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Subject: Re: [virtio-comment] [PATCH v2] virtio-net: Define per-packet hash reporting feature
On Sat, Feb 01, 2020 at 12:01:07PM +0200, Yuri Benditovich wrote: > Fixes: https://github.com/oasis-tcs/virtio-spec/issues/66 > Define respective feature bit for virtio-net. > Extend packet layout to populate hash value and type. > Move the definition of IP/TCP/UDP header fields to > calculate the hash out of RSS section to common network > device section. > > Signed-off-by: Yuri Benditovich <yuri.benditovich@daynix.com> Some comments and a question below. > --- > content.tex | 299 ++++++++++++++++++++++++++++++++-------------------- > 1 file changed, 184 insertions(+), 115 deletions(-) > > diff --git a/content.tex b/content.tex > index fb10061..2836e0a 100644 > --- a/content.tex > +++ b/content.tex > @@ -2895,6 +2895,9 @@ \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_REPORT(58)] Device can report per-packet hash > + value and a type of calculated hash. > + > \item[VIRTIO_NET_F_GUEST_HDRLEN(59)] Driver can provide the exact \field{hdr_len} > value. Device benefits from knowing the exact header length. > > @@ -2981,35 +2984,18 @@ \subsection{Device configuration layout}\label{sec:Device Types / Network Device > le32 supported_hash_types; > }; > \end{lstlisting} > -\label{sec:Device Types / Network Device / Device configuration layout / RSS} > -Three following fields, \field{rss_max_key_size}, \field{rss_max_indirection_table_length} > -and \field{supported_hash_types} only exist if VIRTIO_NET_F_RSS is set. > +Two following fields, \field{rss_max_key_size} and \field{rss_max_indirection_table_length} > +only exist if VIRTIO_NET_F_RSS is set. > > Field \field{rss_max_key_size} specifies the maximal supported length of RSS key in bytes. > > Field \field{rss_max_indirection_table_length} specifies the maximal number of 16-bit entries in RSS indirection table. > > -Field \field{supported_hash_types} contains the bitmask of supported RSS hash types. > +The next field, \field{supported_hash_types} exists only if the device supports hash calculation, > +i.e. suggests VIRTIO_NET_F_HASH_REPORT or VIRTIO_NET_F_RSS. i.e. if VIRTIO_NET_F_HASH_REPORT or VIRTIO_NET_F_RSS is set. correct? > > -Hash types applicable for IPv4 packets: > -\begin{lstlisting} > -#define VIRTIO_NET_RSS_HASH_TYPE_IPv4 (1 << 0) > -#define VIRTIO_NET_RSS_HASH_TYPE_TCPv4 (1 << 1) > -#define VIRTIO_NET_RSS_HASH_TYPE_UDPv4 (1 << 2) > -\end{lstlisting} > -Hash types applicable for IPv6 packets without extension headers > -\begin{lstlisting} > -#define VIRTIO_NET_RSS_HASH_TYPE_IPv6 (1 << 3) > -#define VIRTIO_NET_RSS_HASH_TYPE_TCPv6 (1 << 4) > -#define VIRTIO_NET_RSS_HASH_TYPE_UDPv6 (1 << 5) > -\end{lstlisting} > -Hash types applicable for IPv6 packets with extension headers > -\begin{lstlisting} > -#define VIRTIO_NET_RSS_HASH_TYPE_IP_EX (1 << 6) > -#define VIRTIO_NET_RSS_HASH_TYPE_TCP_EX (1 << 7) > -#define VIRTIO_NET_RSS_HASH_TYPE_UDP_EX (1 << 8) > -\end{lstlisting} > -For the exact meaning of VIRTIO_NET_RSS_HASH_TYPE_ flags see \ref{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Receive-side scaling (RSS) / RSS hash types}. > +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. > > \devicenormative{\subsubsection}{Device configuration layout}{Device Types / Network Device / Device configuration layout} > > @@ -3159,6 +3145,8 @@ \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_type; (Only if VIRTIO_NET_F_HASH_REPORT negotiated) > }; > \end{lstlisting} > > @@ -3481,6 +3469,12 @@ \subsubsection{Processing of Incoming Packets}\label{sec:Device Types / Network > > \end{enumerate} > > +If applicable, the device calculates per-packet hash for incoming packets as > +defined in \ref{sec:Device Types / Network Device / Device Operation / Processing of Incoming Packets / Hash calculation for incoming packets}. > + > +If applicable, the device reports hash information for incoming packets as > +defined in \ref{sec:Device Types / Network Device / Device Operation / Processing of Incoming Packets / Hash reporting for incoming packets}. > + > \devicenormative{\paragraph}{Processing of Incoming Packets}{Device Types / Network Device / Device Operation / Processing of Incoming Packets} > \label{devicenormative:Device Types / Network Device / Device Operation / Processing of Packets}%old label for latexdiff > > @@ -3583,6 +3577,168 @@ \subsubsection{Processing of Incoming Packets}\label{sec:Device Types / Network > If neither VIRTIO_NET_HDR_F_NEEDS_CSUM nor > VIRTIO_NET_HDR_F_DATA_VALID is set, the driver MUST NOT > rely on the packet checksum being correct. > + > +\paragraph{Hash calculation for incoming packets} > +\label{sec:Device Types / Network Device / Device Operation / Processing of Incoming Packets / Hash calculation for incoming packets} > + > +A device attempts to calculate per-packet hash in following cases: 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 receive virtqueue to place incoming packet to. the receive virtqueue to place incoming packets > +\item The feature VIRTIO_NET_F_HASH_REPORT was negotiated. The device reports hash value and hash type with the packet. the hash value and the hash type > +\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. the 'Enabled hash types' > +\item The device uses \field{hash_key_data} of the virtio_net_rss_config structure. > +\end{itemize} > +See the definition of virtio_net_rss_config structure in \ref{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Receive-side scaling (RSS) / Setting RSS parameters} > + > +If the feature VIRTIO_NET_F_RSS was not negotiated, the device uses internal configuration > +of enabled hash types and a key used for hash calculation. I don't understand this last paragraph. Could you clarify? > + > +\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} > +Hash types applicable for IPv4 packets: > +\begin{lstlisting} > +#define VIRTIO_NET_HASH_TYPE_IPv4 (1 << 0) > +#define VIRTIO_NET_HASH_TYPE_TCPv4 (1 << 1) > +#define VIRTIO_NET_HASH_TYPE_UDPv4 (1 << 2) > +\end{lstlisting} > +Hash types applicable for IPv6 packets without extension headers > +\begin{lstlisting} > +#define VIRTIO_NET_HASH_TYPE_IPv6 (1 << 3) > +#define VIRTIO_NET_HASH_TYPE_TCPv6 (1 << 4) > +#define VIRTIO_NET_HASH_TYPE_UDPv6 (1 << 5) > +\end{lstlisting} > +Hash types applicable for IPv6 packets with extension headers > +\begin{lstlisting} > +#define VIRTIO_NET_HASH_TYPE_IP_EX (1 << 6) > +#define VIRTIO_NET_HASH_TYPE_TCP_EX (1 << 7) > +#define VIRTIO_NET_HASH_TYPE_UDP_EX (1 << 8) > +\end{lstlisting} > + > +\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: > +\begin{itemize} > +\item If VIRTIO_NET_HASH_TYPE_TCPv4 is set and the packet has > +a TCP header, the hash is calculated over the following fields: > +\begin{itemize} > +\item Source IP address > +\item Destination IP address > +\item Source TCP port > +\item Destination TCP port > +\end{itemize} > +\item Else if VIRTIO_NET_HASH_TYPE_UDPv4 is set and the > +packet has a UDP header, the hash is calculated over the following fields: > +\begin{itemize} > +\item Source IP address > +\item Destination IP address > +\item Source UDP port > +\item Destination UDP port > +\end{itemize} > +\item Else if VIRTIO_NET_HASH_TYPE_IPv4 is set, the hash is > +calculated over the following fields: > +\begin{itemize} > +\item Source IP address > +\item Destination IP address > +\end{itemize} > +\item Else the device does not calculate the hash > +\end{itemize} > + > +\subparagraph{IPv6 packets without extension header} > +\label{sec:Device Types / Network Device / Device Operation / Processing of Incoming Packets / Hash calculation for incoming packets / IPv6 packets without extension header} > +The device calculates the hash on IPv6 packets without extension > +headers to 'Enabled hash types' bitmask as follows: headers to -> headers according to > +\begin{itemize} > +\item If VIRTIO_NET_HASH_TYPE_TCPv6 is set and the packet has > +a TCPv6 header, the hash is calculated over the following fields: > +\begin{itemize} > +\item Source IPv6 address > +\item Destination IPv6 address > +\item Source TCP port > +\item Destination TCP port > +\end{itemize} > +\item Else if VIRTIO_NET_HASH_TYPE_UDPv6 is set and the > +packet has a UDPv6 header, the hash is calculated over the following fields: > +\begin{itemize} > +\item Source IPv6 address > +\item Destination IPv6 address > +\item Source UDP port > +\item Destination UDP port > +\end{itemize} > +\item Else if VIRTIO_NET_HASH_TYPE_IPv6 is set, the hash is > +calculated over the following fields: > +\begin{itemize} > +\item Source IPv6 address > +\item Destination IPv6 address > +\end{itemize} > +\item Else the device does not calculate the hash > +\end{itemize} > + > +\subparagraph{IPv6 packets with extension header} > +\label{sec:Device Types / Network Device / Device Operation / Processing of Incoming Packets / Hash calculation for incoming packets / IPv6 packets