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Subject: Re: [virtio-dev] RE: [EXT] [virtio-dev] Re: [virtio-comment] [PATCH v2] virtio-net: support the RSS context
Hi Satananda! å 2023/10/10 äå7:46, Satananda Burla åé:
-----Original Message----- From: virtio-dev@lists.oasis-open.org <virtio-dev@lists.oasis-open.org> On Behalf Of Heng Qi Sent: Tuesday, September 5, 2023 7:04 PM To: virtio-comment@lists.oasis-open.org; virtio-dev@lists.oasis-open.org Cc: Michael S . Tsirkin <mst@redhat.com>; Parav Pandit <parav@nvidia.com>; Jason Wang <jasowang@redhat.com>; Xuan Zhuo <xuanzhuo@linux.alibaba.com>; Yuri Benditovich <yuri.benditovich@daynix.com> Subject: [EXT] [virtio-dev] Re: [virtio-comment] [PATCH v2] virtio-net: support the RSS context External Email ---------------------------------------------------------------------- Hi all! Do you have any comments on this? Thanks! å 2023/9/1 äå5:34, Heng Qi åé:Commit 84a1d9c48200 ("net: ethtool: extend RXNFC API to support RSSspreading offilter matches") adds support for RSS context as a destination forreceive flow filters(see WIP work: https://urldefense.proofpoint.com/v2/url?u=https-3A__lists.oasis-2Dopen.org_archives_virtio- 2Dcomment_202308_msg00194.html&d=DwIDaQ&c=nKjWec2b6R0mOyPaz7xtfQ&r=NHDPs fcAYlN2z- NXHHG4WB09qqS0voo_nf6_kGS625A&m=4OCN2dGMPgHxDFGtU81zZGzzaFYjTALBtQsWL230 DoinsHzHA- RVOOoF4XqITQuy&s=8MdvZRKdXb3tdMZuldE3Ed6VGmaKPPxc8vGxVyRb_Qc&e= ).An RSS context consists of configurable parameters specified byreceive-side scaling.Use case: When users want some data flows to be steered to specific multiplerxqs, they can setreceive flow filter rules for these data flows to an RSS context withdesired rxqs.How to set/configure an RSS context: Assuming no RSS context has been created before. 1. ethtool -X eth0 context new start 5 equal 8 This command creates an RSS context with an id=1 for eth0, and fillsin the indirectiontable with rxq indexes 5-8 circularly. The hash key and hash typesreuse the defaultRSS configuration. Then, we can use 'ethtool -x eth0 context 1' to query the aboveconfiguration.2. ethtool -X eth0 context new start 6 equal 7 \ hkey 8f:bf:dd:11:23:58:d2:8a:00:31:d0:32:a3:b5:1f:\1f:e4:d1:fe:47:7f:64:42:fd:d0:61:16:b8:b0:f9:71:e8:2d:36:7f:18:dd:4d:c8: f3This command creates an RSS context with an id=2 for eth0, and fillsin the indirectiontable with rxq indexes 6-7 circularly. The hash key is8f:bf:dd:11:23:58:d2:8a:00:31:d0\ :32:a3:b5:1f:1f:e4:d1:fe:47:7f:64:42:fd:d0:61:16:b8:b0:f9:71:e8:2d:36:7f :18:dd:4d:c8:f3.Hash types reuse the default RSS configuration. 3. ethtool -N eth0 rx-flow-hash tcp4 sdfn context 1 This command specifies the hash types for the RSS context whose id=1on eth0.Now this RSS context only has the hash key to reuse the default RSSconfiguration.4. ethtool -N eth0 flow-type udp4 src-ip 1.1.1.1 context 1 This command configures a receive flow filter rule for eth0, and thedata flow matchingthis rule will continue to select the final rxq according to the RSScontext configurationwith id=1. Signed-off-by: Heng Qi <hengqi@linux.alibaba.com> Signed-off-by: Parav Pandit <parav@nvidia.com> --- v1->v2: 1. u8 to le16 for field rss_ctx_id. 2. Add normativation when device resetting. @Yuri Benditovich 3. Use ctrlq cmd to query rss context