On Tue, Aug 15, 2023 at 07:07:42PM +0800, Zhu, Lingshan wrote: > > > On 8/14/2023 11:00 PM, Stefan Hajnoczi wrote: > > On Tue, Aug 15, 2023 at 03:29:02AM +0800, Zhu Lingshan wrote: > > > This commit specifies the actions to be taken by the device upon > > > SUSPEND. > > > > > > Signed-off-by: Jason Wang <[email protected]> > > > Signed-off-by: Eugenio PÃrez <[email protected]> > > > Signed-off-by: Zhu Lingshan <[email protected]> > > > --- > > > 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: > > "when SUSPEND is set" is ambigious. It could mean when the driver writes > > the Device Status Field, when the device transitions to SUSPEND, or > > something else. Maybe "before the device reports the SUSPEND bit set in > > the Device Status Field"? > Nice catch! will fix: when the driver sets SUSPEND, before the device > reports the > SUSPEND bit set in the \field{device status}, the device MUST perform the > following actions. > > > > > +\begin{itemize} > > > +\item Stop comsuming any descriptors > > "consuming" > yes > > > > It may be more consistent to talk about virtqueue buffers (i.e. > > requests) rather than descriptors here. > yes > > > > > +\item Mark all finished descriptors as used and send used buffer > > > notification to the driver > > The device has to complete everything that is in flight, just completing > > "finished" stuff is not enough. Does "finished descriptors" really mean > > "in-flight virtqueue buffers"? > A patch of tracking in-flight descriptors is planned. Here I expect > "finished" mean "done" buffers, transmitted and received ACK.
Yes, I don't mean tracking in-flight virtqueue buffers, I mean waiting
until they are marked as used. I think "finished" is unclear and the
text should explain that the device waits for in-flight virtqueue
buffers (in the future this could be relaxed with in-flight tracking
functionality).
> >
> > "send a used buffer notification" or "send used buffer notifications"
> Yes will fix
> >
> > > +\item Record Virtqueue State of each enabled virtqueue, see section
> > > \ref{sec:Virtqueues / Virtqueue State}
> > Does "Record" mean that Virtqueue State fields can only be accessed by
> > the driver while device is paused (they may be outdated or invalid while
> > the device is unpaused)?
> Yes, to avoid race with the device and make device implementation easier,
> this is also mentioned in Patch 4.
> >
> > > +\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}
> > What does "preserve" mean? Does it mean the Device Configuration Space
> > is not allowed to change during SUSPEND?
> Yes, once the device presents SUSPEND in its device status, it should not
> change any
> fields in its Device Configuration Space.
>
> Thanks for your review
> >
> > > +\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
> > >
> > >
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>
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