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Subject: Re: [virtio-dev] Re: [PATCH 2/2] virtio_net: support inner header hash for GRE-encapsulated packets
On Thu, Nov 17, 2022 at 3:49 PM Heng Qi <hengqi@linux.alibaba.com> wrote:
>
>
>
> å 2022/11/17 äå2:09, Jason Wang åé:
> > On Thu, Nov 17, 2022 at 2:00 PM Heng Qi <hengqi@linux.alibaba.com> wrote:
> >>
> >>
> >> å 2022/11/17 äå1:34, Jason Wang åé:
> >>> On Thu, Nov 17, 2022 at 1:01 PM Heng Qi <hengqi@linux.alibaba.com> wrote:
> >>>>
> >>>> å 2022/11/17 äå12:29, Jason Wang åé:
> >>>>> On Thu, Nov 17, 2022 at 10:53 AM Heng Qi <hengqi@linux.alibaba.com> wrote:
> >>>>>> å 2022/11/17 äå7:32, Yuri Benditovich åé:
> >>>>>>> I would suggest to specify also the hash type the device should report
> >>>>>>> in case the hash reporting feature is enabled. For example, should the
> >>>>>>> device specify somehow in the report that the hash was calculated on
> >>>>>>> the inner header or on the regular header?
> >>>>>> It seems unnecessary. The calculation of RSS hash using the regular or
> >>>>>> inner header is actually
> >>>>>> transparent to the driver, and after the hash value and hash type
> >>>>>> calculated by the device,
> >>>>>> the feedback on skb is that skb only has L4 or L3 hash boolean type.
> >>>>> I think what Yuri meant is what if the user wants to calculate hash
> >>>>> based on the inner header? Do we need VIRTIO_NET_HASH_TYPE_GRE_XXX?
> >>>> Yes, if the user wants to calculate the hash on the inner header, then
> >>>> we need VIRTIO_NET_HASH_TYPE_GRE_INNER,
> >>>> if the user wants to calculate the hash on the outer header, then we
> >>>> donât need to use VIRTIO_NET_HASH_TYPE_GRE_INNER,
> >>>> just keep the previous default behavior.
> >>> I actually meant should we add VIRTIO_NET_HASH_REPORT_GRE_XXX?
> >> VIRTIO_NET_HASH_REPORT_GRE_XXX does not seem to need to be added.
> >>
> >> _HASH_TYPE_GRE_INNER is a special hash type, which is used in
> >> combination with other hash types,
> >> indicating that the sd, sdfn, etc. of the inner or outer header are used
> >> to calculate the hash.
> >> The device can report the following true types to the driver to meet the
> >> subsequent requirements of driver.
> >>
> >> \begin{lstlisting}
> >> #define VIRTIO_NET_HASH_REPORT_NONE 0
> >> #define VIRTIO_NET_HASH_REPORT_IPv4 1
> >> #define VIRTIO_NET_HASH_REPORT_TCPv4 2
> >> #define VIRTIO_NET_HASH_REPORT_UDPv4 3
> >> #define VIRTIO_NET_HASH_REPORT_IPv6 4
> >> #define VIRTIO_NET_HASH_REPORT_TCPv6 5
> >> #define VIRTIO_NET_HASH_REPORT_UDPv6 6
> >> #define VIRTIO_NET_HASH_REPORT_IPv6_EX 7
> >> #define VIRTIO_NET_HASH_REPORT_TCPv6_EX 8
> >> #define VIRTIO_NET_HASH_REPORT_UDPv6_EX 9
> >> \end{lstlisting}
> >>
> >> As for whether the device uses the outer or inner header to calculate
> >> the hash information,
> >> the driver does not seem to need to know?
> > We can't assume the behaviour of the driver actually. E.g driver may
> > try to do rx classification based on the rxhash.
>
> Ok, I think this is reasonable and we shouldn't hide certain information.
>
> Then I'll add VIRTIO_NET_HASH_REPORT_GRE_INNER, considering that
> \field{hash_types} is a 32-bit bitmap,
> and \field{hash_report} is a 16-bit integer, in order to be compatible
> with existing hash computing devices,
> we can use the first 8 bits of \field{hash_report} as a tunnel-related
> flag, and the last 8 bits of \field{hash_report}
> represent the hash five-tuple, e.g. VIRTIO_NET_HASH_TYPE_TCPv4.