capability instead ofreading config space. @Parav Panditdevice-types/net/description.tex | 85+++++++++++++++++++++++++device-types/net/device-conformance.tex | 1 + device-types/net/driver-conformance.tex | 1 + 3 files changed, 87 insertions(+) diff --git a/device-types/net/description.tex b/device-types/net/description.texindex 76585b0..55cd86d 100644 --- a/device-types/net/description.tex +++ b/device-types/net/description.tex @@ -88,6 +88,8 @@ \subsection{Feature bits}\label{sec:Device Types /Network Device / Feature bits\item[VIRTIO_NET_F_CTRL_MAC_ADDR(23)] Set MAC address throughcontrolchannel. +\item[VIRTIO_NET_F_RSS_CONTEXT(50)] Device supports multiple RSScontexts.+ \item[VIRTIO_NET_F_HASH_TUNNEL(51)] Device supports inner headerhash for encapsulated packets.\item[VIRTIO_NET_F_VQ_NOTF_COAL(52)] Device supports virtqueuenotification coalescing.@@ -150,6 +152,7 @@ \subsubsection{Feature bitrequirements}\label{sec:Device Types / Network Device\item[VIRTIO_NET_F_RSS] Requires VIRTIO_NET_F_CTRL_VQ. \item[VIRTIO_NET_F_VQ_NOTF_COAL] Requires VIRTIO_NET_F_CTRL_VQ. \item[VIRTIO_NET_F_HASH_TUNNEL] Requires VIRTIO_NET_F_CTRL_VQ alongwith VIRTIO_NET_F_RSS or VIRTIO_NET_F_HASH_REPORT.+\item[VIRTIO_NET_F_RSS_CONTEXT] Requires VIRTIO_NET_F_CTRL_VQ andVIRTIO_NET_F_RSS.\end{description} \subsubsection{Legacy Interface: Feature bits}\label{sec:DeviceTypes / Network Device / Feature bits / Legacy Interface: Feature bits}@@ -1606,6 +1609,88 @@ \subsubsection{ControlVirtqueue}\label{sec:Device Types / Network Device / Devi\item If the destination receive queue is being reset (See\ref{sec:Basic Facilities of a Virtio Device / Virtqueues / Virtqueue Reset}), the device MUST drop the packet.\end{itemize} +\paragraph{RSS Context}\label{sec:Device Types / Network Device /Device Operation / Control Virtqueue / RSS Context}+ +An RSS context consists of configurable parameters specified by\ref{sec:Device Types / Network Device+/ Device Operation / Control Virtqueue / Receive-side scaling (RSS)}. + +The RSS configuration supported by VIRTIO_NET_F_RSS is considered thedefault RSS configuration.+ +The device offers the feature VIRTIO_NET_F_RSS_CONTEXT if it supportsone or multiple RSS contexts+(excluding the default RSS configuration) and configurableparameters.+ +\subparagraph{Querying RSS Context Capability}\label{sec:Device Types/ Network Device / Device Operation / Control Virtqueue / RSS Context / Querying RSS Context Capability}+ +\begin{lstlisting} +#define VIRTNET_RSS_CTX_CTRL 8 + #define VIRTNET_RSS_CTX_CTRL_CAP_GET 0 + #define VIRTNET_RSS_CTX_CTRL_ADD 1 + #define VIRTNET_RSS_CTX_CTRL_MOD 2 + #define VIRTNET_RSS_CTX_CTRL_DEL 3 + +struct virtnet_rss_ctx_cap { + le16 max_rss_contexts; +} +\end{lstlisting} + +Field \field{max_rss_contexts} specifies the maximum number of RSScontexts \ref{sec:Device Types / Network Device /+Device Operation / Control Virtqueue / RSS Context} supported by thedevice.+ +The driver queries the RSS context capability of the device bysending the command VIRTNET_RSS_CTX_CTRL_CAP_GET+with the structure virtnet_rss_ctx_cap. + +For the command VIRTNET_RSS_CTX_CTRL_CAP_GET, the structurevirtnet_rss_ctx_cap is write-only for the device.