[PATCH v2 06/11] transport-fabrics: introduce command set

[zhenwei pi <pizhenwei@bytedance.com>]

Introduce command structures for Virtio-oF.

Signed-off-by: zhenwei pi <pizhenwei@bytedance.com>
---
 transport-fabrics.tex | 209 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 209 insertions(+)

diff --git a/transport-fabrics.tex b/transport-fabrics.tex
index 7711321..37f57c6 100644
--- a/transport-fabrics.tex
+++ b/transport-fabrics.tex
@@ -495,3 +495,212 @@ \subsubsection{Buffer Mapping Definition}\label{sec:Virtio Transport Options / V
                     |value |  -> 8193 (value.u32)
                     +------+
 \end{lstlisting}
+
+\subsubsection{Commands Definition}\label{sec:Virtio Transport Options / Virtio Over Fabrics / Transmission Protocol / Commands Definition}
+This section defines command structures for Virtio Over Fabrics.
+
+A common structure virtio_of_value is fixed to 8 bytes and MUST be used as one
+of the following format:
+
+\begin{itemize}
+\item u8
+\item le16
+\item le32
+\item le64
+\end{itemize}
+
+\paragraph{Command ID}\label{sec:Virtio Transport Options / Virtio Over Fabrics / Transmission Protocol / Commands Definition / Command ID}
+There is command_id(le16) field in each Command and Completion:
+
+\begin{itemize}
+\item Generally the initiator allocates a Command ID and specifies the
+command_id field of a Command, and the target MUST specify the same Command ID
+in command_id field of Completion.
+\item The initiator MUST guarantee each Command ID is unique in the inflight Commands.
+\item Command ID 0xff00 - 0xffff is reserved for control queue to delivery asynchronous event.
+\end{itemize}
+
+The reserved Command ID for control queue is defined as follows:
+
+\begin{tabular}{ |l|l| }
+\hline
+Command ID & Description \\
+\hline \hline
+0xffff & Keepalive. The initiator SHOULD ignore this event \\
+\hline
+0xfffe & Config change. The initiator SHOULD generate config change interrupt to device \\
+\hline
+0xff00 - 0xfffd & Reserved \\
+\hline
+\end{tabular}
+
+\paragraph{Connect Command}\label{sec:Virtio Transport Options / Virtio Over Fabrics / Transmission Protocol / Commands Definition / Connect Command}
+The Connect Command is used to establish Virtio Over Fabrics queue. The control
+queue MUST be established firstly, then the Connect command establishes an
+association between the initiator and the target.
+
+The Target ID of 0xffff is reserved, then:
+\begin{itemize}
+\item The Target ID of 0xffff MUST be specified as the Target ID in a Connect
+Command for the control queue.
+\item The target SHOULD allocate any available Target ID to the initiator,
+and return the allocated Target ID in the Completion.
+\item The returned Target ID MUST be specified as the Target ID, and the Queue ID
+MUST be specified in a Connect Command for the virtqueue.
+\end{itemize}
+
+The Connect Command has following structure:
+
+\begin{lstlisting}
+struct virtio_of_command_connect {
+        le16 opcode;
+        le16 command_id;
+        le16 target_id;
+        le16 queue_id;
+        le16 ndesc;
+#define VIRTIO_OF_CONNECTION_TCP     1
+#define VIRTIO_OF_CONNECTION_RDMA    2
+        u8 oftype;
+        u8 padding[5];
+};
+\end{lstlisting}
+
+The Connect commands MUST contains one Segment Descriptor and one structure
+virtio_of_command_connect to specify Initiator VQN and Target VNQ,
+virtio_of_command_connect has following structure:
+
+\begin{lstlisting}
+struct virtio_of_connect {
+        u8 ivqn[256];
+        u8 tvqn[256];
+        u8 padding[512];
+};
+\end{lstlisting}
+
+\paragraph{Feature Command}\label{sec:Virtio Transport Options / Virtio Over Fabrics / Transmission Protocol / Commands Definition / Feature Command}
+
+The control queue uses Feature Command to get or set features. This command is used for:
+
+\begin{itemize}
+\item The initiator/target features. This is used to negotiate transport layer features.
+\item The driver/device features. This is used to negotiate Virtio Based device
+features which is similar to PCI based device.
+\end{itemize}
+
