[PATCH v3 4/4] dts: add test case that utilizes offload to pmd_buffer_scatter

[jspewock@iol.unh.edu]

From: Jeremy Spewock <jspewock@iol.unh.edu>

Some NICs tested in DPDK allow for the scattering of packets without an
offload and others enforce that you enable the scattered_rx offload in
testpmd. The current version of the suite for testing support of
scattering packets only tests the case where the NIC supports testing
without the offload, so an expansion of coverage is needed to cover the
second case as well.

depends-on: patch-139227 ("dts: skip test cases based on capabilities")

Signed-off-by: Jeremy Spewock <jspewock@iol.unh.edu>
---
 dts/tests/TestSuite_pmd_buffer_scatter.py | 77 ++++++++++++++++-------
 1 file changed, 56 insertions(+), 21 deletions(-)

diff --git a/dts/tests/TestSuite_pmd_buffer_scatter.py b/dts/tests/TestSuite_pmd_buffer_scatter.py
index 41f6090a7e..76eabb51f6 100644
--- a/dts/tests/TestSuite_pmd_buffer_scatter.py
+++ b/dts/tests/TestSuite_pmd_buffer_scatter.py
@@ -16,14 +16,19 @@
 """
 
 import struct
+from typing import ClassVar
 
 from scapy.layers.inet import IP  # type: ignore[import]
 from scapy.layers.l2 import Ether  # type: ignore[import]
-from scapy.packet import Raw  # type: ignore[import]
+from scapy.packet import Raw, Packet  # type: ignore[import]
 from scapy.utils import hexstr  # type: ignore[import]
 
-from framework.remote_session.testpmd_shell import TestPmdForwardingModes, TestPmdShell
-from framework.test_suite import TestSuite
+from framework.remote_session.testpmd_shell import (
+    NicCapability,
+    TestPmdForwardingModes,
+    TestPmdShell,
+)
+from framework.test_suite import TestSuite, requires
 
 
 class TestPmdBufferScatter(TestSuite):
@@ -48,6 +53,14 @@ class TestPmdBufferScatter(TestSuite):
        and a single byte of packet data stored in a second buffer alongside the CRC.
     """
 
+    #: Parameters for testing scatter using testpmd which are universal across all test cases.
+    base_testpmd_parameters: ClassVar[list[str]] = [
+        "--mbcache=200",
+        "--max-pkt-len=9000",
+        "--port-topology=paired",
+        "--tx-offloads=0x00008000",
+    ]
+
     def set_up_suite(self) -> None:
         """Set up the test suite.
 
@@ -64,19 +77,19 @@ def set_up_suite(self) -> None:
         self.tg_node.main_session.configure_port_mtu(9000, self._tg_port_egress)
         self.tg_node.main_session.configure_port_mtu(9000, self._tg_port_ingress)
 
-    def scatter_pktgen_send_packet(self, pktsize: int) -> str:
+    def scatter_pktgen_send_packet(self, pktsize: int) -> list[Packet]:
         """Generate and send a packet to the SUT then capture what is forwarded back.
 
         Generate an IP packet of a specific length and send it to the SUT,
-        then capture the resulting received packet and extract its payload.
-        The desired length of the packet is met by packing its payload
+        then capture the resulting received packets and filter them down to the ones that have the
+        correct layers. The desired length of the packet is met by packing its payload
         with the letter "X" in hexadecimal.
 
         Args:
             pktsize: Size of the packet to generate and send.
 
         Returns:
-            The payload of the received packet as a string.
+            The filtered down list of packets.
         """
         packet = Ether() / IP() / Raw()
         packet.getlayer(2).load = ""
@@ -86,12 +99,15 @@ def scatter_pktgen_send_packet(self, pktsize: int) -> str:
         for X_in_hex in payload:
             packet.load += struct.pack("=B", int("%s%s" % (X_in_hex[0], X_in_hex[1]), 16))
         received_packets = self.send_packet_and_capture(packet)
+        # filter down the list to packets that have the appropriate structure
+        received_packets = list(
+            filter(lambda p: Ether in p and IP in p and Raw in p, received_packets)
+        )
         self.verify(len(received_packets) > 0, "Did not receive any packets.")
-        load = hexstr(received_packets[0].getlayer(2), onlyhex=1)
 
-        return load
+        return received_packets
 
-    def pmd_scatter(self, mbsize: int) -> None:
+    def pmd_scatter(self, mbsize: int, testpmd_params: list[str]) -> None:
         """Testpmd support of receiving and sending scattered multi-segment packets.
 
         Support for scattered packets is shown by sending 5 packets of differing length
@@ -103,34 +119,53 @@ def pmd_scatter(self, mbsize: int) -> None:
         """
         testpmd_shell = self.sut_node.create_interactive_shell(
             TestPmdShell,
-            app_parameters=(
-                "--mbcache=200 "
-                f"--mbuf-size={mbsize} "
-                "--max-pkt-len=9000 "
-                "--port-topology=paired "
-                "--tx-offloads=0x00008000"
-            ),
+            app_parameters=" ".join(testpmd_params),
             privileged=True,
         )
         with testpmd_shell as testpmd:
             testpmd.set_forward_mode(TestPmdForwardingModes.mac)
+            # adjust the MTU of the SUT ports
+            for port_id in range(testpmd.number_of_ports):
+                testpmd.set_port_mtu(port_id, 9000)
             testpmd.start()
 
             for offset in [-1, 0, 1, 4, 5]:
-                recv_payload = self.scatter_pktgen_send_packet(mbsize + offset)
+                # This list should only ever contain one element
+                recv_packets = self.scatter_pktgen_send_packet(mbsize + offset)
                 self._logger.debug(
-                    f"Payload of scattered packet after forwarding: \n{recv_payload}"
+                    f"Relevant captured packets: \n{recv_packets}"
                 )
+
                 self.verify(
-                    ("58 " * 8).strip() in recv_payload,
+                    any(
+                        " ".join(["58"]*8) in hexstr(pakt.getlayer(2), onlyhex=1)
+                        for pakt in recv_packets
+                    ),
                     "Payload of scattered packet did not match expected payload with offset "
                     f"{offset}.",
                 )
             testpmd.stop()
+            # reset the MTU of the SUT ports
+            for port_id in range(testpmd.number_of_ports):
+                testpmd.set_port_mtu(port_id, 1500)
 
+    @requires(NicCapability.scattered_rx)
     def test_scatter_mbuf_2048(self) -> None:
         """Run the :meth:`pmd_scatter` test with `mbsize` set to 2048."""
-        self.pmd_scatter(mbsize=2048)
+        self.pmd_scatter(
+            mbsize=2048, testpmd_params=[*(self.base_testpmd_parameters), "--mbuf-size=2048"]
+        )
+
+    def test_scatter_mbuf_2048_with_offload(self) -> None:
+        """Run the :meth:`pmd_scatter` test with `mbsize` set to 2048 and rx_scatter offload."""
+        self.pmd_scatter(
+            mbsize=2048,
+            testpmd_params=[
+                *(self.base_testpmd_parameters),
+                "--mbuf-size=2048",
+                "--enable-scatter",
+            ],
+        )
 
     def tear_down_suite(self) -> None:
         """Tear down the test suite.
-- 
2.45.1