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vdpa/mlx5: should exclude header length and fcs from mtu

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[ Upstream commit d084d996aa ]

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: 1a86b377aa ("vdpa/mlx5: Add VDPA driver for supported mlx5 devices")
Signed-off-by: Si-Wei Liu <si-wei.liu@oracle.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Acked-by: Eli Cohen <elic@nvidia.com>
Link: https://lore.kernel.org/r/20210408091047.4269-2-elic@nvidia.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Si-Wei Liu 2021-04-08 12:10:43 +03:00 committed by Greg Kroah-Hartman
parent 5700c3d4ab
commit 0ddb34c2cc
2 changed files with 18 additions and 1 deletions
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4
drivers/vdpa/mlx5/core/mlx5_vdpa.h
View file

@ -4,9 +4,13 @@
#ifndef __MLX5_VDPA_H__
#define __MLX5_VDPA_H__
#include <linux/etherdevice.h>
#include <linux/if_vlan.h>
#include <linux/vdpa.h>
#include <linux/mlx5/driver.h>
#define MLX5V_ETH_HARD_MTU (ETH_HLEN + VLAN_HLEN + ETH_FCS_LEN)
struct mlx5_vdpa_direct_mr {
u64 start;
u64 end;

15
drivers/vdpa/mlx5/net/mlx5_vnet.c
View file

@ -1887,6 +1887,19 @@ 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;
@ -1969,7 +1982,7 @@ void *mlx5_vdpa_add_dev(struct mlx5_core_dev *mdev)
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;