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Subject: Re: [virtio-comment] Re: [virtio-dev] Re: [PATCH v8] virtio-net: support inner header hash
On Fri, Feb 17, 2023 at 09:25:01AM -0500, Michael S. Tsirkin wrote:
> On Thu, Feb 16, 2023 at 10:11:58PM +0800, Heng Qi wrote:
> >
> >
> > å 2023/2/16 äå7:59, Michael S. Tsirkin åé:
> > > On Thu, Feb 16, 2023 at 03:20:17PM +0800, Heng Qi wrote:
> > > >
> > > > å 2023/2/14 äå6:20, Michael S. Tsirkin åé:
> > > > > On Wed, Feb 08, 2023 at 05:08:36PM +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_tunnel_types}, which instructs the device to calculate the
> > > > > > hash using the inner headers of tunnel-encapsulated packets. Besides,
> > > > > > values in \field{hash_report_tunnel_types} are added to report tunnel types.
> > > > > >
> > > > > > Note that VIRTIO_NET_F_HASH_TUNNEL only indicates the ability of the inner
> > > > > > header hash, and does not give the device the ability to use the hash value
> > > > > > to select a receiving queue to place the packet.
> > > > > This is the part I am missing. Where is this in the proposal?
> > > > The core function of the inner header hash feature is to provide a hash
> > > > value calculated using the inner header.
> > > > This is its semantics. We just tell the device that if this feature is
> > > > negotiated, the value of \field{hash_value}
> > > > comes from the inner header. VIRTIO_NET_F_HASH_REPORT is also such a
> > > > function, it tells the device that you
> > > > need to provide the hash value and hash type. If the device needs to use the
> > > > calculated hash value to select the
> > > > queue to place packets, then use VIRTIO_NET_F_RSS at the same time.
> > > >
> > > > Thanks.
> > > So VIRTIO_NET_F_HASH_TUNNEL indeed does not give the device the ability to use the hash value
> > > to select a receiving queue to place the packet.
> >
> > Yes.
> >
> > > However, the new hash_tunnel_types introduced here do give the device
> > > this ability if enabled by VIRTIO_NET_F_RSS.
> > >
> > > Asymmetrical.
> >
> > supported_hash_types only means that the device has the ability to calculate
> > hash, and does not force the device
> > to use hash to select a queue and place the packets. Even if only
> > VIRTIO_NET_F_HASH_REPORT is negotiated and
> > VIRTIO_NET_F_RSS is not negotiated, the device can also have the ability to
> > calculate hash instead of selecting a
> > queue based on supported_hash_types.
> >
> > VIRTIO_NET_F_HASH_TUNNEL is similar to VIRTIO_NET_F_HASH_REPORT, and
> > supported_tunnel_hash_types is also similar to supported_hash_types,
>
> yes
>
> > which has nothing to do with selecting a queue to place packets.
>
> no
>
> If you enable VIRTIO_NET_F_RSS then hash whatever it is
> will affect the queue selected. So "nothing to do" is wrong
> is it not?
Yes. And sorry I didn't express clearly, what I mean is that
VIRTIO_NET_F_HASH_TUNNEL provides the capability of inner header hash
calculation, and VIRTIO_NET_F_RSS may use this hash value to select a queue.
>
>
> > Take an example in the spec:
> > "The next field, \field{supported_hash_types} only exists if the device
> > supports hash calculation,
> > i.e. if VIRTIO_NET_F_RSS or VIRTIO_NET_F_HASH_REPORT is set."
> >
> > >
> > > To me, VIRTIO_NET_F_HASH_TUNNEL makes sense if we keep
> > > hash_report_tunnel. And Parav insists we should drop hash_report_tunnel.
> >
> > If we really don't have a practical use case for hash_report_tunnel_type, we
> > can merge its type into hash_report.
> >
> > >
> > > So I have a suggestion:
> > >
> > > Disconnect VIRTIO_NET_F_HASH_TUNNEL from hash calculation.
> > > Just make it imply that hash_report_tunnel is valid.
> > >
Is there any better advantage of disconnecting VIRTIO_NET_F_HASH_TUNNEL from hash calculation?
Can you explain more clearly?
I think both VIRTIO_NET_F_HASH_REPORT and VIRTIO_NET_F_RSS indicate by
default that the device can compute hash, controlling the presence of
related structures and hash_types. VIRTIO_NET_F_HASH_TUNNEL also makes
sense to do so.
