mean: > > virtio_admin_legacy_io_write(sruct pci_device *, ....) > > > > > > internally it starts from vf gets the pf (or vf itself or whatever > > the transport is) sends command gets status returns. > > > > what is cyclic here? > > > virtio-pci depends on virtio [1]. > > If we put the commands in the generic layer as we expect it to be (i.e. > virtio), then trying to call internally call for virtio_pci_vf_get_pf_dev() > to get the PF from the VF will end-up by a linker cyclic error as of below > [2]. > > As of that, someone can suggest to put the commands in virtio-pci, however > this will fully bypass the generic layer of virtio and future clients won't > be able to use it. virtio_pci would get pci device. virtio pci convers that to virtio device of owner + group member id and calls virtio. no cycles and minimal transport specific code, right? > In addition, passing in the VF PCI pointer instead of the VF group member ID > + the VIRTIO PF device, will require in the future to duplicate each command > once we'll use SIOV devices. I don't think anyone knows how will SIOV look. But shuffling APIs around is not a big deal. We'll see. > Instead, we suggest the below API for the above example. > > virtio_admin_legacy_io_write(virtio_device *virtio_dev, u64 > group_member_id, ....) > > [1] > [yishaih@reg-l-vrt-209 linux]$ modinfo virtio-pci > filename: /lib/modules/6.6.0-rc2+/kernel/drivers/virtio/virtio_pci.ko > version: 1 > license: GPL > description: virtio-pci > author: Anthony Liguori <aliguori@xxxxxxxxxx> > srcversion: 7355EAC9408D38891938391 > alias: pci:v00001AF4d*sv*sd*bc*sc*i* > depends: virtio_pci_modern_dev,virtio,virtio_ring,virtio_pci_legacy_dev > retpoline: Y > intree: Y > name: virtio_pci > vermagic: 6.6.0-rc2+ SMP preempt mod_unload modversions > parm: force_legacy:Force legacy mode for transitional virtio 1 > devices (bool) > > [2] > > depmod: ERROR: Cycle detected: virtio -> virtio_pci -> virtio > depmod: ERROR: Found 2 modules in dependency cycles! > make[2]: *** [scripts/Makefile.modinst:128: depmod] Error 1 > make[1]: *** [/images/yishaih/src/kernel/linux/Makefile:1821: > modules_install] Error 2 > > Yishai virtio absolutely must not depend on virtio pci, it is used on systems without pci at all.
