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i40e: change Rx buffer size for legacy-rx to support XDP multi-buffer

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Adding support for XDP multi-buffer entails adding information of all
the fragments of the packet in the xdp_buff. This approach implies that
underlying buffer has to provide tailroom for skb_shared_info.

In the legacy-rx mode, driver can only configure up to 2k sized Rx buffers
and with the current configuration of 2k sized Rx buffers there is no way
to do tailroom reservation for skb_shared_info. Hence size of Rx buffers
is now lowered to 2048 - sizeof(skb_shared_info). Also, driver can only
chain up to 5 Rx buffers and this means max MTU supported for legacy-rx
is now 8614 (5 * rx_buffer_len  - ETH header with VLAN).

Signed-off-by: Tirthendu Sarkar <tirthendu.sarkar@intel.com>
Tested-by: Chandan Kumar Rout <chandanx.rout@intel.com> (A Contingent Worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
This commit is contained in:
Tirthendu Sarkar 2023-03-10 00:26:09 +05:30 committed by Tony Nguyen
parent a4ba62906d
commit f7f732a719
2 changed files with 16 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
drivers/net/ethernet/intel/i40e/i40e_ethtool.c
View File

@ -5402,6 +5402,13 @@ flags_complete:
return -EOPNOTSUPP;
}
if ((changed_flags & I40E_FLAG_LEGACY_RX) &&
I40E_2K_TOO_SMALL_WITH_PADDING) {
dev_warn(&pf->pdev->dev,
"2k Rx buffer is too small to fit standard MTU and skb_shared_info\n");
return -EOPNOTSUPP;
}
if ((changed_flags & new_flags &
I40E_FLAG_LINK_DOWN_ON_CLOSE_ENABLED) &&
(new_flags & I40E_FLAG_MFP_ENABLED))

12
drivers/net/ethernet/intel/i40e/i40e_main.c
View File

@ -2903,7 +2903,7 @@ static void i40e_sync_filters_subtask(struct i40e_pf *pf)
static u16 i40e_calculate_vsi_rx_buf_len(struct i40e_vsi *vsi)
{
if (!vsi->netdev || (vsi->back->flags & I40E_FLAG_LEGACY_RX))
return I40E_RXBUFFER_2048;
return SKB_WITH_OVERHEAD(I40E_RXBUFFER_2048);
return PAGE_SIZE < 8192 ? I40E_RXBUFFER_3072 : I40E_RXBUFFER_2048;
}
@ -3661,10 +3661,16 @@ static int i40e_configure_rx_ring(struct i40e_ring *ring)
}
/* configure Rx buffer alignment */
if (!vsi->netdev || (vsi->back->flags & I40E_FLAG_LEGACY_RX))
if (!vsi->netdev || (vsi->back->flags & I40E_FLAG_LEGACY_RX)) {
if (I40E_2K_TOO_SMALL_WITH_PADDING) {
dev_info(&vsi->back->pdev->dev,
"2k Rx buffer is too small to fit standard MTU and skb_shared_info\n");
return -EOPNOTSUPP;
}
clear_ring_build_skb_enabled(ring);
else
} else {
set_ring_build_skb_enabled(ring);
}
ring->rx_offset = i40e_rx_offset(ring);