Re: [PATCHv2 2/2] pci: warn if a running device is unaware of reset

[Niklas Schnelle <schnelle@linux.ibm.com>]

On Mon, 2024-11-04 at 10:01 -0700, Keith Busch wrote:
> On Mon, Nov 04, 2024 at 10:44:23AM +0100, Niklas Schnelle wrote:
> > 
> > One more question though, what would happen with this reset for a bus
> > with an SR-IOV device with more than 256 VFs i.e. where
> > pci_iov_virtfn_bus() returns anything other than 0. I'm guessing since
> > VFs are physically still controlled by the bridge all VFs would be
> > reset but at the same time virtfn_add_bus() sets the bridge device for
> > the added bus as NULL so I think it might look odd in sysfs, sadly I
> > don't have such a device to test with. Still, this might actually be an
> > argument for having the attribute on the bridge.
> 
> I assume everything is reset at the PCI level.
> 
> Are you asking what the kernel does? I don't think it does anything
> special with SR-IOV functions. Those pci_dev's aren't attached to the
> bridge pci_dev; you have to go through the pci_bus' children instead.
> 

I just want to make sure we're okay with the behavior with such VFs as
it seems like the one case where a reset via the bridge affects PCI
functions which aren't attached to the bridge pci_dev otherwise. And
for example as I understand it these would not be covered by the
pci_bus_save_and_disable_locked().

Thanks,
Niklas