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Subject: Re: [PATCH 5/6] vdpa: introduce virtio pci driver
To:     "Michael S. Tsirkin" <mst@redhat.com>
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From:   Jason Wang <jasowang@redhat.com>
Message-ID: <a1b1b7fb-b097-17b7-2e3a-0da07d2e48ae@redhat.com>
Date:   Mon, 8 Jun 2020 17:18:44 +0800
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On 2020/6/8 下午2:32, Michael S. Tsirkin wrote:
> On Mon, Jun 08, 2020 at 11:32:31AM +0800, Jason Wang wrote:
>> On 2020/6/7 下午9:51, Michael S. Tsirkin wrote:
>>> On Fri, Jun 05, 2020 at 04:54:17PM +0800, Jason Wang wrote:
>>>> On 2020/6/2 下午3:08, Jason Wang wrote:
>>>>>>> +static const struct pci_device_id vp_vdpa_id_table[] = {
>>>>>>> +    { PCI_DEVICE(PCI_VENDOR_ID_REDHAT_QUMRANET, PCI_ANY_ID) },
>>>>>>> +    { 0 }
>>>>>>> +};
>>>>>> This looks like it'll create a mess with either virtio pci
>>>>>> or vdpa being loaded at random. Maybe just don't specify
>>>>>> any IDs for now. Down the road we could get a
>>>>>> distinct vendor ID or a range of device IDs for this.
>>>>> Right, will do.
>>>>>
>>>>> Thanks
>>>> Rethink about this. If we don't specify any ID, the binding won't work.
>>> We can bind manually. It's not really for production anyway, so
>>> not a big deal imho.
>>
>> I think you mean doing it via "new_id", right.
> I really meant driver_override. This is what people have been using
> with pci-stub for years now.


Do you want me to implement "driver_overrid" in this series, or a NULL 
id_table is sufficient?


>
>>>> How about using a dedicated subsystem vendor id for this?
>>>>
>>>> Thanks
>>> If virtio vendor id is used then standard driver is expected
>>> to bind, right? Maybe use a dedicated vendor id?
>>
>> I meant something like:
>>
>> static const struct pci_device_id vp_vdpa_id_table[] = {
>>      { PCI_DEVICE_SUB(PCI_VENDOR_ID_REDHAT_QUMRANET, PCI_ANY_ID,
>> VP_TEST_VENDOR_ID, VP_TEST_DEVICE_ID) },
>>      { 0 }
>> };
>>
>> Thanks
>>
> Then regular virtio will still bind to it. It has
>
> drivers/virtio/virtio_pci_common.c:     { PCI_DEVICE(PCI_VENDOR_ID_REDHAT_QUMRANET, PCI_ANY_ID) },
>
>

IFCVF use this to avoid the binding to regular virtio device. Looking at 
pci_match_one_device() it checks both subvendor and subdevice there.

Thanks