[PATCH v7 bpf-next 6/9] bpf: cpumap: implement XDP_REDIRECT for eBPF programs attached to map entries

Lorenzo Bianconi
2020-07-14T13:57:27Z

Introduce XDP_REDIRECT support for eBPF programs attached to cpumap
entries.
This patch has been tested on Marvell ESPRESSObin using a modified
version of xdp_redirect_cpu sample in order to attach a XDP program
to CPUMAP entries to perform a redirect on the mvneta interface.
In particular the following scenario has been tested:

rq (cpu0) --> mvneta - XDP_REDIRECT (cpu0) --> CPUMAP - XDP_REDIRECT (cpu1) --> mvneta

$./xdp_redirect_cpu -p xdp_cpu_map0 -d eth0 -c 1 -e xdp_redirect \
-f xdp_redirect_kern.o -m tx_port -r eth0

tx: 285.2 Kpps rx: 285.2 Kpps

Attaching a simple XDP program on eth0 to perform XDP_TX gives
comparable results:

tx: 288.4 Kpps rx: 288.4 Kpps

Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Co-developed-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
include/net/xdp.h | 1 +
include/trace/events/xdp.h | 6 ++++--
kernel/bpf/cpumap.c | 17 +++++++++++++++--
3 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/include/net/xdp.h b/include/net/xdp.h
index 83b9e0142b52..5be0d4d65b94 100644
--- a/include/net/xdp.h
+++ b/include/net/xdp.h
@@ -99,6 +99,7 @@ struct xdp_frame {
};

struct xdp_cpumap_stats {
+ unsigned int redirect;
unsigned int pass;
unsigned int drop;
};
diff --git a/include/trace/events/xdp.h b/include/trace/events/xdp.h
index e2c99f5bee39..cd24e8a59529 100644
--- a/include/trace/events/xdp.h
+++ b/include/trace/events/xdp.h
@@ -190,6 +190,7 @@ TRACE_EVENT(xdp_cpumap_kthread,
__field(int, sched)
__field(unsigned int, xdp_pass)
__field(unsigned int, xdp_drop)
+ __field(unsigned int, xdp_redirect)
),

TP_fast_assign(
@@ -201,18 +202,19 @@ TRACE_EVENT(xdp_cpumap_kthread,
__entry->sched = sched;
__entry->xdp_pass = xdp_stats->pass;
__entry->xdp_drop = xdp_stats->drop;
+ __entry->xdp_redirect = xdp_stats->redirect;
),

TP_printk("kthread"
" cpu=%d map_id=%d action=%s"
" processed=%u drops=%u"
" sched=%d"
- " xdp_pass=%u xdp_drop=%u",
+ " xdp_pass=%u xdp_drop=%u xdp_redirect=%u",
__entry->cpu, __entry->map_id,
__print_symbolic(__entry->act, __XDP_ACT_SYM_TAB),
__entry->processed, __entry->drops,
__entry->sched,
- __entry->xdp_pass, __entry->xdp_drop)
+ __entry->xdp_pass, __entry->xdp_drop, __entry->xdp_redirect)
);

TRACE_EVENT(xdp_cpumap_enqueue,
diff --git a/kernel/bpf/cpumap.c b/kernel/bpf/cpumap.c
index b3a8aea81ee5..4c95d0615ca2 100644
--- a/kernel/bpf/cpumap.c
+++ b/kernel/bpf/cpumap.c
@@ -239,7 +239,7 @@ static int cpu_map_bpf_prog_run_xdp(struct bpf_cpu_map_entry *rcpu,
if (!rcpu->prog)
return n;

- rcu_read_lock();
+ rcu_read_lock_bh();

xdp_set_return_frame_no_direct();
xdp.rxq = &rxq;
@@ -267,6 +267,16 @@ static int cpu_map_bpf_prog_run_xdp(struct bpf_cpu_map_entry *rcpu,
stats->pass++;
}
break;
+ case XDP_REDIRECT:
+ err = xdp_do_redirect(xdpf->dev_rx, &xdp,
+ rcpu->prog);
+ if (unlikely(err)) {
+ xdp_return_frame(xdpf);
+ stats->drop++;
+ } else {
+ stats->redirect++;
+ }
+ break;
default:
bpf_warn_invalid_xdp_action(act);
/* fallthrough */
@@ -277,9 +287,12 @@ static int cpu_map_bpf_prog_run_xdp(struct bpf_cpu_map_entry *rcpu,
}
}

+ if (stats->redirect)
+ xdp_do_flush_map();
+
xdp_clear_return_frame_no_direct();

- rcu_read_unlock();
+ rcu_read_unlock_bh(); /* resched point, may call do_softirq() */

return nframes;
}
--
2.26.2