>
> That is, if the value of the obtained \field{hash_report} is greater
> than 256, it means that the driver wants
> the device to calculate the hash for the inner header of the
> tunnel-encapsulated packet . And if the value is less
> than 256, the default outer header hashing will be performed.
>
> Do you think this proposal is feasible?ð
Any advantages of this over simply making padding_reserved a part of
the hash report?
Thanks
>
> Thanks.
>
> >
> > Thanks
> >
> >> Thanks.
> >>
> >>> Thanks
> >>>
> >>>> This is a configurable hash specification.
> >>>>
> >>>> Thanks.
> >>>>
> >>>>> Thanks
> >>>>>
> >>>>>> Thanks.
> >>>>>>
> >>>>>>> On Thu, Nov 10, 2022 at 5:41 AM Heng Qi <hengqi@linux.alibaba.com> wrote:
> >>>>>>>> å 2022/11/10 äå11:35, Jason Wang åé:
> >>>>>>>>> On Wed, Nov 9, 2022 at 7:33 PM Heng Qi <hengqi@linux.alibaba.com> wrote:
> >>>>>>>>>> From: Heng Qi <henqqi@linux.alibaba.com>
> >>>>>>>>>>
> >>>>>>>>>> When VIRTIO_NET_F_RSS is negotiated and 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 VIRTIO_NET_HASH_TYPE_GRE_INNER bitmask in \field{hash_types},
> >>>>>>>>>> which instructs the device to calculate the hash using the inner headers
> >>>>>>>>>> of GRE-encapsulated packets.
> >>>>>>>>>>
> >>>>>>>>>> Signed-off-by: Heng Qi <henqqi@linux.alibaba.com>
> >>>>>>>>>> Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
> >>>>>>>>>> ---
> >>>>>>>>>> content.tex | 116 ++++++++++++++++++++++++++++++++++++++++++++++++++++
> >>>>>>>>>> 1 file changed, 116 insertions(+)
> >>>>>>>>>>
> >>>>>>>>>> diff --git a/content.tex b/content.tex
> >>>>>>>>>> index 6fabf1d..319d401 100644
> >>>>>>>>>> --- a/content.tex
> >>>>>>>>>> +++ b/content.tex
> >>>>>>>>>> @@ -3883,6 +3883,10 @@ \subsubsection{Processing of Incoming Packets}\label{sec:Device Types / Network
> >>>>>>>>>> #define VIRTIO_NET_HASH_TYPE_TCP_EX (1 << 7)
> >>>>>>>>>> #define VIRTIO_NET_HASH_TYPE_UDP_EX (1 << 8)
> >>>>>>>>>> \end{lstlisting}
> >>>>>>>>>> +Hash types applicable to inner payloads of GRE-encapsulated packets
> >>>>>>>>>> +\begin{lstlisting}
> >>>>>>>>>> +#define VIRTIO_NET_HASH_TYPE_GRE_INNER (1 << 9)
> >>>>>>>>>> +\end{lstlisting}
> >>>>>>>>>>
> >>>>>>>>>> \subparagraph{IPv4 packets}
> >>>>>>>>>> \label{sec:Device Types / Network Device / Device Operation / Processing of Incoming Packets / Hash calculation for incoming packets / IPv4 packets}
> >>>>>>>>>> @@ -3975,6 +3979,114 @@ \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 payloads of GRE-encapsulated packets}
> >>>>>>>>>> +\label{sec:Device Types / Network Device / Device Operation / Processing of Incoming Packets / Hash calculation for incoming packets / Inner payloads of GRE-encapsulated packets}}
> >>>>>>>>>> +VIRTIO_NET_HASH_TYPE_GRE_INNER bit MUST be set at the same time as one of
> >>>>>>>>>> +the bits between VIRTIO_NET_HASH_TYPE_IPv4 and VIRTIO_NET_HASH_TYPE_UDP_EX.
> >>>>>>>>> "MUST" keyword must belong to the normative section.
> >>>>>>>> Okay. Thanks for pointing out.