> > > Whether hash is calculated over the inner header is controlled
> > > by the hash_report_tunnel_types.
> >
We assume that hash_report_tunnel_types is still present in the next
version, but it only exists in virtio net hdr and should be populated by
the device after the hash calculation. hash_tunnel_types already
controls whether the device computes internal header hashes.
> > I don't really follow this, hash_report_tunnel_type is better off keeping it
> > "report" literally.
>
>
> Talking about VIRTIO_NET_F_HASH_TUNNEL here. Not
> hash_report_tunnel_type.
Ok.
Thanks.
>
> > >
> > >
> > >
> > > > > We currently have:
> > > > >
> > > > > The device MUST determine the destination queue for a network packet as follows:
> > > > > \begin{itemize}
> > > > > \item Calculate the hash of the packet as defined in \ref{sec:Device Types / Network Device / Device Operation / Processing of Incoming Packets / Hash calculation for incoming packets}.
> > > > > \item If the device did not calculate the hash for the specific packet, the device directs the packet to the receiveq specified by \field{unclassified_queue} of virtio_net_rss_config structure (value of 0 corresponds to receiveq1).
> > > > > \item Apply \field{indirection_table_mask} to the calculated hash and use the result as the index in the indirection table to get 0-based number of destination receiveq (value of 0 corresponds to receiveq1).
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > > 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>
> > > > > > ---
> > > > > > v7->v8:
> > > > > > 1. Add supported_hash_tunnel_types. @Jason Wang, @Parav Pandit
> > > > > > 2. Change hash_report_tunnel to hash_report_tunnel_types. @Parav Pandit
> > > > > > 3. Removed re-definition for inner packet hashing. @Parav Pandit
> > > > > > 4. Fix some typos. @Michael S . Tsirkin
> > > > > > 5. Clarify some sentences. @Michael S . Tsirkin
> > > > > >
> > > > > > v6->v7:
> > > > > > 1. Modify the wording of some sentences for clarity. @Michael S. Tsirkin
> > > > > > 2. Fix some syntax issues. @Michael S. Tsirkin
> > > > > >
> > > > > > v5->v6:
> > > > > > 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->v5:
> > > > > > 1. Clarify some paragraphs. @Cornelia Huck
> > > > > > 2. Fix the u8 type. @Cornelia Huck
> > > > > >
> > > > > > v3->v4:
> > > > > > 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->v3:
> > > > > > 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->v2:
> > > > > > 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 | 135 ++++++++++++++++++++++++++++++++++++++++++-----
> > > > > > introduction.tex | 19 +++++++
> > > > > > 2 files changed, 140 insertions(+), 14 deletions(-)
> > > > > >
> > > > > > diff --git a/content.tex b/content.tex
> > > > > > index e863709..2598d96 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 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, 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}
> > > > > > @@ -3199,20 +3204,27 @@ \subsection{Device configuration layout}\label{sec:Device Types / Network Device
> > > > > > u8 rss_max_key_size;
> > > > > > le16 rss_max_indirection_table_length;
> > > > > > le32 supported_hash_types;
> > > > > > + le32 supported_tunnel_hash_types;
> > > > > > };
> > > > > > \end{lstlisting}
> > > > > > -The following field, \field{rss_max_key_size} only exists if VIRTIO_NET_F_RSS or VIRTIO_NET_F_HASH_REPORT is set.
> > > > > > +The following field, \field{rss_max_key_size} only exists if VIRTIO_NET_F_RSS, VIRTIO_NET_F_HASH_REPORT or VIRTIO_NET_F_HASH_TUNNEL is set.
> > > > > > It specifies the maximum supported length of RSS key in bytes.
> > > > > > The following field, \field{rss_max_indirection_table_length} only exists if VIRTIO_NET_F_RSS is set.
> > > > > > It specifies the maximum number of 16-bit entries in RSS indirection table.
> > > > > > The next field, \field{supported_hash_types} only exists if the device supports hash calculation,
> > > > > > -i.e. if VIRTIO_NET_F_RSS or VIRTIO_NET_F_HASH_REPORT is set.
> > > > > > +i.e. if VIRTIO_NET_F_RSS, VIRTIO_NET_F_HASH_REPORT or VIRTIO_NET_F_HASH_TUNNEL is set.
