Re: [virtio-dev] [PATCH v3 1/2] content: net: Add VIRTIO_NET_F_CTRL_STEERING_MODE feature

[Vijayabhaskar Balakrishna <vijay.balakrishna@oracle.com>]

Hi Sameeh,

See inline..
On 4/18/2018 3:46 AM, Sameeh Jubran wrote:
> From: Sameeh Jubran <sameeh.j@gmail.com>
>
> This commit introduces steering mode into network device. Steering
> mode is a general infrastructure for various steering modes that can
> be implemented on top of it such as Automatic and RSS.
>
> Signed-off-by: Sameeh Jubran <sjubran@redhat.com>
> ---
>   content.tex | 61 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 61 insertions(+)
>
> diff --git a/content.tex b/content.tex
> index c840588..6b1f7ca 100644
> --- a/content.tex
> +++ b/content.tex
> @@ -3115,6 +3115,9 @@ features.
>   
>   \item[VIRTIO_NET_F_CTRL_MAC_ADDR(23)] Set MAC address through control
>       channel.
> +
> +\item[VIRTIO_NET_F_CTRL_STEERING_MODE(60)] Device supports configurable steering
> +    mode.
>   \end{description}
>   
>   \subsubsection{Feature bit requirements}\label{sec:Device Types / Network Device / Feature bits / Feature bit requirements}
> @@ -3317,6 +3320,8 @@ struct virtio_net_hdr {
>           le16 csum_start;
>           le16 csum_offset;
>           le16 num_buffers;
> +// Only if VIRTIO_NET_F_CTRL_STEERING_MODE has been negotiated
> +        le64 hash;
>   };
>   \end{lstlisting}
>   
> @@ -4013,6 +4018,62 @@ MUST format \field{virtqueue_pairs}
>   according to the native endian of the guest rather than
>   (necessarily when not using the legacy interface) little-endian.
>   
> +\paragraph{Steering mode}\label{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Steering mode}
> +
> +\begin{lstlisting}
> +// steering mode flags
> +#define STEERING_MODE_AUTO          0x1
> +
> +// Used by the devide for returning to the driver the supported steering modes
> +struct virtio_net_steering_modes {
> +le32 steering_modes;
> +};
> +
> +struct virtio_net_steering_mode {
> +le32 steering_mode;
> +le32 command;
> +
> +// A union which can be used for passing structures to one of the sub modes
> +    union {
> +    }
> +};
> +
> +#define VIRTIO_NET_F_CTRL_STEERING_MODE     27
> +
> +#define VIRTIO_NET_CTRL_STEERING_MODE                7
> +#define VIRTIO_NET_CTRL_SM_GET_SUPPORTED_MODES        0
> +#define VIRTIO_NET_CTRL_SM_CONTROL                    1
> +\end{lstlisting}
> +
> +If the VIRTIO_NET_F_CTRL_STEERING_MODE is negotiated the driver can send control commands for the
> +configuring the steering mode. There are multiple steering modes and they can be configured using
> +the VIRTIO_NET_CTRL_SM_CONTROL command. Each mode has it's own set of commands.
> +
> +The auto steering mode is the default mode if nothing else has been configured by the driver
> +and the VIRTIO_NET_F_CTRL_STEERING_MODE feature is acked by the driver.
> +
> +The class VIRTIO_NET_CTRL_STEERING_MODE has two commands:
> +
> +\begin{enumerate}
> +
> +\item VIRTIO_NET_CTRL_SM_GET_SUPPORTED_MODES is used for getting the supported steering modes by the device.
> +	The command should be executed by the driver before attempting to configure the steering mode. Once the device
> +	receives this command it should fill the virtio_net_steering_modes structure with the supported steering mode
> +	flags.
> +
> +\item The command VIRTIO_NET_CTRL_SM_CONTROL is used for controlling the different steering modes. Each steering mode
> +	has its own set of commands. When executing this command the structure virtio_net_steering_mode should be used as follows:
> +	the \field{steering_mode} should be filled with one of the steering mode flags along with an appropriate command from the chosen
should we say? should be filled with one of the supported steering mode
> +	steering mode. The union of virtio_net_steering_mode should be used and filled as the mode's command suggests.
> +\end{enumerate}
> +
> +If this feature has been negotiated, the virtio header has an additional
should say:
virtio net header has an additional
> +\field{hash} field attached to it.
> +
> +\subparagraph{Automatic Receive Steering}{Device Types / Network Device / Device Operation / Control Virtqueue / Steering mode / Automatic Receive Steering}
> +
> +This is the default steering mode, please refer to the "Automatic receive steering in multiqueue" section.
I see referred section named in the spec as "Automatic receive steering 
in multiqueue mode".
> +
>   \paragraph{Offloads State Configuration}\label{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Offloads State Configuration}
>   
>   If the VIRTIO_NET_F_CTRL_GUEST_OFFLOADS feature is negotiated, the driver can