selftests: net: Add busy_poll_test

Add an epoll busy poll test using netdevsim.

This test is comprised of:
  - busy_poller (via busy_poller.c)
  - busy_poll_test.sh which loads netdevsim, sets up network namespaces,
    and runs busy_poller to receive data and socat to send data.

The selftest tests two different scenarios:
  - busy poll (the pre-existing version in the kernel)
  - busy poll with suspend enabled (what this series adds)

The data transmit is a 1MiB temporary file generated from /dev/urandom
and the test is considered passing if the md5sum of the input file to
socat matches the md5sum of the output file from busy_poller.

netdevsim was chosen instead of veth due to netdevsim's support for
netdev-genl.

For now, this test uses the functionality that netdevsim provides. In the
future, perhaps netdevsim can be extended to emulate device IRQs to more
thoroughly test all pre-existing kernel options (like defer_hard_irqs)
and suspend.

Signed-off-by: Joe Damato <jdamato@fastly.com>
Co-developed-by: Martin Karsten <mkarsten@uwaterloo.ca>
Signed-off-by: Martin Karsten <mkarsten@uwaterloo.ca>
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20241109050245.191288-6-jdamato@fastly.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

4 files changed, 521 insertions, 0 deletions

diff --git a/tools/testing/selftests/net/.gitignore b/tools/testing/selftests/net/.gitignore
index a78debbd1fe7..48973e78d46b 100644
--- a/tools/testing/selftests/net/.gitignore
+++ b/tools/testing/selftests/net/.gitignore
@@ -2,6 +2,7 @@
 bind_bhash
 bind_timewait
 bind_wildcard
+busy_poller
 cmsg_sender
 diag_uid
 epoll_busy_poll
diff --git a/tools/testing/selftests/net/Makefile b/tools/testing/selftests/net/Makefile
index 9322b904ad00..2b2a5ec7fa6a 100644
--- a/tools/testing/selftests/net/Makefile
+++ b/tools/testing/selftests/net/Makefile
@@ -97,6 +97,11 @@ TEST_PROGS += fq_band_pktlimit.sh
 TEST_PROGS += vlan_hw_filter.sh
 TEST_PROGS += bpf_offload.py
 TEST_PROGS += ipv6_route_update_soft_lockup.sh
+TEST_PROGS += busy_poll_test.sh
+
+# YNL files, must be before "include ..lib.mk"
+YNL_GEN_FILES := busy_poller
+TEST_GEN_FILES += $(YNL_GEN_FILES)
 
 TEST_FILES := settings
 TEST_FILES += in_netns.sh lib.sh net_helper.sh setup_loopback.sh setup_veth.sh
@@ -107,6 +112,10 @@ TEST_INCLUDES := forwarding/lib.sh
 