with extension header} > +The device calculates the hash on IPv6 packets with extension > +headers according to to 'Enabled hash types' bitmask as follows: > +\begin{itemize} > +\item If VIRTIO_NET_HASH_TYPE_TCP_EX is set and the packet > +has a TCPv6 header, the hash is calculated over the following fields: > +\begin{itemize} > +\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 TCP port > +\item Destination TCP port > +\end{itemize} > +\item Else if VIRTIO_NET_HASH_TYPE_UDP_EX is set and the > +packet has a UDPv6 header, the hash is calculated over the following fields: > +\begin{itemize} > +\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 VIRTIO_NET_HASH_TYPE_IP_EX is set, the hash is > +calculated over the following fields: > +\begin{itemize} > +\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 an IPv6 packet without extension headers > +(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} > + > +\paragraph{Hash reporting for incoming packets} > +\label{sec:Device Types / Network Device / Device Operation / Processing of Incoming Packets / Hash reporting for incoming packets}%old label for latexdiff > + > +If feature VIRTIO_NET_F_HASH_REPORT was negotiated and > + the device has calculated the hash for the packet, the device fills \field{hash_type} with the type of calculated hash > +and \field{hash_value} with the value of calculated hash. > + > +If VIRTIO_NET_F_HASH_REPORT was negotiated but due to any reason the > +has was not calculated, the device sets \field{hash_type} to VIRTIO_NET_HASH_REPORT_NONE. has was -> hash was > + > +Possible values that the device can report in \field{hash_type} are defined below. > +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} > +as follows: > + > +VIRTIO_NET_HASH_TYPE_XXX = 1 << (VIRTIO_NET_HASH_REPORT_XXX - 1) > + > +\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} > + > \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 > @@ -3928,7 +4084,7 @@ \subsubsection{Control Virtqueue}\label{sec:Device Types / Network Device / Devi > \paragraph{Receive-side scaling (RSS)}\label{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Receive-side scaling (RSS)} > A device offers the feature VIRTIO_NET_F_RSS if it supports RSS receive steering with Toeplitz hash calculation and configurable parameters. > > -A driver queries RSS capabilities of the device by reading device configuration as defined in \ref{sec:Device Types / Network Device / Device configuration layout / RSS} > +A driver queries RSS capabilities of the device by reading device configuration as defined in \ref{sec:Device Types / Network Device / Device configuration layout} > > \subparagraph{Setting RSS parameters}\label{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Receive-side scaling (RSS) / Setting RSS parameters} > > @@ -3945,7 +4101,8 @@ \subsubsection{Control Virtqueue}\label{sec:Device Types / Network Device / Devi > }; > \end{lstlisting} > Field \field{hash_types} contains a bitmask of allowed hash types as > -defined in \ref{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Receive-side scaling (RSS) / RSS 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}. > > Field \field{indirection_table_mask} is a mask to be applied to > the calculated hash to produce an index in the > @@ -3959,94 +4116,6 @@ \subsubsection{Control Virtqueue}\label{sec:Device Types / Network Device / Devi > > A driver sets \field{max_tx_vq} to inform a device how many transmit virtqueues it may use (transmitq1\ldots transmitq \field{max_tx_vq}). > > -\subparagraph{RSS hash types}\label{sec:Device Types / Network Device / Device Operation / Control Virtqueue / Receive-side scaling (RSS) / RSS hash types} > - > -The device calculates the hash on IPv4 packets according to the > -field \field{hash_types} of the virtio_net_rss_config structure as follows: > -\begin{itemize} > -\item If VIRTIO_NET_RSS_HASH_TYPE_TCPv4 is set and the packet has > -a TCP header, the hash is calculated over the following fields: > -\begin{itemize} > -\item Source IP address > -\item Destination IP address > -\item Source TCP port > -\item Destination TCP port > -\end{itemize} > -\item Else if VIRTIO_NET_RSS_HASH_TYPE_UDPv4 is set and the > -packet has a UDP header, the hash is calculated over the following fields: > -\begin{itemize} > -\item Source IP address > -\item Destination IP address > -\item Source UDP port > -\item Destination UDP port > -\end{itemize} > -\item Else if VIRTIO_NET_RSS_HASH_TYPE_IPv4 is