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Subject: [PATCH] virtio-net: define support for receive-side scaling
Added support for RSS receive steering mode.
Signed-off-by: Yuri Benditovich <yuri.benditovich@daynix.com>
---
conformance.tex | 2 +
content.tex | 170 ++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 172 insertions(+)
diff --git a/conformance.tex b/conformance.tex
index 0ac58aa..bd31ba3 100644
--- a/conformance.tex
+++ b/conformance.tex
@@ -101,6 +101,7 @@ \section{Conformance Targets}\label{sec:Conformance / Conformance Targets}
\item \ref{drivernormative:Device Types / Network Device / Device Operation / Control Virtqueue / Gratuitous Packet Sending}
\item \ref{drivernormative:Device Types / Network Device / Device Operation / Control Virtqueue / Automatic receive steering in multiqueue mode}
\item \ref{drivernormative:Device Types / Network Device / Device Operation / Control Virtqueue / Offloads State Configuration / Setting Offloads State}
+\item \ref{drivernormative:Device Types / Network Device / Device Operation / Control Virtqueue / Receive-side scaling (RSS) / Using RSS commands}
\end{itemize}
\conformance{\subsection}{Block Driver Conformance}\label{sec:Conformance / Driver Conformance / Block Driver Conformance}
@@ -257,6 +258,7 @@ \section{Conformance Targets}\label{sec:Conformance / Conformance Targets}
\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 / 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}
\end{itemize}
\conformance{\subsection}{Block Device Conformance}\label{sec:Conformance / Device Conformance / Block Device Conformance}
diff --git a/content.tex b/content.tex
index 679391e..5672299 100644
--- a/content.tex
+++ b/content.tex
@@ -2811,6 +2811,9 @@ \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_RSS(60)] Device supports RSS (receive-side scaling)
+ with Toeplitz hash calculation and configurable hash parameters for receive steering
+
\item[VIRTIO_NET_F_RSC_EXT(61)] Device can process duplicated ACKs
and report number of coalesced segments and duplicated ACKs
@@ -2840,6 +2843,7 @@ \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_RSS] Requires VIRTIO_NET_F_MQ
\end{description}
\subsubsection{Legacy Interface: Feature bits}\label{sec:Device Types / Network Device / Feature bits / Legacy Interface: Feature bits}
@@ -3785,6 +3789,172 @@ \subsubsection{Control Virtqueue}\label{sec:Device Types / Network Device / Devi
according to the native endian of the guest rather than
(necessarily when not using the legacy interface) little-endian.
+\paragraph{Receive-side scaling (RSS)}\label{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Receive-side scaling (RSS)}
+The device indicates presence of this feature if in addition to automatic receive steering it supports RSS steering with Toeplitz hash calculation and configurable parameters.
+
+Driver uses following value as \field{class} for RSS-related commands.
+\begin{lstlisting}
+#define VIRTIO_NET_CTRL_RSS 6
+\end{lstlisting}
+Driver uses following values as \field{command} for RSS-related commands.
+\begin{lstlisting}
+#define VIRTIO_NET_CTRL_RSS_QUERY_CAPABILITIES 0
+#define VIRTIO_NET_CTRL_RSS_SET_PARAMETERS 1
+\end{lstlisting}
+
+\subparagraph{Querying RSS capabilities}\label{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Receive-side scaling (RSS) / Querying RSS capabilities}
+
+Driver sends VIRTIO_NET_CTRL_RSS_QUERY_CAPABILITIES command to query device capabilities related to RSS.
+Device responds the command using following format for \field{command-specific-data}:
+\begin{lstlisting}
+struct virtio_net_rss_capabilities {
+ le16 hash_types_v4; (bitmask of supported hash types for IPv4 packets)
+ le16 hash_types_v6; (bitmask of supported hash types for IPv6 packets)
+ le16 max_indirection_table_len; (maximal number of queue indices in indirection table)
+ u8 max_key_length; (maximal length of RSS key in bytes)
+};
+\end{lstlisting}
+To describe supported/enabled hash types device and driver use following definitions:
+
+Hash types applicable for IPv4 packets and for IPv6 packets without extension headers
+\begin{lstlisting}
+#define VIRTIO_NET_RSS_HASH_TYPE_IP (1 << 0)
+#define VIRTIO_NET_RSS_HASH_TYPE_TCP (1 << 1)
+#define VIRTIO_NET_RSS_HASH_TYPE_UDP (1 << 2)
+\end{lstlisting}
+Hash types applicable for IPv6 packets with extension headers
+\begin{lstlisting}
+#define VIRTIO_NET_RSS_HASH_TYPE_IP_EX (1 << 4) (only for IPv6)
+#define VIRTIO_NET_RSS_HASH_TYPE_TCP_EX (1 << 5) (only for IPv6)
+#define VIRTIO_NET_RSS_HASH_TYPE_UDP_EX (1 << 6) (only for IPv6)
+\end{lstlisting}
+For exact meaning of VIRTIO_NET_RSS_HASH_TYPE_ flags see \ref{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Receive-side scaling (RSS) / RSS hash types}.