+ +\subparagraph{Setting RSS Context Parameters}\label{sec:Device Types/ Network Device / Device Operation / Control Virtqueue / RSS Context / Setting RSS Context Parameters}+ +\begin{lstlisting} +struct virtnet_rss_ctx_add_modify { + le16 rss_ctx_id; + le16 padding; + struct virtio_net_rss_config rss; +}; + +struct virtnet_rss_ctx_del { + le16 rss_ctx_id; +}; +\end{lstlisting} + +RSS context parameters: +\begin{itemize} +\item \field{rss_ctx_id}: ID of the specific RSS context. +\item \field{rss}: RSS context parameters of the specific RSScontext whose id is \field{rss_ctx_id}.+\end{itemize} + +\field{padding} is reserved and it is ignored by the device. + +If the feature VIRTIO_NET_F_RSS_CONTEXT has been negotiated, thedriver can send the following+VIRTNET_RSS_CTX_CTRL class commands: +\begin{enumerate} +\item VIRTNET_RSS_CTX_CTRL_ADD: use the structurevirtnet_rss_ctx_add_modify to+ add an RSS context configured as \field{rss} and id as\field{rss_ctx_id} for the device.+\item VIRTNET_RSS_CTX_CTRL_MOD: use the structurevirtnet_rss_ctx_add_modify to+ configure parameters of the RSS context whose id is\field{rss_ctx_id} as \field{rss} for the device.+\item VIRTNET_RSS_CTX_CTRL_DEL: use the structure virtnet_rss_ctx_delto delete+ the RSS context whose id is \field{rss_ctx_id} for the device. +\end{enumerate} + +For commands VIRTNET_RSS_CTX_CTRL_ADD and VIRTNET_RSS_CTX_CTRL_MOD,the structure virtnet_rss_ctx_add_modify is read-only for the device.+For the command VIRTNET_RSS_CTX_CTRL_DEL, the structurevirtnet_rss_ctx_del is read-only for the device.+ +\devicenormative{\subparagraph}{RSS Context}{Device Types / NetworkDevice / Device Operation / Control Virtqueue / RSS Context}+ +The device MUST set \field{max_rss_contexts} to at least 1 if itoffers VIRTIO_NET_F_RSS_CONTEXT.+ +Upon reset, the device MUST clear all previously configured RSScontexts.+ +\drivernormative{\subparagraph}{RSS Context}{Device Types / NetworkDevice / Device Operation / Control Virtqueue / RSS Context}+ +The driver MUST have negotiated the VIRTIO_NET_F_RSS_CONTEXT featurewhen issuing the VIRTNET_RSS_CTX_CTRL class commands.+ +The driver MUST set \field{rss_ctx_id} to between 1 and\field{max_rss_contexts} inclusive.+ +The driver MUST NOT send the command VIRTIO_NET_CTRL_MQ_VQ_PAIRS_SETwhen the device has successfully configured at least one RSS context.+What happens if a rss context with flow classification rules associated with it is deleted? Are the rules are also then deleted? Or is such a delete operation not allowed? Can we add a statement describing
The RSS context cannot be deleted when it is referenced by a rule in RFF.The RSS context can then be deleted when all rules that referenced it have been removed.
Why is this not added to the requirement:RSS context is not yet referenced by RFF (i.e. the destination of RFF is a single rxq). This is because we keep the RSS context and RFF orthogonal for the time being. So that the RSS context does
not block the advancement of RFF.Also, RFF is not merged into mainline now. When the RSS context is complete, we can update the statement in the RFF requirements; or when the RFF is complete, we can update the statement
in both the RFF and RSS context. Thanks!
the behavior? Otherwise looks good to me. Regards Satananda
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