set, the hash is > -calculated over the following fields: > -\begin{itemize} > -\item Source IP address > -\item Destination IP address > -\end{itemize} > -\item Else the device does not calculate the hash > -\end{itemize} > - > -\label{itm:Device Types / Network Device / Device Operation / Control Virtqueue / Receive-side scaling (RSS) / RSS hash types/hash on IPv6 packets without extension headers} > -The device calculates the hash on IPv6 packets without extension > -headers according to the field \field{hash_types} of the virtio_net_rss_config structure as follows: > -\begin{itemize} > -\item If VIRTIO_NET_RSS_HASH_TYPE_TCPv6 is set and the packet has > -a TCPv6 header, the hash is calculated over the following fields: > -\begin{itemize} > -\item Source IPv6 address > -\item Destination IPv6 address > -\item Source TCP port > -\item Destination TCP port > -\end{itemize} > -\item Else if VIRTIO_NET_RSS_HASH_TYPE_UDPv6 is set and the > -packet has a UDPv6 header, the hash is calculated over the following fields: > -\begin{itemize} > -\item Source IPv6 address > -\item Destination IPv6 address > -\item Source UDP port > -\item Destination UDP port > -\end{itemize} > -\item Else if VIRTIO_NET_RSS_HASH_TYPE_IPv6 is set, the hash is > -calculated over the following fields: > -\begin{itemize} > -\item Source IPv6 address > -\item Destination IPv6 address > -\end{itemize} > -\item Else the device does not calculate the hash > -\end{itemize} > - > -The device calculates the hash on IPv6 packets with extension > -headers according to the field \field{hash_types} of the virtio_net_rss_config structure as follows: > -\begin{itemize} > -\item If VIRTIO_NET_RSS_HASH_TYPE_TCP_EX is set and the packet > -has a TCPv6 header, the hash is calculated over the following fields: > -\begin{itemize} > -\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 TCP port > -\item Destination TCP port > -\end{itemize} > -\item Else if VIRTIO_NET_RSS_HASH_TYPE_UDP_EX is set and the > -packet has a UDPv6 header, the hash is calculated over the following fields: > -\begin{itemize} > -\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 VIRTIO_NET_RSS_HASH_TYPE_IP_EX is set, the hash is > -calculated over the following fields: > -\begin{itemize} > -\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 an IPv6 packet without extension headers (see \ref{itm:Device Types / Network Device / Device Operation / Control Virtqueue / Receive-side scaling (RSS) / RSS hash types/hash on IPv6 packets without extension headers}). > -\end{itemize} > - > \drivernormative{\subparagraph}{Setting RSS parameters}{Device Types / Network Device / Device Operation / Control Virtqueue / Receive-side scaling (RSS) } > > A driver MUST NOT send the VIRTIO_NET_CTRL_MQ_RSS_CONFIG command if the feature VIRTIO_NET_F_RSS has not been negotiated. > @@ -4057,12 +4126,12 @@ \subsubsection{Control Virtqueue}\label{sec:Device Types / Network Device / Devi > > A driver MUST use \field{indirection_table_mask} values that are less than \field{rss_max_indirection_table_length} reported by a device. > > -A driver MUST NOT set any VIRTIO_NET_RSS_HASH_TYPE_ flags that are not supported by a device. > +A driver MUST NOT set any VIRTIO_NET_HASH_TYPE_ flags that are not supported by a device. > > \devicenormative{\subparagraph}{RSS processing}{Device Types / Network Device / Device Operation / Control Virtqueue / Receive-side scaling (RSS) / RSS processing} > 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 / Control Virtqueue / Receive-side scaling (RSS) / RSS hash types} > +\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). > \end{itemize} > -- > 2.17.1 > > > This publicly archived list offers a means to provide input to the > OASIS Virtual I/O Device (VIRTIO) TC. > > In order to verify user consent to the Feedback License terms and > to minimize spam in the list archive, subscription is required > before posting. > > Subscribe: virtio-comment-subscribe@lists.oasis-open.org > Unsubscribe: virtio-comment-unsubscribe@lists.oasis-open.org > List help: virtio-comment-help@lists.oasis-open.org > List archive: https://lists.oasis-open.org/archives/virtio-comment/ > Feedback License: https://www.oasis-open.org/who/ipr/feedback_license.pdf > List Guidelines: https://www.oasis-open.org/policies-guidelines/mailing-lists > Committee: https://www.oasis-open.org/committees/virtio/ > Join OASIS: https://www.oasis-open.org/join/
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