Re: [PATCH v6 4/5] Add admin_queue_index register to PCI common configuration structure

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

On Sun, Jul 31, 2022 at 06:43:53PM +0300, Max Gurtovoy wrote:
> This new register will be used for querying the index of the admin
> virtqueue of a virtio device. To configure, reset or enable the admin
> virtqueue, the driver should follow existing queue configuration/setup
> sequence.
> 
> Reviewed-by: Parav Pandit <parav@nvidia.com>
> Signed-off-by: Max Gurtovoy <mgurtovoy@nvidia.com>


Can you please at least add text to MMIO and CCW that drivers and
devices must not negotiate the new feature bit? Will help avoid confusion.

> ---
>  content.tex | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/content.tex b/content.tex
> index c15423e..5fda1a0 100644
> --- a/content.tex
> +++ b/content.tex
> @@ -904,6 +904,9 @@ \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 admin virtqueue. */
> +        le16 admin_queue_index;         /* read-only for driver */
>  };
>  \end{lstlisting}
>  
> @@ -989,6 +992,10 @@ \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 admin virtqueue.
> +        This field always exists. Its value 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}

we have a mess with this exists versus valid. I think exists is the same
is valid personally. Do others object if we say same as for reset here?
Not a big deal either way, we need to clean this up later.

> @@ -1075,6 +1082,9 @@ \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}).
>  
> +For configuring the admin virtqueue, the driver MUST use the value of \field{admin_queue_index}.
> +For more details on virtqueue configuration see section \ref{sec:Virtio Transport Options / Virtio Over PCI Bus / PCI-specific Initialization And Device Operation / Device Initialization / Virtqueue Configuration}.
> +
>  \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
> -- 
> 2.21.0