From: Maxim Mikityanskiy <maximmi@nvidia.com>
Date: Tue, 18 Jan 2022 13:31:54 +0200
Subject: net/mlx5e: Don't treat small ceil values as unlimited in HTB offload
Patch-mainline: v5.17-rc3
Git-commit: 736dfe4e68b868829a1e89dfef4a44c1580d4478
References: git-fixes

The hardware spec defines max_average_bw == 0 as "unlimited bandwidth".
max_average_bw is calculated as `ceil / BYTES_IN_MBIT`, which can become
0 when ceil is small, leading to an undesired effect of having no
bandwidth limit.

This commit fixes it by rounding up small values of ceil to 1 Mbit/s.

Fixes: 214baf22870c ("net/mlx5e: Support HTB offload")
Signed-off-by: Maxim Mikityanskiy <maximmi@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/ethernet/mellanox/mlx5/core/en/qos.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/net/ethernet/mellanox/mlx5/core/en/qos.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en/qos.c
@@ -569,7 +569,8 @@ static int mlx5e_htb_convert_rate(struct
 
 static void mlx5e_htb_convert_ceil(struct mlx5e_priv *priv, u64 ceil, u32 *max_average_bw)
 {
-	*max_average_bw = div_u64(ceil, BYTES_IN_MBIT);
+	/* Hardware treats 0 as "unlimited", set at least 1. */
+	*max_average_bw = max_t(u32, div_u64(ceil, BYTES_IN_MBIT), 1);
 
 	qos_dbg(priv->mdev, "Convert: ceil %llu -> max_average_bw %u\n",
 		ceil, *max_average_bw);