[virtio-comment] [PATCH] virtio-net: support the outer source port hash for UDP-encapsulated packets

[Heng Qi <hengqi@linux.alibaba.com>]

UDP tunneling protocols usually identify a flow using the outer source UDP
port, which is useful for processing UDP-encapsulated packets, such as
increasing entropy for RSS queue selection or hashing the same flow to the
same receive queue. Therefore, we extend it as a new RSS configuration.

Signed-off-by: Heng Qi <hengqi@linux.alibaba.com>
Reviewed-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
---
 device-types/net/description.tex        | 49 ++++++++++++++++++++++++-
 device-types/net/device-conformance.tex |  1 +
 2 files changed, 48 insertions(+), 2 deletions(-)

diff --git a/device-types/net/description.tex b/device-types/net/description.tex
index 76585b0..366775a 100644
--- a/device-types/net/description.tex
+++ b/device-types/net/description.tex
@@ -88,6 +88,9 @@ \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_HASH_UDP_TUNNEL_SRCPORT(50)] Device supports outer source port hash
+    for UDP-encapsulated packets.
+
 \item[VIRTIO_NET_F_HASH_TUNNEL(51)] Device supports inner header hash for encapsulated packets.
 
 \item[VIRTIO_NET_F_VQ_NOTF_COAL(52)] Device supports virtqueue notification coalescing.
@@ -150,6 +153,7 @@ \subsubsection{Feature bit requirements}\label{sec:Device Types / Network Device
 \item[VIRTIO_NET_F_RSS] Requires VIRTIO_NET_F_CTRL_VQ.
 \item[VIRTIO_NET_F_VQ_NOTF_COAL] Requires VIRTIO_NET_F_CTRL_VQ.
 \item[VIRTIO_NET_F_HASH_TUNNEL] Requires VIRTIO_NET_F_CTRL_VQ along with VIRTIO_NET_F_RSS or VIRTIO_NET_F_HASH_REPORT.
+\item[VIRTIO_NET_F_HASH_UDP_TUNNEL_SRCPORT] Requires VIRTIO_NET_F_CTRL_VQ along with VIRTIO_NET_F_RSS or VIRTIO_NET_F_HASH_REPORT.
 \end{description}
 
 \subsubsection{Legacy Interface: Feature bits}\label{sec:Device Types / Network Device / Feature bits / Legacy Interface: Feature bits}
@@ -927,11 +931,29 @@ \subsubsection{Processing of Incoming Packets}\label{sec:Device Types / Network
 #define VIRTIO_NET_HASH_TYPE_UDP_EX            (1 << 8)
 \end{lstlisting}
 