> >>>>>>>>
> >>>>>>>>>> +
> >>>>>>>>>> +The device calculates the hash on GRE-encapsulated packets whose inner payloads
> >>>>>>>>>> +are IPv4 packets according to 'Enabled hash types' bitmasks as follows:
> >>>>>>>>>> +\begin{itemize}
> >>>>>>>>>> + \item If both VIRTIO_NET_HASH_TYPE_GRE_INNER and VIRTIO_NET_HASH_TYPE_TCPv4 bits
> >>>>>>>>>> + are set, and the GRE-encapsulated packet has an inner TCPv4 header in its
> >>>>>>>>>> + payload, 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 both VIRTIO_NET_HASH_TYPE_GRE_INNER and VIRTIO_NET_HASH_TYPE_UDPv4
> >>>>>>>>>> + bits are set, and the GRE-encapsulated packet has an inner UDPv4 header in
> >>>>>>>>>> + its payload, 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 both VIRTIO_NET_HASH_TYPE_GRE_INNER and VIRTIO_NET_HASH_TYPE_IPv4
> >>>>>>>>>> + bits are 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 GRE-encapsulated packets whose inner payloads
> >>>>>>>>>> +are IPv6 packets without extension headers according to 'Enabled hash types'
> >>>>>>>>>> +bitmasks as follows:
> >>>>>>>>>> +\begin{itemsize}
> >>>>>>>>>> + \item If both VIRTIO_NET_HASH_TYPE_GRE_INNER and VIRTIO_NET_HASH_TYPE_TCPv6
> >>>>>>>>>> + bits are set, and the GRE-encapsulated packet has an inner TCPv6 header in
> >>>>>>>>>> + its payload, 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 both VIRTIO_NET_HASH_TYPE_GRE_INNER and VIRTIO_NET_HASH_TYPE_UDPv6
> >>>>>>>>>> + bits are set, and the GRE-encapsulated packet has an inner UDPv6 header in
> >>>>>>>>>> + its payload, 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 both VIRTIO_NET_HASH_TYPE_GRE_INNER and VIRTIO_NET_HASH_TYPE_IPv6
> >>>>>>>>>> + bits are 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 GRE-encapsulated packets whose inner payloads
> >>>>>>>>>> +are IPv6 packets with extension headers according to 'Enabled hash types'
> >>>>>>>>>> +bitmasks as follows:
> >>>>>>>>>> +\begin{itemsize}
> >>>>>>>>>> + \item If both VIRTIO_NET_HASH_TYPE_GRE_INNER and VIRTIO_NET_HASH_TYPE_TCP_EX
> >>>>>>>>>> + bits are set, and the GRE-encapsulated packet has an inner TCPv6 header in
> >>>>>>>>>> + its payload, the hash is calculated over the following fields:
> >>>>>>>>>> + \begin{itemize}
> >>>>>>>>>> + \item Home address from the home address option in the IPv6 destination options
> >>>>>>>>> Is this inner or outer?
> >>>>>>>>>
> >>>>>>>>> Thanks
> >>>>>>>>>
> >>>>>>>>>> + 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 both VIRTIO_NET_HASH_TYPE_GRE_INNER and VIRTIO_NET_HASH_TYPE_UDP_EX
> >>>>>>>>>> + bits are set, and the GRE-encapsulated packet has an inner UDPv6 header in its
> >>>>>>>>>> + payload, the hash is calculated over the following fields:
> >>>>>>>>>> + \begin{itemsize}
> >>>>>>>>>> + \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 both VIRTIO_NET_HASH_TYPE_GRE_INNER and VIRTIO_NET_HASH_TYPE_IP_EX
> >>>>>>>>>> + bits are set, the hash is calculated over the following fields:
> >>>>>>>>>> + \begin{itemsize}
> >>>>>>>>>> + \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 for
> >>>>>>>>>> + a GRE-encapsulated packet whose inner payload is an IPv6 packet without
> >>>>>>>>>> + extension headers
> >>>>>>>>>> +\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}
> >>>>>>>>>>
> >>>>>>>>>> @@ -4005,6 +4117,10 @@ \subsubsection{Processing of Incoming Packets}\label{sec:Device Types / Network
> >>>>>>>>>> #define VIRTIO_NET_HASH_REPORT_UDPv6_EX 9
> >>>>>>>>>> \end{lstlisting}
> >>>>>>>>>>
> >>>>>>>>>> +VIRTIO_NET_HASH_TYPE_GRE_INNER bit is not included in \field{hash_report},
> >>>>>>>>>> +it just indicates that the hash is calculated using the inner header inside
> >>>>>>>>>> +the GRE-encapsulated packet.
> >>>>>>>>>> +
> >>>>>>>>>> \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
> >>>>>>>>>> --
> >>>>>>>>>> 2.19.1.6.gb485710b
> >>>>>>>>>>
> >>>>>>>> ---------------------------------------------------------------------
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