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Subject: Re: [virtio-comment] [PATCH] virtio-net: introduce admin control virtqueue
On Fri, 22 Jan 2021 16:23:25 +0800 Jason Wang <jasowang@redhat.com> wrote: > When implementing multiple (sub)functions virtio device like SRIOV or > sub-function. We're suffering from several issues: > > - There's no management interface for management function (PF) to > configure features, attributes for a (sub)function > - Per (sub)function control virtqueue could be too expensive as the > number of (sub)functions could be very large > - Virtualize per (sub)function control virtqueue could be very > challenge as we need the support of DMA isolation at queue level > > So this patch introduces the feature of VIRTIO_NET_CTRL_ADMIN_VQ. This > allows the device to implement a single admin control virtqueue to > manage per (sub)function features and attributes. > > The idea is simple, a new function id is introduced on top of the > exist virtio_net_ctrl structure. This id is transport or device > specific to uniquely identify a (sub)function. > > With this, we get a way of using management function (PF) to configure > per (sub)function features and attributes. And since the admin control > virtqueue belongs to management function (PF), the DMA is naturally > isolated at (sub)function level instead of the queue level for per > (sub)function control vq. > > Signed-off-by: Jason Wang <jasowang@redhat.com> > --- > content.tex | 23 +++++++++++++++++++++++ > 1 file changed, 23 insertions(+) > > diff --git a/content.tex b/content.tex > index 620c0e2..98592a4 100644 > --- a/content.tex > +++ b/content.tex > @@ -2940,6 +2940,9 @@ \subsection{Feature bits}\label{sec:Device Types / Network Device / Feature bits > \item[VIRTIO_NET_F_CTRL_MAC_ADDR(23)] Set MAC address through control > channel. > > +\item[VIRTIO_NET_F_ADMIN_CTRL_VQ(56)] Admin control channel is > + available. > + > \item[VIRTIO_NET_F_HASH_REPORT(57)] Device can report per-packet hash > value and a type of calculated hash. > > @@ -3864,6 +3867,26 @@ \subsubsection{Control Virtqueue}\label{sec:Device Types / Network Device / Devi > do except issue a diagnostic if \field{ack} is not > VIRTIO_NET_OK. > > +\subsubsection{Admin Control Virtqueue}\label{sec:Device Types / Network Device / Device Operation / Control Virtqueue} > + > +When VIRTIO_NET_F_ADMIN_CTRL_VQ is negotiated, the driver can use the > +control virtqueue to manipulate features of individual function where > +the control virtqueues is not easily implemented in each function. What is a 'function' in the context of the virtio-net device? I don't think that this term is universal across transports. > + > +All commands are of the following form: > + > +\begin{lstlisting} > +struct virtio_net_admin_ctrl { > + u32 function_id; > + struct virtio_net_ctrl ctrl; > +}; > + > +\end{lstlisting} > + > +The \field{function_id} is an unique transport or device specific > +identifier for a function. E.g for the case of PCI SRIOV, it's the id > +of PCI function. > + > \paragraph{Packet Receive Filtering}\label{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Packet Receive Filtering} > \label{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Setting Promiscuous Mode}%old label for latexdiff >
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