[PATCH net-next 7/7] selftests: drv-net: devmem: TX from a hugepage-backed dmabuf
From: Stanislav Fomichev
Date: Mon Nov 02 2026 - 14:16:58 EST
TX net_iovs are now sized from the dmabuf layout, but the TX tests
use a regular memfd, which usually keeps them small. Add -H to ncdevmem
to back the udmabuf with 2MB hugepages and a TX test which sends a 3MB
buffer from it, so that frags end at and continue past the 2MB net_iov
boundary. The payload has a 7 byte period to catch offset errors.
Signed-off-by: Stanislav Fomichev <sdf@xxxxxxxxxxx>
---
.../selftests/drivers/net/hw/devmem.py | 10 ++++-
.../selftests/drivers/net/hw/devmem_lib.py | 43 +++++++++++++++++--
.../selftests/drivers/net/hw/ncdevmem.c | 8 +++-
.../selftests/drivers/net/hw/nk_devmem.py | 11 ++++-
4 files changed, 63 insertions(+), 9 deletions(-)
diff --git a/tools/testing/selftests/drivers/net/hw/devmem.py b/tools/testing/selftests/drivers/net/hw/devmem.py
index 82c11ffc4add..aa7141fb36f7 100755
--- a/tools/testing/selftests/drivers/net/hw/devmem.py
+++ b/tools/testing/selftests/drivers/net/hw/devmem.py
@@ -3,7 +3,7 @@
from os import path
from devmem_lib import (setup_test, run_rx, run_tx, run_tx_chunks, run_rx_hds,
- run_rx_large_niov)
+ run_rx_large_niov, run_tx_large_niov)
from lib.py import ksft_run, ksft_exit, ksft_disruptive
from lib.py import NetDrvEpEnv
@@ -36,12 +36,18 @@ from lib.py import NetDrvEpEnv
run_rx_large_niov(cfg)
+@ksft_disruptive
+def check_tx_large_niov(cfg) -> None:
+ """Run the devmem TX test from a hugepage-backed dmabuf."""
+ run_tx_large_niov(cfg)
+
+
def main() -> None:
"""Run the devmem test cases."""
with NetDrvEpEnv(__file__) as cfg:
setup_test(cfg, path.abspath(path.dirname(__file__) + "/ncdevmem"))
ksft_run([check_rx, check_tx, check_tx_chunks, check_rx_hds,
- check_rx_large_niov],
+ check_rx_large_niov, check_tx_large_niov],
args=(cfg,))
ksft_exit()
diff --git a/tools/testing/selftests/drivers/net/hw/devmem_lib.py b/tools/testing/selftests/drivers/net/hw/devmem_lib.py
index 71b916c16196..8058fd1ddd50 100644
--- a/tools/testing/selftests/drivers/net/hw/devmem_lib.py
+++ b/tools/testing/selftests/drivers/net/hw/devmem_lib.py
@@ -2,6 +2,7 @@
# pylint: disable=invalid-name,too-many-arguments
"""Shared helpers for devmem TCP selftests."""
+import hashlib
import os
import re
@@ -42,15 +43,17 @@ NR_HUGEPAGES_FILE = "/proc/sys/vm/nr_hugepages"
defer(_restore_nr_hugepages, nr_hugepages)
-def _probe_devmem(cfg, rx_page_size):
+def _probe_devmem(cfg, rx_page_size, hugepages=False):
"""Return True if ncdevmem can bind cfg.ifname at @rx_page_size."""
probe_command = f"{cfg.bin_local} -f {cfg.ifname}"
if rx_page_size != RX_PAGE_SIZE_DEFAULT:
probe_command += f" -b {rx_page_size}"
+ if hugepages:
+ probe_command += " -H"
return cmd(probe_command, fail=False, shell=True).ret == 0
-def require_devmem(cfg, rx_page_size=RX_PAGE_SIZE_DEFAULT):
+def require_devmem(cfg, rx_page_size=RX_PAGE_SIZE_DEFAULT, hugepages=False):
"""Probe ncdevmem on cfg.ifname and SKIP the test if devmem isn't supported."""
if rx_page_size not in PROBE_RX_PAGE_SIZES:
raise RuntimeError(
@@ -63,10 +66,15 @@ NR_HUGEPAGES_FILE = "/proc/sys/vm/nr_hugepages"
# ncdevmem's queue range and cause the probe to fail.
cfg.devmem_supported = {size: _probe_devmem(cfg, size)
for size in PROBE_RX_PAGE_SIZES}
+ cfg.devmem_hugepages = _probe_devmem(cfg, RX_PAGE_SIZE_DEFAULT,
+ hugepages=True)
if not cfg.devmem_supported[RX_PAGE_SIZE_DEFAULT]:
raise KsftSkipEx("Test requires devmem support")
+ if hugepages and not cfg.devmem_hugepages:
+ raise KsftSkipEx("Test requires a 2MB hugepage-backed dmabuf")
+
if rx_page_size != RX_PAGE_SIZE_DEFAULT:
page_size = os.sysconf("SC_PAGE_SIZE")
if not _is_aligned(rx_page_size, page_size):
@@ -169,7 +177,7 @@ def ncdevmem_rx(cfg, port, verify=True, fail_on_linear=False, flow_steer=False,
return " ".join(parts)
-def ncdevmem_tx(cfg, port, chunk_size=0):
+def ncdevmem_tx(cfg, port, chunk_size=0, hugepages=False):
"""Build the ncdevmem TX send command."""
if hasattr(cfg, 'netns'):
ifname = cfg.nk_guest_ifname
@@ -182,6 +190,8 @@ def ncdevmem_rx(cfg, port, verify=True, fail_on_linear=False, flow_steer=False,
if chunk_size:
extras.append(f"-z {chunk_size}")
+ if hugepages:
+ extras.append("-H")
parts = [cfg.bin_local, f"-f {ifname}", f"-s {addr}",
f"-p {port}", *extras]
@@ -269,6 +279,33 @@ def ncdevmem_rx(cfg, port, verify=True, fail_on_linear=False, flow_steer=False,
ksft_eq(socat.stdout.strip(), "hello\nworld")
+def run_tx_large_niov(cfg):
+ """Run the devmem TX test from a 2MB hugepage-backed dmabuf.
