Re: [PATCH RFC v2 00/18] Add VFIO mediated device support and DEV-MSI support for the idxd driver

[Jason Gunthorpe]

On Tue, Jul 21, 2020 at 11:54:49PM +0000, Tian, Kevin wrote:
> In a nutshell, applications don't require raw WQ controllability as guest
> kernel drivers may expect. Extending DSA user space interface to be another
> passthrough interface just for virtualization needs is less compelling than
> leveraging established VFIO/mdev framework (with the major merit that
> existing user space VMMs just work w/o any change as long as they already
> support VFIO uAPI).

Sure, but the above is how the cover letter should have summarized
that discussion, not as "it is not much code difference"

> In last review you said that you didn't hard nak this approach and would
> like to hear opinion from virtualization guys. In this version we CCed KVM
> mailing list, Paolo (VFIO/Qemu), Alex (VFIO), Samuel (Rust-VMM/Cloud
> hypervisor), etc. Let's see how they feel about this approach.

Yes, the VFIO community should decide.

If we are doing emulation tasks in the kernel now, then I can think of
several nice semi-emulated mdevs to propose.

This will not be some one off, but the start of a widely copied
pattern.

Jason