From 5ee15c101f29e0093ffb5448773ccbc786eb313b Mon Sep 17 00:00:00 2001 From: Matteo Croce Date: Thu, 11 Apr 2019 12:26:32 +0200 Subject: [PATCH 1/2] net: thunderx: raise XDP MTU to 1508 The thunderx driver splits frames bigger than 1530 bytes to multiple pages, making impossible to run an eBPF program on it. This leads to a maximum MTU of 1508 if QinQ is in use. The thunderx driver forbids to load an eBPF program if the MTU is higher than 1500 bytes. Raise the limit to 1508 so it is possible to use L2 protocols which need some more headroom. Fixes: 05c773f52b96e ("net: thunderx: Add basic XDP support") Signed-off-by: Matteo Croce Acked-by: Jesper Dangaard Brouer Signed-off-by: David S. Miller --- drivers/net/ethernet/cavium/thunder/nicvf_main.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/drivers/net/ethernet/cavium/thunder/nicvf_main.c b/drivers/net/ethernet/cavium/thunder/nicvf_main.c index 28eac9056211..debc8c861c6b 100644 --- a/drivers/net/ethernet/cavium/thunder/nicvf_main.c +++ b/drivers/net/ethernet/cavium/thunder/nicvf_main.c @@ -32,6 +32,13 @@ #define DRV_NAME "nicvf" #define DRV_VERSION "1.0" +/* NOTE: Packets bigger than 1530 are split across multiple pages and XDP needs + * the buffer to be contiguous. Allow XDP to be set up only if we don't exceed + * this value, keeping headroom for the 14 byte Ethernet header and two + * VLAN tags (for QinQ) + */ +#define MAX_XDP_MTU (1530 - ETH_HLEN - VLAN_HLEN * 2) + /* Supported devices */ static const struct pci_device_id nicvf_id_table[] = { { PCI_DEVICE_SUB(PCI_VENDOR_ID_CAVIUM, @@ -1830,8 +1837,10 @@ static int nicvf_xdp_setup(struct nicvf *nic, struct bpf_prog *prog) bool bpf_attached = false; int ret = 0; - /* For now just support only the usual MTU sized frames */ - if (prog && (dev->mtu > 1500)) { + /* For now just support only the usual MTU sized frames, + * plus some headroom for VLAN, QinQ. + */ + if (prog && dev->mtu > MAX_XDP_MTU) { netdev_warn(dev, "Jumbo frames not yet supported with XDP, current MTU %d.\n", dev->mtu); return -EOPNOTSUPP; From 1f227d16083b2e280b7dde4ca78883d75593f2fd Mon Sep 17 00:00:00 2001 From: Matteo Croce Date: Thu, 11 Apr 2019 12:26:33 +0200 Subject: [PATCH 2/2] net: thunderx: don't allow jumbo frames with XDP The thunderx driver forbids to load an eBPF program if the MTU is too high, but this can be circumvented by loading the eBPF, then raising the MTU. Fix this by limiting the MTU if an eBPF program is already loaded. Fixes: 05c773f52b96e ("net: thunderx: Add basic XDP support") Signed-off-by: Matteo Croce Acked-by: Jesper Dangaard Brouer Signed-off-by: David S. Miller --- drivers/net/ethernet/cavium/thunder/nicvf_main.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/net/ethernet/cavium/thunder/nicvf_main.c b/drivers/net/ethernet/cavium/thunder/nicvf_main.c index debc8c861c6b..c032bef1b776 100644 --- a/drivers/net/ethernet/cavium/thunder/nicvf_main.c +++ b/drivers/net/ethernet/cavium/thunder/nicvf_main.c @@ -1589,6 +1589,15 @@ static int nicvf_change_mtu(struct net_device *netdev, int new_mtu) struct nicvf *nic = netdev_priv(netdev); int orig_mtu = netdev->mtu; + /* For now just support only the usual MTU sized frames, + * plus some headroom for VLAN, QinQ. + */ + if (nic->xdp_prog && new_mtu > MAX_XDP_MTU) { + netdev_warn(netdev, "Jumbo frames not yet supported with XDP, current MTU %d.\n", + netdev->mtu); + return -EINVAL; + } + netdev->mtu = new_mtu; if (!netif_running(netdev))