On Wed, Apr 27, 2022 at 01:58:21AM +0300, Max Gurtovoy wrote:
> In one of the many use cases a user wants to manipulate features and
> configuration of the virtio devices regardless of the device type
> (net/block/console). For that the admin command set introduced. The
> admin virtqueue will be the first management interface to issue admin
> commands.
>
> Currently virtio specification defines control virtqueue to manipulate
> features and configuration of the device it operates on. However,
> control virtqueue commands are device type specific, which makes it very
> difficult to extend for device agnostic commands.
>
> To support this requirement in elegant way, this patch introduces a new
> admin virtqueue interface.
>
> Manipulate features via admin virtqueue is asynchronous, scalable, easy
> to extend and doesn't require additional and expensive on-die resources
> to be allocated for every new feature that will be added in the future.
>
> Reviewed-by: Parav Pandit <[email protected]>
> Signed-off-by: Max Gurtovoy <[email protected]>
> ---
> admin.tex | 17 +++++++++++++++++
> conformance.tex | 1 +
> content.tex | 6 ++++--
> 3 files changed, 22 insertions(+), 2 deletions(-)
>
> diff --git a/admin.tex b/admin.tex
> index f816c3b..d09683d 100644
> --- a/admin.tex
> +++ b/admin.tex
> @@ -131,3 +131,20 @@ \subsection{VIRTIO ADMIN DEVICE CAPS ACCEPT
> command}\label{sec:Basic Facilities
> u8 reserved[112];
> };
> \end{lstlisting}
> +
> +\section{Admin Virtqueues}\label{sec:Basic Facilities of a Virtio Device /
> Admin Virtqueues}
> +
> +An admin virtqueue is a management interface of a device that can be used to
> send administrative
> +commands (see \ref{sec:Basic Facilities of a Virtio Device / Administration
> command set}) to manipulate
> +various features of the device and/or to manipulate various features, if
> possible, of another device.
> +
> +An admin virtqueue exists for a certain device if VIRTIO_F_ADMIN_VQ feature
> is
> +negotiated. The index of the admin virtqueue is exposed by the device in a
> +transport specific manner.
> +
> +If VIRTIO_F_ADMIN_VQ has been negotiated, the driver will use the admin
> virtqueue to send all admin commands.
> +
> +\devicenormative{\subsection}{Admin Virtqueues}{Basic Facilities of a Virtio
> Device / Admin Virtqueues}
> +A device that advertises VIRTIO_F_ADMIN_VQ capability MUST support all the
> mandatory admin commands.
don't see where these are defined.
> +
> +A device that advertises VIRTIO_F_ADMIN_VQ capability MAY support one or
> more optional admin commands.
> diff --git a/conformance.tex b/conformance.tex
> index 9807c30..3c7b7bc 100644
> --- a/conformance.tex
> +++ b/conformance.tex
> @@ -342,6 +342,7 @@ \section{Conformance Targets}\label{sec:Conformance /
> Conformance Targets}
> \item \ref{devicenormative:Basic Facilities of a Virtio Device / Virtqueues
> / Available Buffer Notification Suppression}
> \item \ref{devicenormative:Basic Facilities of a Virtio Device / Shared
> Memory Regions}
> \item \ref{devicenormative:Reserved Feature Bits}
> +\item \ref{devicenormative:Basic Facilities of a Virtio Device / Admin
> Virtqueues}
> \end{itemize}
>
> \conformance{\subsection}{PCI Device Conformance}\label{sec:Conformance /
> Device Conformance / PCI Device Conformance}
> diff --git a/content.tex b/content.tex
> index 2e1df84..163cb34 100644
> --- a/content.tex
> +++ b/content.tex
> @@ -99,10 +99,10 @@ \section{Feature Bits}\label{sec:Basic Facilities of a
> Virtio Device / Feature B
> \begin{description}
> \item[0 to 23, and 50 to 127] Feature bits for the specific device type
>
> -\item[24 to 40] Feature bits reserved for extensions to the queue and
> +\item[24 to 41] Feature bits reserved for extensions to the queue and
> feature negotiation mechanisms
>
> -\item[41 to 49, and 128 and above] Feature bits reserved for future
> extensions.
> +\item[42 to 49, and 128 and above] Feature bits reserved for future
> extensions.
> \end{description}
>
> \begin{note}
> @@ -6849,6 +6849,8 @@ \chapter{Reserved Feature Bits}\label{sec:Reserved
> Feature Bits}
> that the driver can reset a queue individually.
> 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.
> +
> \end{description}
>
> \drivernormative{\section}{Reserved Feature Bits}{Reserved Feature Bits}
> --
> 2.21.0
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