net/mlx5: E-Switch, Initialize MAC Address for Default GID

[ Upstream commit 5d1a04f347e6cbf5ffe74da409a5d71fbe8c5f19 ]

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>
Reviewed-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
Link: https://patch.msgid.link/20250423083611.324567-3-mbloch@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/rdma.c b/drivers/net/ethernet/mellanox/mlx5/core/rdma.c
index 2389239acadc9a84799b56db9773236e588526af..945d90844f0cbbe88da23969cab4aa407b555c49 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlx5/core/rdma.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/rdma.c
@@ -130,8 +130,8 @@ 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,