netdev - [PATCH net-next] net: mvpp2: increase MTU limit when XDP enabled

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Date:   Tue,  5 Jan 2021 18:19:21 +0100
From:   Marek Behún <kabel@...nel.org>
To:     netdev@...r.kernel.org
Cc:     davem@...emloft.net, Jakub Kicinski <kuba@...nel.org>,
        Marek Behún <kabel@...nel.org>,
        Sven Auhagen <sven.auhagen@...eatech.de>,
        Matteo Croce <mcroce@...rosoft.com>,
        Lorenzo Bianconi <lorenzo@...nel.org>
Subject: [PATCH net-next] net: mvpp2: increase MTU limit when XDP enabled

Currently mvpp2_xdp_setup won't allow attaching XDP program if
  mtu > ETH_DATA_LEN (1500).

The mvpp2_change_mtu on the other hand checks whether
  MVPP2_RX_PKT_SIZE(mtu) > MVPP2_BM_LONG_PKT_SIZE.

These two checks are semantically different.

Moreover this limit can be increased to MVPP2_MAX_RX_BUF_SIZE, since in
mvpp2_rx we have
  xdp.data = data + MVPP2_MH_SIZE + MVPP2_SKB_HEADROOM;
  xdp.frame_sz = PAGE_SIZE;

Change the checks to check whether
  mtu > MVPP2_MAX_RX_BUF_SIZE

Signed-off-by: Marek Behún <kabel@...nel.org>
Cc: Sven Auhagen <sven.auhagen@...eatech.de>
Cc: Matteo Croce <mcroce@...rosoft.com>
Cc: Lorenzo Bianconi <lorenzo@...nel.org>
---
 drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
index afdd22827223..65490a0eb657 100644
--- a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
+++ b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
@@ -4623,11 +4623,12 @@ static int mvpp2_change_mtu(struct net_device *dev, int mtu)
 		mtu = ALIGN(MVPP2_RX_PKT_SIZE(mtu), 8);
 	}
 
+	if (port->xdp_prog && mtu > MVPP2_MAX_RX_BUF_SIZE) {
+		netdev_err(dev, "Illegal MTU value %d for XDP mode\n", mtu);
+		return -EINVAL;
+	}
+
 	if (MVPP2_RX_PKT_SIZE(mtu) > MVPP2_BM_LONG_PKT_SIZE) {
-		if (port->xdp_prog) {
-			netdev_err(dev, "Jumbo frames are not supported with XDP\n");
-			return -EINVAL;
-		}
 		if (priv->percpu_pools) {
 			netdev_warn(dev, "mtu %d too high, switching to shared buffers", mtu);
 			mvpp2_bm_switch_buffers(priv, false);
@@ -4913,8 +4914,8 @@ static int mvpp2_xdp_setup(struct mvpp2_port *port, struct netdev_bpf *bpf)
 	bool running = netif_running(port->dev);
 	bool reset = !prog != !port->xdp_prog;
 
-	if (port->dev->mtu > ETH_DATA_LEN) {
-		NL_SET_ERR_MSG_MOD(bpf->extack, "XDP is not supported with jumbo frames enabled");
+	if (port->dev->mtu > MVPP2_MAX_RX_BUF_SIZE) {
+		NL_SET_ERR_MSG_MOD(bpf->extack, "MTU too large for XDP");
 		return -EOPNOTSUPP;
 	}
 
-- 
2.26.2