From mboxrd@z Thu Jan 1 00:00:00 1970 From: John Fastabend Subject: [net PATCH] net: virtio: cap mtu when XDP programs are running Date: Mon, 02 Jan 2017 14:30:31 -0800 Message-ID: <20170102223031.11541.28717.stgit@john-Precision-Tower-5810> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Cc: john.r.fastabend@intel.com, netdev@vger.kernel.org, john.fastabend@gmail.com, alexei.starovoitov@gmail.com, daniel@iogearbox.net To: jasowang@redhat.com, mst@redhat.com Return-path: Received: from mail-pg0-f67.google.com ([74.125.83.67]:36123 "EHLO mail-pg0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751837AbdABWar (ORCPT ); Mon, 2 Jan 2017 17:30:47 -0500 Received: by mail-pg0-f67.google.com with SMTP id n5so31521679pgh.3 for ; Mon, 02 Jan 2017 14:30:47 -0800 (PST) Sender: netdev-owner@vger.kernel.org List-ID: XDP programs can not consume multiple pages so we cap the MTU to avoid this case. Virtio-net however only checks the MTU at XDP program load and does not block MTU changes after the program has loaded. This patch sets/clears the max_mtu value at XDP load/unload time. Signed-off-by: John Fastabend --- drivers/net/virtio_net.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 5deeda6..783e842 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -1699,6 +1699,9 @@ static void virtnet_init_settings(struct net_device *dev) .set_settings = virtnet_set_settings, }; +#define MIN_MTU ETH_MIN_MTU +#define MAX_MTU ETH_MAX_MTU + static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog *prog) { unsigned long int max_sz = PAGE_SIZE - sizeof(struct padded_vnet_hdr); @@ -1748,6 +1751,9 @@ static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog *prog) virtnet_set_queues(vi, curr_qp); return PTR_ERR(prog); } + dev->max_mtu = max_sz; + } else { + dev->max_mtu = ETH_MAX_MTU; } vi->xdp_queue_pairs = xdp_qp; @@ -2133,9 +2139,6 @@ static bool virtnet_validate_features(struct virtio_device *vdev) return true; } -#define MIN_MTU ETH_MIN_MTU -#define MAX_MTU ETH_MAX_MTU - static int virtnet_probe(struct virtio_device *vdev) { int i, err;