net: ena: fix incorrect default RSS key

Bug description:
When running "ethtool -x <if_name>" the key shows up as all zeros.

When we use "ethtool -X <if_name> hfunc toeplitz hkey <some:random:key>" to
set the key and then try to retrieve it using "ethtool -x <if_name>" then
we return the correct key because we return the one we saved.

Bug cause:
We don't fetch the key from the device but instead return the key
that we have saved internally which is by default set to zero upon
allocation.

Fix:
This commit fixes the issue by initializing the key to a random value
using netdev_rss_key_fill().

Fixes: 1738cd3e ("net: ena: Add a driver for Amazon Elastic Network Adapters (ENA)")
Signed-off-by: Sameeh Jubran <sameehj@amazon.com>
Signed-off-by: Arthur Kiyanovski <akiyano@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/amazon/ena/ena_com.c

@@ -1041,6 +1041,19 @@ static int ena_com_get_feature(struct ena_com_dev *ena_dev,
 				      feature_ver);
 }
 
+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 =
+		(ena_dev->rss).hash_key;
+
+	netdev_rss_key_fill(&hash_key->key, sizeof(hash_key->key));
+	/* The key is stored in the device in u32 array
+	 * as well as the API requires the key to be passed in this
+	 * format. Thus the size of our array should be divided by 4
+	 */
+	hash_key->keys_num = sizeof(hash_key->key) / sizeof(u32);
+}
+
 static int ena_com_hash_key_allocate(struct ena_com_dev *ena_dev)
 {
 	struct ena_rss *rss = &ena_dev->rss;
@@ -2631,6 +2644,8 @@ int ena_com_rss_init(struct ena_com_dev *ena_dev, u16 indr_tbl_log_size)
 	if (unlikely(rc))
 		goto err_hash_key;
 
+	ena_com_hash_key_fill_default_key(ena_dev);
+
 	rc = ena_com_hash_ctrl_init(ena_dev);
 	if (unlikely(rc))
 		goto err_hash_ctrl;

drivers/net/ethernet/amazon/ena/ena_com.h

@@ -44,6 +44,7 @@
 #include <linux/spinlock.h>
 #include <linux/types.h>
 #include <linux/wait.h>
+#include <linux/netdevice.h>
 
 #include "ena_common_defs.h"
 #include "ena_admin_defs.h"