Re: [virtio-comment] [PATCH 5/5] virtio-pci: implement VIRTIO_F_QUEUE_STATE

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

On 9/14/2023 7:27 PM, Michael S. Tsirkin wrote:
> On Wed, Sep 06, 2023 at 04:16:37PM +0800, Zhu Lingshan wrote:
> > This patch adds two new le16 fields to common configuration structure
> > to support VIRTIO_F_QUEUE_STATE in PCI transport layer.
> >
> > Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
> > ---
> >   transport-pci.tex | 18 ++++++++++++++++++
> >   1 file changed, 18 insertions(+)
> >
> > diff --git a/transport-pci.tex b/transport-pci.tex
> > index a5c6719..3161519 100644
> > --- a/transport-pci.tex
> > +++ b/transport-pci.tex
> > @@ -325,6 +325,10 @@ \subsubsection{Common configuration structure layout}\label{sec:Virtio Transport
> >           /* About the administration virtqueue. */
> >           le16 admin_queue_index;         /* read-only for driver */
> >           le16 admin_queue_num;         /* read-only for driver */
> > +
> > +	/* Virtqueue state */
> > +        le16 queue_avail_state;         /* read-write */
> > +        le16 queue_used_state;          /* read-write */
> >   };
> >   \end{lstlisting}
> >   
> > @@ -428,6 +432,17 @@ \subsubsection{Common configuration structure layout}\label{sec:Virtio Transport
> >   	The value 0 indicates no supported administration virtqueues.
> >   	This field is valid only if VIRTIO_F_ADMIN_VQ has been
> >   	negotiated.
> > +
> > +\item[\field{queue_avail_state}]
> > +        This field is valid only if VIRTIO_F_QUEUE_STATE has been
> > +        negotiated. The driver sets and gets the available state of
> > +        the virtqueue here (see \ref{sec:Virtqueues / Virtqueue State}).
> > +
> > +\item[\field{queue_used_state}]
> > +        This field is valid only if VIRTIO_F_QUEUE_STATE has been
> > +        negotiated. The driver sets and gets the used state of the
> > +        virtqueue here (see \ref{sec:Virtqueues / Virtqueue State}).
> I see no description either here or in the generic patch
> of what does it mean to set or get the state.
When SUSPEND, the device stores vq state here, then migrate to the
destination, then the destination hypervisor restores vq state
from here.

I will add more description in V2
> > +
> >   \end{description}
> >   
> >   \devicenormative{\paragraph}{Common configuration structure layout}{Virtio Transport Options / Virtio Over PCI Bus / PCI Device Layout / Common configuration structure layout}
> > @@ -488,6 +503,9 @@ \subsubsection{Common configuration structure layout}\label{sec:Virtio Transport
> >   present either a value of 0 or a power of 2 in
> >   \field{queue_size}.
> >   
> > +If VIRTIO_F_QUEUE_STATE has not been negotiated, the device MUST ignore
> > +any accesses to \field{queue_avail_state} and \field{queue_used_state}.
> > +
> >   If VIRTIO_F_ADMIN_VQ has been negotiated, the value
> >   \field{admin_queue_index} MUST be equal to, or bigger than
> >   \field{num_queues}; also, \field{admin_queue_num} MUST be
> > --
> > 2.35.3
> >
> >
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