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@eho.link Signed-off-by: Emmanuel Deloget emmanuel.deloget@eho.link Reviewed-by: Marcin Wojtas mw@semihalf.com Acked-by: John Fastabend john.fastabend@gmail.com Acked-by: Jesper Dangaard Brouer brouer@redhat.com
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