Re: [PATCH V1 vfio 9/9] vfio/virtio: Introduce a vfio driver over virtio devices

Michael S. Tsirkin
2023-10-26T12:13:28Z

On Thu, Oct 26, 2023 at 03:08:12PM +0300, Yishai Hadas wrote:
> > > Makes sense ?
> > So do I understand correctly that virtio dictates the subsystem device
> > ID for all subsystem vendor IDs that implement a legacy virtio
> > interface? Ok, but this device didn't actually implement a legacy
> > virtio interface. The device itself is not tranistional, we're imposing
> > an emulated transitional interface onto it. So did the subsystem vendor
> > agree to have their subsystem device ID managed by the virtio committee
> > or might we create conflicts? I imagine we know we don't have a
> > conflict if we also virtualize the subsystem vendor ID.
> >
> The non transitional net device in the virtio spec defined as the below
> tuple.
> T_A: VID=0x1AF4, DID=0x1040, Subsys_VID=FOO, Subsys_DID=0x40.
>
> And transitional net device in the virtio spec for a vendor FOO is defined
> as:
> T_B: VID=0x1AF4,DID=0x1000,Subsys_VID=FOO, subsys_DID=0x1
>
> This driver is converting T_A to T_B, which both are defined by the virtio
> spec.
> Hence, it does not conflict for the subsystem vendor, it is fine.

You are talking about legacy guests, what 1.X spec says about them
is much less important than what guests actually do.
Check the INF of the open source windows drivers and linux code, at least.

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MST