Re: [PATCH v7] virtio-net: support inner header hash

["Michael S. Tsirkin" <mst@redhat.com>]

On Wed, Jan 04, 2023 at 03:14:01PM +0800, Heng Qi wrote:
> If the tunnel is used to encapsulate the packets, the hash calculated
> using the outer header of the receive packets is always fixed for the
> same flow packets, i.e. they will be steered to the same receive queue.
> 
> We add a feature bit VIRTIO_NET_F_HASH_TUNNEL and related bitmasks
> in \field{hash_types}, which instructs the device to calculate the
> hash using the inner headers of tunnel-encapsulated packets. Besides,
> values in \field{hash_report_tunnel} are added to report tunnel types.
> 
> Fixes: https://github.com/oasis-tcs/virtio-spec/issues/151
> 
> Reviewed-by: Jason Wang <jasowang@redhat.com>
> Signed-off-by: Heng Qi <hengqi@linux.alibaba.com>
> Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>


ok close to being ready. a couple of minor comments.

> ---
> v6:
> 	1. Modify the wording of some sentences for clarity. @Michael S. Tsirkin
> 	2. Fix some syntax issues. @Michael S. Tsirkin
> 
> v5:
> 	1. Fix some syntax and capitalization issues. @Michael S. Tsirkin
> 	2. Use encapsulated/encaptulation uniformly. @Michael S. Tsirkin
> 	3. Move the links to introduction section. @Michael S. Tsirkin
> 	4. Clarify some sentences. @Michael S. Tsirkin
> 
> v4:
> 	1. Clarify some paragraphs. @Cornelia Huck
> 	2. Fix the u8 type. @Cornelia Huck
> 
> v3:
> 	1. Rename VIRTIO_NET_F_HASH_GRE_VXLAN_GENEVE_INNER to VIRTIO_NET_F_HASH_TUNNEL. @Jason Wang
> 	2. Make things clearer. @Jason Wang @Michael S. Tsirkin
> 	3. Keep the possibility to use inner hash for automatic receive steering. @Jason Wang
> 	4. Add the "Tunnel packet" paragraph to avoid repeating the GRE etc. many times. @Michael S. Tsirkin
> 
> v2:
> 	1. Add a feature bit for GRE/VXLAN/GENEVE inner hash. @Jason Wang
> 	2. Chang \field{hash_tunnel} to \field{hash_report_tunnel}. @Jason Wang, @Michael S. Tsirkin
> 
> v1:
> 	1. Remove the patch for the bitmask fix. @Michael S. Tsirkin
> 	2. Clarify some paragraphs. @Jason Wang
> 	3. Add \field{hash_tunnel} and VIRTIO_NET_HASH_REPORT_GRE. @Yuri Benditovich
> 
>  content.tex      | 191 +++++++++++++++++++++++++++++++++++++++++++++--
>  introduction.tex |  19 +++++
>  2 files changed, 203 insertions(+), 7 deletions(-)
> 
> diff --git a/content.tex b/content.tex
> index e863709..7845f6c 100644
> --- a/content.tex
> +++ b/content.tex
> @@ -3084,6 +3084,9 @@ \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_TUNNEL(52)] Device supports inner
> +    header hash for GRE, VXLAN and GENEVE tunnel-encapsulated packets.

I would probably drop the list of tunnel types here.