+
+\subparagraph{Setting RSS parameters}\label{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Receive-side scaling (RSS) / Setting RSS parameters}
+
+Driver sends VIRTIO_NET_CTRL_RSS_SET_PARAMETERS command using following format for \field{command-specific-data}:
+\begin{lstlisting}
+struct virtio_net_rss_params {
+ u8 enable_rss;
+ u8 hash_key_length;
+ le16 hash_types_v4; (bitmask of allowed hash types for IPv4 packets)
+ le16 hash_types_v6; (bitmask of allowed hash types for IPv6 packets)
+ le16 indirection_table_length; (number of queue indices in indirection_table array)
+ le16 unclassified_queue; (queue to place unclassified packets in)
+ le16 indirection_table[indirection_table_length];
+ u8 hash_key_data[hash_key_length];
+};
+
+\end{lstlisting}
+Driver sets \field{enable_rss} to 0 to disable RSS processing by the device and use automatic steering mode instead.
+
+Driver sets \field{enable_rss} to 1 to enable RSS processing by the device using provided parameters.
+
+\subparagraph{RSS hash types}\label{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Receive-side scaling (RSS) / RSS hash types}
+
+The device calculates hash on IPv4 packets according to the field \field{hash_types_v4} of virtio_net_rss_params structure as follows:
+\begin{itemize}
+\item If VIRTIO_NET_RSS_HASH_TYPE_TCP is set and the packet has TCP header, 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 Else if VIRTIO_NET_RSS_HASH_TYPE_UDP is set and the packet has UDP header, 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 Else if VIRTIO_NET_RSS_HASH_TYPE_IP is set, the hash is calculated over following fields:
+\begin{itemize}
+\item Source IP address
+\item Destination IP address
+\end{itemize}
+\item Else the device does not calculate the hash
+\end{itemize}
+
+
+The device calculates hash on IPv6 packets without extension headers according to the field \field{hash_types_v6} of virtio_net_rss_params structure as follows:
+\begin{itemize}
+\item If VIRTIO_NET_RSS_HASH_TYPE_TCP is set and the packet has TCPv6 header, 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 Else if VIRTIO_NET_RSS_HASH_TYPE_UDP is set and the packet has UDPv6 header, 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 Else if VIRTIO_NET_RSS_HASH_TYPE_IP is set, the hash is calculated over following fields:
+\begin{itemize}
+\item Source IPv6 address
+\item Destination IPv6 address
+\end{itemize}
+\item Else the device does not calculate the hash
+\end{itemize}
+
+
+The device calculates hash on IPv6 packets with extension headers according to the field \field{hash_types_v6} of virtio_net_rss_params structure as follows:
+\begin{itemize}
+\item If VIRTIO_NET_RSS_HASH_TYPE_TCP_EX is set and the packet has TCPv6 header, 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.
+\item Source TCP port
+\item Destination TCP port
+\end{itemize}
+\item Else if VIRTIO_NET_RSS_HASH_TYPE_UDP_EX is set and the packet has UDPv6 header, 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.
+\item Source UDP port
+\item Destination UDP port
+\end{itemize}
+\item Else if VIRTIO_NET_RSS_HASH_TYPE_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 Else skip IPv6 extension headers and calculate the hash as defined above for IPv6 packet without extension headers
+\end{itemize}
+
+
+\drivernormative{\subparagraph}{Using RSS commands}{Device Types / Network Device / Device Operation / Control Virtqueue / Receive-side scaling (RSS) / Using RSS commands}
+
+A driver MUST NOT use RSS commands if the feature VIRTIO_NET_F_RSS has not been negotiated.
+
+A driver MUST NOT set RSS parameters before it successfully enabled operation with multiple queues.
+
+A driver MUST fill \field{indirection_table} array only with indices of enabled queues.
+
+An \field{indirection_table_length} MUST be power of two.
+
+A driver MUST NOT set any VIRTIO_NET_RSS_HASH_TYPE_ flags that are not supported by device.
+
+A driver MUST NOT set any bits below for \field{hash_types_v4}:
+\begin{itemize}
+\item VIRTIO_NET_RSS_HASH_TYPE_IP_EX
+\item VIRTIO_NET_RSS_HASH_TYPE_TCP_EX
+\item VIRTIO_NET_RSS_HASH_TYPE_UDP_EX
+\end{itemize}
+
+\devicenormative{\subparagraph}{RSS processing}{Device Types / Network Device / Device Operation / Control Virtqueue / Receive-side scaling (RSS) / RSS processing}
+If the device reports support for VIRTIO_NET_F_RSS it MUST support keys of at least 40 bytes and indirection table of at least 128 entries.
+
+The device MUST determine destination queue for network packet as follows:
+\begin{itemize}
+\item Calculate hash of the packet as defined in \ref{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Receive-side scaling (RSS) / RSS hash types}
+\item If the device did not calculate the hash for specific packet, the device directs the packet to the queue specified by \field{unclassified_queue} of virtio_net_rss_params structure
+\item Apply mask of (indirection_table_length - 1) to the calculated hash and use the result as the index in the indirection table to get 0-based number of destination receive queue
+\end{itemize}
\subsubsection{Legacy Interface: Framing Requirements}\label{sec:Device
Types / Network Device / Legacy Interface: Framing Requirements}
--
2.17.2
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