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Subject: Re: [virtio-comment] Re: [PATCH v4 1/1] virtio-net: Define per-packet hash reporting feature
On Thu, Feb 20, 2020 at 12:09:01AM -0500, Yuri Benditovich wrote: > > > âââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââ > > From: "Michael S. Tsirkin" <mst@redhat.com> > To: "Yuri Benditovich" <ybendito@redhat.com> > Cc: "Yuri Benditovich" <yuri.benditovich@daynix.com>, > virtio-comment@lists.oasis-open.org > Sent: Wednesday, February 19, 2020 4:56:04 PM > Subject: Re: [virtio-comment] Re: [PATCH v4 1/1] virtio-net: Define > per-packet hash reporting feature > > On Wed, Feb 19, 2020 at 09:49:37AM -0500, Yuri Benditovich wrote: > > > > > > > âââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââ > > > > From: "Michael S. Tsirkin" <mst@redhat.com> > > To: "Yuri Benditovich" <ybendito@redhat.com> > > Cc: "Yuri Benditovich" <yuri.benditovich@daynix.com>, > > virtio-comment@lists.oasis-open.org > > Sent: Wednesday, February 19, 2020 4:35:49 PM > > Subject: Re: [virtio-comment] Re: [PATCH v4 1/1] virtio-net: Define > > per-packet hash reporting feature > > > > On Wed, Feb 19, 2020 at 06:07:13AM -0500, Yuri Benditovich wrote: > > > > > > > > > > > > âââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââ > > > > > > From: "Michael S. Tsirkin" <mst@redhat.com> > > > To: "Yuri Benditovich" <yuri.benditovich@daynix.com> > > > Cc: virtio-comment@lists.oasis-open.org > > > Sent: Wednesday, February 19, 2020 11:12:40 AM > > > Subject: [virtio-comment] Re: [PATCH v4 1/1] virtio-net: Define > > per-packet > > > hash reporting feature > > > > > > On Wed, Feb 19, 2020 at 09:53:37AM +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> > > > > --- > > > > content.tex | 347 > > ++++++++++++++++++++++++++++++++++------------------ > > > > 1 file changed, 229 insertions(+), 118 deletions(-) > > > > > > > > diff --git a/content.tex b/content.tex > > > > index b91a132..d7d4e42 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(57)] 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. > > > > > > > > @@ -2995,35 +2998,17 @@ \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. > > > > +The following field, \field{rss_max_key_size} only exist if > > > VIRTIO_NET_F_RSS or VIRTIO_NET_F_HASH_REPORT is set. > > > > +It specifies the maximal supported length of RSS key in > bytes. > > > > > > > > -Field \field{rss_max_key_size} specifies the maximal > supported > > length of > > > RSS key in bytes. > > > > +The following field, \field > {rss_max_indirection_table_length} only > > exist > > > if VIRTIO_NET_F_RSS is set. > > > > +It specifies the maximal number of 16-bit entries in RSS > > indirection > > > table. > > > > > > > > -Field \field{rss_max_indirection_table_length} specifies the > > maximal > > > number of 16-bit entries in RSS indirection table. > > > > +The next field, \field{supported_hash_types} exists only if > the > > device > > > supports hash calculation, > > > > +i.e. if VIRTIO_NET_F_RSS or VIRTIO_NET_F_HASH_REPORT is set. > > > > > > > > -Field \field{supported_hash_types} contains the bitmask of > > supported RSS > > > hash types. > > > > - > > > > -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} > > > > > > > > @@ -3048,7 +3033,7 @@ \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. > > > > +VIRTIO_NET_F_RSS or VIRTIO_NET_F_HASH_REPORT. > > > > > > > > The device MUST set \field{rss_max_indirection_table_length} > to at > > least > > > 128, if it offers > > > > VIRTIO_NET_F_RSS. > > > > @@ -3195,6 +3180,8 @@ \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) > > > > }; > > > > > > Just noticed this - it's a bit problematic as it might force > > > compilers to add 2 bytes of padding at the end. Let's add extra > 2 > > bytes > > > of padding explicitly? > > > > > > OK, no problem > > > > > > > > > > > > > > > > \end{lstlisting} > > > > > > > > @@ -3517,6 +3504,12 @@ \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 > > > > > > > > @@ -3619,6 +3612,181 @@ \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 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. > > > > +\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 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 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 > > > > +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 > > > > + \ref{sec:Device Types / Network Device / Device Operation / > > Control > > > Virtqueue / Receive-side scaling (RSS) / Setting RSS > parameters}. > > > > +\item Otherwise the device MUST support > > VIRTIO_NET_CTRL_MQ_HASH_CONFIG > > > command per > > > > + \ref{sec:Device Types / Network Device / Device Operation / > > Control > > > Virtqueue / Automatic receive steering in multiqueue mode / > Hash > > > calculation}. > > > > +\end{itemize} > > > > + > > > > +\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 according to 'Enabled hash types' bitmask as > follows: > > > > +\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 '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} > > > > + > > > > +If 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 > > > > +hash was not calculated, the device sets \field{hash_type} > to > > > VIRTIO_NET_HASH_REPORT_NONE. > > > > + > > > > +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) > > > > > > > > > So hash_type is the HASH_REPORT value then? That's quite > confusing. > > > Let's rename to hash_report? > > > > > > No problem to rename anything, but I'd like to do it one time. > > > Currently meaningful hash