 include ../lib.mk
 
+# YNL build
+YNL_GENS := netdev
+include ynl.mk
+
 $(OUTPUT)/epoll_busy_poll: LDLIBS += -lcap
 $(OUTPUT)/reuseport_bpf_numa: LDLIBS += -lnuma
 $(OUTPUT)/tcp_mmap: LDLIBS += -lpthread -lcrypto
diff --git a/tools/testing/selftests/net/busy_poll_test.sh b/tools/testing/selftests/net/busy_poll_test.sh
new file mode 100755
index 000000000000..7db292ec4884
--- /dev/null
+++ b/tools/testing/selftests/net/busy_poll_test.sh
@@ -0,0 +1,165 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+source net_helper.sh
+
+NSIM_SV_ID=$((256 + RANDOM % 256))
+NSIM_SV_SYS=/sys/bus/netdevsim/devices/netdevsim$NSIM_SV_ID
+NSIM_CL_ID=$((512 + RANDOM % 256))
+NSIM_CL_SYS=/sys/bus/netdevsim/devices/netdevsim$NSIM_CL_ID
+
+NSIM_DEV_SYS_NEW=/sys/bus/netdevsim/new_device
+NSIM_DEV_SYS_DEL=/sys/bus/netdevsim/del_device
+NSIM_DEV_SYS_LINK=/sys/bus/netdevsim/link_device
+NSIM_DEV_SYS_UNLINK=/sys/bus/netdevsim/unlink_device
+
+SERVER_IP=192.168.1.1
+CLIENT_IP=192.168.1.2
+SERVER_PORT=48675
+
+# busy poll config
+MAX_EVENTS=8
+BUSY_POLL_USECS=0
+BUSY_POLL_BUDGET=16
+PREFER_BUSY_POLL=1
+
+# IRQ deferral config
+NAPI_DEFER_HARD_IRQS=100
+GRO_FLUSH_TIMEOUT=50000
+SUSPEND_TIMEOUT=20000000
+
+setup_ns()
+{
+	set -e
+	ip netns add nssv
+	ip netns add nscl
+
+	NSIM_SV_NAME=$(find $NSIM_SV_SYS/net -maxdepth 1 -type d ! \
+		-path $NSIM_SV_SYS/net -exec basename {} \;)
+	NSIM_CL_NAME=$(find $NSIM_CL_SYS/net -maxdepth 1 -type d ! \
+		-path $NSIM_CL_SYS/net -exec basename {} \;)
+
+	# ensure the server has 1 queue
+	ethtool -L $NSIM_SV_NAME combined 1 2>/dev/null
+
+	ip link set $NSIM_SV_NAME netns nssv
+	ip link set $NSIM_CL_NAME netns nscl
+
+	ip netns exec nssv ip addr add "${SERVER_IP}/24" dev $NSIM_SV_NAME
+	ip netns exec nscl ip addr add "${CLIENT_IP}/24" dev $NSIM_CL_NAME
+
+	ip netns exec nssv ip link set dev $NSIM_SV_NAME up
+	ip netns exec nscl ip link set dev $NSIM_CL_NAME up
+
+	set +e
+}
+
+cleanup_ns()
+{
+	ip netns del nscl
+	ip netns del nssv
+}
+
+test_busypoll()
+{
+	suspend_value=${1:-0}
+	tmp_file=$(mktemp)
+	out_file=$(mktemp)
+
+	# fill a test file with random data
+	dd if=/dev/urandom of=${tmp_file} bs=1M count=1 2> /dev/null
+
+	timeout -k 1s 30s ip netns exec nssv ./busy_poller         \
+					     -p${SERVER_PORT}      \
+					     -b${SERVER_IP}        \
+					     -m${MAX_EVENTS}       \
+					     -u${BUSY_POLL_USECS}  \
+					     -P${PREFER_BUSY_POLL} \
+					     -g${BUSY_POLL_BUDGET} \
+					     -i${NSIM_SV_IFIDX}    \
+					     -s${suspend_value}    \
+					     -o${out_file}&
+
+	wait_local_port_listen nssv ${SERVER_PORT} tcp
+
+	ip netns exec nscl socat -u $tmp_file TCP:${SERVER_IP}:${SERVER_PORT}
+
+	wait
+
+	tmp_file_md5sum=$(md5sum $tmp_file | cut -f1 -d' ')
+	out_file_md5sum=$(md5sum $out_file | cut -f1 -d' ')
+
+	if [ "$tmp_file_md5sum" = "$out_file_md5sum" ]; then
+		res=0
+	else
+		echo "md5sum mismatch"
+		echo "input file md5sum: ${tmp_file_md5sum}";
+		echo "output file md5sum: ${out_file_md5sum}";
+		res=1
+	fi
+