+
+ The kernel sizes TX niovs from the dmabuf layout. Send a single buffer
+ larger than a hugepage so that frags end at and continue past the niov
+ boundary.
+ """
+ require_devmem(cfg, hugepages=True)
+ _reserve_hugepages()
+ configure_nic(cfg)
+ netns = getattr(cfg, "netns", None)
+ port = rand_port()
+ size = 3 * 1024 * 1024
+ pattern = "abcdefg"
+ expected = (pattern * (size // len(pattern) + 1))[:size]
+ tx_cmd = ncdevmem_tx(cfg, port, hugepages=True)
+ # Hash on the remote, bkg() only drains stdout once the command exits.
+ listen_cmd = f"{socat_listen(cfg, port)} | sha256sum"
+
+ with bkg(listen_cmd, host=cfg.remote, exit_wait=True) as socat:
+ wait_port_listen(port, host=cfg.remote)
+ cmd(f"bash -c 'yes {pattern} | tr -d \"\\n\" | head -c {size} | {tx_cmd}'",
+ ns=netns, shell=True)
+ ksft_eq(socat.stdout.split()[0],
+ hashlib.sha256(expected.encode()).hexdigest())
+
+
def run_rx_large_niov(cfg):
"""Run the devmem RX test with a large niov (rx-page-size > PAGE_SIZE).
diff --git a/tools/testing/selftests/drivers/net/hw/ncdevmem.c b/tools/testing/selftests/drivers/net/hw/ncdevmem.c
index 918e3b51f3b8..e29ff27087e7 100644
--- a/tools/testing/selftests/drivers/net/hw/ncdevmem.c
+++ b/tools/testing/selftests/drivers/net/hw/ncdevmem.c
@@ -104,6 +104,7 @@ static uint32_t tx_dmabuf_id;
static int waittime_ms = 500;
static bool fail_on_linear;
static uint32_t rx_page_size;
+static bool use_hugepages;
/* System state loaded by current_config_load() */
#define MAX_FLOWS 8
@@ -162,7 +163,7 @@ static struct memory_buffer *udmabuf_alloc(size_t size)
}
memfd_flags = MFD_ALLOW_SEALING;
- if (rx_page_size > getpagesize())
+ if (use_hugepages || rx_page_size > getpagesize())
memfd_flags |= MFD_HUGETLB | MFD_HUGE_2MB;
ctx->memfd = memfd_create("udmabuf-test", memfd_flags);
@@ -1428,11 +1429,14 @@ int main(int argc, char *argv[])
int is_server = 0, opt;
int ret, err = 1;
- while ((opt = getopt(argc, argv, "Lls:c:p:v:q:t:f:z:nb:")) != -1) {
+ while ((opt = getopt(argc, argv, "Lls:c:p:v:q:t:f:z:nb:H")) != -1) {
switch (opt) {
case 'L':
fail_on_linear = true;
break;
+ case 'H':
+ use_hugepages = true;
+ break;
case 'l':
is_server = 1;
break;
diff --git a/tools/testing/selftests/drivers/net/hw/nk_devmem.py b/tools/testing/selftests/drivers/net/hw/nk_devmem.py
index 61c6f31f01e5..799030db7c12 100755
--- a/tools/testing/selftests/drivers/net/hw/nk_devmem.py
+++ b/tools/testing/selftests/drivers/net/hw/nk_devmem.py
@@ -4,7 +4,7 @@
import os
from devmem_lib import (setup_test, run_rx, run_tx, run_tx_chunks, run_rx_hds,
- run_rx_large_niov)
+ run_rx_large_niov, run_tx_large_niov)
from lib.py import ksft_run, ksft_exit, ksft_disruptive
from lib.py import NetDrvContEnv
@@ -37,6 +37,12 @@ from lib.py import NetDrvContEnv
run_rx_large_niov(cfg)
+@ksft_disruptive
+def check_nk_tx_large_niov(cfg) -> None:
+ """Run the devmem TX large-niov test through netkit."""
+ run_tx_large_niov(cfg)
+
+
def main() -> None:
"""Run the netkit devmem test cases."""
with NetDrvContEnv(__file__, rxqueues=2, primary_rx_redirect=True) as cfg:
@@ -44,7 +50,8 @@ from lib.py import NetDrvContEnv
os.path.join(os.path.dirname(os.path.abspath(__file__)),
"ncdevmem"))
ksft_run([check_nk_rx, check_nk_tx, check_nk_tx_chunks,
- check_nk_rx_hds, check_nk_rx_large_niov], args=(cfg,))
+ check_nk_rx_hds, check_nk_rx_large_niov,
+ check_nk_tx_large_niov], args=(cfg,))
ksft_exit()
--
2.53.0-Meta