From: Xia, Chenbo <redacted>
Sent: Tuesday, June 15, 2021 11:03 AM

Hi Parav,

quoted

-----Original Message-----
From: Parav Pandit <redacted>
Sent: Tuesday, June 15, 2021 12:05 PM
To: Xia, Chenbo <redacted>; NBU-Contact-Thomas Monjalon
[off-list ref]; Yigit, Ferruh [off-list ref]
Cc: Xueming(Steven) Li <redacted>; Slava Ovsiienko
[off-list ref]; dev@dpdk.org; Jason Gunthorpe
[off-list ref]
Subject: RE: [dpdk-dev] [RFC 00/14] mlx5: support SubFunction

Hi Chenbo,

quoted

From: Xia, Chenbo <redacted>
Sent: Tuesday, June 15, 2021 7:41 AM

Hi Thomas,

quoted

From: Thomas Monjalon <redacted>
Sent: Friday, June 11, 2021 3:54 PM

[..]

quoted

Yes. In our term it's called Assignable Device Interface (ADI)
introduced in Intel Scalable IOV
(https://01.org/blogs/2019/assignable-interfaces-intel-
scalable-i/o-virtualization-linux)

And vfio-mdev is chosen to be the software framework for it. I start
to

realize

quoted

there is difference between SF and ADI: SF considers multi-function
devices which may include net/regex/vdpa/...

Yes. net, rdma, vdpa, regex ++.
And eventually vfio_device to map to VM too.

Non mdev framework is chosen so that all the use cases of kernel only,
or user only or mix modes can be supported.

OK. Got it.

quoted

quoted

But ADI only focuses on the
virtualization of the devices and splitting devices to logic parts
and

providing

quoted

huge number of interfaces to host APP. I think SF also considers
this but is mainly used for multi-function devices (like DPU in your term?
Correct me if I'm wrong).

SF also supports DPU mode too but it is in addition to above use cases.
SF will expose mdev (or a vfio_device) to map to a VM.

So your SW actually supports vfio-mdev? I suppose the device-specific mdev
Kernel module is out-of-tree?

mlx5 driver doesn't support vfio_device for SFs. 
Kernel plumbing for PASID assignment to SF is WIP currently kernel community.
We do not have any out-of-tree kernel module.

Just FYI:

We are introducing a new mdev bus for DPDK:
http://patchwork.dpdk.org/project/dpdk/cover/20210601030644.3318-1-
chenbo.xia@intel.com/

I am yet to read about it. But I am not sure what value does it add.
A user can open a vfio device using vfio subsystem and operate on it. 
A vfio device can be a create as a result of binding PCI VF/PF to vfio-pci driver or a SF by binding SF to vfio_foo driver.
There is kernel work in progress to use vfio core as library.
So we do not anticipate to use add mdev layer and uuid to create a vfio device for a SF.

For Intel, ADI will never has any netdevs or rdma dev?