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Subject: [PATCH v2] virtio-net: define support for controlled steering mode
Introducing feature bit and set of control commands
for steering mode configuration.
Implements https://github.com/oasis-tcs/virtio-spec/issues/48
---
content.tex | 194 ++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 194 insertions(+)
diff --git a/content.tex b/content.tex
index 8f0498e..679d492 100644
--- a/content.tex
+++ b/content.tex
@@ -2732,6 +2732,9 @@ \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_CTRL_STEERING_MODE(61)] Device supports selectable
+ steering mode and/or control of steering mode parameters.
+
\item[VIRTIO_NET_F_RSC_EXT(61)] Device can process duplicated ACKs
and report number of coalesced segments and duplicated ACKs
@@ -2761,6 +2764,7 @@ \subsubsection{Feature bit requirements}\label{sec:Device Types / Network Device
\item[VIRTIO_NET_F_MQ] Requires VIRTIO_NET_F_CTRL_VQ.
\item[VIRTIO_NET_F_CTRL_MAC_ADDR] Requires VIRTIO_NET_F_CTRL_VQ.
\item[VIRTIO_NET_F_RSC_EXT] Requires VIRTIO_NET_F_HOST_TSO4 or VIRTIO_NET_F_HOST_TSO6.
+\item[VIRTIO_NET_F_CTRL_STEERING_MODE] Requires VIRTIO_NET_F_MQ.
\end{description}
\subsubsection{Legacy Interface: Feature bits}\label{sec:Device Types / Network Device / Feature bits / Legacy Interface: Feature bits}
@@ -3700,8 +3704,198 @@ \subsubsection{Control Virtqueue}\label{sec:Device Types / Network Device / Devi
MUST format \field{offloads}
according to the native endian of the guest rather than
(necessarily when not using the legacy interface) little-endian.
+\paragraph{Controlled steering mode}\label{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Controlled steering mode}
+Device indicates presence of this feature if it supports selectable/configurable steering modes.
+\subparagraph{Querying and setting steering mode}\label{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Controlled steering mode / Querying and setting steering mode}
+There are two kinds of defined commands: GET and SET.
+
+For both types of commands driver sends output buffer containing \field{virtio_net_ctrl}, as defined by the \ref{sec:Device Types / Network Device / Device Operation / Control Virtqueue}.
+
+For GET commands driver provides input buffer for response structure defined for respective GET command.
+
+Each response structure includes first byte for \field{ack} code of regular response for control command.
+
+Driver uses following value as \field{class} for all the commands related to steering control.
+\begin{lstlisting}
+#define VIRTIO_NET_CTRL_STEERING_MODE 6
+\end{lstlisting}
+To query available steering modes driver uses following value as \field{command}.
+
+Device responds with \field{ack} following by bitmask designating supported steering modes.
+
+\begin{lstlisting}
+#define VIRTIO_NET_CTRL_SM_GET_SUPPORTED_MODES 0
+/* automatic steering mode (default defined by the device) */
+#define STEERING_MODE_AUTO (1 << 0)
+/* RSS (Receive Side Scaling): input queue defined by
+ calculated hash and indirection table */
+#define STEERING_MODE_RSS (1 << 1)
+struct virtio_net_supported_steering_modes {
+ u8 ack;
+ u8 steering_modes;
+};
+\end{lstlisting}
+
+For all operation related to specific steering mode driver uses following value as \field{command}
+and uses following structure for \field{command-specific-data}.
+\begin{lstlisting}
+#define VIRTIO_NET_CTRL_SM_CONTROL 1
+
+struct virtio_net_steering_mode_control {
+ u8 steering_mode;
+ u8 mode_command;
+};
+\end{lstlisting}
+In case of \field{steering_mode}=STEERING_MODE_AUTO the value of \field{mode_command} is ignored.
+
+In case of \field{steering_mode}=STEERING_MODE_RSS possible values of \field{mode_command} are:
+\begin{lstlisting}
+#define VIRTIO_NET_SM_CTRL_RSS_SET 0
+#define VIRTIO_NET_SM_CTRL_RSS_GET_SUPPORTED_FUNCTIONS 1
+#define VIRTIO_NET_SM_CTRL_RSS_GET_SUPPORTED_HASHES 2
+\end{lstlisting}
+Response on VIRTIO_NET_SM_CTRL_RSS_GET_SUPPORTED_FUNCTIONS is a structure containing bitmask value:
+\begin{lstlisting}
+struct virtio_net_supported_hash_functions {
+ u8 ack;
+ u8 supported_hash_functions;
+};
+#define VIRTIO_RSS_HASH_FUNCTION_TOEPLITZ (1 << 0)
+#define VIRTIO_RSS_HASH_FUNCTION_SYMMETRIC (1 << 1)
+\end{lstlisting}
+Response on VIRTIO_NET_SM_CTRL_RSS_GET_SUPPORTED_HASHES command is a structure containing bitmask values
+for supported hash types and capabilities related to hash calculation.