+A UDP-encapsulated packet uses UDP as the transport protocol in the outer header
+\ref{sec:Device Types / Network Device / Device Operation / Processing of Incoming Packets / Hash calculation for incoming packets / Encapsulated packet}.
+UDP tunneling protocols usually use the outer source UDP port to identify a specific flow.
+The hash calculated over the outer source UDP port can thus be used by the device to queue these different flows
+on different receive queues or queue the same specific flow on the same receive queue.
+
+If additionally the feature VIRTIO_NET_F_HASH_UDP_TUNNEL_SRCPORT was negotiated,
+the following hash types are applicable for UDP-encapsulated packets:
+\begin{lstlisting}
+#define VIRTIO_NET_HASH_TYPE_UDPv4_TUNNEL_SRCPORT (1 << 9)
+#define VIRTIO_NET_HASH_TYPE_UDPv6_TUNNEL_SRCPORT (1 << 10)
+\end{lstlisting}
+
 \subparagraph{IPv4 packets}
 \label{sec:Device Types / Network Device / Device Operation / Processing of Incoming Packets / Hash calculation for incoming packets / IPv4 packets}
 The device calculates the hash on IPv4 packets according to 'Enabled hash types' bitmask as follows:
 \begin{itemize}
-\item If VIRTIO_NET_HASH_TYPE_TCPv4 is set and the packet has
+\item If additionally VIRTIO_NET_HASH_TYPE_UDPv4_TUNNEL_SRCPORT is set and a received encapsulated
+packet has an outer UDPv4 header, the hash is calculated over the following fields:
+\begin{itemize}
+\item Outer source UDP port
+\end{itemize}
+\item Else if VIRTIO_NET_HASH_TYPE_TCPv4 is set and the packet has
 a TCP header, the hash is calculated over the following fields:
 \begin{itemize}
 \item Source IP address
@@ -961,7 +983,12 @@ \subsubsection{Processing of Incoming Packets}\label{sec:Device Types / Network
 The device calculates the hash on IPv6 packets without extension
 headers according to 'Enabled hash types' bitmask as follows:
 \begin{itemize}
-\item If VIRTIO_NET_HASH_TYPE_TCPv6 is set and the packet has
+\item If additionally VIRTIO_NET_HASH_TYPE_UDPv6_TUNNEL_SRCPORT is set and a received encapsulated
+packet has an outer UDPv6 header, the hash is calculated over the following fields:
+\begin{itemize}
+\item Outer source UDP port
+\end{itemize}
+\item Else if VIRTIO_NET_HASH_TYPE_TCPv6 is set and the packet has
 a TCPv6 header, the hash is calculated over the following fields:
 \begin{itemize}
 \item Source IPv6 address
@@ -991,6 +1018,11 @@ \subsubsection{Processing of Incoming Packets}\label{sec:Device Types / Network
 The device calculates the hash on IPv6 packets with extension
 headers according to 'Enabled hash types' bitmask as follows:
 \begin{itemize}
+\item If additionally VIRTIO_NET_HASH_TYPE_UDPv6_TUNNEL_SRCPORT is set and a received encapsulated
+packet has an outer UDPv6 header, the hash is calculated over the following fields:
+\begin{itemize}
+\item Outer source UDP port
+\end{itemize}
 \item If VIRTIO_NET_HASH_TYPE_TCP_EX is set and the packet
 has a TCPv6 header, the hash is calculated over the following fields:
 \begin{itemize}
@@ -1139,8 +1171,21 @@ \subsubsection{Processing of Incoming Packets}\label{sec:Device Types / Network
 #define VIRTIO_NET_HASH_REPORT_IPv6_EX         7
 #define VIRTIO_NET_HASH_REPORT_TCPv6_EX        8
 #define VIRTIO_NET_HASH_REPORT_UDPv6_EX        9
+#define VIRTIO_NET_HASH_REPORT_UDPv4_TUNNEL_SRCPORT 10 /* Only if additionally VIRTIO_NET_F_HASH_UDP_TUNNEL_SRCPORT was negotiated */
+#define VIRTIO_NET_HASH_REPORT_UDPv6_TUNNEL_SRCPORT 11 /* Only if additionally VIRTIO_NET_F_HASH_UDP_TUNNEL_SRCPORT was negotiated */
 \end{lstlisting}
 
+\devicenormative{\subparagraph}{Outer Source UDP Port}{Device Types / Network Device / Device Operation / Outer Source UDP Port}
+
+When all the following cases occur:
+\begin{itemize}
+\item Both VIRTIO_NET_F_HASH_UDP_TUNNEL_SRCPORT and VIRTIO_NET_F_HASH_TUNNEL are negotiated.
+\item A received UDP-encapsulated packet's outer header matches one of the encapsulation types enabled in \field{enabled_tunnel_types}.
+\item VIRTIO_NET_HASH_TYPE_UDPv4_TUNNEL_SRCPORT is set in \field{hash_types} and a received encapsulated packet has an outer UDPv4 header or
+      VIRTIO_NET_HASH_TYPE_UDPv6_TUNNEL_SRCPORT is set in \field{hash_types} and a received encapsulated packet has an outer UDPv6 header.
+\end{itemize}
+the device MUST calculate the hash over the inner header rather than the outer source UDP port.
+
 \subsubsection{Control Virtqueue}\label{sec:Device Types / Network Device / Device Operation / Control Virtqueue}
 
 The driver uses the control virtqueue (if VIRTIO_NET_F_CTRL_VQ is
diff --git a/device-types/net/device-conformance.tex b/device-types/net/device-conformance.tex
index f88f48b..4fd036b 100644
--- a/device-types/net/device-conformance.tex
+++ b/device-types/net/device-conformance.tex
@@ -7,6 +7,7 @@
 \item \ref{devicenormative:Device Types / Network Device / Device Operation / Packet Transmission}
 \item \ref{devicenormative:Device Types / Network Device / Device Operation / Setting Up Receive Buffers}
 \item \ref{devicenormative:Device Types / Network Device / Device Operation / Processing of Incoming Packets}
+\item \ref{devicenormative:Device Types / Network Device / Device Operation / Outer Source UDP Port}
 \item \ref{devicenormative:Device Types / Network Device / Device Operation / Control Virtqueue / Packet Receive Filtering}
 \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 / VLAN Filtering}
-- 
2.19.1.6.gb485710b


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