[PATCH V2 net 10/12] net: ena: make ena rxfh support ETH_RSS_HASH_NO_CHANGE

[<sameehj@amazon.com>]

From: Arthur Kiyanovski <akiyano@amazon.com>

As the name suggests ETH_RSS_HASH_NO_CHANGE is received upon changing
the key or indirection table using ethtool while keeping the same hash
function.

Also add a function for retrieving the current hash function from
the ena-com layer.

Fixes: 1738cd3ed342 ("net: ena: Add a driver for Amazon Elastic Network Adapters (ENA)")
Signed-off-by: Sameeh Jubran <sameehj@amazon.com>
Signed-off-by: Saeed Bshara <saeedb@amazon.com>
Signed-off-by: Arthur Kiyanovski <akiyano@amazon.com>
---
 drivers/net/ethernet/amazon/ena/ena_com.c     | 5 +++++
 drivers/net/ethernet/amazon/ena/ena_com.h     | 8 ++++++++
 drivers/net/ethernet/amazon/ena/ena_ethtool.c | 3 +++
 3 files changed, 16 insertions(+)

diff --git a/drivers/net/ethernet/amazon/ena/ena_com.c b/drivers/net/ethernet/amazon/ena/ena_com.c
index 74743fd8a..0f93d1092 100644
--- a/drivers/net/ethernet/amazon/ena/ena_com.c
+++ b/drivers/net/ethernet/amazon/ena/ena_com.c
@@ -1041,6 +1041,11 @@ static int ena_com_get_feature(struct ena_com_dev *ena_dev,
 				      feature_ver);
 }
 
+int ena_com_get_current_hash_function(struct ena_com_dev *ena_dev)
+{
+	return ena_dev->rss.hash_func;
+}
+
 static void ena_com_hash_key_fill_default_key(struct ena_com_dev *ena_dev)
 {
 	struct ena_admin_feature_rss_flow_hash_control *hash_key =
diff --git a/drivers/net/ethernet/amazon/ena/ena_com.h b/drivers/net/ethernet/amazon/ena/ena_com.h
index 9b5bd28ed..469f29819 100644
--- a/drivers/net/ethernet/amazon/ena/ena_com.h
+++ b/drivers/net/ethernet/amazon/ena/ena_com.h
@@ -656,6 +656,14 @@ int ena_com_rss_init(struct ena_com_dev *ena_dev, u16 log_size);
  */
 void ena_com_rss_destroy(struct ena_com_dev *ena_dev);
 
+/* ena_com_get_current_hash_function - Get RSS hash function
+ * @ena_dev: ENA communication layer struct
+ *
+ * Return the current hash function.
+ * @return: 0 or one of the ena_admin_hash_functions values.
+ */
+int ena_com_get_current_hash_function(struct ena_com_dev *ena_dev);
+
 /* ena_com_fill_hash_function - Fill RSS hash function
  * @ena_dev: ENA communication layer struct
  * @func: The hash function (Toeplitz or crc)
diff --git a/drivers/net/ethernet/amazon/ena/ena_ethtool.c b/drivers/net/ethernet/amazon/ena/ena_ethtool.c
index 610a7c63e..b8ce7adb2 100644
--- a/drivers/net/ethernet/amazon/ena/ena_ethtool.c
+++ b/drivers/net/ethernet/amazon/ena/ena_ethtool.c
@@ -736,6 +736,9 @@ static int ena_set_rxfh(struct net_device *netdev, const u32 *indir,
 	}
 
 	switch (hfunc) {
+	case ETH_RSS_HASH_NO_CHANGE:
+		func = ena_com_get_current_hash_function(ena_dev);
+		break;
 	case ETH_RSS_HASH_TOP:
 		func = ENA_ADMIN_TOEPLITZ;
 		break;
-- 
2.24.1.AMZN