> > > > > > Field \field{supported_hash_types} contains the bitmask of supported hash types.
> > > > > > See \ref{sec:Device Types / Network Device / Device Operation / Processing of Incoming Packets / Hash calculation for incoming packets / Supported/enabled hash types} for details of supported hash types.
> > > > > > +The next field, \field{supported_tunnel_hash_types} only exists if the device
> > > > > > +supports inner hash calculation, i.e. if VIRTIO_NET_F_HASH_TUNNEL is set.
> > > > > > +
> > > > > > +Field \field{supported_tunnel_hash_types} contains the bitmask of supported tunnel hash types.
> > > > > > +See \ref{sec:Device Types / Network Device / Device Operation / Processing of Incoming Packets / Hash calculation for incoming packets / Supported/enabled tunnel hash types} for details of supported tunnel hash types.
> > > > > > +
> > > > > > \devicenormative{\subsubsection}{Device configuration layout}{Device Types / Network Device / Device configuration layout}
> > > > > > The device MUST set \field{max_virtqueue_pairs} to between 1 and 0x8000 inclusive,
> > > > > > @@ -3236,7 +3248,7 @@ \subsection{Device configuration layout}\label{sec:Device Types / Network Device
> > > > > > negotiated.
> > > > > > The device MUST set \field{rss_max_key_size} to at least 40, if it offers
> > > > > > -VIRTIO_NET_F_RSS or VIRTIO_NET_F_HASH_REPORT.
> > > > > > +VIRTIO_NET_F_RSS, VIRTIO_NET_F_HASH_REPORT or VIRTIO_NET_F_HASH_TUNNEL.
> > > > > > The device MUST set \field{rss_max_indirection_table_length} to at least 128, if it offers
> > > > > > VIRTIO_NET_F_RSS.
> > > > > > @@ -3384,9 +3396,10 @@ \subsection{Device Operation}\label{sec:Device Types / Network Device / Device O
> > > > > > le16 csum_start;
> > > > > > le16 csum_offset;
> > > > > > 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)
> > > > > > + le32 hash_value; (Only if VIRTIO_NET_F_HASH_REPORT negotiated)
> > > > > > + le16 hash_report; (Only if VIRTIO_NET_F_HASH_REPORT negotiated)
> > > > > > + u8 hash_report_tunnel_types; (Only if VIRTIO_NET_F_HASH_REPORT negotiated, only valid if VIRTIO_NET_F_HASH_TUNNEL negotiated, otherwise reserved)
> > > > > > + u8 padding_reserved; (Only if VIRTIO_NET_F_HASH_REPORT negotiated)
> > > > > > };
> > > > > > \end{lstlisting}
> > > > > > @@ -3838,11 +3851,15 @@ \subsubsection{Processing of Incoming Packets}\label{sec:Device Types / Network
> > > > > > \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.
> > > > > > + If additionally VIRTIO_NET_F_HASH_TUNNEL was negotiated, the device reports the encapsulation type as well.
> > > > > > +\item The feature VIRTIO_NET_F_HASH_TUNNEL was negotiated. The device supports inner hash calculation.
> > > > > > \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.
> > > > > > + If additionally VIRTIO_NET_F_HASH_TUNNEL was negotiated, the device uses \field{hash_tunnel_types} of the
> > > > > > + virtio_net_rss_config structure as 'Enabled hash tunnel types' bitmask.
> > > > > > \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}
> > > > > > @@ -3850,11 +3867,13 @@ \subsubsection{Processing of Incoming Packets}\label{sec:Device Types / Network
> > > > > > 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.
> > > > > > + If additionally VIRTIO_NET_F_HASH_TUNNEL was negotiated, the device uses \field{hash_tunnel_types} of the
> > > > > > + virtio_net_hash_config structure as 'Enabled hash tunnel types' bitmask.
> > > > > > \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}
> > > > > > -Note that if the device offers VIRTIO_NET_F_HASH_REPORT, even if it supports only one pair of virtqueues, it MUST support
> > > > > > +Note that if the device offers VIRTIO_NET_F_HASH_REPORT or VIRTIO_NET_F_HASH_TUNNEL, even if it supports only one pair of virtqueues, it MUST support
> > > > > > at least one of commands of VIRTIO_NET_CTRL_MQ class to configure reported hash parameters:
> > > > > > \begin{itemize}
> > > > > > \item If the device offers VIRTIO_NET_F_RSS, it MUST support VIRTIO_NET_CTRL_MQ_RSS_CONFIG command per
> > > > > > @@ -3863,8 +3882,37 @@ \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_tunnel_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 tunnel types}.
