virtio — archive

[Michael S. Tsirkin <parav@nvidia.com>]

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 <parav@nvidia.com> > Signed-off-by: Max Gurtovoy <mgurtovoy@nvidia.com> > --- > 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