linux-kernel - Re: [PATCH 8/9] vfio/pci: use x86 naming instead of igd

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Message-ID: <5bf0b8f7-38fb-bfdf-d093-d8d9b28b9679@nvidia.com>
Date:   Mon, 8 Feb 2021 14:44:14 +0200
From:   Max Gurtovoy <mgurtovoy@...dia.com>
To:     Alexey Kardashevskiy <aik@...abs.ru>,
        Jason Gunthorpe <jgg@...dia.com>
CC:     Cornelia Huck <cohuck@...hat.com>,
        Alex Williamson <alex.williamson@...hat.com>,
        Matthew Rosato <mjrosato@...ux.ibm.com>, <kvm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <liranl@...dia.com>,
        <oren@...dia.com>, <tzahio@...dia.com>, <leonro@...dia.com>,
        <yarong@...dia.com>, <aviadye@...dia.com>, <shahafs@...dia.com>,
        <artemp@...dia.com>, <kwankhede@...dia.com>, <ACurrid@...dia.com>,
        <gmataev@...dia.com>, <cjia@...dia.com>, <yishaih@...dia.com>
Subject: Re: [PATCH 8/9] vfio/pci: use x86 naming instead of igd


On 2/5/2021 2:42 AM, Alexey Kardashevskiy wrote:
>
>
> On 04/02/2021 23:51, Jason Gunthorpe wrote:
>> On Thu, Feb 04, 2021 at 12:05:22PM +1100, Alexey Kardashevskiy wrote:
>>
>>> It is system firmware (==bios) which puts stuff in the device tree. The
>>> stuff is:
>>> 1. emulated pci devices (custom pci bridges), one per nvlink, 
>>> emulated by
>>> the firmware, the driver is "ibmnpu" and it is a part on the nvidia 
>>> driver;
>>> these are basically config space proxies to the cpu's side of nvlink.
>>> 2. interconnect information - which of 6 gpus nvlinks connected to 
>>> which
>>> nvlink on the cpu side, and memory ranges.
>>
>> So what is this vfio_nvlink driver supposed to be bound to?
>>
>> The "emulated pci devices"?
>
> Yes.
>
>> A real GPU function?
>
> Yes.
>
>> A real nvswitch function?
>
> What do you mean by this exactly? The cpu side of nvlink is "emulated 
> pci devices", the gpu side is not in pci space at all, the nvidia 
> driver manages it via the gpu's mmio or/and cfg space.
>
>> Something else?
>
> Nope :)
> In this new scheme which you are proposing it should be 2 drivers, I 
> guess.

I see.

So should it be nvidia_vfio_pci.ko ? and it will do the NVLINK stuff in 
case the class code matches and otherwise just work as simple vfio_pci GPU ?

What about the second driver ? should it be called ibmnpu_vfio_pci.ko ?

>
>>
>> Jason
>>
>