> > > > > > +
> > > > > > +If both VIRTIO_NET_F_HASH_REPORT and VIRTIO_NET_F_HASH_TUNNEL are negotiated,
> > > > > > +and the corresponding encapsulation type is set in \field{hash_tunnel_types},
> > > > > > +the device supports inner hash calculation for the encapsulated packet,
> > > > > > +For example, if the encapsulated packets \hyperref[intro:GRE]{[GRE]},
> > > > > > +\hyperref[intro:VXLAN]{[VXLAN]} and \hyperref[intro:GENEVE]{[GENEVE]} are hashed in inner
> > > > > > +headers, then \field{hash_tunnel_types} should be set to VIRTIO_NET_HASH_TUNNEL_TYPE_{GRE, VXLAN, GENEVE}
> > > > > > +respectively, and \field{hash_report_tunnel_types} should be respectively set to
> > > > > > +VIRTIO_NET_HASH_TUNNEL_REPORT_{GRE, VXLAN, GENEVE}.
> > > > > > +
> > > > > > +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_types} 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 +3932,24 @@ \subsubsection{Processing of Incoming Packets}\label{sec:Device Types / Network
> > > > > > #define VIRTIO_NET_HASH_TYPE_UDP_EX (1 << 8)
> > > > > > \end{lstlisting}
> > > > > > +\subparagraph{Supported/enabled tunnel hash types}
> > > > > > +\label{sec:Device Types / Network Device / Device Operation / Processing of Incoming Packets / Hash calculation for incoming packets / Supported/enabled tunnel hash types}
> > > > > > +If the feature VIRTIO_NET_F_HASH_TUNNEL is negotiated, the encapsulation
> > > > > > +hash type 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_TUNNEL_TYPE_GRE (1 << 0)
> > > > > > +\end{lstlisting}
> > > > > > +Hash type applicable for inner payload of the vxlan-encapsulated packet
> > > > > > +\begin{lstlisting}
> > > > > > +#define VIRTIO_NET_HASH_TUNNEL_TYPE_VXLAN (1 << 1)
> > > > > > +\end{lstlisting}
> > > > > > +Hash type applicable for inner payload of the geneve-encapsulated packet
> > > > > > +\begin{lstlisting}
> > > > > > +#define VIRTIO_NET_HASH_TUNNEL_TYPE_GENEVE (1 << 2)
> > > > > > +\end{lstlisting}
> > > are these the only tunnel types we can thinkably support?
> >
> > This is the tunnel types our group currently uses, do you think we should
> > add more tunnel types?
>
> I would try to be inclusive, yes.
>
> > >
> > > > > > \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 +4041,26 @@ \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 hash calculation of an encapsulated packet}
> > > > > > +If the feature VIRTIO_NET_F_HASH_TUNNEL is negotiated and the corresponding
> > > > > > +encapsulation hash type is set in \field{hash_tunnel_types}, the device calculates the
> > > > > > +hash on the inner header of an encapsulated packet (See \ref{sec:Device Types
> > > > > > +/ Network Device / Device Operation / Processing of Incoming Packets /
> > > > > > +Hash calculation for incoming packets / Tunnel/Encapsulated packet}), and
> > > > > > +\field{hash_report_tunnel_types} contains the valid outer tunnel type.
> > > > > > +
> > > > > > \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_types} with the report type of the encapsulated packet,
> > > > > > +and it is set to VIRTIO_NET_HASH_TUNNEL_REPORT_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_types} to VIRTIO_NET_HASH_TUNNEL_REPORT_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 +4082,26 @@ \subsubsection{Processing of Incoming Packets}\label{sec:Device Types / Network
> > > > > > #define VIRTIO_NET_HASH_REPORT_UDPv6_EX 9
> > > > > > \end{lstlisting}
> > > > > > +\field{hash_report_tunnel} can report the type of the encapsulated
> > > > > > +packet to the driver when the inner header hash is calculated.
> > > > > > +Possible values that the device can report in \field{hash_report_tunnel_types}
> > > > > > +are defined below.
