Re: [virtio-comment] Re: [PATCH v1 3/8] device-context: Define the device context fields for device migration

[Jason Wang <jasowang@redhat.com>]

On Tue, Oct 31, 2023 at 1:17âPM Parav Pandit <parav@nvidia.com> wrote:
>
>
>
> > From: virtio-comment@lists.oasis-open.org <virtio-comment@lists.oasis-
> > open.org> On Behalf Of Jason Wang
> > Sent: Tuesday, October 31, 2023 7:07 AM
> >
> > On Mon, Oct 30, 2023 at 12:28âPM Parav Pandit <parav@nvidia.com> wrote:
> > >
> > >
> > > > From: Jason Wang <jasowang@redhat.com>
> > > > Sent: Monday, October 30, 2023 9:35 AM
> > > >
> > > > å 2023/10/26 11:50, Parav Pandit åé:
> > > > >> From: virtio-comment@lists.oasis-open.org
> > > > >> <virtio-comment@lists.oasis- open.org> On Behalf Of Jason Wang
> > > > >> For example, you still haven't succeeded in defining passthrough.
> > > > > It was defined on 19th Oct in [1].
> > > > > What part is not clear to you in definition of passthrough device?
> > > > >
> > > > > [1]
> > > > > https://lore.kernel.org/virtio-
> > > > comment/PH0PR12MB5481EA6A4D0C64C5AF6D3A
> > > > > 57DCD4A@PH0PR12MB5481.namprd12.prod.outlook.com/
> > > >
> > > >
> > > > Let me copy-paste it again:
> > > >
> > > > For example, assuming you are correct, you still fail to explain
> > > >
> > > > 1) what is trapped and what's not, or what's the boundary
> > > Passthrough definition was replied few times.
> > > One of them is here,
> > > https://lore.kernel.org/virtio-
> > comment/PH0PR12MB5481EA6A4D0C64C5AF6D3A
> > > 57DCD4A@PH0PR12MB5481.namprd12.prod.outlook.com/
> > > I donât know what you mean by 'explain'. What do you want to be explained?
> > > What is trapped is listed in
> > > https://lore.kernel.org/virtio-
> > comment/PH0PR12MB5481EA6A4D0C64C5AF6D3A
> > > 57DCD4A@PH0PR12MB5481.namprd12.prod.outlook.com/
> > > What is not trapped is also listed in
> > > https://lore.kernel.org/virtio-
> > comment/PH0PR12MB5481EA6A4D0C64C5AF6D3A
> > > 57DCD4A@PH0PR12MB5481.namprd12.prod.outlook.com/
> > > So what more do you want to explain in there?
> >
> > You explained that MSI-X is trapped but not the others. People may know why.
> > or what's the boundary to choose to trap or not.
> >
> If a platform can support without trapping, it can be avoided as well and can be added in the future.

Who is going to do that synchronization?

>
> > >
> > > > 2) if the hypervisor is not developed with those assumptions, things
> > > > can work
> > > What to explain in #2. :)
> > > Things can expand when such hypervisor is born.
> >
> > So the point is still, to make your proposal to be useful in more use cases.
> >
> When a use case arise, device context can be expanded.

It's not device context.

> No point in making things no one implements or not present in hypervisor.
> The infrastructure is extendible so spec is covered for it.

It would be problematic if you stick to claim "passthrough" but not.

Thanks