From: Tirthendu Sarkar <tirthendu.sarkar@xxxxxxxxx>
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@xxxxxxxxx>
Tested-by: Chandan Kumar Rout <chandanx.rout@xxxxxxxxx> (A Contingent Worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@xxxxxxxxx>
---
drivers/net/ethernet/intel/i40e/i40e_ethtool.c | 7 +++++++
drivers/net/ethernet/intel/i40e/i40e_main.c | 12 +++++++++---
2 files changed, 16 insertions(+), 3 deletions(-)
diff --git a/drivers/net/ethernet/intel/i40e/i40e_ethtool.c b/drivers/net/ethernet/intel/i40e/i40e_ethtool.c
index 4934ff58332c..afc4fa8c66af 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_ethtool.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_ethtool.c
@@ -5402,6 +5402,13 @@ static int i40e_set_priv_flags(struct net_device *dev, u32 flags)
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))
diff --git a/drivers/net/ethernet/intel/i40e/i40e_main.c b/drivers/net/ethernet/intel/i40e/i40e_main.c
index d375d7940308..e8cf5644bf10 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_main.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_main.c
@@ -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);
--
2.38.1
