[dpdk-dev] [PATCH v2 0/3] ethdev: configure SR-IOV VF from host

[Ilya Maximets]

On 01.11.2019 10:06, Ilya Maximets wrote:
> On 01.11.2019 1:24, Thomas Monjalon wrote:
>> 30/10/2019 10:24, Jerin Jacob:
>>> On Wed, Oct 30, 2019 at 12:52 PM Shahaf Shuler <shahafs at mellanox.com> wrote:
>>>> Wednesday, October 30, 2019 6:09 AM, Jerin Jacob:
>>>>> Subject: Re: [dpdk-dev] [PATCH v2 0/3] ethdev: configure SR-IOV VF from
>>>>> host
>>>>>
>>>>> On Wed, Oct 30, 2019 at 12:21 AM Thomas Monjalon
>>>>> <thomas at monjalon.net> wrote:
>>>>>>
>>>>>> In a virtual environment, the network controller may have to configure
>>>>>> some SR-IOV VF parameters for security reasons.
>>>>>
>>>>> Just to understand, Could you explain more details/examples for security
>>>>> reasons?
>>>>>
>>>>>>
>>>>>> When the PF (host port) is driven by DPDK (OVS-DPDK case), we face two
>>>>>> different cases:
>>>>>>      - driver is bifurcated (Mellanox case),
>>>>>>        so the VF can be configured via the kernel.
>>>>>>      - driver is on top of UIO or VFIO, so DPDK API is required,
>>>>>
>>>>> Not true. Both UIO and VFIO are NOT allowed to create SRIOV VF from the
>>>>> PF device.
>>>>> It is only allowed through igb-uio out of tree driver without iommu support.
>>>>
>>>> Per my understanding Thomas proposal is not to create the VFs
>>>> from the PF device. it is to configure their network attributes
>>>> from the PF after they have been created.
>>>
>>> Yes. My question is without creating the VF, How do you control them?
>>
>> We can create the VF via the kernel PF driver, before binding the PF to VFIO.
> 
> AFAIK, this is not possible. VFs are gone as soon as you're unbinding kernel
> PF driver.  And after binding of vfio-pci you can no longer create VFs.
> 
> I tried to check some representor functionality about 2 months ago and didn't
> find a way to enable VFs on Intel NICs if PF is under control of vfio-pci.

Likely it was i40e driver from the kernel side.  I see from the lkml thread that
some drivers might not clear sriov on exit (ixgbe), but that wasn't my case and
it's actually a controversial feature in general.