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Subject: Re: [PATCH] virtio-net: define support for receive-side scaling
On Wed, Oct 02, 2019 at 07:41:39PM +0300, Yuri Benditovich wrote: > Added support for RSS receive steering mode. > > Signed-off-by: Yuri Benditovich <yuri.benditovich@daynix.com> could you pls list the changes from the previous versions? > --- > 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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