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Date:   Tue, 8 Jun 2021 19:45:17 -0300
From:   Jason Gunthorpe <jgg@nvidia.com>
To:     Alex Williamson <alex.williamson@redhat.com>
Cc:     Max Gurtovoy <mgurtovoy@nvidia.com>, cohuck@redhat.com,
        kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
        aviadye@nvidia.com, oren@nvidia.com, shahafs@nvidia.com,
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        ACurrid@nvidia.com, cjia@nvidia.com, yishaih@nvidia.com,
        kevin.tian@intel.com, hch@infradead.org, targupta@nvidia.com,
        shameerali.kolothum.thodi@huawei.com, liulongfang@huawei.com,
        yan.y.zhao@intel.com
Subject: Re: [PATCH 09/11] PCI: add matching checks for driver_override
 binding
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 <20210608152643.2d3400c1.alex.williamson@redhat.com>
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On Tue, Jun 08, 2021 at 03:26:43PM -0600, Alex Williamson wrote:
> > drivers that specifically opt into this feature and the driver now has
> > the opportunity to provide a proper match table that indicates what HW
> > it can properly support. vfio-pci continues to support everything.
> 
> In doing so, this also breaks the new_id method for vfio-pci.  

Does it? How? The driver_override flag is per match entry not for the
entire device so new_id added things will work the same as before as
their new match entry's flags will be zero.

> Sorry, with so many userspace regressions, crippling the
> driver_override interface with an assumption of such a narrow focus,
> creating a vfio specific match flag, I don't see where this can go.
> Thanks,

On the other hand it overcomes all the objections from the last go
round: how userspace figures out which driver to use with
driver_override and integrating the universal driver into the scheme.

pci_stub could be delt with by marking it for driver_override like
vfio_pci.

But driverctl as a general tool working with any module is not really
addressable.

Is the only issue the blocking of the arbitary binding? That is not a
critical peice of this, IIRC

Jason