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Subject: Re: [PATCH 8/9] vfio/pci: export nvlink2 support into vendor vfio_pci
 drivers
To:     Jason Gunthorpe <jgg@nvidia.com>
Cc:     Max Gurtovoy <mgurtovoy@nvidia.com>, alex.williamson@redhat.com,
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 <20210311013443.GH2356281@nvidia.com>
From:   Alexey Kardashevskiy <aik@ozlabs.ru>
Message-ID: <d862adf9-6fe7-a99e-6c14-8413aae70cd4@ozlabs.ru>
Date:   Thu, 11 Mar 2021 12:42:56 +1100
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On 11/03/2021 12:34, Jason Gunthorpe wrote:
> On Thu, Mar 11, 2021 at 12:20:33PM +1100, Alexey Kardashevskiy wrote:
> 
>>> It is supposed to match exactly the same match table as the pci_driver
>>> above. We *don't* want different behavior from what the standrd PCI
>>> driver matcher will do.
>>
>> This is not a standard PCI driver though
> 
> It is now, that is what this patch makes it into. This is why it now
> has a struct pci_driver.
> 
>> and the main vfio-pci won't have a
>> list to match ever.
> 
> ?? vfio-pci uses driver_override or new_id to manage its match list


Exactly, no list to update.


>> IBM NPU PCI id is unlikely to change ever but NVIDIA keeps making
>> new devices which work in those P9 boxes, are you going to keep
>> adding those ids to nvlink2gpu_vfio_pci_table?
> 
> Certainly, as needed. PCI list updates is normal for the kernel.
> 
>> btw can the id list have only vendor ids and not have device ids?
> 
> The PCI matcher is quite flexable, see the other patch from Max for
> the igd


ah cool, do this for NVIDIA GPUs then please, I just discovered another 
P9 system sold with NVIDIA T4s which is not in your list.


> But best practice is to be as narrow as possible as I hope this will
> eventually impact module autoloading and other details.

The amount of device specific knowledge is too little to tie it up to 
device ids, it is a generic PCI driver with quirks. We do not have a 
separate drivers for the hardware which requires quirks.

And how do you hope this should impact autoloading?


-- 
Alexey