On Thu, Aug 04, 2022 at 01:51:20PM -0300, Jason Gunthorpe wrote:
On Mon, Aug 01, 2022 at 09:49:28AM -0600, Alex Williamson wrote:
> > > > > Fortunately these new vendor/device-specific drivers can be
easily
> > > > > identified as being "vfio-pci + extra stuff" - all
that's needed is to
> > > > > look at the output of the "modinfo $driver_name"
command to see if
> > > > > "vfio_pci" is in the alias list for the driver.
We are moving in a direction on the kernel side to expose a sysfs
under the PCI device that definitively says it is VFIO enabled, eg
something like
/sys/devices/pci0000:00/0000:00:1f.6/vfio/<N>
Which is how every other subsystem in the kernel works. When this
lands libvirt can simply stat the vfio directory and confirm that the
device handle it is looking at is vfio enabled, for all things that
vfio support.
My thinking had been to do the above work a bit later, but if libvirt
needs it right now then lets do it right away so we don't have to
worry about this hacky modprobe stuff down the road?
I wouldn't go so far as to say libvirt "needs" it, as obviously we can
make it work using module.alias information. I would say that exposing
this in sysfs though makes it simpler and faster, because the check then
essentially turns into a single stat() call. So from that POV libvirt
would be happy to see that improvement.
With regards,
Daniel
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