6.18-stable review patch. If anyone has any objections, please let me know.
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From: Cosmin Ratiu cratiu@nvidia.com
[ Upstream commit 4198a14c8c6252fd1191afaa742dd515dcaf3487 ]
Commit [1] added the 40 bytes required by the PSP header+trailer and the UDP header to MLX5E_ETH_HARD_MTU, which limits the device-wide max software MTU that could be set. This is not okay, because most packets are not PSP packets and it doesn't make sense to always reserve space for headers which won't get added in most cases.
As it turns out, for TCP connections, PSP overhead is already taken into account in the TCP MSS calculations via inet_csk(sk)->icsk_ext_hdr_len. This was added in commit [2]. This means that the extra space reserved in the hard MTU for mlx5 ends up unused and wasted.
Remove the unnecessary 40 byte reservation from hard MTU.
[1] commit e5a1861a298e ("net/mlx5e: Implement PSP Tx data path") [2] commit e97269257fe4 ("net: psp: update the TCP MSS to reflect PSP packet overhead")
Fixes: e5a1861a298e ("net/mlx5e: Implement PSP Tx data path") Signed-off-by: Cosmin Ratiu cratiu@nvidia.com Reviewed-by: Shahar Shitrit shshitrit@nvidia.com Signed-off-by: Tariq Toukan tariqt@nvidia.com Link: https://patch.msgid.link/1765284977-1363052-10-git-send-email-tariqt@nvidia.... Signed-off-by: Paolo Abeni pabeni@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/ethernet/mellanox/mlx5/core/en.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en.h b/drivers/net/ethernet/mellanox/mlx5/core/en.h index a163f81f07c13..a6479e4d8d8c6 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/en.h +++ b/drivers/net/ethernet/mellanox/mlx5/core/en.h @@ -69,7 +69,7 @@ struct page_pool; #define MLX5E_METADATA_ETHER_TYPE (0x8CE4) #define MLX5E_METADATA_ETHER_LEN 8
-#define MLX5E_ETH_HARD_MTU (ETH_HLEN + PSP_ENCAP_HLEN + PSP_TRL_SIZE + VLAN_HLEN + ETH_FCS_LEN) +#define MLX5E_ETH_HARD_MTU (ETH_HLEN + VLAN_HLEN + ETH_FCS_LEN)
#define MLX5E_HW2SW_MTU(params, hwmtu) ((hwmtu) - ((params)->hard_mtu)) #define MLX5E_SW2HW_MTU(params, swmtu) ((swmtu) + ((params)->hard_mtu))