selftests: mlxsw: Add test for ip_forward_update_priority

Verify that with that sysctl turned off, DSCP prioritization and rewrite
works the same way as in qos_dscp_bridge test. However when the sysctl
is charged, there should be a reprioritization after routing stage,
which will be observed by a different DSCP rewrite on egress.
Signed-off-by: NPetr Machata <petrm@mellanox.com>
Reviewed-by: NIdo Schimmel <idosch@mellanox.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

tools/testing/selftests/drivers/net/mlxsw/qos_dscp_router.sh

+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+# Test for DSCP prioritization in the router.
+#
+# With ip_forward_update_priority disabled, the packets are expected to keep
+# their DSCP (which in this test uses only values 0..7) intact as they are
+# forwarded by the switch. That is verified at $h2. ICMP responses are formed
+# with the same DSCP as the requests, and likewise pass through the switch
+# intact, which is verified at $h1.
+#
+# With ip_forward_update_priority enabled, router reprioritizes the packets
+# according to the table in reprioritize(). Thus, say, DSCP 7 maps to priority
+# 4, which on egress maps back to DSCP 4. The response packet then gets
+# reprioritized to 6, getting DSCP 6 on egress.
+#
+# +----------------------+                             +----------------------+
+# | H1                   |                             |                   H2 |
+# |    + $h1             |                             |            $h2 +     |
+# |    | 192.0.2.1/28    |                             |  192.0.2.18/28 |     |
+# +----|-----------------+                             +----------------|-----+
+#      |                                                                |
+# +----|----------------------------------------------------------------|-----+
+# | SW |                                                                |     |
+# |    + $swp1                                                    $swp2 +     |
+# |      192.0.2.2/28                                     192.0.2.17/28       |
+# |      APP=0,5,0 .. 7,5,7                          APP=0,5,0 .. 7,5,7       |
+# +---------------------------------------------------------------------------+
+
+ALL_TESTS="
+	ping_ipv4
+	test_update
+	test_no_update
+"
+
+lib_dir=$(dirname $0)/../../../net/forwarding
+
+NUM_NETIFS=4
+source $lib_dir/lib.sh
+
+reprioritize()
+{
+	local in=$1; shift
+
+	# This is based on rt_tos2priority in include/net/route.h. Assuming 1:1
+	# mapping between priorities and TOS, it yields a new priority for a
+	# packet with ingress priority of $in.
+	local -a reprio=(0 0 2 2 6 6 4 4)
+
+	echo ${reprio[$in]}
+}
+
+h1_create()
+{
+	local dscp;
+
+	simple_if_init $h1 192.0.2.1/28
+	tc qdisc add dev $h1 clsact
+	dscp_capture_install $h1 0
+	ip route add vrf v$h1 192.0.2.16/28 via 192.0.2.2
+}
+
+h1_destroy()
+{
+	ip route del vrf v$h1 192.0.2.16/28 via 192.0.2.2
+	dscp_capture_uninstall $h1 0
+	tc qdisc del dev $h1 clsact
+	simple_if_fini $h1 192.0.2.1/28
+}
+
+h2_create()
+{
+	simple_if_init $h2 192.0.2.18/28
+	tc qdisc add dev $h2 clsact
+	dscp_capture_install $h2 0
