ethtool: add netlink based get rss support

Add netlink based support for "ethtool -x <dev> [context x]"
command by implementing ETHTOOL_MSG_RSS_GET netlink message.
This is equivalent to functionality provided via ETHTOOL_GRSSH
in ioctl path. It sends RSS table, hash key and hash function
of an interface to user space.

This patch implements existing functionality available
in ioctl path and enables addition of new RSS context
based parameters in future.

Signed-off-by: Sudheer Mogilappagari <sudheer.mogilappagari@intel.com>
Link: https://lore.kernel.org/r/20221202002555.241580-1-sudheer.mogilappagari@intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 153 insertions, 0 deletions

diff --git a/net/ethtool/rss.c b/net/ethtool/rss.c
new file mode 100644
index 000000000000..ebe6145aed3f
--- /dev/null
+++ b/net/ethtool/rss.c
@@ -0,0 +1,153 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include "netlink.h"
+#include "common.h"
+
+struct rss_req_info {
+	struct ethnl_req_info		base;
+	u32				rss_context;
+};
+
+struct rss_reply_data {
+	struct ethnl_reply_data		base;
+	u32				indir_size;
+	u32				hkey_size;
+	u32				hfunc;
+	u32				*indir_table;
+	u8				*hkey;
+};
+
+#define RSS_REQINFO(__req_base) \
+	container_of(__req_base, struct rss_req_info, base)
+
+#define RSS_REPDATA(__reply_base) \
+	container_of(__reply_base, struct rss_reply_data, base)
+
+const struct nla_policy ethnl_rss_get_policy[] = {
+	[ETHTOOL_A_RSS_HEADER] = NLA_POLICY_NESTED(ethnl_header_policy),
+	[ETHTOOL_A_RSS_CONTEXT] = { .type = NLA_U32 },
+};
+
+static int
+rss_parse_request(struct ethnl_req_info *req_info, struct nlattr **tb,
+		  struct netlink_ext_ack *extack)
+{
+	struct rss_req_info *request = RSS_REQINFO(req_info);
+
+	if (tb[ETHTOOL_A_RSS_CONTEXT])
+		request->rss_context = nla_get_u32(tb[ETHTOOL_A_RSS_CONTEXT]);
+
+	return 0;
+}
+
+static int
+rss_prepare_data(const struct ethnl_req_info *req_base,
+		 struct ethnl_reply_data *reply_base, struct genl_info *info)
+{
+	struct rss_reply_data *data = RSS_REPDATA(reply_base);
+	struct rss_req_info *request = RSS_REQINFO(req_base);
+	struct net_device *dev = reply_base->dev;
+	const struct ethtool_ops *ops;
+	u32 total_size, indir_bytes;
+	u8 dev_hfunc = 0;
+	u8 *rss_config;
+	int ret;
+
+	ops = dev->ethtool_ops;
+	if (!ops->get_rxfh)
+		return -EOPNOTSUPP;
+
+	/* Some drivers don't handle rss_context */
+	if (request->rss_context && !ops->get_rxfh_context)
+		return -EOPNOTSUPP;
+
+	ret = ethnl_ops_begin(dev);
+	if (ret < 0)
+		return ret;
+
+	data->indir_size = 0;
+	data->hkey_size = 0;
+	if (ops->get_rxfh_indir_size)
+		data->indir_size = ops->get_rxfh_indir_size(dev);
+	if (ops->get_rxfh_key_size)
+		data->hkey_size = ops->get_rxfh_key_size(dev);
+
+	indir_bytes = data->indir_size * sizeof(u32);
+	total_size = indir_bytes + data->hkey_size;
+	rss_config = kzalloc(total_size, GFP_KERNEL);
+	if (!rss_config) {
+		ret = -ENOMEM;
+		goto out_ops;
+	}
+
+	if (data->indir_size)
+		data->indir_table = (u32 *)rss_config;
+
+	if (data->hkey_size)
+		data->hkey = rss_config + indir_bytes;
+
+	if (request->rss_context)
+		ret = ops->get_rxfh_context(dev, data->indir_table, data->hkey,
+					    &dev_hfunc, request->rss_context);
+	else
+		ret = ops->get_rxfh(dev, data->indir_table, data->hkey,
+				    &dev_hfunc);
+
+	if (ret)
+		goto out_ops;
+
+	data->hfunc = dev_hfunc;
+out_ops:
+	ethnl_ops_complete(dev);
+	return ret;
+}
+
+static int
+rss_reply_size(const struct ethnl_req_info *req_base,
+	       const struct ethnl_reply_data *reply_base)
+{
+	const struct rss_reply_data *data = RSS_REPDATA(reply_base);
+	int len;
+
+	len = nla_total_size(sizeof(u32)) +	/* _RSS_HFUNC */
+	      nla_total_size(sizeof(u32) * data->indir_size) + /* _RSS_INDIR */
+	      nla_total_size(data->hkey_size);	/* _RSS_HKEY */
+
+	return len;
+}
+
+static int
+rss_fill_reply(struct sk_buff *skb, const struct ethnl_req_info *req_base,
+	       const struct ethnl_reply_data *reply_base)
+{
+	const struct rss_reply_data *data = RSS_REPDATA(reply_base);
+
+	if (nla_put_u32(skb, ETHTOOL_A_RSS_HFUNC, data->hfunc) ||
+	    nla_put(skb, ETHTOOL_A_RSS_INDIR,
+		    sizeof(u32) * data->indir_size, data->indir_table) ||
+	    nla_put(skb, ETHTOOL_A_RSS_HKEY, data->hkey_size, data->hkey))
+		return -EMSGSIZE;
+
+	return 0;
+}
+
+static void rss_cleanup_data(struct ethnl_reply_data *reply_base)
+{
+	const struct rss_reply_data *data = RSS_REPDATA(reply_base);
+
+	kfree(data->indir_table);
+}
+
+const struct ethnl_request_ops ethnl_rss_request_ops = {
+	.request_cmd		= ETHTOOL_MSG_RSS_GET,
+	.reply_cmd		= ETHTOOL_MSG_RSS_GET_REPLY,
+	.hdr_attr		= ETHTOOL_A_RSS_HEADER,
+	.req_info_size		= sizeof(struct rss_req_info),
+	.reply_data_size	= sizeof(struct rss_reply_data),
+
+	.parse_request		= rss_parse_request,
+	.prepare_data		= rss_prepare_data,
+	.reply_size		= rss_reply_size,
+	.fill_reply		= rss_fill_reply,
+	.cleanup_data		= rss_cleanup_data,
+};