[PATCH net 2/5] net/mlx5: E-Switch, Initialize MAC Address for Default GID

Mark Bloch
2025-04-23T08:36:45Z

From: Maor Gottlieb <maorg@nvidia.com>

Initialize the source MAC address when creating the default GID entry.
Since this entry is used only for loopback traffic, it only needs to
be a unicast address. A zeroed-out MAC address is sufficient for this
purpose.
Without this fix, random bits would be assigned as the source address.
If these bits formed a multicast address, the firmware would return an
error, preventing the user from switching to switchdev mode:

Error: mlx5_core: Failed setting eswitch to offloads.
kernel answers: Invalid argument

Fixes: 80f09dfc237f ("net/mlx5: Eswitch, enable RoCE loopback traffic")
Signed-off-by: Maor Gottlieb <maorg@nvidia.com>
Signed-off-by: Mark Bloch <mbloch@nvidia.com>
---
drivers/net/ethernet/mellanox/mlx5/core/rdma.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/rdma.c b/drivers/net/ethernet/mellanox/mlx5/core/rdma.c
index a42f6cd99b74..f585ef5a3424 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/rdma.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/rdma.c
@@ -118,8 +118,8 @@ static void mlx5_rdma_make_default_gid(struct mlx5_core_dev *dev, union ib_gid *

static int mlx5_rdma_add_roce_addr(struct mlx5_core_dev *dev)
{
+ u8 mac[ETH_ALEN] = {};
union ib_gid gid;
- u8 mac[ETH_ALEN];

mlx5_rdma_make_default_gid(dev, &gid);
return mlx5_core_roce_gid_set(dev, 0,
--
2.34.1