> +
>  \item[VIRTIO_NET_F_NOTF_COAL(53)] Device supports notifications coalescing.
>  
>  \item[VIRTIO_NET_F_GUEST_USO4 (54)] Driver can receive USOv4 packets.
> @@ -3095,7 +3098,8 @@ \subsection{Feature bits}\label{sec:Device Types / Network Device / Feature bits
>   to several segments when each of these smaller packets has UDP header.
>  
>  \item[VIRTIO_NET_F_HASH_REPORT(57)] Device can report per-packet hash
> -    value and a type of calculated hash.
> +    value, a type of calculated hash, and, if VIRTIO_NET_F_HASH_TUNNEL
> +    is negotiated, an encapsulation packet type.
>  
>  \item[VIRTIO_NET_F_GUEST_HDRLEN(59)] Driver can provide the exact \field{hdr_len}
>      value. Device benefits from knowing the exact header length.
> @@ -3140,6 +3144,7 @@ \subsubsection{Feature bit requirements}\label{sec:Device Types / Network Device
>  \item[VIRTIO_NET_F_NOTF_COAL] 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_CTRL_VQ.
> +\item[VIRTIO_NET_F_HASH_TUNNEL] Requires VIRTIO_NET_F_CTRL_VQ.
>  \end{description}
>  
>  \subsubsection{Legacy Interface: Feature bits}\label{sec:Device Types / Network Device / Feature bits / Legacy Interface: Feature bits}
> @@ -3386,7 +3391,8 @@ \subsection{Device Operation}\label{sec:Device Types / Network Device / Device O
>          le16 num_buffers;
>          le32 hash_value;        (Only if VIRTIO_NET_F_HASH_REPORT negotiated)
>          le16 hash_report;       (Only if VIRTIO_NET_F_HASH_REPORT negotiated)
> -        le16 padding_reserved;  (Only if VIRTIO_NET_F_HASH_REPORT negotiated)
> +        u8 hash_report_tunnel;  (Only if VIRTIO_NET_F_HASH_REPORT negotiated, only valid of VIRTIO_NET_F_HASH_TUNNEL negotiated)
> +        u8 padding_reserved;    (Only if VIRTIO_NET_F_HASH_REPORT negotiated)
>  };
>  \end{lstlisting}
>  
> @@ -3837,7 +3843,8 @@ \subsubsection{Processing of Incoming Packets}\label{sec:Device Types / Network
>  A device attempts to calculate a per-packet hash in the following cases:
>  \begin{itemize}
>  \item The feature VIRTIO_NET_F_RSS was negotiated. The device uses the hash to determine the receive virtqueue to place incoming packets.
> -\item The feature VIRTIO_NET_F_HASH_REPORT was negotiated. The device reports the hash value and the hash type with the packet.
> +\item The feature VIRTIO_NET_F_HASH_REPORT was negotiated. The device reports the hash value and the hash type. If additionally
> +VIRTIO_NET_F_HASH_TUNNEL was negotiated, the device reports the encapsulation type as well.
>  \end{itemize}
>  
>  If the feature VIRTIO_NET_F_RSS was negotiated:
> @@ -3863,8 +3870,36 @@ \subsubsection{Processing of Incoming Packets}\label{sec:Device Types / Network
>   \ref{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Automatic receive steering in multiqueue mode / Hash calculation}.
>  \end{itemize}
>  
> +\subparagraph{Tunnel/Encapsulated packet}
> +\label{sec:Device Types / Network Device / Device Operation / Processing of Incoming Packets / Hash calculation for incoming packets / Tunnel/Encapsulated packet}
> +A tunnel packet is encapsulated from the original packet based on the tunneling
> +protocol (only a single level of encapsulation is currently supported). The
> +encapsulated packet contains an outer header and an inner header, and the device
> +calculates the hash over either the inner header or the outer header.
> +
> +When the feature VIRTIO_NET_F_HASH_TUNNEL is negotiated and the corresponding
> +encapsulation type is set in \field{hash_types}, the hash for a specific type of
> +encapsulated packet is calculated over the inner as opposed to outer header.
> +Supported encapsulation types are listed in \ref{sec:Device Types / Network Device /
> +Device Operation / Processing of Incoming Packets / Hash calculation for incoming packets /
> +Supported/enabled hash types}.
> +
> +If both VIRTIO_NET_F_HASH_REPORT and VIRTIO_NET_F_HASH_TUNNEL are negotiated,
> +the device can support inner hash calculation for \hyperref[intro:GRE]{[GRE]},
> +\hyperref[intro:VXLAN]{[VXLAN]} and \hyperref[intro:GENEVE]{[GENEVE]}
> +encapsulated packets, and the corresponding encapsulation type in \field{hash_types}
> +is VIRTIO_NET_HASH_TYPE_{GRE, VXLAN, GENEVE}_INNER respectively. The value in
> +\field{hash_report_tunnel} is VIRTIO_NET_HASH_REPORT_{NONE, GRE, VXLAN, GENEVE} respectively.
