linux/net/ethtool/rss.c, branch v6.17

ethtool: rss: support removing contexts via Netlink

2025-07-22T01:21:19Z

Implement removing additional RSS contexts via Netlink. Technically it'd be possible to shoehorn the delete operation into ethnl_request_ops-compatible handler. The code ends up longer than open coded version, and I think we'll need a custom way of sending notifications at some stage (if we allow tying the context lifetime to the netlink socket, in the future). Link: https://patch.msgid.link/20250717234343.2328602-8-kuba@kernel.org Signed-off-by: Jakub Kicinski

ethtool: rss: support creating contexts via Netlink

2025-07-22T01:20:43Z

Support creating contexts via Netlink. Setting flow hashing fields on the new context is not supported at this stage, it can be added later. An empty indirection table is not supported. This is a carry over from the IOCTL interface where empty indirection table meant delete. We can repurpose empty indirection table in Netlink but for now to avoid confusion reject it using the policy. Support letting user choose the ID for the new context. This was not possible in IOCTL since the context ID field for the create action had to be set to the ETH_RXFH_CONTEXT_ALLOC magic value. Link: https://patch.msgid.link/20250717234343.2328602-7-kuba@kernel.org Signed-off-by: Jakub Kicinski

ethtool: rss: factor out populating response from context

2025-07-22T01:20:19Z

Similarly to previous change, factor out populating the response. We will use this after the context was allocated to send a notification so this time factor out from the additional context handling, rather than context 0 handling (for request context didn't exist, for response it does). Reviewed-by: Gal Pressman Link: https://patch.msgid.link/20250717234343.2328602-5-kuba@kernel.org Signed-off-by: Jakub Kicinski

ethtool: rss: factor out allocating memory for response

2025-07-22T01:20:19Z

To ease the code reuse for RSS_CREATE we'll want to prepare struct rss_reply_data for the new context. Unfortunately we can't depend on the exiting scaffolding because the context doesn't exist (ctx=NULL) when we start preparing. Factor out the portion of the context 0 handling responsible for allocation of request memory, so that we can call it directly. Link: https://patch.msgid.link/20250717234343.2328602-4-kuba@kernel.org Signed-off-by: Jakub Kicinski

ethtool: rejig the RSS notification machinery for more types

2025-07-22T01:20:19Z

In anticipation for CREATE and DELETE notifications - explicitly pass the notification type to ethtool_rss_notify(), when calling from the IOCTL code. Reviewed-by: Gal Pressman Link: https://patch.msgid.link/20250717234343.2328602-3-kuba@kernel.org Signed-off-by: Jakub Kicinski

ethtool: rss: support setting flow hashing fields

2025-07-17T23:13:59Z

Add support for ETHTOOL_SRXFH (setting hashing fields) in RSS_SET. The tricky part is dealing with symmetric hashing. In netlink user can change the hashing fields and symmetric hash in one request, in IOCTL the two used to be set via different uAPI requests. Since fields and hash function config are still separate driver callbacks - changes to the two are not atomic. Keep things simple and validate the settings against both pre- and post- change ones. Meaning that we will reject the config request if user tries to correct the flow fields and set input_xfrm in one request, or disables input_xfrm and makes flow fields non-symmetric. We can adjust it later if there's a real need. Starting simple feels right, and potentially partially applying the settings isn't nice, either. Reviewed-by: Gal Pressman Link: https://patch.msgid.link/20250716000331.1378807-11-kuba@kernel.org Signed-off-by: Jakub Kicinski

ethtool: rss: support setting input-xfrm via Netlink

2025-07-17T23:13:59Z

Support configuring symmetric hashing via Netlink. We have the flow field config prepared as part of SET handling, so scan it for conflicts instead of querying the driver again. Reviewed-by: Gal Pressman Link: https://patch.msgid.link/20250716000331.1378807-10-kuba@kernel.org Signed-off-by: Jakub Kicinski

ethtool: rss: support setting hkey via Netlink

2025-07-17T23:13:58Z

Support setting RSS hashing key via ethtool Netlink. Use the Netlink policy to make sure user doesn't pass an empty key, "resetting" the key is not a thing. Reviewed-by: Gal Pressman Link: https://patch.msgid.link/20250716000331.1378807-7-kuba@kernel.org Signed-off-by: Jakub Kicinski

ethtool: rss: support setting hfunc via Netlink

2025-07-17T23:13:58Z

Support setting RSS hash function / algo via ethtool Netlink. Like IOCTL we don't validate that the function is within the range known to the kernel. The drivers do a pretty good job validating the inputs, and the IDs are technically "dynamically queried" rather than part of uAPI. Only change should be that in Netlink we don't support user explicitly passing ETH_RSS_HASH_NO_CHANGE (0), if no change is requested the attribute should be absent. The ETH_RSS_HASH_NO_CHANGE is retained in driver-facing API for consistency (not that I see a strong reason for it). Reviewed-by: Gal Pressman Link: https://patch.msgid.link/20250716000331.1378807-6-kuba@kernel.org Signed-off-by: Jakub Kicinski

ethtool: rss: initial RSS_SET (indirection table handling)

2025-07-17T23:13:58Z

Add initial support for RSS_SET, for now only operations on the indirection table are supported. Unlike the ioctl don't check if at least one parameter is being changed. This is how other ethtool-nl ops behave, so pick the ethtool-nl consistency vs copying ioctl behavior. There are two special cases here: 1) resetting the table to defaults; 2) support for tables of different size. For (1) I use an empty Netlink attribute (array of size 0). (2) may require some background. AFAICT a lot of modern devices allow allocating RSS tables of different sizes. mlx5 can upsize its tables, bnxt has some "table size calculation", and Intel folks asked about RSS table sizing in context of resource allocation in the past. The ethtool IOCTL API has a concept of table size, but right now the user is expected to provide a table exactly the size the device requests. Some drivers may change the table size at runtime (in response to queue count changes) but the user is not in control of this. What's not great is that all RSS contexts share the same table size. For example a device with 128 queues enabled, 16 RSS contexts 8 queues in each will likely have 256 entry tables for each of the 16 contexts, while 32 would be more than enough given each context only has 8 queues. To address this the Netlink API should avoid enforcing table size at the uAPI level, and should allow the user to express the min table size they expect. To fully solve (2) we will need more driver plumbing but at the uAPI level this patch allows the user to specify a table size smaller than what the device advertises. The device table size must be a multiple of the user requested table size. We then replicate the user-provided table to fill the full device size table. This addresses the "allow the user to express the min table size" objective, while not enforcing any fixed size. From Netlink perspective .get_rxfh_indir_size() is now de facto the "max" table size supported by the device. We may choose to support table replication in ethtool, too, when we actually plumb this thru the device APIs. Initially I was considering moving full pattern generation to the kernel (which queues to use, at which frequency and what min sequence length). I don't think this complexity would buy us much and most if not all devices have pow-2 table sizes, which simplifies the replication a lot. Reviewed-by: Gal Pressman Link: https://patch.msgid.link/20250716000331.1378807-2-kuba@kernel.org Signed-off-by: Jakub Kicinski