On Wed, Aug 16, 2023 at 12:25:39PM +0800, Zhu, Lingshan wrote:
>
>
> On 8/15/2023 8:33 PM, Stefan Hajnoczi wrote:
> > 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 <jasow...@redhat.com>
> > > > > Signed-off-by: Eugenio PÃrez <epere...@redhat.com>
> > > > > Signed-off-by: Zhu Lingshan <lingshan....@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:
> > > > "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).
> Sure, I can add this in the next version: the device MUST wait until all
> descriptors that being processed to finish and mark them as used
Sounds good.
> And we can replace it with tracking in-flight descriptors in the future
>
> Thanks
> >
> > > > "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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>
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