> > > > > > +They correspond to supported hash tunnel types defined in
> > > > > > +\ref{sec:Device Types / Network Device / Device Operation / Processing of Incoming Packets / Hash calculation for incoming packets / Supported/enabled hash tunnel types}
> > > > > > +as follows:
> > > > > > +
> > > > > > +VIRTIO_NET_HASH_TUNNEL_TYPE_XXX = 1 << (VIRTIO_NET_HASH_TUNNEL_REPORT_XXX -1)
> > > > > > +
> > > > > > +\begin{lstlisting}
> > > > > > +#define VIRTIO_NET_HASH_TUNNEL_REPORT_NONE 0
> > > > > > +#define VIRTIO_NET_HASH_TUNNEL_REPORT_GRE 1
> > > > > > +#define VIRTIO_NET_HASH_TUNNEL_REPORT_VXLAN 2
> > > > > > +#define VIRTIO_NET_HASH_TUNNEL_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
> > > > > > @@ -4364,6 +4461,7 @@ \subsubsection{Control Virtqueue}\label{sec:Device Types / Network Device / Devi
> > > > > > \begin{lstlisting}
> > > > > > struct virtio_net_hash_config {
> > > > > > le32 hash_types;
> > > > > > + le32 hash_tunnel_types;
> > > > > > le16 reserved[4];
> > > wait a second. this must be reserved[2] now.
> > >
> >
> > Thanks for pointing it out. I'll fix it.
> >
> > >
> > >
> > > > > > u8 hash_key_length;
> > > > > > u8 hash_key_data[hash_key_length];
> > > > > > @@ -4372,7 +4470,12 @@ \subsubsection{Control Virtqueue}\label{sec:Device Types / Network Device / Devi
> > > > > > Field \field{hash_types} contains a bitmask of allowed hash types as
> > > > > > defined in
> > > > > > \ref{sec:Device Types / Network Device / Device Operation / Processing of Incoming Packets / Hash calculation for incoming packets / Supported/enabled hash types}.
> > > > > > -Initially the device has all hash types disabled and reports only VIRTIO_NET_HASH_REPORT_NONE.
> > > > > > +
> > > > > > +Field \field{hash_tunnel_types} contains a bitmask of allowed hash tunnel types as
> > > > > > +defined in \ref{sec:Device Types / Network Device / Device Operation / Processing of Incoming Packets / Hash calculation for incoming packets / Supported/enabled hash tunnel types}.
> > > > > > +
> > > > > > +Initially the device has all hash types and hash tunnel types disabled and reports only
> > > > > > +VIRTIO_NET_HASH_REPORT_NONE and VIRTIO_NET_HASH_TUNNEL_REPORT_NONE respectively.
> > > > > > Field \field{reserved} MUST contain zeroes. It is defined to make the structure to match the layout of virtio_net_rss_config structure,
> > > > > > defined in \ref{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Receive-side scaling (RSS)}.
> > > > > > @@ -4390,6 +4493,7 @@ \subsubsection{Control Virtqueue}\label{sec:Device Types / Network Device / Devi
> > > > > > \begin{lstlisting}
> > > > > > struct virtio_net_rss_config {
> > > > > > le32 hash_types;
> > > > > > + le32 hash_tunnel_types;
> > > > > > le16 indirection_table_mask;
> > > > > > le16 unclassified_queue;
> > > > > > le16 indirection_table[indirection_table_length];
> > > > > > @@ -4402,6 +4506,9 @@ \subsubsection{Control Virtqueue}\label{sec:Device Types / Network Device / Devi
> > > > > > defined in
> > > > > > \ref{sec:Device Types / Network Device / Device Operation / Processing of Incoming Packets / Hash calculation for incoming packets / Supported/enabled hash types}.
> > > > > > +Field \field{hash_tunnel_types} contains a bitmask of allowed hash tunnel types as
> > > > > > +defined in \ref{sec:Device Types / Network Device / Device Operation / Processing of Incoming Packets / Hash calculation for incoming packets / Supported/enabled hash tunnel types}.
> > > > > > +
> > > > > > Field \field{indirection_table_mask} is a mask to be applied to
> > > > > > the calculated hash to produce an index in the
> > > > > > \field{indirection_table} array.
> > > > > > 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
> > > > > ---------------------------------------------------------------------
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