+The Feature Command has following structure:
+
+\begin{lstlisting}
+struct virtio_of_command_feature {
+        le16 opcode;
+        le16 command_id;
+        le32 feature_select;
+        le64 value;        /* ignore this field on GET */
+};
+\end{lstlisting}
+
+\paragraph{Queue Command}\label{sec:Virtio Transport Options / Virtio Over Fabrics / Transmission Protocol / Commands Definition / Queue Command}
+
+The control queue uses Queue Command to get or set properties on a specific queue.
+The Queue Command has following structure:
+
+\begin{lstlisting}
+struct virtio_of_command_queue {
+        le16 opcode;
+        le16 command_id;
+        le16 queue_id;
+        u8 padding6;
+        u8 padding7;
+        struct virtio_of_value value;   /* ignore this field on GET */
+};
+\end{lstlisting}
+
+
+\paragraph{Config Command}\label{sec:Virtio Transport Options / Virtio Over Fabrics / Transmission Protocol / Commands Definition / Config Command}
+
+The control queue uses Config Command to get or set configure on device.
+The Config Command has following structure:
+
+\begin{lstlisting}
+struct virtio_of_command_config {
+        le16 opcode;
+        le16 command_id;
+        le16 offset;
+        u8 bytes;
+        u8 padding7;
+        struct virtio_of_value value;        /* ignore this field on GET */
+};
+\end{lstlisting}
+
+The bytes field supports on Get only:
+
+\begin{itemize}
+\item 1, then the initiator reads from value field of Completion as u8
+\item 2, then the initiator reads from value field of Completion as le16
+\item 4, then the initiator reads from value field of Completion as le32
+\item 8, then the initiator reads from value field of Completion as le64
+\end{itemize}
+
+The bytes field supports on Set only:
+
+\begin{itemize}
+\item 1, then the initiator specifies the value field of Config Command as u8
+\item 2, then the initiator specifies the value field of Config Command as le16
+\item 4, then the initiator specifies the value field of Config Command as le32
+\item 8, then the initiator specifies the value field of Config Command as le64
+\end{itemize}
+
+\paragraph{Common Command}\label{sec:Virtio Transport Options / Virtio Over Fabrics / Transmission Protocol / Commands Definition / Common Command}
+
+The control queue uses Common Command to get or set common properties on
+device(i.e. get device ID). The Common Command has following structure:
+
+\begin{lstlisting}
+struct virtio_of_command_common {
+        le16 opcode;
+        le16 command_id;
+        u8 padding4;
+        u8 padding5;
+        u8 padding6;
+        u8 padding7;
+        struct virtio_of_value value;        /* ignore this field on GET */
+};
+\end{lstlisting}
+
+
+\paragraph{Vring Command}\label{sec:Virtio Transport Options / Virtio Over Fabrics / Transmission Protocol / Commands Definition / Vring Command}
+
+Both control queue and virtqueue use Vring Command to transmit buffer.
+The Vring Command has following structure:
+
+\begin{lstlisting}
+struct virtio_of_command_vring {
+        le16 opcode;
+        le16 command_id;
+        /* Total buffer size this command contains(not include command&descriptors). */
+        le32 length;
+        /* How many descriptors this command contains */
+        le16 ndesc;
+        u8 padding[6];
+};
+\end{lstlisting}
+
+\paragraph{Completion}\label{sec:Virtio Transport Options / Virtio Over Fabrics / Transmission Protocol / Commands Definition / Completion}
+
+The target responses Completion to the initiator to report command status,
+device properties, and transmit buffer. The Completion has following structure:
+
+\begin{lstlisting}
+struct virtio_of_completion {
+        le16 status;
+        le16 command_id;
+        /* How many descriptors this completion contains */
+        le16 ndesc;
+        u8 rsvd6;
+        u8 rsvd7;
+        struct virtio_of_value value;
+};
+\end{lstlisting}
+
+Note that Virtio Over Fabrics does not define an interrupt mechanism, generally
+the initiator receives a Completion, it SHOULD generate a host interrupt
+(if no interrupt suspending on device).
-- 
2.25.1