Re: [virtio-dev] [PATCH v8 2/8] transport-pci: Refer to the vq by its number

[David Edmondson <david.edmondson@oracle.com>]

Parav Pandit <parav@nvidia.com> writes:

> Currently specification uses virtqueue index and
> number interchangeably to refer to the virtqueue.
>
> Instead refer to it by its number.
>
> This patch is on top of [1].
>
> [1] https://lists.oasis-open.org/archives/virtio-dev/202302/msg00527.html
>
> Fixes: https://github.com/oasis-tcs/virtio-spec/issues/163
> Reviewed-by: Max Gurtovoy <mgurtovoy@nvidia.com>
> Reviewed-by: Jiri Pirko <jiri@nvidia.com>
> Signed-off-by: Parav Pandit <parav@nvidia.com>
> ---
> changelog:
> v7->v8:
> - remove note about first virtqueue number
> - skipped Max's comment to put word 'structure' in same line as its
>   crosses 65 chars limit per line
> - reworded queue_notification data set line, as '=' and vq number
>   wording was odd
> v2->v3:
> - addressed comments from Michael
> - changed vqn to virtqueue number in the Note
> - refer to vqn field instead of virtqueue number
> ---
>  transport-pci.tex | 14 ++++++++------
>  1 file changed, 8 insertions(+), 6 deletions(-)
>
> diff --git a/transport-pci.tex b/transport-pci.tex
> index b07a822..a554081 100644
> --- a/transport-pci.tex
> +++ b/transport-pci.tex
> @@ -390,13 +390,15 @@ \subsubsection{Common configuration structure layout}\label{sec:Virtio Transport
>  
>  \item[\field{queue_notify_data}]
>          This field exists only if VIRTIO_F_NOTIF_CONFIG_DATA has been negotiated.
> -        The driver will use this value to put it in the 'virtqueue number' field
> -        in the available buffer notification structure.
> +        The driver will use this value to put it in the field
> +        \field{vqn} in the available buffer notification
> +        structure.

The language here is a bit odd. Suggest:

        The driver will use this value in the \field{vqn} field of the
        available buffer notification structure.

>          See section \ref{sec:Virtio Transport Options / Virtio Over PCI Bus / PCI-specific Initialization And Device Operation / Available Buffer Notifications}.
>          \begin{note}
>          This field provides the device with flexibility to determine how virtqueues
>          will be referred to in available buffer notifications.
> -        In a trivial case the device can set \field{queue_notify_data}=vqn. Some devices
> +        In a trivial case the device can set
> +        \field{queue_notify_data} to the vq number. Some devices
>          may benefit from providing another value, for example an internal virtqueue
>          identifier, or an internal offset related to the virtqueue number.
>          \end{note}
> @@ -1005,7 +1007,7 @@ \subsubsection{Device Initialization}\label{sec:Virtio Transport Options / Virti
>  The driver typically does this as follows, for each virtqueue a device has:
>  
>  \begin{enumerate}
> -\item Write the virtqueue index (first queue is 0) to \field{queue_select}.
> +\item Write the virtqueue number to \field{queue_select}.
>  
>  \item Read the virtqueue size from \field{queue_size}. This controls how big the virtqueue is
>    (see \ref{sec:Basic Facilities of a Virtio Device / Virtqueues}~\nameref{sec:Basic Facilities of a Virtio Device / Virtqueues}). If this field is 0, the virtqueue does not exist.
> @@ -1035,7 +1037,7 @@ \subsubsection{Available Buffer Notifications}\label{sec:Virtio Transport Option
>  
>  When VIRTIO_F_NOTIFICATION_DATA has not been negotiated,
>  the driver sends an available buffer notification to the device by writing
> -the 16-bit virtqueue index
> +the 16-bit virtqueue number
>  of this virtqueue to the Queue Notify address.
>  
>  When VIRTIO_F_NOTIFICATION_DATA has been negotiated,
> @@ -1053,7 +1055,7 @@ \subsubsection{Available Buffer Notifications}\label{sec:Virtio Transport Option
>  If VIRTIO_F_NOTIF_CONFIG_DATA has been negotiated:
>  \begin{itemize}
>  \item If VIRTIO_F_NOTIFICATION_DATA has not been negotiated, the driver MUST use the
> -\field{queue_notify_data} value instead of the virtqueue index.
> +\field{queue_notify_data} value instead of the virtqueue number.
>  \item If VIRTIO_F_NOTIFICATION_DATA has been negotiated, the driver MUST set the
>  \field{vqn} field to the \field{queue_notify_data} value.
>  \end{itemize}
> -- 
> 2.26.2
>
>
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