> +
> +If VIRTIO_NET_F_HASH_REPORT is negotiated but VIRTIO_NET_F_HASH_TUNNEL is not
> +negotiated, the device calculates the hash over the outer header, and
> +\field{hash_report} reports the hash type. \field{hash_report_tunnel}
> +is no longer valid.
> +
>  \subparagraph{Supported/enabled hash types}
>  \label{sec:Device Types / Network Device / Device Operation / Processing of Incoming Packets / Hash calculation for incoming packets / Supported/enabled hash types}
> +This paragraph relies on definitions from \hyperref[intro:IP]{[IP]},
> +\hyperref[intro:UDP]{[UDP]} and \hyperref[intro:TCP]{[TCP]}.
>  Hash types applicable for IPv4 packets:
>  \begin{lstlisting}
>  #define VIRTIO_NET_HASH_TYPE_IPv4              (1 << 0)
> @@ -3884,6 +3919,22 @@ \subsubsection{Processing of Incoming Packets}\label{sec:Device Types / Network
>  #define VIRTIO_NET_HASH_TYPE_UDP_EX            (1 << 8)
>  \end{lstlisting}
>  
> +If the feature VIRTIO_NET_F_HASH_TUNNEL is negotiated, the encapsulation
> +hash type below indicates that the hash is calculated over the inner
> +header of the encapsulated packet:
> +Hash type applicable for inner payload of the gre-encapsulated packet
> +\begin{lstlisting}
> +#define VIRTIO_NET_HASH_TYPE_GRE_INNER         (1 << 9)
> +\end{lstlisting}
> +Hash type applicable for inner payload of the vxlan-encapsulated packet
> +\begin{lstlisting}
> +#define VIRTIO_NET_HASH_TYPE_VXLAN_INNER       (1 << 10)
> +\end{lstlisting}
> +Hash type applicable for inner payload of the geneve-encapsulated packet
> +\begin{lstlisting}
> +#define VIRTIO_NET_HASH_TYPE_GENEVE_INNER      (1 << 11)
> +\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:
> @@ -3975,15 +4026,125 @@ \subsubsection{Processing of Incoming Packets}\label{sec:Device Types / Network
>  (see \ref{sec:Device Types / Network Device / Device Operation / Processing of Incoming Packets / Hash calculation for incoming packets / IPv6 packets without extension header}).
>  \end{itemize}
>  
> +\subparagraph{Inner payload of an encapsulated packet}
> +\label{sec:Device Types / Network Device / Device Operation / Processing of Incoming Packets / Hash calculation for incoming packets / Inner payload of the encapsulated packet}
> +If the feature VIRTIO_NET_F_HASH_TUNNEL is negotiated and the corresponding
> +encapsulation hash type is set in \field{hash_types}, the device calculates the
> +inner header hash on an encapsulated packet (See \ref{sec:Device Types
> +/ Network Device / Device Operation / Processing of Incoming Packets /
> +Hash calculation for incoming packets / Tunnel/Encapsulated packet}) as follows:
> +
> +The device calculates the hash on the inner IPv4 packet of an encapsulated packet
> +according to 'Enabled hash types' bitmask as follows:
> +\begin{itemize}
> +  \item If VIRTIO_NET_HASH_TYPE_TCPv4 is set and the encapsulated packet has an inner
> +	TCPv4 header, the hash is calculated over the following fields:
> +        \begin{itemsize}
> +          \item inner Source IP address
> +          \item inner Destination IP address
> +          \item inner Source TCP port
> +          \item inner Destination TCP port
> +        \end{itemsize}
> +  \item Else if VIRTIO_NET_HASH_TYPE_UDPv4 is set and the encapsulated packet has an
> +	inner UDPv4 header, the hash is calculated over the following fields:
> +        \begin{itemsize}
> +          \item inner Source IP address
> +          \item inner Destination IP address
> +          \item inner Source UDP port
> +          \item inner Destination UDP port
> +        \end{itemize}
> +  \item Else if VIRTIO_NET_HASH_TYPE_IPv4 is set, the hash is calculated over the
> +	following fields:
> +        \begin{itemsize}
> +          \item inner Source IP address
> +          \item inner Destination IP address
> +        \end{itemsize}
> +  \item Else the device does not calculate the hash
> +\end{itemize}
> +
> +The device calculates the hash on the inner IPv6 packet without an extension header
> +of an encapsulated packet according to 'Enabled hash types' bitmask as follows:
> +\begin{itemize}
> +  \item If VIRTIO_NET_HASH_TYPE_TCPv6 is set and the encapsulated packet has an inner
> +	TCPv6 header, the hash is calculated over the following fields:
