Re: [PATCH v9 05/10] pci: add admin vq registers to virtio over pci

[Jason Wang <jasowang@redhat.com>]

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

>  };
>  \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
>