Re: [PATCH 3/5] virtqueue: constraints for virtqueue state

["Zhu, Lingshan" <lingshan.zhu@intel.com>]

On 9/14/2023 7:30 PM, Michael S. Tsirkin wrote:
> On Wed, Sep 06, 2023 at 04:16:35PM +0800, Zhu Lingshan wrote:
> > This commit specifies the constraints of the virtqueue state,
> > and the actions should be taken by the device when SUSPEND
> > and DRIVER_OK is set
> >
> > Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
> > Signed-off-by: Jason Wang <jasowang@redhat.com>
> > Signed-off-by: Eugenio PÃrez <eperezma@redhat.com>
> > ---
> >   content.tex | 19 +++++++++++++++++++
> >   1 file changed, 19 insertions(+)
> >
> > diff --git a/content.tex b/content.tex
> > index 0fab537..9d727ce 100644
> > --- a/content.tex
> > +++ b/content.tex
> > @@ -594,6 +594,25 @@ \subsection{\field{Used State} Field}
> >   When VIRTIO_RING_F_PACKED is not negotiated, the 16-bit value of \field{used_idx}
> >   is always 0
> >   
> > +\drivernormative{\subsection}{Virtqueue State}{Basic Facilities of a Virtio Device / Virtqueue State}
> > +
> > +If VIRTIO_F_QUEUE_STATE has been negotiated but VIRTIO_RING_F_PACKED not been negotiated,
> > +the driver SHOULD NOT access \field{Used State} of any virtqueues, it SHOULD use the
> > +used index in the used ring.
> > +
> > +\devicenormative{\subsection}{Virtqueue State}{Basic Facilities of a Virtio Device / Virtqueue State}
> > +
> > +If VIRTIO_F_QUEUE_STATE has been negotiated, the device SHOULD only accept setting
> > +Virtqueue State of any virtqueues when DRIVER_OK is not set in \field{device status},
> > +or both of DRIVER_OK and SUSPEND are set in \field{device status}.
> > +Otherwise the device MUST ignore any writes to Virtqueue State of any virtqueues.
> > +
> > +If VIRTIO_F_QUEUE_STATE have been negotiated, when SUSPEND is set,
> > +the device MUST record the Virtqueue State of every enabled virtqueue
> > +in \field{Available State} and \field{Used State} respectively,
> record how?
This is transport specific, for PCI they are recorded in the common 
config space,
two new fields of them are introduced in patch 5.
> > +and correspondingly restore the Virtqueue State of every enabled virtqueue
> > +from \field{Available State} and \field{Used State} when DRIVER_OK is set.
> when is that?
When the DRIVER sets DRIVER_OK and done before the device presents 
DRIVER_OK.
> > +
> >   \input{admin.tex}
> >   
> >   \chapter{General Initialization And Device Operation}\label{sec:General Initialization And Device Operation}
> > --
> > 2.35.3