From d084d996aaf53c0cc583dc75a4fc2a67fe485846 Mon Sep 17 00:00:00 2001 From: Si-Wei Liu Date: Thu, 8 Apr 2021 12:10:43 +0300 Subject: vdpa/mlx5: should exclude header length and fcs from mtu When feature VIRTIO_NET_F_MTU is negotiated on mlx5_vdpa, 22 extra bytes worth of MTU length is shown in guest. This is because the mlx5_query_port_max_mtu API returns the "hardware" MTU value, which does not just contain the Ethernet payload, but includes extra lengths starting from the Ethernet header up to the FCS altogether. Fix the MTU so packets won't get dropped silently. Fixes: 1a86b377aa21 ("vdpa/mlx5: Add VDPA driver for supported mlx5 devices") Signed-off-by: Si-Wei Liu Acked-by: Jason Wang Acked-by: Eli Cohen Link: https://lore.kernel.org/r/20210408091047.4269-2-elic@nvidia.com Signed-off-by: Michael S. Tsirkin --- drivers/vdpa/mlx5/core/mlx5_vdpa.h | 4 ++++ drivers/vdpa/mlx5/net/mlx5_vnet.c | 15 ++++++++++++++- 2 files changed, 18 insertions(+), 1 deletion(-) (limited to 'drivers/vdpa') diff --git a/drivers/vdpa/mlx5/core/mlx5_vdpa.h b/drivers/vdpa/mlx5/core/mlx5_vdpa.h index 08f742fd2409..b6cc53ba980c 100644 --- a/drivers/vdpa/mlx5/core/mlx5_vdpa.h +++ b/drivers/vdpa/mlx5/core/mlx5_vdpa.h @@ -4,9 +4,13 @@ #ifndef __MLX5_VDPA_H__ #define __MLX5_VDPA_H__ +#include +#include #include #include +#define MLX5V_ETH_HARD_MTU (ETH_HLEN + VLAN_HLEN + ETH_FCS_LEN) + struct mlx5_vdpa_direct_mr { u64 start; u64 end; diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c index 71397fdafa6a..a49ebb250253 100644 --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c @@ -1907,6 +1907,19 @@ static const struct vdpa_config_ops mlx5_vdpa_ops = { .free = mlx5_vdpa_free, }; +static int query_mtu(struct mlx5_core_dev *mdev, u16 *mtu) +{ + u16 hw_mtu; + int err; + + err = mlx5_query_nic_vport_mtu(mdev, &hw_mtu); + if (err) + return err; + + *mtu = hw_mtu - MLX5V_ETH_HARD_MTU; + return 0; +} + static int alloc_resources(struct mlx5_vdpa_net *ndev) { struct mlx5_vdpa_net_resources *res = &ndev->res; @@ -1992,7 +2005,7 @@ static int mlx5v_probe(struct auxiliary_device *adev, init_mvqs(ndev); mutex_init(&ndev->reslock); config = &ndev->config; - err = mlx5_query_nic_vport_mtu(mdev, &ndev->mtu); + err = query_mtu(mdev, &ndev->mtu); if (err) goto err_mtu; -- cgit v1.2.3