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Subject: Re: [PATCH v3] virtio_net: support inner header hash
On Mon, Dec 5, 2022 at 2:36 PM Heng Qi <hengqi@linux.alibaba.com> wrote:
>
> 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_F_HASH_GRE_VXLAN_GENEVE_INNER feature bit and
I think we can simply use VIRTIO_NET_F_HASH_TUNNEL now. And introduce
VIRTIO_NET_F_HASH_TUNNEL_XYZ for future extension?
> related bitmasks in \field{hash_types}, which instructs the device
> to calculate the hash using the inner headers of GRE, VXLAN or
> GENEVE-encapsulated packets. Besides, \field{hash_report_tunnel} are
> added to report packet type when calculating hash over the inner header.
>
> Signed-off-by: Heng Qi <hengqi@linux.alibaba.com>
> Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
> ---
> 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 | 190 +++++++++++++++++++++++++++++++++++++++++++++++++---
> 1 file changed, 181 insertions(+), 9 deletions(-)
>
> diff --git a/content.tex b/content.tex
> index e863709..675da87 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_GRE_VXLAN_GENEVE_INNER(52)] Device supports inner
> + header hash for GRE, VXLAN and GENEVE-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 a tunnel packet type if
> + VIRTIO_NET_F_HASH_GRE_VXLAN_GENEVE_INNER is negotiated.
>
> \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_GRE_VXLAN_GENEVE_INNER] Requires VIRTIO_NET_F_CTRL_VQ and VIRTIO_NET_F_RSS.
> \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)
> + le8 hash_report_tunnel; (Only if VIRTIO_NET_F_HASH_REPORT negotiated)
Only if both VIRTIO_NET_F_HASH_REPORT and
VIRTIO_NET_F_HASH_GRE_VXLAN_GENEVE_INNER are negotiated?
> + le8 padding_reserved; (Only if VIRTIO_NET_F_HASH_REPORT negotiated)
> };
> \end{lstlisting}
>
> @@ -3837,19 +3843,22 @@ \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, the hash type and the tunnel packet type.
The tunnel type can only be reported when both HASH_REPORT and
HASH_GRE_VXLAN_GENEVE_INNER are negotiated?
> \end{itemize}
>
> If the feature VIRTIO_NET_F_RSS was negotiated:
> \begin{itemize}
> -\item The device uses \field{hash_types} of the virtio_net_rss_config structure as 'Enabled hash types' bitmask.
> +\item The device uses \field{hash_types} of the virtio_net_rss_config structure as 'Enabled hash types' bitmask,
> +but VIRTIO_NET_HASH_TYPE_GRE_INNER, VIRTIO_NET_HASH_TYPE_VXLAN_INNER and VIRTIO_NET_HASH_TYPE_GENEVE_INNER in
> +\field{hash_types} can only be used when the feature VIRTIO_NET_F_HASH_GRE_VXLAN_GENEVE_INNER is negotiated.
I think we can avoid this change by clarifying the feature dependency
where the tunnel hash types are defined.
> \item The device uses a key as defined in \field{hash_key_data} and \field{hash_key_length} of the virtio_net_rss_config structure (see
> \ref{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Receive-side scaling (RSS) / Setting RSS parameters}).
> \end{itemize}
>
> If the feature VIRTIO_NET_F_RSS was not negotiated:
> \begin{itemize}
> -\item The device uses \field{hash_types} of the virtio_net_hash_config structure as 'Enabled hash types' bitmask.
> +\item The device uses \field{hash_types} of the virtio_net_hash_config structure as 'Enabled hash types' bitmask,
> +except VIRTIO_NET_HASH_TYPE_GRE_INNER, VIRTIO_NET_HASH_TYPE_VXLAN_INNER and VIRTIO_NET_HASH_TYPE_GENEVE_INNER.
Why exclude those tunnel hash types from _F_MQ? Or do we want to say
the automatic packet steering could be done via the inner packet when
negotiated?
> \item The device uses a key as defined in \field{hash_key_data} and \field{hash_key_length} of the virtio_net_hash_config structure (see
> \ref{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Automatic receive steering in multiqueue mode / Hash calculation}).
> \end{itemize}
> @@ -3883,6 +3892,18 @@ \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}
> +Hash types applicable to inner payloads of VXLAN-encapsulated packets
> +\begin{lstlisting}
> +#define VIRTIO_NET_HASH_TYPE_VXLAN_INNER (1 << 10)
> +\end{lstlisting}
> +Hash types applicable to inner payloads of GENEVE-encapsulated packets
> +\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}
> @@ -3975,15 +3996,148 @@ \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, VXLAN or GENEVE-encapsulated packets}
> +\label{sec:Device Types / Network Device / Device Operation / Processing of Incoming Packets / Hash calculation for incoming packets / Inner payloads of GRE, VXLAN or GENEVE-encapsulated packets}}
> +VIRTIO_NET_HASH_TYPE_GRE_INNER, VIRTIO_NET_HASH_TYPE_VXLAN_INNER or
> +VIRTIO_NET_HASH_TYPE_GENEVE_INNER bit is set at the same time as one of
> +the bits between VIRTIO_NET_HASH_TYPE_IPv4 and VIRTIO_NET_HASH_TYPE_UDP_EX.
