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    SubjectRe: [PATCH 09/11] PCI: add matching checks for driver_override binding
    On Tue, Jun 15, 2021 at 06:22:45PM -0600, Alex Williamson wrote:
    > On Tue, 15 Jun 2021 20:32:57 -0300
    > Jason Gunthorpe <jgg@nvidia.com> wrote:
    >
    > > On Tue, Jun 15, 2021 at 05:22:42PM -0600, Alex Williamson wrote:
    > >
    > > > > > b) alone is a functional, runtime difference.
    > > > >
    > > > > I would state b) differently:
    > > > >
    > > > > b) Ignore the driver-override-only match entries in the ID table.
    > > >
    > > > No, pci_match_device() returns NULL if a match is found that is marked
    > > > driver-override-only and a driver_override is not specified. That's
    > > > the same as no match at all. We don't then go on to search past that
    > > > match in the table, we fail to bind the driver. That's effectively an
    > > > anti-match when there's no driver_override on the device.
    > >
    > > anti-match isn't the intention. The deployment will have match tables
    > > where all entires are either flags=0 or are driver-override-only.
    >
    > I'd expect pci-pf-stub to have one of each, an any-id with
    > override-only flag and the one device ID currently in the table with
    > no flag.

    Oh Hum. Actually I think this shows the anti-match behavior is
    actually a bug.. :(

    For something like pci_pf_stub_whitelist, if we add a
    driver_override-only using the PCI any id then it effectively disables
    new_id completely because the match search will alway find the
    driver_override match first and stop searching. There is no chance to
    see things new_id adds.

    We have to fix this patch so flags isn't an anti-match to make it work
    without user regression.

    Jason

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