Re: [Intel-gfx] [PATCH v3 09/14] vfio/pci: Change vfio_pci_try_bus_reset() to use the dev_set

Alex Williamson
2021-08-03T16:52:33Z

On Tue, 3 Aug 2021 13:41:52 -0300
Jason Gunthorpe <jgg@nvidia.com> wrote:
> On Tue, Aug 03, 2021 at 10:34:06AM -0600, Alex Williamson wrote:
> > I think the vfio_pci_find_reset_target() function needs to be re-worked
> > to just tell us true/false that it's ok to reset the provided device,
> > not to anoint an arbitrary target device. Thanks,
>
> Yes, though this logic is confusing, why do we need to check if any
> device needs a reset at this point? If we are being asked to reset
> vdev shouldn't vdev needs_reset?
>
> Or is the function more of a 'synchronize pending reset' kind of
> thing?

Yes, the latter. For instance think about a multi-function PCI device
such as a GPU. The functions have dramatically different capabilities,
some might have function level reset abilities and others not. We want
to be able to trigger a bus reset as the last device of the set is
released, no matter the order they're released and no matter the
capabilities of the device we're currently processing. Thanks,

Alex