[PATCH V1 net 07/11] net: ena: fix incorrectly saving queue numbers when setting RSS indirection table

[Sameeh Jubran <sameehj@amazon.com>]

From: Arthur Kiyanovski <akiyano@amazon.com>

The indirection table has the indices of the Rx queues. When we store it
during set indirection operation, we convert the indices to our internal
representation of the indices.

Our internal representation of the indices is: even indices for Tx and
odd indices for Rx, where every Tx/Rx pair are in a consecutive order
starting from 0. For example if the driver has 3 queues (3 for Tx and 3
for Rx) then the indices are as follows:
0  1  2  3  4  5
Tx Rx Tx Rx Tx Rx

The BUG:
The issue is that when we satisfy a get request for the indirection
table, we don't convert the indices back to the original representation.

The FIX:
Simply apply the inverse function for the indices of the indirection
table after we set it.

Also move the set code to a standalone function for code clarity.

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_ethtool.c | 72 ++++++++++++++-----
 drivers/net/ethernet/amazon/ena/ena_netdev.h  |  2 +
 2 files changed, 55 insertions(+), 19 deletions(-)

diff --git a/drivers/net/ethernet/amazon/ena/ena_ethtool.c b/drivers/net/ethernet/amazon/ena/ena_ethtool.c
index d0d91dbe0..accc4c8d1 100644
--- a/drivers/net/ethernet/amazon/ena/ena_ethtool.c
+++ b/drivers/net/ethernet/amazon/ena/ena_ethtool.c
@@ -636,6 +636,54 @@ static u32 ena_get_rxfh_key_size(struct net_device *netdev)
 	return ENA_HASH_KEY_SIZE;
 }
 
+static int ena_indirection_table_set(struct ena_adapter *adapter,
+				     const u32 *indir)
+{
+	struct ena_com_dev *ena_dev = adapter->ena_dev;
+	int i, rc;
+
+	for (i = 0; i < ENA_RX_RSS_TABLE_SIZE; i++) {
+		rc = ena_com_indirect_table_fill_entry(ena_dev,
+						       i,
+						       ENA_IO_RXQ_IDX(indir[i]));
+		if (unlikely(rc)) {
+			netif_err(adapter, drv, adapter->netdev,
+				  "Cannot fill indirect table (index is too large)\n");
+			return rc;
+		}
+	}
+
+	rc = ena_com_indirect_table_set(ena_dev);
+	if (rc) {
+		netif_err(adapter, drv, adapter->netdev,
+			  "Cannot set indirect table\n");
+		return rc == -EPERM ? -EOPNOTSUPP : rc;
+	}
+	return rc;
+}
+
+static int ena_indirection_table_get(struct ena_adapter *adapter, u32 *indir)
+{
+	struct ena_com_dev *ena_dev = adapter->ena_dev;
+	int i, rc;
+
+	if (!indir)
+		return 0;
+
+	rc = ena_com_indirect_table_get(ena_dev, indir);
+	if (rc)
+		return rc;
+
+	/* Our internal representation of the indices is: even indices
+	 * for Tx and uneven indices for Rx. We need to convert the Rx
+	 * indices to be consecutive
+	 */
+	for (i = 0; i < ENA_RX_RSS_TABLE_SIZE; i++)
+		indir[i] = ENA_IO_RXQ_IDX_TO_COMBINED_IDX(indir[i]);
+
+	return rc;
+}
+
 static int ena_get_rxfh(struct net_device *netdev, u32 *indir, u8 *key,
 			u8 *hfunc)
 {
@@ -644,7 +692,7 @@ static int ena_get_rxfh(struct net_device *netdev, u32 *indir, u8 *key,
 	u8 func;
 	int rc;
 
-	rc = ena_com_indirect_table_get(adapter->ena_dev, indir);
+	rc = ena_indirection_table_get(adapter, indir);
 	if (rc)
 		return rc;
 
@@ -681,26 +729,12 @@ static int ena_set_rxfh(struct net_device *netdev, const u32 *indir,
 	struct ena_adapter *adapter = netdev_priv(netdev);
 	struct ena_com_dev *ena_dev = adapter->ena_dev;
 	enum ena_admin_hash_functions func;
-	int rc, i;
+	int rc;
 
 	if (indir) {
-		for (i = 0; i < ENA_RX_RSS_TABLE_SIZE; i++) {
-			rc = ena_com_indirect_table_fill_entry(ena_dev,
-							       i,
-							       ENA_IO_RXQ_IDX(indir[i]));
-			if (unlikely(rc)) {
-				netif_err(adapter, drv, netdev,
-					  "Cannot fill indirect table (index is too large)\n");
-				return rc;
-			}
-		}
-
-		rc = ena_com_indirect_table_set(ena_dev);
-		if (rc) {
-			netif_err(adapter, drv, netdev,
-				  "Cannot set indirect table\n");
-			return rc == -EPERM ? -EOPNOTSUPP : rc;
-		}
+		rc = ena_indirection_table_set(adapter, indir);
+		if (rc)
+			return rc;
 	}
 
 	switch (hfunc) {
diff --git a/drivers/net/ethernet/amazon/ena/ena_netdev.h b/drivers/net/ethernet/amazon/ena/ena_netdev.h
index bffd778f2..2fe5eeea6 100644
--- a/drivers/net/ethernet/amazon/ena/ena_netdev.h
+++ b/drivers/net/ethernet/amazon/ena/ena_netdev.h
@@ -129,6 +129,8 @@
 
 #define ENA_IO_TXQ_IDX(q)	(2 * (q))
 #define ENA_IO_RXQ_IDX(q)	(2 * (q) + 1)
+#define ENA_IO_TXQ_IDX_TO_COMBINED_IDX(q)	((q) / 2)
+#define ENA_IO_RXQ_IDX_TO_COMBINED_IDX(q)	(((q) - 1) / 2)
 
 #define ENA_MGMNT_IRQ_IDX		0
 #define ENA_IO_IRQ_FIRST_IDX		1
-- 
2.24.1.AMZN