ethtool: make ethtool_ops::cap_rss_ctx_supported optional

cap_rss_ctx_supported was created because the API for creating
and configuring additional contexts is mux'ed with the normal
RSS API. Presence of ops does not imply driver can actually
support rss_context != 0 (in fact drivers mostly ignore that
field). cap_rss_ctx_supported lets core check that the driver
is context-aware before calling it.

Now that we have .create_rxfh_context, there is no such
ambiguity. We can depend on presence of the op.
Make setting the bit optional.
Reviewed-by: Gal Pressman <gal@nvidia.com>
Reviewed-by: Edward Cree <ecree.xilinx@gmail.com>
Reviewed-by: Joe Damato <jdamato@fastly.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/ethtool.h

@@ -727,7 +727,8 @@ struct kernel_ethtool_ts_info {
  * @cap_link_lanes_supported: indicates if the driver supports lanes
  *	parameter.
  * @cap_rss_ctx_supported: indicates if the driver supports RSS
- *	contexts.
+ *	contexts via legacy API, drivers implementing @create_rxfh_context
+ *	do not have to set this bit.
  * @cap_rss_sym_xor_supported: indicates if the driver supports symmetric-xor
  *	RSS.
  * @rxfh_indir_space: max size of RSS indirection tables, if indirection table

net/ethtool/ioctl.c

@@ -1227,7 +1227,8 @@ static noinline_for_stack int ethtool_get_rxfh(struct net_device *dev,
 	if (rxfh.rsvd8[0] || rxfh.rsvd8[1] || rxfh.rsvd32)
 		return -EINVAL;
 	/* Most drivers don't handle rss_context, check it's 0 as well */
-	if (rxfh.rss_context && !ops->cap_rss_ctx_supported)
+	if (rxfh.rss_context && !(ops->cap_rss_ctx_supported ||
+				  ops->create_rxfh_context))
 		return -EOPNOTSUPP;
 
 	rxfh.indir_size = rxfh_dev.indir_size;
@@ -1357,7 +1358,8 @@ static noinline_for_stack int ethtool_set_rxfh(struct net_device *dev,
 	if (rxfh.rsvd8[0] || rxfh.rsvd8[1] || rxfh.rsvd32)
 		return -EINVAL;
 	/* Most drivers don't handle rss_context, check it's 0 as well */
-	if (rxfh.rss_context && !ops->cap_rss_ctx_supported)
+	if (rxfh.rss_context && !(ops->cap_rss_ctx_supported ||
+				  ops->create_rxfh_context))
 		return -EOPNOTSUPP;
 	/* Check input data transformation capabilities */
 	if (rxfh.input_xfrm && rxfh.input_xfrm != RXH_XFRM_SYM_XOR &&

net/ethtool/rss.c

@@ -60,7 +60,8 @@ rss_prepare_data(const struct ethnl_req_info *req_base,
 		return -EOPNOTSUPP;
 
 	/* Some drivers don't handle rss_context */
-	if (request->rss_context && !ops->cap_rss_ctx_supported)
+	if (request->rss_context && !(ops->cap_rss_ctx_supported ||
+				      ops->create_rxfh_context))
 		return -EOPNOTSUPP;
 
 	ret = ethnl_ops_begin(dev);