> +        \begin{itemsize}
> +          \item inner Source IPv6 address
> +          \item inner Destination IPv6 address
> +          \item inner Source TCP port
> +          \item inner Destination TCP port
> +        \end{itemsize}
> +  \item Else if VIRTIO_NET_HASH_TYPE_UDPv6 is set and the encapsulated packet has an
> +	inner UDPv6 header, the hash is calculated over the following fields:
> +        \begin{itemsize}
> +          \item inner Source IPv6 address
> +          \item inner Destination IPv6 address
> +          \item inner Source UDP port
> +          \item inner Destination UDP port
> +        \end{itemize}
> +  \item Else if VIRTIO_NET_HASH_TYPE_IPv6 is set, the hash is calculated over the
> +	following fields:
> +        \begin{itemsize}
> +          \item inner Source IPv6 address
> +          \item inner Destination IPv6 address
> +        \end{itemsize}
> +  \item Else the device does not calculate the hash
> +\end{itemize}
> +
> +The device calculates the hash on the inner IPv6 packet with an extension header
> +of an encapsulated packet according to 'Enabled hash types' bitmask as follows:
> +\begin{itemsize}
> +  \item If VIRTIO_NET_HASH_TYPE_TCP_EX is set and the encapsulated packet has an inner
> +	TCPv6 header, the hash is calculated over the following fields:
> +        \begin{itemize}
> +          \item Home address from the home address option in the inner IPv6 destination
> +              options header. If the inner extension header is not present, use the
> +              inner Source IPv6 address.
> +          \item IPv6 address that is contained in the Routing-Header-Type-2 from the
> +              associated inner extension header. If the inner extension header is not
> +              present, use the inner Destination IPv6 address.
> +          \item inner Source TCP port
> +          \item inner Destination TCP port
> +        \end{itemize}
> +  \item Else if VIRTIO_NET_HASH_TYPE_UDP_EX is set and the encapsulated packet has an inner
> +	UDPv6 header, the hash is calculated over the following fields:
> +        \begin{itemsize}
> +          \item Home address from the home address option in the inner IPv6 destination
> +              options header. If the inner extension header is not present, use the
> +              inner Source IPv6 address.
> +          \item IPv6 address that is contained in the Routing-Header-Type-2 from the
> +              associated inner extension header. If the inner extension header is not
> +              present, use the inner Destination IPv6 address.
> +          \item inner Source UDP port
> +          \item inner Destination UDP port
> +        \end{itemize}
> +  \item Else if VIRTIO_NET_HASH_TYPE_IP_EX is set, the hash is calculated over the
> +	following fields:
> +        \begin{itemsize}
> +          \item Home address from the home address option in the inner IPv6 destination
> +              options header. If the inner extension header is not present, use the
> +              inner Source IPv6 address.
> +          \item IPv6 address that is contained in the Routing-Header-Type-2 from the
> +              associated inner extension header. If the inner extension header is not
> +              present, use the inner Destination IPv6 address.
> +        \end{itemize}
> +  \item Else skip the inner IPv6 extension header and calculate the inner header hash as
> +	defined for an encapsulated packet whose inner payload is an IPv6 packet without
> +	an extension header.
> +\end{itemsize}
> +
>  \paragraph{Hash reporting for incoming packets}
>  \label{sec:Device Types / Network Device / Device Operation / Processing of Incoming Packets / Hash reporting for incoming packets}
>  
> -If VIRTIO_NET_F_HASH_REPORT was negotiated and
> - the device has calculated the hash for the packet, the device fills \field{hash_report} with the report type of calculated hash
> -and \field{hash_value} with the value of calculated hash.
> +If VIRTIO_NET_F_HASH_REPORT was negotiated and the device has calculated the
> +hash for the packet, the device fills \field{hash_report} with the report type
> +of calculated hash, and \field{hash_value} with the value of calculated hash.
> +Also, if VIRTIO_NET_F_HASH_TUNNEL was negotiated, the device needs to fill

