Re: [RFC PATCH 3/5] virtio: The actions by the device upon SUSPEND

[Jason Wang <jasowang@redhat.com>]

On Mon, Aug 14, 2023 at 7:29âPM Zhu Lingshan <lingshan.zhu@intel.com> wrote:
>
> This commit specifies the actions to be taken by the device upon
> SUSPEND.
>
> Signed-off-by: Jason Wang <jasowang@redhat.com>
> Signed-off-by: Eugenio PÃrez <eperezma@redhat.com>
> Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
> ---
>  content.tex | 9 +++++++++
>  1 file changed, 9 insertions(+)
>
> diff --git a/content.tex b/content.tex
> index 074f43e..43bd5de 100644
> --- a/content.tex
> +++ b/content.tex
> @@ -96,6 +96,15 @@ \section{\field{Device Status} Field}\label{sec:Basic Facilities of a Virtio Dev
>  If VIRTIO_F_SUSPEND is negotiated and SUSPEND is set, the device MUST clear SUSPEND
>  and resumes operation upon DRIVER_OK.
>
> +If VIRTIO_F_SUSPEND is negotiated, when SUSPEND is set, the device MUST perform the following operations:
> +\begin{itemize}
> +\item Stop comsuming any descriptors

Typo.

> +\item Mark all finished descriptors as used and send used buffer notification to the driver

What happens to the unfinished descriptors?

> +\item Record Virtqueue State of each enabled virtqueue, see section \ref{sec:Virtqueues / Virtqueue State}

This basically means those states are only available after suspending
or not? It would be still useful for debugging if we allow it without
suspending.

> +\item Pause its operation and preserve all configurations in its Device Configuration Space, see \ref{sec:Basic Facilities of a Virtio Device / Device Configuration Space}

We probably need to define the "pause" here (e.g what happens to the
inflight descriptors).

Thanks

> +\item Present SUSPEND in \field{device status}
> +\end{itemize}
> +
>  \section{Feature Bits}\label{sec:Basic Facilities of a Virtio Device / Feature Bits}
>
>  Each virtio device offers all the features it understands.  During
> --
> 2.35.3
>