virtio — archive

[Michael S. Tsirkin <mst@redhat.com>]

On Thu, Nov 24, 2022 at 03:46:00PM +0800, Jason Wang wrote: > On Thu, Nov 24, 2022 at 3:14 PM Michael S. Tsirkin <mst@redhat.com> wrote: > > > > On Thu, Nov 24, 2022 at 02:00:54PM +0800, Jason Wang wrote: > > > On Thu, Nov 24, 2022 at 5:08 AM Michael S. Tsirkin <mst@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 <mgurtovoy@nvidia.com> > > > > Signed-off-by: Michael S. Tsirkin <mst@redhat.com> > > > > --- > > > > content.tex | 34 ++++++++++++++++++++++++++++++++++ > > > > 1 file changed, 34 insertions(+) > > > > > > > > diff --git a/content.tex b/content.tex > > > > index 04235da..aa68926 100644 > > > > --- a/content.tex > > > > +++ b/content.tex > > > > @@ -946,6 +946,10 @@ \subsubsection{Common configuration structure layout}\label{sec:Virtio Transport > > > > le64 queue_device; /* read-write */ > > > > le16 queue_notify_data; /* read-only for driver */ > > > > le16 queue_reset; /* read-write */ > > > > + > > > > + /* About the administration virtqueue. */ > > > > + le16 admin_queue_index; /* read-only for driver */ > > > > + le16 admin_queue_num; /* read-only for driver */ > > > > > > If we are adding more queue related functionality, it would be placed > > > under the above two fields which seems not elegant. I wonder if a new > > > structure is needed here. > > > > > > Thanks > > > > I don't expect more, if that happens we can always refactor it. > > I may miss something but it should be a part of ABI. How could we > refactor it without breaking ABI? > > Thanks /* About the administration virtqueue. */ - le16 admin_queue_index; /* read-only for driver */ - le16 admin_queue_num; /* read-only for driver */ + struct { /* read-only for driver */ + le16 index; + le16 num; + } admin_queue; does not affect the ABI. But the order of things makes it less readable. We would also have to change references to admin_queue_index with admin_queue.index and explain the "." notation in introduction. All doable but this patchset is large enough as it is. > > Generally this is not C, no one compiles this directly. > > So we do not need to add structures unless > > they are referred to in spec text. > > > > > > }; > > > > \end{lstlisting} > > > > > > > > @@ -1031,6 +1035,19 @@ \subsubsection{Common configuration structure layout}\label{sec:Virtio Transport > > > > This field exists only if VIRTIO_F_RING_RESET has been > > > > negotiated. (see \ref{sec:Basic Facilities of a Virtio Device / Virtqueues / Virtqueue Reset}). > > > > > > > > +\item[\field{admin_queue_index}] > > > > + The device uses this to report the index of the first administration virtqueue. > > > > + This field is valid only if VIRTIO_F_ADMIN_VQ has been negotiated. > > > > +\item[\field{admin_queue_num}] > > > > + The device uses this to report the number of the > > > > + supported administration virtqueues. Virtqueues with index > > > > + between \field{admin_queue_index} and (\field{admin_queue_index} + > > > > + \field{admin_queue_num}) inclusive serve as administration > > > > + virtqueues. > > > > + Thus the number of administration virtqueues equals > > > > + (\field{admin_queue_num} + 1). > > > > + This field is valid only if VIRTIO_F_ADMIN_VQ has been > > > > + negotiated. > > > > \end{description} > > > > > > > > \devicenormative{\paragraph}{Common configuration structure layout}{Virtio Transport Options / Virtio Over PCI Bus / PCI Device Layout / Common configuration structure layout} > > > > @@ -1117,6 +1134,14 @@ \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. > > > > + > > > > \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 > > > > @@ -6992,6 +7017,15 @@ \chapter{Reserved Feature Bits}\label{sec:Reserved Feature Bits} > > > > > > > > \item[VIRTIO_F_ADMIN_VQ(41)] This feature indicates that the device exposes one or more > > > > administration virtqueues. > > > > + 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} > > > > > > > > -- > > > > MST > > > > > >