needs to fill -> fills

for consistency

> +\field{hash_report_tunnel} with the report type of the encapsulated packet, and
> +it is set to VIRTIO_NET_HASH_REPORT_TUNNEL_NONE for the unencapsulated packet.
>  
>  If VIRTIO_NET_F_HASH_REPORT was negotiated but due to any reason the
> -hash was not calculated, the device sets \field{hash_report} to VIRTIO_NET_HASH_REPORT_NONE.
> +hash was not calculated, the device sets \field{hash_report} to VIRTIO_NET_HASH_REPORT_NONE,
> +and sets \field{hash_report_tunnel} to VIRTIO_NET_HASH_REPORT_TUNNEL_NONE.
>  
>  Possible values that the device can report in \field{hash_report} are defined below.
>  They correspond to supported hash types defined in
> @@ -4005,6 +4166,22 @@ \subsubsection{Processing of Incoming Packets}\label{sec:Device Types / Network
>  #define VIRTIO_NET_HASH_REPORT_UDPv6_EX        9
>  \end{lstlisting}
>  
> +If \field{hash_report} differs from VIRTIO_NET_HASH_REPORT_NONE,
> +\field{hash_report_tunnel} can report the type of the encapsulated
> +packet to the driver over the inner header hash calculation.
> +Possible values that the device can report in \field{hash_report_tunnel}
> +are defined below:
> +
> +\begin{lstlisting}
> +#define VIRTIO_NET_HASH_REPORT_TUNNEL_NONE     0
> +#define VIRTIO_NET_HASH_REPORT_GRE             1
> +#define VIRTIO_NET_HASH_REPORT_VXLAN           2
> +#define VIRTIO_NET_HASH_REPORT_GENEVE          3
> +\end{lstlisting}
> +
> +They correspond to supported hash types defined in
> +\ref{sec:Device Types / Network Device / Device Operation / Processing of Incoming Packets / Hash calculation for incoming packets / Supported/enabled hash types}.
> +
>  \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/introduction.tex b/introduction.tex
> index 287c5fc..ff01a9b 100644
> --- a/introduction.tex
> +++ b/introduction.tex
> @@ -98,6 +98,25 @@ \section{Normative References}\label{sec:Normative References}
>  	\phantomsection\label{intro:SEC1}\textbf{[SEC1]} &
>      Standards for Efficient Cryptography Group(SECG), ``SEC1: Elliptic Cureve Cryptography'', Version 1.0, September 2000.
>  	\newline\url{https://www.secg.org/sec1-v2.pdf}\\
> +	\phantomsection\label{intro:GRE}\textbf{[GRE]} &
> +	Generic Routing Encapsulation
> +	\newline\url{https://datatracker.ietf.org/doc/rfc2784/}\\
> +	\phantomsection\label{intro:VXLAN}\textbf{[VXLAN]} &
> +	Virtual eXtensible Local Area Network
> +	\newline\url{https://datatracker.ietf.org/doc/rfc7348/}\\
> +	\phantomsection\label{intro:GENEVE}\textbf{[GENEVE]} &
> +	Generic Network Virtualization Encapsulation
> +	\newline\url{https://datatracker.ietf.org/doc/rfc8926/}\\
> +	\phantomsection\label{intro:IP}\textbf{[IP]} &
> +	INTERNET PROTOCOL
> +	\newline\url{https://www.rfc-editor.org/rfc/rfc791}\\
> +	\phantomsection\label{intro:UDP}\textbf{[UDP]} &
> +	User Datagram Protocol
> +	\newline\url{https://www.rfc-editor.org/rfc/rfc768}\\
> +	\phantomsection\label{intro:TCP}\textbf{[TCP]} &
> +	TRANSMISSION CONTROL PROTOCOL
> +	\newline\url{https://www.rfc-editor.org/rfc/rfc793}\\
> +
>  
>  \end{longtable}
>  
> -- 
> 2.19.1.6.gb485710b