Re: [PATCH v2 1/2] content: net: Add VIRTIO_NET_F_CTRL_STEERING_MODE feature

[Sameeh Jubran <sameeh@daynix.com>]

On Tue, Apr 17, 2018 at 4:30 AM, Vijayabhaskar Balakrishna <vijay.balakrishna@oracle.com> wrote:

On 4/16/2018 6:05 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 | 59 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
  1 file changed, 59 insertions(+)

diff --git a/content.tex b/content.tex
index c840588..3d538e8 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(27)] 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}
  @@ -4007,6 +4012,60 @@ VIRTIO_NET_CTRL_MQ_VQ_PAIRS_SET command.
  The device MUST NOT queue packets on receive queues greater than
  \field{virtqueue_pairs} once it has placed the VIRTIO_NET_CTRL_MQ_VQ_PAIRS_SET command in the used ring.
  +\paragraph{Steering mode}\label{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Steering mode}
+
+\begin{lstlisting}
+// steering mode flags
+#define STEERING_MODE_AUTO          1

As steering mode flags is a bit field, should it be 0x1?

They are indeed bit fields, will dd 0x in order to clarify that. 

+
+struct virtio_net_steering_modes {
+le32 steering_modes;
+};
+
+struct virtio_net_steering_mode {
+le32 steering_mode;
+le32 command;
+
+    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
+       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
+\field{hash} field attached to it.

may be say: ..virtio net header has additional field{hash} 

+
+\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.
+
  \subparagraph{Legacy Interface: Automatic receive steering in multiqueue mode}\label{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Automatic receive steering in multiqueue mode / Legacy Interface: Automatic receive steering in multiqueue mode}
  When using the legacy interface, transitional devices and drivers
  MUST format \field{virtqueue_pairs}

--

Respectfully,

Sameeh Jubran

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Software Engineer @ Daynix.