On Wed, Dec 21 2022, Heng Qi <[email protected]> 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 tunnel 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.
>
> Signed-off-by: Heng Qi <[email protected]>
> Signed-off-by: Xuan Zhuo <[email protected]>
> ---
> 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 | 198 ++++++++++++++++++++++++++++++++++++++++++++++++++--
> 1 file changed, 191 insertions(+), 7 deletions(-)
>
> diff --git a/content.tex b/content.tex
> index e863709..dac21f1 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-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_TUNNEL is negotiated.
This might be mildly confusing -- maybe make this
"Device can report per-packet hash value, a type of calculated hash,
and, if VIRTIO_NET_F_HASH_TUNNEL is negotiated, a tunnel 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)
> + le8 hash_report_tunnel; (Only if both VIRTIO_NET_F_HASH_REPORT and
> VIRTIO_NET_F_HASH_TUNNEL are negotiated)
> + le8 padding_reserved; (Only if VIRTIO_NET_F_HASH_REPORT negotiated)
We still have the same length of the header without F_HASH_TUNNEL, I
think? So hash_report_tunnel would be "Only if VIRTIO_NET_F_HASH_REPORT
negotiated, only valid of VIRTIO_NET_F_HASH_TUNNEL negotiated" (or a
better wording...)
Also, there's no le8, just plain u8 :)
> };
> \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. The tunnel type can only
> +be reported when both VIRTIO_NET_F_HASH_REPORT and VIRTIO_NET_F_HASH_TUNNEL
> are negotiated.
Maybe "If additionally VIRTIO_NET_F_HASH_TUNNEL was negotiated, the
device reports the tunnel type as well." ?
> \end{itemize}
>
> If the feature VIRTIO_NET_F_RSS was negotiated:
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