+	rm $out_file $tmp_file
+
+	return $res
+}
+
+test_busypoll_with_suspend()
+{
+	test_busypoll ${SUSPEND_TIMEOUT}
+
+	return $?
+}
+
+###
+### Code start
+###
+
+modprobe netdevsim
+
+# linking
+
+echo $NSIM_SV_ID > $NSIM_DEV_SYS_NEW
+echo $NSIM_CL_ID > $NSIM_DEV_SYS_NEW
+udevadm settle
+
+setup_ns
+
+NSIM_SV_FD=$((256 + RANDOM % 256))
+exec {NSIM_SV_FD}</var/run/netns/nssv
+NSIM_SV_IFIDX=$(ip netns exec nssv cat /sys/class/net/$NSIM_SV_NAME/ifindex)
+
+NSIM_CL_FD=$((256 + RANDOM % 256))
+exec {NSIM_CL_FD}</var/run/netns/nscl
+NSIM_CL_IFIDX=$(ip netns exec nscl cat /sys/class/net/$NSIM_CL_NAME/ifindex)
+
+echo "$NSIM_SV_FD:$NSIM_SV_IFIDX $NSIM_CL_FD:$NSIM_CL_IFIDX" > \
+     $NSIM_DEV_SYS_LINK
+
+if [ $? -ne 0 ]; then
+	echo "linking netdevsim1 with netdevsim2 should succeed"
+	cleanup_ns
+	exit 1
+fi
+
+test_busypoll
+if [ $? -ne 0 ]; then
+	echo "test_busypoll failed"
+	cleanup_ns
+	exit 1
+fi
+
+test_busypoll_with_suspend
+if [ $? -ne 0 ]; then
+	echo "test_busypoll_with_suspend failed"
+	cleanup_ns
+	exit 1
+fi
+
+echo "$NSIM_SV_FD:$NSIM_SV_IFIDX" > $NSIM_DEV_SYS_UNLINK
+
+echo $NSIM_CL_ID > $NSIM_DEV_SYS_DEL
+
+cleanup_ns
+
+modprobe -r netdevsim
+
+exit 0
diff --git a/tools/testing/selftests/net/busy_poller.c b/tools/testing/selftests/net/busy_poller.c
new file mode 100644
index 000000000000..99b0e8c17fca
--- /dev/null
+++ b/tools/testing/selftests/net/busy_poller.c
@@ -0,0 +1,346 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <assert.h>
+#include <errno.h>
+#include <error.h>
+#include <fcntl.h>
+#include <inttypes.h>
+#include <limits.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <ynl.h>
+
+#include <arpa/inet.h>
+#include <netinet/in.h>
+
+#include <sys/epoll.h>
+#include <sys/ioctl.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+
+#include <linux/genetlink.h>
+#include <linux/netlink.h>
+
+#include "netdev-user.h"
+
+/* The below ifdef blob is required because:
+ *
+ * - sys/epoll.h does not (yet) have the ioctl definitions included. So,
+ *   systems with older glibcs will not have them available. However,
+ *   sys/epoll.h does include the type definition for epoll_data, which is
+ *   needed by the user program (e.g. epoll_event.data.fd)
+ *
+ * - linux/eventpoll.h does not define the epoll_data type, it is simply an
+ *   opaque __u64. It does, however, include the ioctl definition.
+ *
+ * Including both headers is impossible (types would be redefined), so I've
+ * opted instead to take sys/epoll.h, and include the blob below.
+ *
+ * Someday, when glibc is globally up to date, the blob below can be removed.
+ */
+#if !defined(EPOLL_IOC_TYPE)
+struct epoll_params {
+	uint32_t busy_poll_usecs;
+	uint16_t busy_poll_budget;
+	uint8_t prefer_busy_poll;
+
+	/* pad the struct to a multiple of 64bits */
+	uint8_t __pad;
+};
+
+#define EPOLL_IOC_TYPE 0x8A
+#define EPIOCSPARAMS _IOW(EPOLL_IOC_TYPE, 0x01, struct epoll_params)
+#define EPIOCGPARAMS _IOR(EPOLL_IOC_TYPE, 0x02, struct epoll_params)
+#endif
+
+static uint32_t cfg_port = 8000;