+Device reports supported hash types separately for IPv4 and IPv6.
+\begin{lstlisting}
+struct virtio_net_supported_hashes {
+ u8 ack;
+ u8 max_key_length;
+ le16 hash_types_v4;
+ le16 hash_types_v6;
+ /* maximal number of 16-bit entries */
+ le16 max_indirection_table_len;
+};
+#define VIRTIO_NET_SM_HASH_SUPPORT_IP (1 << 0)
+#define VIRTIO_NET_SM_HASH_SUPPORT_IP_EX (1 << 1) (only for IPv6)
+#define VIRTIO_NET_SM_HASH_SUPPORT_TCP (1 << 2)
+#define VIRTIO_NET_SM_HASH_SUPPORT_TCP_EX (1 << 3) (only for IPv6)
+#define VIRTIO_NET_SM_HASH_SUPPORT_UDP (1 << 4)
+#define VIRTIO_NET_SM_HASH_SUPPORT_UDP_EX (1 << 5) (only for IPv6)
+\end{lstlisting}
+For exact meaning of VIRTIO_NET_SM_HASH_SUPPORT_ flags see \ref{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Controlled steering mode / Querying and setting steering mode / RSS Toeplitz implementation}.
+
+For VIRTIO_NET_SM_CTRL_RSS_SET command driver sends following structure:
+\begin{lstlisting}
+struct virtio_net_rss_conf {
+ le16 hash_types_v4; (one or more of VIRTIO_NET_SM_HASH_SUPPORT bits)
+ le16 hash_types_v6; (one or more of VIRTIO_NET_SM_HASH_SUPPORT bits)
+ u8 hash_function; /* one of VIRTIO_RSS_HASH_FUNCTION*/
+ u8 hash_key_length;
+ le16 indirection_table_length;
+ /* queue to place unclassified packets in */
+ le16 default_queue;
+ /* le16 indirection_table[indirection_table_length] */
+ /* u8 hash key data[hash_key_length]*/
+};
+\end{lstlisting}
+\drivernormative{\subparagraph}{Querying and setting steering mode}{Device Types / Network Device / Device Operation / Control Virtqueue / Controlled steering mode / Querying and setting steering mode}
+
+A driver MUST NOT use commands of steering mode control if
+the feature VIRTIO_NET_F_CTRL_STEERING_MODE has not been negotiated
+and before it successfully enabled operation with multiple queues.
+A driver MUST fill \field{indirection_table} array only with indices of enabled queues.
+A \field{indirection_table_length} MUST be power of two.
+
+A driver MUST NOT set any VIRTIO_NET_SM_HASH_SUPPORT flags that are not supported by device.
+
+If a driver sets one of If VIRTIO_NET_SM_HASH_SUPPORT_TCP,If VIRTIO_NET_SM_HASH_SUPPORT_UDP flags, it MUST set also VIRTIO_NET_SM_HASH_SUPPORT_IP flag.
+
+If a driver sets one of If VIRTIO_NET_SM_HASH_SUPPORT_TCP_EX,If VIRTIO_NET_SM_HASH_SUPPORT_UDP_EX flags, it MUST set also VIRTIO_NET_SM_HASH_SUPPORT_IP_EX flag.
+
+\devicenormative{\subparagraph}{RSS Toeplitz implementation}{Device Types / Network Device / Device Operation / Control Virtqueue / Controlled steering mode / Querying and setting steering mode }
+\label{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Controlled steering mode / Querying and setting steering mode / RSS Toeplitz implementation}
+If device reports support for VIRTIO_RSS_HASH_FUNCTION_TOEPLITZ:
+
+It MUST support keys of at least 40 bytes and indirection table of at least 128 entries.
+
+The device applies mask of (indirection_table_length - 1) to the calculated hash and uses the result as the index in the indirection table to get 0-based number of destination receive queue.
+
+If the device did not calculate the hash for specific packet, it directs it to the default queue, as specified by virtio_net_rss_conf.\field{default_queue}.
