On Fri, Dec 10, 2021 at 06:16:20PM +0100, Louis Amas wrote:
> commit a50e659b2a1be14784e80f8492aab177e67c53a2 upstream
>
> The registration of XDP queue information is incorrect because the
> RX queue id we use is invalid. When port->id == 0 it appears to works
> as expected yet it's no longer the case when port->id != 0.
>
> The problem arised while using a recent kernel version on the
> MACCHIATOBin. This board has several ports:
> * eth0 and eth1 are 10Gbps interfaces ; both ports has port->id == 0;
> * eth2 is a 1Gbps interface with port->id != 0.
>
> Code from xdp-tutorial (more specifically advanced03-AF_XDP) was used
> to test packet capture and injection on all these interfaces. The XDP
> kernel was simplified to:
>
> SEC("xdp_sock")
> int xdp_sock_prog(struct xdp_md *ctx)
> {
> int index = ctx->rx_queue_index;
>
> /* A set entry here means that the correspnding queue_id
> * has an active AF_XDP socket bound to it. */
> if (bpf_map_lookup_elem(&xsks_map, &index))
> return bpf_redirect_map(&xsks_map, index, 0);
>
> return XDP_PASS;
> }
>
> Starting the program using:
>
> ./af_xdp_user -d DEV
>
> Gives the following result:
>
> * eth0 : ok
> * eth1 : ok
> * eth2 : no capture, no injection
>
> Investigating the issue shows that XDP rx queues for eth2 are wrong:
> XDP expects their id to be in the range [0..3] but we found them to be
> in the range [32..35].
>
> Trying to force rx queue ids using:
>
> ./af_xdp_user -d eth2 -Q 32
>
> fails as expected (we shall not have more than 4 queues).
>
> When we register the XDP rx queue information (using
> xdp_rxq_info_reg() in function mvpp2_rxq_init()) we tell it to use
> rxq->id as the queue id. This value is computed as:
>
> rxq->id = port->id * max_rxq_count + queue_id
>
> where max_rxq_count depends on the device version. In the MACCHIATOBin
> case, this value is 32, meaning that rx queues on eth2 are numbered
> from 32 to 35 - there are four of them.
>
> Clearly, this is not the per-port queue id that XDP is expecting:
> it wants a value in the range [0..3]. It shall directly use queue_id
> which is stored in rxq->logic_rxq -- so let's use that value instead.
>
> rxq->id is left untouched ; its value is indeed valid but it should
> not be used in this context.
>
> This is consistent with the remaining part of the code in
> mvpp2_rxq_init().
>
> With this change, packet capture is working as expected on all the
> MACCHIATOBin ports.
>
> Fixes: b27db2274ba8 ("mvpp2: use page_pool allocator")
> Signed-off-by: Louis Amas <louis.amas@xxxxxxxx>
> Signed-off-by: Emmanuel Deloget <emmanuel.deloget@xxxxxxxx>
> Reviewed-by: Marcin Wojtas <mw@xxxxxxxxxxxx>
> Acked-by: John Fastabend <john.fastabend@xxxxxxxxx>
> Acked-by: Jesper Dangaard Brouer <brouer@xxxxxxxxxx>
> ---
>
> Patch history
>
> v1 : original submission [1]
> v2 : commit message rework (no change in the patch) [2]
> v3 : commit message rework (no change in the patch) + added Acked-by [3]
> v4 : fix mail corruption by malevolent SMTP + rebase on net/master
> v5 : (this version) add tags back
Now queued up, thanks.
greg k-h
