On Tue, Nov 22 2022, "Michael S. Tsirkin" <m...@redhat.com> wrote:
> On Tue, Nov 22, 2022 at 03:46:38PM +0100, Cornelia Huck wrote: >> On Sun, Nov 20 2022, "Michael S. Tsirkin" <m...@redhat.com> wrote: >> >> > Add new registers to the PCI common configuration structure. >> > >> > These registers will be used for querying the indices of the admin >> > virtqueues of the owner device. To configure, reset or enable the admin >> > virtqueues, the driver should follow existing queue configuration/setup >> > sequence. >> > >> > Signed-off-by: Max Gurtovoy <mgurto...@nvidia.com> >> > Signed-off-by: Michael S. Tsirkin <m...@redhat.com> >> > --- >> > content.tex | 34 ++++++++++++++++++++++++++++++++++ >> > 1 file changed, 34 insertions(+) >> >> (...) >> >> > @@ -1112,6 +1129,14 @@ \subsubsection{Common configuration structure >> > layout}\label{sec:Virtio Transport >> > were used before the queue reset. >> > (see \ref{sec:Basic Facilities of a Virtio Device / Virtqueues / >> > Virtqueue Reset}). >> > >> > +If VIRTIO_F_ADMIN_VQ has been negotiated, and if the driver >> > +configures any administration virtqueues, the driver MUST >> > +configure the administration virtqueues using the index >> > +in the range \field{admin_queue_index} to >> > +\field{admin_queue_index} + \field{admin_queue_num} inclusive. >> > +The driver MAY configure less administration virtqueues than >> > +supported by the device. >> >> Is the driver allowed to pick any admin queue from within the range, >> e.g. queues 2 and 5, and leave the rest? > > I was split on this. In the end I don't see why not. > Do you feel we need to document this? It should work fine, I guess; probably no need to spell it out explicitly. > >> > + >> > \subsubsection{Notification structure layout}\label{sec:Virtio Transport >> > Options / Virtio Over PCI Bus / PCI Device Layout / Notification >> > capability} >> > >> > The notification location is found using the VIRTIO_PCI_CAP_NOTIFY_CFG >> > @@ -6986,6 +7011,15 @@ \chapter{Reserved Feature Bits}\label{sec:Reserved >> > Feature Bits} >> > See \ref{sec:Basic Facilities of a Virtio Device / Virtqueues / >> > Virtqueue Reset}. >> > >> > \item[VIRTIO_F_ADMIN_VQ (41)] This feature indicates that an >> > administration virtqueue is supported. >> > + At the moment this feature is only supported for devices using >> > + \ref{sec:Virtio Transport Options / Virtio Over PCI >> > + Bus}~\nameref{sec:Virtio Transport Options / Virtio Over PCI Bus} >> > + as the transport and is reserved for future use for >> > + devices using other transports (see >> > + \ref{drivernormative:Basic Facilities of a Virtio Device / Feature >> > Bits} >> > + and >> > + \ref{devicenormative:Basic Facilities of a Virtio Device / Feature >> > Bits} for >> > + handling features reserved for future use. >> > >> > \end{description} >> > >> >> We don't say for any other feature which transports support it; do we >> really need to state it here explicitly if we have the rules for >> reserved feature bits in place? It simply will be neither offered nor >> accepted if the device and driver use an unsupported transport. > > It's just easy for someone to add code for feature in transport > agnostic part and then it will be negotiated mistakenly when > we add it for a new transport. > Potential for such a bug is what worries me and this is why I add > this in so many places. Harmless no? By this reasoning, we probably should also add a comment for NOTIFICATION_DATA and RING_RESET? (On top, of course.) --------------------------------------------------------------------- To unsubscribe, e-mail: virtio-dev-unsubscr...@lists.oasis-open.org For additional commands, e-mail: virtio-dev-h...@lists.oasis-open.org