[PATCH V1 net 06/11] net: ena: rss: fix failure to get indirection table

[Sameeh Jubran <sameehj@amazon.com>]

From: Arthur Kiyanovski <akiyano@amazon.com>

Bug:
The get indirection table will fail on older hardware versions. This
happens because getting/setting the hash function is not supported on
this hardware. In short ena_indirection_table_get() succeeds while
the call to ena_com_get_hash_function() fails when ena_get_rxfh() is
executed.

Fix:
Simply set the hash function to the default value - Toeplitz - in case the
error is EOPNOTSUPP.

Also:
* Separate hash and key retrieval
* Fix restoring the hash function in ena_com_fill_hash_function()
* Reverse christmas tree in ena_com_fill_hash_function()

Fixes: 1738cd3ed342 ("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>
---
 drivers/net/ethernet/amazon/ena/ena_com.c     | 24 ++++++++++++-------
 drivers/net/ethernet/amazon/ena/ena_com.h     | 22 ++++++++++++-----
 drivers/net/ethernet/amazon/ena/ena_ethtool.c | 10 +++++---
 3 files changed, 39 insertions(+), 17 deletions(-)

diff --git a/drivers/net/ethernet/amazon/ena/ena_com.c b/drivers/net/ethernet/amazon/ena/ena_com.c
index 9e6c50b97..8bcf76f92 100644
--- a/drivers/net/ethernet/amazon/ena/ena_com.c
+++ b/drivers/net/ethernet/amazon/ena/ena_com.c
@@ -2295,12 +2295,14 @@ int ena_com_fill_hash_function(struct ena_com_dev *ena_dev,
 			       enum ena_admin_hash_functions func,
 			       const u8 *key, u16 key_len, u32 init_val)
 {
-	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;
-	struct ena_admin_feature_rss_flow_hash_control *hash_key =
-		rss->hash_key;
+	enum ena_admin_hash_functions old_func;
+	struct ena_rss *rss = &ena_dev->rss;
 	int rc;
 
+	hash_key = rss->hash_key;
+
 	/* Make sure size is a mult of DWs */
 	if (unlikely(key_len & 0x3))
 		return -EINVAL;
@@ -2338,24 +2340,22 @@ int ena_com_fill_hash_function(struct ena_com_dev *ena_dev,
 		return -EINVAL;
 	}
 
+	old_func = rss->hash_func;
 	rss->hash_func = func;
 	rc = ena_com_set_hash_function(ena_dev);
 
 	/* Restore the old function */
 	if (unlikely(rc))
-		ena_com_get_hash_function(ena_dev, NULL, NULL);
+		rss->hash_func = old_func;
 
 	return rc;
 }
 
 int ena_com_get_hash_function(struct ena_com_dev *ena_dev,
-			      enum ena_admin_hash_functions *func,
-			      u8 *key)
+			      enum ena_admin_hash_functions *func)
 {
 	struct ena_rss *rss = &ena_dev->rss;
 	struct ena_admin_get_feat_resp get_resp;
-	struct ena_admin_feature_rss_flow_hash_control *hash_key =
-		rss->hash_key;
 	int rc;
 
 	rc = ena_com_get_feature_ex(ena_dev, &get_resp,
@@ -2373,6 +2373,14 @@ int ena_com_get_hash_function(struct ena_com_dev *ena_dev,
 	if (func)
 		*func = rss->hash_func;
 
+	return 0;
+}
+
+int ena_com_get_hash_key(struct ena_com_dev *ena_dev, u8 *key)
+{
+	struct ena_admin_feature_rss_flow_hash_control *hash_key =
+		ena_dev->rss.hash_key;
+
 	if (key)
 		memcpy(key, hash_key->key, (size_t)(hash_key->keys_num) << 2);
 
diff --git a/drivers/net/ethernet/amazon/ena/ena_com.h b/drivers/net/ethernet/amazon/ena/ena_com.h
index 91c048872..ea925bb01 100644
--- a/drivers/net/ethernet/amazon/ena/ena_com.h
+++ b/drivers/net/ethernet/amazon/ena/ena_com.h
@@ -687,13 +687,11 @@ int ena_com_fill_hash_function(struct ena_com_dev *ena_dev,
  */
 int ena_com_set_hash_function(struct ena_com_dev *ena_dev);
 
-/* ena_com_get_hash_function - Retrieve the hash function and the hash key
- * from the device.
+/* ena_com_get_hash_function - Retrieve the hash function from the device.
  * @ena_dev: ENA communication layer struct
  * @func: hash function
- * @key: hash key
  *
- * Retrieve the hash function and the hash key from the device.
+ * Retrieve the hash function from the device.
  *
  * @note: If the caller called ena_com_fill_hash_function but didn't flash
  * it to the device, the new configuration will be lost.
@@ -701,8 +699,20 @@ int ena_com_set_hash_function(struct ena_com_dev *ena_dev);
  * @return: 0 on Success and negative value otherwise.
  */
 int ena_com_get_hash_function(struct ena_com_dev *ena_dev,
-			      enum ena_admin_hash_functions *func,
-			      u8 *key);
+			      enum ena_admin_hash_functions *func);
+
+/* ena_com_get_hash_key - Retrieve the hash key
+ * @ena_dev: ENA communication layer struct
+ * @key: hash key
+ *
+ * Retrieve the hash key.
+ *
+ * @note: If the caller called ena_com_fill_hash_key but didn't flash
+ * it to the device, the new configuration will be lost.
+ *
+ * @return: 0 on Success and negative value otherwise.
+ */
+int ena_com_get_hash_key(struct ena_com_dev *ena_dev, u8 *key);
 
 /* ena_com_fill_hash_ctrl - Fill RSS hash control
  * @ena_dev: ENA communication layer struct.
diff --git a/drivers/net/ethernet/amazon/ena/ena_ethtool.c b/drivers/net/ethernet/amazon/ena/ena_ethtool.c
index 8b56383b6..d0d91dbe0 100644
--- a/drivers/net/ethernet/amazon/ena/ena_ethtool.c
+++ b/drivers/net/ethernet/amazon/ena/ena_ethtool.c
@@ -640,7 +640,7 @@ static int ena_get_rxfh(struct net_device *netdev, u32 *indir, u8 *key,
 			u8 *hfunc)
 {
 	struct ena_adapter *adapter = netdev_priv(netdev);
-	enum ena_admin_hash_functions ena_func;
+	enum ena_admin_hash_functions ena_func = ENA_ADMIN_TOEPLITZ;
 	u8 func;
 	int rc;
 
@@ -648,10 +648,14 @@ static int ena_get_rxfh(struct net_device *netdev, u32 *indir, u8 *key,
 	if (rc)
 		return rc;
 
-	rc = ena_com_get_hash_function(adapter->ena_dev, &ena_func, key);
+	rc = ena_com_get_hash_key(adapter->ena_dev, key);
 	if (rc)
 		return rc;
 
+	rc = ena_com_get_hash_function(adapter->ena_dev, &ena_func);
+	if (rc && rc != -EOPNOTSUPP)
+		return rc;
+
 	switch (ena_func) {
 	case ENA_ADMIN_TOEPLITZ:
 		func = ETH_RSS_HASH_TOP;
@@ -668,7 +672,7 @@ static int ena_get_rxfh(struct net_device *netdev, u32 *indir, u8 *key,
 	if (hfunc)
 		*hfunc = func;
 
-	return rc;
+	return 0;
 }
 
 static int ena_set_rxfh(struct net_device *netdev, const u32 *indir,
-- 
2.24.1.AMZN