Hi Jason, I confirm that the patch you sent me, together with "[PATCH net 1/2] virtio-net: disable guest csum during XDP set" and "[PATCH net 2/2] virtio-net: fail XDP set if guest csum is negotiated", have fixed the "bad gso" issue. Cheers Il giorno gio 22 nov 2018 alle ore 03:15 Jason Wang <jasowang@xxxxxxxxxx> ha scritto: > > > On 2018/11/21 上午2:14, Jesper Dangaard Brouer wrote: > > On Tue, 20 Nov 2018 16:47:19 +0100 > > Pavel Popa <pashinho1990@xxxxxxxxx> wrote: > > > >> Well, here's the output from the `ip link` cmd: > >> 3: eth3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 xdp qdisc mq state UP > >> link/ether 52:54:fc:47:e2:d3 brd ff:ff:ff:ff:ff:ff > >> prog/xdp id 1 tag 1cd982ef22273bda jited > >> 4: eth2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 xdp qdisc mq state UP > >> link/ether 52:54:55:d3:50:ee brd ff:ff:ff:ff:ff:ff > >> prog/xdp id 1 tag 1cd982ef22273bda jited > >> > >> As you can see, there's the XDP program ID 1 executing on them. > >> However, there's definitely something interesting happening when > >> bpf_fib_lookup() returns BPF_FIB_LKUP_RET_NO_NEIGH, for which my XDP > >> program just returns XDP_PASS while the following line gets printed in > >> kern.log: > >> eth3: bad gso: type: 164, size: 256 > > > Looks like a bug in virtio-net driver since all gso should be disabled > on host. > > Could you please try the attached patch to see if it fixes the issue? > > > >> > >> No idea what's wrong here. > >> Also, when bpf_fib_lookup() returns BPF_FIB_LKUP_RET_SUCCESS, for > >> which my XDP program executes bpf_redirect_map(&dev_map, > >> fib_params.ifindex, 0), the following gets printed in > >> > >> /sys/kernel/debug/tracing/trace_pipe: > >> xdp_redirect_map_err: prog_id=1 action=REDIRECT ifindex=3 > >> to_ifindex=0 err=-14 map_id=0 map_index=4 > > The err=-14 is -EFAULT. > > > > Notice "ifindex=3" but "to_ifindex=0", which is the problem. The > > "map_index=4" is correct, but "to_ifindex" does a lookup in the map for > > the net_device->ifindex stored in this map. It is fairly unlikely that > > you added device with ifindex=0 to map index 4, I presume? > > > > Then I was thinking, maybe the "map_index=4" doesn't contain anything, > > but reading the code, that will return err=-22 (#define EINVAL 22), > > which it not the case. > > > > Assuming that map_index=4 does contain a valid net_device. Following > > the code via __bpf_tx_xdp_map -> dev_map_enqueue, I simply cannot find > > an -EFAULT err return value. > > > > --Jesper > > > > > >> I feel this last one to be somewhat related to the comment here > >> https://elixir.bootlin.com/linux/v4.18.10/source/samples/bpf/xdp_fwd_kern.c#L107. > >> Is it correct? If so, what does this precisely mean? Is there any way > >> to get around with this? Because what I'm doing is simply using the > >> BPF_MAP_TYPE_DEVMAP with the bpf_redirect_map() helper to forward > >> packets between "XDP ports". > >> > >> Il giorno mar 20 nov 2018 alle ore 15:39 David Ahern > >> <dsahern@xxxxxxxxx> ha scritto: > >>> On 11/20/18 7:18 AM, Pavel Popa wrote: > >>>> Hi all, > >>>> > >>>> I've implemented a XDP forwarding program using the bpf_fib_lookup() > >>>> helper, and loaded it in the kernel as XDP driver mode (i.e. executed > >>>> at the virtio_net driver level). The only problem is that the > >>>> receiving virtio network interface seems to drop the XDP packet after > >>>> successfully executing my XDP program. > >>>> Kernel: 4.18.10 > >>>> > >>>> my_xdp_fwd_kern.c: > >>>> /* made sure this returns 0 (i.e. BPF_FIB_LKUP_RET_SUCCESS) */ > >>>> rc = bpf_fib_lookup(ctx, &fib_params, sizeof(fib_params), > >>>> BPF_FIB_LOOKUP_DIRECT); > >>>> /* made sure this returns 4 (i.e. XDP_REDIRECT) */ > >>>> rc = bpf_redirect_map(&dev_map, fib_params.ifindex, 0); > >>>> return rc; > >>>> > >>>> I checked that rc is indeed XDP_REDIRECT and that fib_params.ifindex > >>>> is the correct dev index from FIB lookup. > >>>> dev_map is setup by the userspace my_xdp_fwd_user.c component as follows: > >>>> for (i = 1; i < 64; i++) > >>>> bpf_map_update_elem(devmap_fd, &i, &i, BPF_ANY); > >>>> > >>>> I'm passing the following to the qemu cmd line for the 2 devices I > >>>> want to run XDP on (as stated here > >>>> https://marc.info/?l=xdp-newbies&m=149486931113651&w=2): > >>>> -device virtio-net-pci,mq=on,vectors=18,rx_queue_size=1024,tx_queue_size=512, > >>>> ... ,gso=off,guest_tso4=off,guest_tso6=off,guest_ecn=off,guest_ufo=off > >>>> \ > >>>> -device virtio-net-pci,mq=on,vectors=18,rx_queue_size=1024,tx_queue_size=512, > >>>> ... ,gso=off,guest_tso4=off,guest_tso6=off,guest_ecn=off,guest_ufo=off > >>>> \ > >>>> > >>>> In the guest enabling also the MultiQueue feature, as stated here > >>>> https://www.linux-kvm.org/page/Multiqueue#Enable_MQ_feature. > >>>> What I'm left with is debugging the virtio_net kernel module by adding > >>>> a bunch of printk() and see what happens, especially here > >>>> https://elixir.bootlin.com/linux/v4.18.10/source/drivers/net/virtio_net.c#L667. > >>>> > >>>> Am I doing something wrong here? What I'm missing? > >>>> > >>> I believe at this point you can drop the gso,tso,ufo and ecn args. I use > >>> virtio for development and these days start my VMs with only: > >>> > >>> ...,mq=on,guest_csum=off,... > > > This looks like another bug that guest_cusm was not disabled > automatically. Let me post a fix for this. > > Thanks. > > > >>> > >>> After that are you installing the xdp program on all interfaces that can > >>> be used for forwarding? ie., if it transmits a packet in XDP mode it > >>> needs the xdp program loaded. For example I use: > >>> > >>> xdp_fwd eth1 eth2 eth3 eth4 > >>> > >>> > >>> From there: > >>> > >>> echo 1 > /sys/kernel/debug/tracing/events/xdp/enable > >>> cat /sys/kernel/debug/tracing/trace_pipe > >>> > > > >
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