[RFC PATCH] ixgbe: Consider xsk pool's frame size for MTU size
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: 2021-06-22 16:26:20
Also in:
intel-wired-lan
Subsystem:
intel ethernet drivers, networking drivers, the rest · Maintainers:
Tony Nguyen, Przemek Kitszel, Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
The driver has to a ensure that a network packet is not using more than one page for its data if a XDP program is used. This results in an upper limit of 1500 bytes. This can be increased a little if the MTU was programmed to 1514..3072 bytes before loading the XDP program. By setting this increased MTU size the driver will set the __IXGBE_RX_3K_BUFFER flag which in turn will allow to use 3KiB as the upper limit. This looks like a hack and the upper limit is could increased further. If the user configured a memory pool then PAGE_SIZE is used as BSIZEPKT and RLPML is set to pool's memory size as is the card's maximum frame size. The result is that a MTU of 3520 bytes can be programmed and every packet is stored a single page. If a RX ring has a pool assigned use its size while comparing for the maximal MTU size. Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> --- According to my traces incoming packets with a size 70 or 3520 bytes all end up in one page. There is currently only one ring/RX-queue. I'm not sure if it is reasonable to assume to have one RX-queue with xsk_pool and one without. drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 21 +++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-)
diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
index 2ac5b82676f3b..d250c20a941e9 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c@@ -6723,6 +6723,23 @@ static void ixgbe_free_all_rx_resources(struct ixgbe_adapter *adapter) ixgbe_free_rx_resources(adapter->rx_ring[i]); } +static int ixgbe_validate_frame_size(unsigned int frame_size, + struct ixgbe_ring *ring) +{ + struct xsk_buff_pool *xsk_pool; + unsigned int buf_len; + + xsk_pool = ring->xsk_pool; + if (xsk_pool) + buf_len = xsk_pool_get_rx_frame_size(xsk_pool); + else + buf_len = ixgbe_rx_bufsz(ring); + + if (frame_size > buf_len) + return -EINVAL; + return 0; +} + /** * ixgbe_change_mtu - Change the Maximum Transfer Unit * @netdev: network interface device structure
@@ -6742,7 +6759,7 @@ static int ixgbe_change_mtu(struct net_device *netdev, int new_mtu) for (i = 0; i < adapter->num_rx_queues; i++) { struct ixgbe_ring *ring = adapter->rx_ring[i]; - if (new_frame_size > ixgbe_rx_bufsz(ring)) { + if (ixgbe_validate_frame_size(new_frame_size, ring)) { e_warn(probe, "Requested MTU size is not supported with XDP\n"); return -EINVAL; }
@@ -10127,7 +10144,7 @@ static int ixgbe_xdp_setup(struct net_device *dev, struct bpf_prog *prog) if (ring_is_rsc_enabled(ring)) return -EINVAL; - if (frame_size > ixgbe_rx_bufsz(ring)) + if (ixgbe_validate_frame_size(frame_size, ring)) return -EINVAL; }
--
2.32.0