Re: [PATCH v6] virtio-net: support inner header hash

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

å 2023/1/3 äå11:41, Michael S. Tsirkin åé:
> On Tue, Jan 03, 2023 at 10:25:18PM +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>
> > ---
> > 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      | 193 +++++++++++++++++++++++++++++++++++++++++++++--
> >   introduction.tex |  19 +++++
> >   2 files changed, 205 insertions(+), 7 deletions(-)
> >
> > diff --git a/content.tex b/content.tex
> > index e863709..89b0039 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.
> > +
> >   \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, a encapsulation packet type.
> an encapsulation

Ok, I'll fix it.

> >   
> >   \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 +3870,38 @@ \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), and the
> > +packet contains an outer header and an inner header. The device calculates the
> > +hash over
> over either

Ok.

> > the inner header or outer header,
> or the outer header

Ok.

> > and uses the hash to determine the
> > +receive virtqueue to place incoming encapsulated packet.
> "and uses the hash" does not belong here, it does not have to be
> used like this e.g. if RSS if off.

This does overlap with \paragraph{Hash calculation for incoming 
packets}, so I'll drop this.

> > +
> > +When the feature VIRTIO_NET_F_HASH_TUNNEL is negotiated and the encapsulation
> > +type
> the encapsulation type seems vague. maybe "the corresponding encapsulation
> type".

Ok, I'll modify it in the next version.

> > is set in \field{hash_types}, the hash for 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_REPORT and VIRTIO_NET_F_HASH_TUNNEL are negotiated,
> > +the device supports
> can support

Ok.

> > 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

Ok.

> > +Besides, the value in \field{hash_report_tunnel} is
> > +VIRTIO_NET_HASH_REPORT_{GRE, VXLAN, GENEVE}.
> Besides what?

I just mean "simultaneously".

> and it can also be set to NONE right?

Yes, I'll fix it in the next version.

> > +
> > +If VIRTIO_NET_F_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 types.
> type

Ok.

> > Besides, \field{hash_report_tunnel}
> > +is set to VIRTIO_NET_HASH_REPORT_TUNNEL_NONE.
> > +
> I don't think we can do this, you are retroactively adding requirements
> for existing devices without VIRTIO_NET_F_HASH_TUNNEL.
> this field is not valid.

You are right, "invalid" instead of "NONE" would be more correct.

> >   \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 +3921,22 @@ \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 to inner payload of the gre-encapsulated packet
> > +\begin{lstlisting}
> > +#define VIRTIO_NET_HASH_TYPE_GRE_INNER         (1 << 9)
> > +\end{lstlisting}
> > +Hash type applicable to inner payload of the vxlan-encapsulated packet
> > +\begin{lstlisting}
> > +#define VIRTIO_NET_HASH_TYPE_VXLAN_INNER       (1 << 10)
> > +\end{lstlisting}
> > +Hash type applicable to inner payload of the geneve-encapsulated packet
> > +\begin{lstlisting}
> > +#define VIRTIO_NET_HASH_TYPE_GENEVE_INNER      (1 << 11)
> > +\end{lstlisting}
> > +
> "Applicable for" not "applicable to".

Ok.

> >   \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 +4028,125 @@ \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 the encapsulated packet}
> an encapsulated packet

Ok.

> > +\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 the encapsulated packet (See \ref{sec:Device Types
> an encapsulated packet

Ok.

> > +/ Network Device / Device Operation / Processing of Incoming Packets /
> > +Hash calculation for incoming packets / Tunnel/Encapsulated packet}) as follows:
> > +
> > +If the inner payload of the encapsulated packet is an IPv4 packet and 'Enabled hash types'
> > +bitmasks are set as follows:
> this is still confusing and agrammatical. original text says things like:
>
> 	The device calculates the hash on IPv4 packets according to 'Enabled hash types' bitmask as follows:
>
> adjust text accordingly.

I will make corresponding adjustments in the next version.

Thanks.

> 	
> 	
>
> > +\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}
> > +
> > +If the inner payload of the encapsulated packet is an IPv6 packet without an extension
> > +header and 'Enabled hash types' bitmasks are set 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}
> > +
> > +If the inner payload of the encapsulated packet is an IPv6 packet with an extension header
> > +and 'Enabled hash types' bitmasks are set 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
> > +\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 +4168,22 @@ \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