report values are (1..9), 0 for none > > > They correspond to bitmask of 9 bits for enabled/supported. > > > It was possible to use the same definitions for enable/support/ > report > > > but then reported kind of hash should be 4 bytes. > > > As you anyway suggests padding at the end of the packet, we can do > that, > > > i.e. add (32 bit hash + 32 bit type) > > > > We can but it seems like a waste, does it not? padding can be used > for > > something later ... > > > > > Or if we stay with the values as they are now: > > > values 0..9 - VIRTIO_NET_WHAT? > > > > I thought that's VIRTIO_NET_HASH_REPORT_XXX > > > > OK, this is exactly what is defined > > > > > > > bits from 0 to 8 - VIRTIO_NET_WHAT? > > > > > > and this one VIRTIO_NET_HASH_TYPE_XXX? > > > > OK, this is also exactly what is defined > > > > > Right I'm saying what's defined is fine, just call the fields > consistently. > > > > > > > Generally what you did here is a bit unusual. Mostly we just define > > bit numbers > > #define VIRTIO_SCSI_F_INOUT 0 > > #define VIRTIO_SCSI_F_HOTPLUG 1 > > #define VIRTIO_SCSI_F_CHANGE 2 > > #define VIRTIO_SCSI_F_T10_PI 3 > > > > > > Value 0 of hash_report is "no hash calculated" and it does not > > participate in support/enable mask. I did not want to > > use value other than zero for "no hash". > > Oh right. > > > So you want bit 0 to be reserved (not used) in enable/support mask > > and then to have all the VIRTIO_NET_HASH_TYPE_XXX to be > > exactly 1 << VIRTIO_NET_HASH_REPORT_XXX? Just say... > > > > We can do that too but it's up to you really. > > So fixing the below you would say > bit 0 curresponding to value 1, > bit 1 corresponding to value 2 etc. > No bit corresponds to value 0 > ? > > Currently defined: > > Reports: > VIRTIO_NET_HASH_REPORT_NONE 0 > VIRTIO_NET_HASH_REPORT_IPv4 1 > VIRTIO_NET_HASH_REPORT_UDPv4 3 > VIRTIO_NET_HASH_REPORT_UDPv6_EX 9 > > Bitmask (VIRTIO_NET_HASH_TYPE_XXX = 1 << (VIRTIO_NET_HASH_REPORT_XXX - 1)): > VIRTIO_NET_HASH_TYPE_IPv4 = (1 << 0) > VIRTIO_NET_HASH_TYPE_UDPv4 = (1 << 2) > VIRTIO_NET_HASH_TYPE_UDP_EX = (1 << 8) > > > How you want it to be changed? > Can you please write here in the same format? IMHO at a minimum, \field{hash_type} should be \field{hash_report}. That's all. > > > > > > and just say that bit numbers are from this table, with bit > > 0 corresponding to the value 0, bit 1 to value 1 etc. > > > > > > maybe that would have been easier on the eyes - I didn't try, > > I'm not even sure. > > > > But what you have is correct enough, we can always try to > > improve the wording later. > > > > > > > > > > > > > > + > > > > +\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 > > > > @@ -3896,6 +4064,7 @@ \subsubsection{Control Virtqueue}\label > > {sec:Device > > > Types / Network Device / Devi > > > > #define VIRTIO_NET_CTRL_MQ 4 > > > > #define VIRTIO_NET_CTRL_MQ_VQ_PAIRS_SET 0 (for > automatic > > receive > > > steering) > > > > #define VIRTIO_NET_CTRL_MQ_RSS_CONFIG 1 (for > > configurable > > > receive steering) > > > > + #define VIRTIO_NET_CTRL_MQ_HASH_CONFIG 2 (for > > configurable hash > > > calculation) > > > > \end{lstlisting} > > > > > > > > If more than one multiqueue mode is negotiated, the > resulting > > device > > > configuration is defined by the last command sent by the > driver. > > > > @@ -3961,10 +4130,37 @@ \subsubsection{Control Virtqueue}\ > label > > > {sec:Device Types / Network Device / Devi > > > > according to the native endian of the guest rather than > > > > (necessarily when not using the legacy interface) > little-endian. > > > > > > > > +\subparagraph{Hash calculation}\label{sec:Device Types / > Network > > Device > > > / Device Operation / Control Virtqueue / Automatic receive > steering > > in > > > multiqueue mode / Hash calculation} > > > > +If VIRTIO_NET_F_HASH_REPORT was negotiated and the device > uses > > automatic > > > receive steering, > > > > +the device MUST support a command to configure hash > calculation > > > parameters. > > > > + > > > > +The driver provides parameters for hash calculation as > follows: > > > > + > > > > +\field{class} VIRTIO_NET_CTRL_MQ, \field{command} > > > VIRTIO_NET_CTRL_MQ_HASH_CONFIG. > > > > + > > > > +The \field{command-specific-data} has following format: > > > > +\begin{lstlisting} > > > > +struct virtio_net_hash_config { > > > > + le32 hash_types; > > > > + le16 reserved[4]; > > > > + u8 hash_key_length; > > > > + u8 hash_key_data[hash_key_length]; > > > > +}; > > > > +\end{lstlisting} > > > > +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{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)}. > > > > + > > > > +Fields \field{hash_key_length} and \field{hash_key_data} > define > > the key > > > to be used in hash calculation. > > > > + > > > > \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} > > > > > > > > @@ -3981,7 +4177,8 @@ \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 > > > > @@ -3995,93 +4192,7 @@ \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} > > > > +Fields \field{hash_key_length} and \field{hash_key_data} > define > > the key > > > to be used in hash calculation. > > > > > > > > \drivernormative{\subparagraph}{Setting RSS parameters} > {Device > > Types / > > > Network Device / Device Operation / Control Virtqueue / > Receive-side > > > scaling (RSS) } > > > > > > > > @@ -4093,12 +4204,12 @@ \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/ > > > > > > > > > > > > > > > > > > > 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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