+	ip route add vrf v$h2 192.0.2.0/28 via 192.0.2.17
+}
+
+h2_destroy()
+{
+	ip route del vrf v$h2 192.0.2.0/28 via 192.0.2.17
+	dscp_capture_uninstall $h2 0
+	tc qdisc del dev $h2 clsact
+	simple_if_fini $h2 192.0.2.18/28
+}
+
+dscp_map()
+{
+	local base=$1; shift
+
+	for prio in {0..7}; do
+		echo app=$prio,5,$((base + prio))
+	done
+}
+
+switch_create()
+{
+	simple_if_init $swp1 192.0.2.2/28
+	__simple_if_init $swp2 v$swp1 192.0.2.17/28
+
+	lldptool -T -i $swp1 -V APP $(dscp_map 0) >/dev/null
+	lldptool -T -i $swp2 -V APP $(dscp_map 0) >/dev/null
+	lldpad_app_wait_set $swp1
+	lldpad_app_wait_set $swp2
+}
+
+switch_destroy()
+{
+	lldptool -T -i $swp2 -V APP -d $(dscp_map 0) >/dev/null
+	lldptool -T -i $swp1 -V APP -d $(dscp_map 0) >/dev/null
+	lldpad_app_wait_del
+
+	__simple_if_fini $swp2 192.0.2.17/28
+	simple_if_fini $swp1 192.0.2.2/28
+}
+
+setup_prepare()
+{
+	h1=${NETIFS[p1]}
+	swp1=${NETIFS[p2]}
+
+	swp2=${NETIFS[p3]}
+	h2=${NETIFS[p4]}
+
+	vrf_prepare
+
+	sysctl_set net.ipv4.ip_forward_update_priority 1
+	h1_create
+	h2_create
+	switch_create
+}
+
+cleanup()
+{
+	pre_cleanup
+
+	switch_destroy
+	h2_destroy
+	h1_destroy
+	sysctl_restore net.ipv4.ip_forward_update_priority
+
+	vrf_cleanup
+}
+
+ping_ipv4()
+{
+	ping_test $h1 192.0.2.18
+}
+
+dscp_ping_test()
+{
+	local vrf_name=$1; shift
+	local sip=$1; shift
+	local dip=$1; shift
+	local prio=$1; shift
+	local reprio=$1; shift
+	local dev1=$1; shift
+	local dev2=$1; shift
+
+	local prio2=$($reprio $prio)   # ICMP Request egress prio
+	local prio3=$($reprio $prio2)  # ICMP Response egress prio
+
+	local dscp=$((prio << 2))     # ICMP Request ingress DSCP
+	local dscp2=$((prio2 << 2))   # ICMP Request egress DSCP
+	local dscp3=$((prio3 << 2))   # ICMP Response egress DSCP
+
+	RET=0
+
+	eval "local -A dev1_t0s=($(dscp_fetch_stats $dev1 0))"
+	eval "local -A dev2_t0s=($(dscp_fetch_stats $dev2 0))"
+
+	ip vrf exec $vrf_name \
+	   ${PING} -Q $dscp ${sip:+-I $sip} $dip \
+		   -c 10 -i 0.1 -w 2 &> /dev/null
+
+	eval "local -A dev1_t1s=($(dscp_fetch_stats $dev1 0))"
+	eval "local -A dev2_t1s=($(dscp_fetch_stats $dev2 0))"
+
+	for i in {0..7}; do
+		local dscpi=$((i << 2))
+		local expect2=0
+		local expect3=0
+
+		if ((i == prio2)); then
+			expect2=10
+		fi
+		if ((i == prio3)); then
+			expect3=10
+		fi
+
+		local delta=$((dev2_t1s[$i] - dev2_t0s[$i]))
+		((expect2 == delta))
+		check_err $? "DSCP $dscpi@$dev2: Expected to capture $expect2 packets, got $delta."
+
+		delta=$((dev1_t1s[$i] - dev1_t0s[$i]))
+		((expect3 == delta))
+		check_err $? "DSCP $dscpi@$dev1: Expected to capture $expect3 packets, got $delta."
+	done
+
+	log_test "DSCP rewrite: $dscp-(prio $prio2)-$dscp2-(prio $prio3)-$dscp3"
+}
+
+__test_update()
+{
+	local update=$1; shift
+	local reprio=$1; shift
+
+	sysctl_restore net.ipv4.ip_forward_update_priority
+	sysctl_set net.ipv4.ip_forward_update_priority $update
+
+	for prio in {0..7}; do
+		dscp_ping_test v$h1 192.0.2.1 192.0.2.18 $prio $reprio $h1 $h2
+	done
+}
+
+test_update()
+{
+	__test_update 1 reprioritize
+}
+
+test_no_update()
+{
+	__test_update 0 echo
+}
+
+trap cleanup EXIT
+
+setup_prepare
+setup_wait
+
+tests_run
+
+exit $EXIT_STATUS