On 08/18/2017 07:12 AM, Alex Williamson wrote:
On Fri, 18 Aug 2017 15:42:31 +0200
Jan Glauber <jan.glauber@xxxxxxxxxxxxxxxxxx> wrote:
On Thu, Aug 17, 2017 at 07:00:17AM -0600, Alex Williamson wrote:
On Thu, 17 Aug 2017 10:14:23 +0200
Jan Glauber <jglauber@xxxxxxxxxx> wrote:
If a PCI device supports neither function-level reset, nor slot
or bus reset then refuse to probe it. A line is printed to inform
the user.
But that's not what this does, this requires that the device is on a
reset-able bus. This is a massive regression. With this we could no
longer assign devices on the root complex or any device which doesn't
return from bus reset and currently makes use of the NO_BUS_RESET flag
and works happily otherwise. Full NAK. Thanks,
Looks like I missed the slot reset check. So how about this:
if (pci_probe_reset_slot(pdev->slot) && pci_probe_reset_bus(pdev->bus)) {
dev_warn(...);
return -ENODEV;
}
Or am I still missing something here?
We don't require that a device is on a reset-able bus/slot, so any
attempt to impose that requirement means that there are devices that
might work perfectly fine that are now excluded from assignment. The
entire premise is unacceptable. Thanks,
You previously rejected the idea to silently ignore bus reset requests
on buses that do not support it.
So this leaves us with two options:
1) Do nothing, and crash the kernel on systems with bad combinations of
PCIe target devices and cn88xx when vfio_pci is used.
2) Do something else.
We are trying to figure out what that something else should be. The
general concept we are working on is that if vfio_pci wants to reset a
device, *and* bus reset is the only option available, *and* cn88xx, then
make vfio_pci fail.
What is your opinion of doing that (assuming it is properly implemented)?
Thanks,
David Daney
