2026年3月10日(火) 12:02 Jason Wang <[email protected]>:
>
> On Mon, Mar 9, 2026 at 2:19 PM Yui Washizu <[email protected]> wrote:
> >
> >
> > On 3/9/2026 12:33 PM, Jason Wang wrote:
> > > On Mon, Mar 9, 2026 at 10:37 AM Yui Washizu <[email protected]> wrote:
> > >> Recent QEMU versions added support for virtio SR-IOV emulation,
> > >> allowing virtio devices to expose SR-IOV VFs to the guest.
> > >> However, virtio_bus does not implement the num_vf callback of bus_type,
> > >> causing dev_num_vf() to return 0 for virtio devices even when
> > >> SR-IOV VFs are active.
> > >>
> > >> net/core/rtnetlink.c calls dev_num_vf(dev->dev.parent) to populate
> > >> IFLA_NUM_VF and IFLA_VFINFO_LIST
> > > Patch looks good but,
> > >
> > > If I understand correctly, ndo_get_vf_config is needed for
> > > IFLA_VFINFO_LIST but not implemeted in this patch?
> >
> > Thank you for your comment.
> >
> > I submitted this patch because I confirmed
> > that "ip link show" returns the correct VF IDs with this implementation.
> >
> > In the current implementation,
> > I believe there is no information that would need to be referenced
> > through IFLA_VFINFO_LIST.
> > Therefore, I did not include ndo_get_vf_config in this patch,
> > as it did not seem essential at this stage.
> >
> > Would it be better to implement IFLA_VFINFO_LIST support together with this?
>
> Then it's not, I think it's better to not mention IFLA_VFINFO_LIST in
> the commit log as it may confuse people.
>
> Thanks
>

Thank you.
I'll update the commit message to remove the reference to IFLA_VFINFO_LIST
and send a v2.
Regards,

>
> >
> > Regards,
> >
> >
> > >> in RTM_GETLINK responses.  For a
> > >> virtio-net device, dev.parent points to the virtio_device, whose bus
> > >> is virtio_bus.  Without num_vf, SR-IOV VF information is silently
> > >> omitted from tools that rely on rtnetlink, such as 'ip link show'.
> > >>
> > >> Add a num_vf callback that delegates to dev_num_vf(dev->parent),
> > >> which in turn reaches the underlying transport (pci_bus_type for
> > >> virtio-pci) where the actual VF count is tracked.  Non-PCI transports
> > >> are unaffected as dev_num_vf() returns 0 when no num_vf callback is
> > >> present.
> > >>
> > >> Signed-off-by: Yui Washizu <[email protected]>
> > >> ---
> > >>   drivers/virtio/virtio.c | 9 +++++++++
> > >>   1 file changed, 9 insertions(+)
> > >>
> > >> diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
> > >> index 5bdc6b82b30b..299fa83be1d5 100644
> > >> --- a/drivers/virtio/virtio.c
> > >> +++ b/drivers/virtio/virtio.c
> > >> @@ -435,6 +435,14 @@ static void virtio_dev_shutdown(struct device *_d)
> > >>          dev->config->reset(dev);
> > >>   }
> > >>
> > >> +static int virtio_dev_num_vf(struct device *dev)
> > >> +{
> > >> +       struct virtio_device *vdev = dev_to_virtio(dev);
> > >> +
> > >> +       return dev_num_vf(vdev->dev.parent);
> > >> +}
> > >> +
> > >> +
> > >>   static const struct bus_type virtio_bus = {
> > >>          .name  = "virtio",
> > >>          .match = virtio_dev_match,
> > >> @@ -444,6 +452,7 @@ static const struct bus_type virtio_bus = {
> > >>          .remove = virtio_dev_remove,
> > >>          .irq_get_affinity = virtio_irq_get_affinity,
> > >>          .shutdown = virtio_dev_shutdown,
> > >> +       .num_vf = virtio_dev_num_vf,
> > >>   };
> > >>
> > >>   int __register_virtio_driver(struct virtio_driver *driver, struct 
> > >> module *owner)
> > >> --
> > >> 2.47.3
> > >>
> > > Thanks
> > >
> >
>

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