Re: [PATCH v5] virtio-network: Clarify VLAN filter table configuration

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

On Fri, Jan 06, 2023 at 08:48:36PM +0200, Parav Pandit wrote:
> The filtering behavior of the VLAN filter commands is not very clear as
> discussed in thread [1].
> 
> Hence, add the command description and device requirements for it.
> 
> [1] https://www.mail-archive.com/qemu-devel@nongnu.org/msg912392.html
> Fixes: https://github.com/oasis-tcs/virtio-spec/issues/147
> Suggested-by: Si-Wei Liu <si-wei.liu@oracle.com>
> Signed-off-by: Parav Pandit <parav@nvidia.com>
> ---
> changelog:
> v4->v5:
> - reworded 'vlan filtering table' to 'vlan filter table' to match
>   to the existing description about vlan filtering
> - remove confusing text around VLAN_DEL command description
> - added missing article
> - reword device match configuration to device configuration
> - changed 'found' to 'present' and 'not found' to 'absent' to
>   consider vlan filter table as config table rather
>   than search table
> v3->v4:
> - added description for accepting vlan tagged packets when vlan
>   filter is not negotiated
> v2->v3:
> - corrected grammar
> - simplified description for untagged packets
> v1->v2:
> - adapt to new file path
> v0->v1:
> - added missing conformance section link
> ---
>  .../virtio-network/device-conformance.tex     |  1 +
>  device-types/virtio-network/device.tex        | 20 +++++++++++++++++++
>  2 files changed, 21 insertions(+)
> 
> diff --git a/device-types/virtio-network/device-conformance.tex b/device-types/virtio-network/device-conformance.tex
> index c686377..54f6783 100644
> --- a/device-types/virtio-network/device-conformance.tex
> +++ b/device-types/virtio-network/device-conformance.tex
> @@ -9,6 +9,7 @@
>  \item \ref{devicenormative:Device Types / Network Device / Device Operation / Processing of Incoming Packets}
>  \item \ref{devicenormative:Device Types / Network Device / Device Operation / Control Virtqueue / Packet Receive Filtering}
>  \item \ref{devicenormative:Device Types / Network Device / Device Operation / Control Virtqueue / Setting MAC Address Filtering}
> +\item \ref{devicenormative:Device Types / Network Device / Device Operation / Control Virtqueue / VLAN Filtering}
>  \item \ref{devicenormative:Device Types / Network Device / Device Operation / Control Virtqueue / Gratuitous Packet Sending}
>  \item \ref{devicenormative:Device Types / Network Device / Device Operation / Control Virtqueue / Automatic receive steering in multiqueue mode}
>  \item \ref{devicenormative:Device Types / Network Device / Device Operation / Control Virtqueue / Receive-side scaling (RSS) / RSS processing}
> diff --git a/device-types/virtio-network/device.tex b/device-types/virtio-network/device.tex
> index e7cdd6f..0fff7e5 100644
> --- a/device-types/virtio-network/device.tex
> +++ b/device-types/virtio-network/device.tex
> @@ -1210,6 +1210,26 @@ \subsubsection{Control Virtqueue}\label{sec:Device Types / Network Device / Devi
>  Both the VIRTIO_NET_CTRL_VLAN_ADD and VIRTIO_NET_CTRL_VLAN_DEL
>  command take a little-endian 16-bit VLAN id as the command-specific-data.
>  
> +VIRTIO_NET_CTRL_VLAN_ADD command adds the specified VLAN to the
> +VLAN filter table.
> +
> +VIRTIO_NET_CTRL_VLAN_DEL command removes the specified VLAN from
> +the VLAN filter table.
> +
> +\devicenormative{\subparagraph}{VLAN Filtering}{Device Types / Network Device / Device Operation / Control Virtqueue / VLAN Filtering}
> +
> +When VIRTIO_NET_F_CTRL_VLAN is not negotiated, the device accepts
> +all VLAN tagged packets as per the device configuration.

To be more specific, the vlan tag in the
packet does not affect filtering of incoming packets, right?

> +When VIRTIO_NET_F_CTRL_VLAN is negotiated, the device starts with
> +an empty VLAN filter table.
> +
> +When VIRTIO_NET_F_CTRL_VLAN is negotiated, the device accepts all
> +VLAN tagged packets whose VLAN tag is present in the VLAN
> +filter table; the device should drop all VLAN tagged packets
> +whose VLAN tag is absent in the VLAN filter table. The
> +VLAN filter table applies only to the VLAN tagged packets.

to VLAN tagged packets

> +
>  \subparagraph{Legacy Interface: VLAN Filtering}\label{sec:Device Types / Network Device / Device Operation / Control Virtqueue / VLAN Filtering / Legacy Interface: VLAN Filtering}
>  When using the legacy interface, transitional devices and drivers
>  MUST format the VLAN id
> -- 
> 2.26.2