On Thu, Aug 12, 2021 at 10:27:28AM -0300, Jason Gunthorpe wrote:
> On Wed, Aug 11, 2021 at 02:07:37PM -0500, Bjorn Helgaas wrote:
> > On Thu, Aug 05, 2021 at 09:23:57PM -0300, Jason Gunthorpe wrote:
> > Do the other bus types have a flag analogous to
> > PCI_ID_F_VFIO_DRIVER_OVERRIDE? If we're doing something similar to
> > other bus types, it'd be nice if the approach were similar.
>
> They could, this series doesn't attempt it. I expect the approach to
> be similar as driver_override was copied from PCI to other
> busses. When this is completed I hope to take a look at it.
I think this would make more sense as two patches:
- Add a "PCI_ID_DRIVER_OVERRIDE" flag. This is not VFIO-specific,
since nothing in PCI depends on the VFIO-ness of drivers that use
the flag. The only point here is that driver id_table entries
with this flag only match when driver_override matches the driver.
- Update file2alias.c to export the flags and the "vfio_pci:" alias.
This seems to be the only place where VFIO comes into play, and
putting it in a separate patch will make it much smaller and it
will be clear how it could be extended for other buses.
> > I assume somewhere in here you need to unbind mlx5_core before binding
> > mlx5_vfio_pci?
>
> Er, yes, I skipped some steps here where unbind/bind has to be done
>
> > > 6) cat the matched module name to driver_override:
> > > echo mlx5_vfio_pci > /sys/bus/pci/devices/0000:01:00.0/driver_override
> >
> > Don't you need something here to trigger the driver attach, i.e.,
> > should step 5 and step 6 be swapped? What if the driver is already
> > loaded?
>
> The full sequence is more like:
>
> echo mlx5_vfio_pci > /sys/bus/pci/devices/0000:01:00.0/driver_override
> echo 0000:01:00.0 > /sys/bus/pci/devices/0000:01:00.0/driver/unbind
> echo 0000:01:00.0 > /sys/bus/pci/drivers_probe
Thanks a lot for this! I didn't know about drivers_probe (see
drivers_probe_store()), and it doesn't seem to be documented anywhere
except sysfs-bus-usb, where it's only incidental to USB.
Bjorn
