net: ena: rss: do not allocate key when not supported

Currently we allocate the key whether the device supports setting the
key or not. This commit adds a check to the allocation function and
handles the error accordingly.

Fixes: 1738cd3 ("net: ena: Add a driver for Amazon Elastic Network Adapters (ENA)")
Signed-off-by: Sameeh Jubran <sameehj@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

@@ -1057,6 +1057,20 @@ static void ena_com_hash_key_fill_default_key(struct ena_com_dev *ena_dev)
 static int ena_com_hash_key_allocate(struct ena_com_dev *ena_dev)
 {
 	struct ena_rss *rss = &ena_dev->rss;
+	struct ena_admin_feature_rss_flow_hash_control *hash_key;
+	struct ena_admin_get_feat_resp get_resp;
+	int rc;
+
+	hash_key = (ena_dev->rss).hash_key;
+
+	rc = ena_com_get_feature_ex(ena_dev, &get_resp,
+				    ENA_ADMIN_RSS_HASH_FUNCTION,
+				    ena_dev->rss.hash_key_dma_addr,
+				    sizeof(ena_dev->rss.hash_key), 0);
+	if (unlikely(rc)) {
+		hash_key = NULL;
+		return -EOPNOTSUPP;
+	}
 
 	rss->hash_key =
 		dma_alloc_coherent(ena_dev->dmadev, sizeof(*rss->hash_key),
@@ -2640,11 +2654,15 @@ int ena_com_rss_init(struct ena_com_dev *ena_dev, u16 indr_tbl_log_size)
 	if (unlikely(rc))
 		goto err_indr_tbl;
 
+	/* The following function might return unsupported in case the
+	 * device doesn't support setting the key / hash function. We can safely
+	 * ignore this error and have indirection table support only.
+	 */
 	rc = ena_com_hash_key_allocate(ena_dev);
-	if (unlikely(rc))
+	if (unlikely(rc) && rc != -EOPNOTSUPP)
 		goto err_hash_key;
-
-	ena_com_hash_key_fill_default_key(ena_dev);
+	else if (rc != -EOPNOTSUPP)
+		ena_com_hash_key_fill_default_key(ena_dev);
 
 	rc = ena_com_hash_ctrl_init(ena_dev);
 	if (unlikely(rc))