> +
> +The device calculates the hash on GRE, VXLAN or GENEVE-encapsulated packets whose inner
> +payloads are IPv4 packets according to 'Enabled hash types' bitmasks as follows:
> +\begin{itemize}
> + \item If VIRTIO_NET_HASH_TYPE_TCPv4 is set along with one of
> + VIRTIO_NET_HASH_TYPE_GRE_INNER, VIRTIO_NET_HASH_TYPE_VXLAN_INNER and
> + VIRTIO_NET_HASH_TYPE_GENEVE_INNER, and the GRE, VXLAN or GENEVE-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 VIRTIO_NET_HASH_TYPE_UDPv4 is set along with one of
> + VIRTIO_NET_HASH_TYPE_GRE_INNER, VIRTIO_NET_HASH_TYPE_VXLAN_INNER and
> + VIRTIO_NET_HASH_TYPE_GENEVE_INNER, and the GRE, VXLAN or GENEVE-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 VIRTIO_NET_HASH_TYPE_IPv4 is set along with one of
> + VIRTIO_NET_HASH_TYPE_GRE_INNER, VIRTIO_NET_HASH_TYPE_VXLAN_INNER and
> + VIRTIO_NET_HASH_TYPE_GENEVE_INNER, 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, VXLAN or GENEVE-encapsulated packets whose inner
> +payloads are IPv6 packets without extension headers according to 'Enabled hash types'
> +bitmasks as follows:
> +\begin{itemize}
> + \item If VIRTIO_NET_HASH_TYPE_TCPv6 is set along with one of
> + VIRTIO_NET_HASH_TYPE_GRE_INNER, VIRTIO_NET_HASH_TYPE_VXLAN_INNER and
> + VIRTIO_NET_HASH_TYPE_GENEVE_INNER, and the GRE, VXLAN or GENEVE-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 VIRTIO_NET_HASH_TYPE_UDPv6 is set along with one of
> + VIRTIO_NET_HASH_TYPE_GRE_INNER, VIRTIO_NET_HASH_TYPE_VXLAN_INNER and
> + VIRTIO_NET_HASH_TYPE_GENEVE_INNER, and the GRE, VXLAN or GENEVE-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 VIRTIO_NET_HASH_TYPE_IPv6 is set along with one of
> + VIRTIO_NET_HASH_TYPE_GRE_INNER, VIRTIO_NET_HASH_TYPE_VXLAN_INNER and
> + VIRTIO_NET_HASH_TYPE_GENEVE_INNER, 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, VXLAN or GENEV-encapsulated packets whose inner
> +payloads are IPv6 packets with extension headers according to 'Enabled hash types'
> +bitmasks as follows:
> +\begin{itemsize}
> + \item If VIRTIO_NET_HASH_TYPE_TCP_EX is set along with one of
> + VIRTIO_NET_HASH_TYPE_GRE_INNER, VIRTIO_NET_HASH_TYPE_VXLAN_INNER and
> + VIRTIO_NET_HASH_TYPE_GENEVE_INNER, and the GRE, VXLAN or GENEVE-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 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 along with one of
> + VIRTIO_NET_HASH_TYPE_GRE_INNER, VIRTIO_NET_HASH_TYPE_VXLAN_INNER and
> + VIRTIO_NET_HASH_TYPE_GENEVE_INNER, and the GRE, VXLAN or GENEVE-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 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 along with one of
> + VIRTIO_NET_HASH_TYPE_GRE_INNER, VIRTIO_NET_HASH_TYPE_VXLAN_INNER and
> + VIRTIO_NET_HASH_TYPE_GENEVE_INNER, 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 inner IPv6 extension headers and calculate the hash as defined
> + for a GRE, VXLAN or GENEVE-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}
>
> -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.
> +And if VIRTIO_NET_F_HASH_GRE_VXLAN_GENEVE_INNER was negotiated, the device also
> +needs to fills \field{hash_report_tunnel} with the type of the tunnel 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 \field{hash_report_tunnel} is no longer valid.
>
> Possible values that the device can report in \field{hash_report} are defined below.
> They correspond to supported hash types defined in
> @@ -4005,6 +4159,24 @@ \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 tunnel-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_GRE 1
> +#define VIRTIO_NET_HASH_REPORT_VXLAN 2
> +#define VIRTIO_NET_HASH_REPORT_GENEVE 3
> +\end{lstlisting}
> +
> +The values VIRTIO_NET_HASH_REPORT_GRE, VIRTIO_NET_HASH_REPORT_VXLAN and
> +VIRTIO_NET_HASH_REPORT_GENEVE correspond to VIRTIO_NET_HASH_TYPE_GRE_INNER,
> +VIRTIO_NET_HASH_TYPE_VXLAN_INNER and VIRTIO_NET_HASH_TYPE_GENEVE_INNER bits
> +of supported hash types defined in respectively
> +\ref{sec:Device Types / Network Device / Device Operation / Processing of Incoming Packets / Hash calculation for incoming packets / Supported/enabled hash types}.
> +
I think we can simply say "They correspond to supported hash types
defined in \ref{xyz}" as what is done for non-tunnel hash types?
Thanks
> \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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