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Subject: Re: [PATCH v5 4/7] Introduce virtio admin virtqueue
On Wed, May 18, 2022 at 05:37:11PM +0300, Max Gurtovoy wrote: > > On 5/15/2022 5:59 PM, Michael S. Tsirkin wrote: > > 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. > > In the command table (M - mandatory, O - optional) > Add a link then. > > > > > + > > > +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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