+
+The device calculates hash on IPV4 packets as following according to virtio_net_rss_conf.\field{hash_types_v4}:
+\begin{itemize}
+\item If VIRTIO_NET_SM_HASH_SUPPORT_IP is set, the hash is calculated over following fields:
+\begin{itemize}
+\item Source IP address
+\item Destination IP address
+\end{itemize}
+\item If VIRTIO_NET_SM_HASH_SUPPORT_TCP is set, the hash is calculated over following fields:
+\begin{itemize}
+\item Source IP address
+\item Destination IP address
+\item Source TCP port
+\item Destination TCP port
+\end{itemize}
+\item If VIRTIO_NET_SM_HASH_SUPPORT_UDP is set, the hash is calculated over following fields:
+\begin{itemize}
+\item Source IP address
+\item Destination IP address
+\item Source UDP port
+\item Destination UDP port
+\end{itemize}
+\item If one of VIRTIO_NET_SM_HASH_SUPPORT_TCP, VIRTIO_NET_SM_HASH_SUPPORT_UDP is set,
+the device MUST skip over any IP header options. If the device can not skip over
+IP header options, if MUST not calculate the hash. If the packet is not TCP or UDP packet respectively, the device falls back to VIRTIO_NET_SM_HASH_SUPPORT_IP case.
+\end{itemize}
+
+The device calculates hash on IPV6 packets as following according to virtio_net_rss_conf.\field{hash_types_v6}:
+\begin{itemize}
+\item If VIRTIO_NET_SM_HASH_SUPPORT_IP is set, the hash is calculated over following fields:
+\begin{itemize}
+\item Source IPv6 address
+\item Destination IPv6 address
+\end{itemize}
+\item If VIRTIO_NET_SM_HASH_SUPPORT_TCP is set, the hash is calculated over following fields:
+\begin{itemize}
+\item Source IPv6 address
+\item Destination IPv6 address
+\item Source TCP port
+\item Destination TCP port
+\end{itemize}
+\item If VIRTIO_NET_SM_HASH_SUPPORT_UDP is set, the hash is calculated over following fields:
+\begin{itemize}
+\item Source IPv6 address
+\item Destination IPv6 address
+\item Source UDP port
+\item Destination UDP port
+\end{itemize}
+\item If one of VIRTIO_NET_SM_HASH_SUPPORT_TCP, VIRTIO_NET_SM_HASH_SUPPORT_UDP is set,
+the device MUST skip over any IPv6 header options. If the device can not skip over
+IPv6 header options, if MUST not calculate the hash. If the packet is not TCP or UDP packet respectively, the device falls back to VIRTIO_NET_SM_HASH_SUPPORT_IP case.
+\item If VIRTIO_NET_SM_HASH_SUPPORT_IP_EX is set, the hash is calculated over following fields:
+\begin{itemize}
+\item Home address from the home address option in the IPv6 destination options header. If the extension header is not present, use the Source IPv6 address.
+\item IPv6 address that is contained in the Routing-Header-Type-2 from the associated extension header. If the extension header is not present, use the Destination IPv6 address.
+\end{itemize}
+\item If VIRTIO_NET_SM_HASH_SUPPORT_TCP_EX is set, the hash is calculated over following fields:
+\begin{itemize}
+\item Source IPv6 address as specified for VIRTIO_NET_SM_HASH_SUPPORT_IP_EX
+\item Destination IPv6 address as specified for VIRTIO_NET_SM_HASH_SUPPORT_IP_EX
+\item Source TCP port
+\item Destination TCP port
+\end{itemize}
+\item If VIRTIO_NET_SM_HASH_SUPPORT_UDP_EX is set, the hash is calculated over following fields:
+\begin{itemize}
+\item Source IPv6 address as specified for VIRTIO_NET_SM_HASH_SUPPORT_IP_EX
+\item Destination IPv6 address as specified for VIRTIO_NET_SM_HASH_SUPPORT_IP_EX
+\item Source UDP port
+\item Destination UDP port
+\end{itemize}
+\item If one of VIRTIO_NET_SM_HASH_SUPPORT_TCP_EX, VIRTIO_NET_SM_HASH_SUPPORT_UDP_EX is set
+and the packet is not TCP or UDP packet respectively, the device falls back to VIRTIO_NET_SM_HASH_SUPPORT_IP_EX case.
+\end{itemize}
\subsubsection{Legacy Interface: Framing Requirements}\label{sec:Device
Types / Network Device / Legacy Interface: Framing Requirements}
--
2.17.2
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