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

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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>

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This commit is contained in:

Si-Wei Liu 2021-04-08 12:10:43 +03:00 • committed by Michael S. Tsirkin

parent e49d033bdd

commit d084d996aa

2 changed files with 18 additions and 1 deletions

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4

drivers/vdpa/mlx5/core/mlx5_vdpa.h

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15

drivers/vdpa/mlx5/net/mlx5_vnet.c

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