+static struct in_addr cfg_bind_addr = { .s_addr = INADDR_ANY };
+static char *cfg_outfile;
+static int cfg_max_events = 8;
+static int cfg_ifindex;
+
+/* busy poll params */
+static uint32_t cfg_busy_poll_usecs;
+static uint32_t cfg_busy_poll_budget;
+static uint32_t cfg_prefer_busy_poll;
+
+/* IRQ params */
+static uint32_t cfg_defer_hard_irqs;
+static uint64_t cfg_gro_flush_timeout;
+static uint64_t cfg_irq_suspend_timeout;
+
+static void usage(const char *filepath)
+{
+	error(1, 0,
+	      "Usage: %s -p<port> -b<addr> -m<max_events> -u<busy_poll_usecs> -P<prefer_busy_poll> -g<busy_poll_budget> -o<outfile> -d<defer_hard_irqs> -r<gro_flush_timeout> -s<irq_suspend_timeout> -i<ifindex>",
+	      filepath);
+}
+
+static void parse_opts(int argc, char **argv)
+{
+	int ret;
+	int c;
+
+	if (argc <= 1)
+		usage(argv[0]);
+
+	while ((c = getopt(argc, argv, "p:m:b:u:P:g:o:d:r:s:i:")) != -1) {
+		switch (c) {
+		case 'u':
+			cfg_busy_poll_usecs = strtoul(optarg, NULL, 0);
+			if (cfg_busy_poll_usecs == ULONG_MAX ||
+			    cfg_busy_poll_usecs > UINT32_MAX)
+				error(1, ERANGE, "busy_poll_usecs too large");
+			break;
+		case 'P':
+			cfg_prefer_busy_poll = strtoul(optarg, NULL, 0);
+			if (cfg_prefer_busy_poll == ULONG_MAX ||
+			    cfg_prefer_busy_poll > 1)
+				error(1, ERANGE,
+				      "prefer busy poll should be 0 or 1");
+			break;
+		case 'g':
+			cfg_busy_poll_budget = strtoul(optarg, NULL, 0);
+			if (cfg_busy_poll_budget == ULONG_MAX ||
+			    cfg_busy_poll_budget > UINT16_MAX)
+				error(1, ERANGE,
+				      "busy poll budget must be [0, UINT16_MAX]");
+			break;
+		case 'p':
+			cfg_port = strtoul(optarg, NULL, 0);
+			if (cfg_port > UINT16_MAX)
+				error(1, ERANGE, "port must be <= 65535");
+			break;
+		case 'b':
+			ret = inet_aton(optarg, &cfg_bind_addr);
+			if (ret == 0)
+				error(1, errno,
+				      "bind address %s invalid", optarg);
+			break;
+		case 'o':
+			cfg_outfile = strdup(optarg);
+			if (!cfg_outfile)
+				error(1, 0, "outfile invalid");
+			break;
+		case 'm':
+			cfg_max_events = strtol(optarg, NULL, 0);
+
+			if (cfg_max_events == LONG_MIN ||
+			    cfg_max_events == LONG_MAX ||
+			    cfg_max_events <= 0)
+				error(1, ERANGE,
+				      "max events must be > 0 and < LONG_MAX");
+			break;
+		case 'd':
+			cfg_defer_hard_irqs = strtoul(optarg, NULL, 0);
+
+			if (cfg_defer_hard_irqs == ULONG_MAX ||
+			    cfg_defer_hard_irqs > INT32_MAX)
+				error(1, ERANGE,
+				      "defer_hard_irqs must be <= INT32_MAX");
+			break;
+		case 'r':
+			cfg_gro_flush_timeout = strtoull(optarg, NULL, 0);
+
+			if (cfg_gro_flush_timeout == ULLONG_MAX)
+				error(1, ERANGE,
+				      "gro_flush_timeout must be < ULLONG_MAX");
+			break;
+		case 's':
+			cfg_irq_suspend_timeout = strtoull(optarg, NULL, 0);
+
+			if (cfg_irq_suspend_timeout == ULLONG_MAX)
+				error(1, ERANGE,
+				      "irq_suspend_timeout must be < ULLONG_MAX");
+			break;
+		case 'i':
+			cfg_ifindex = strtoul(optarg, NULL, 0);
+			if (cfg_ifindex == ULONG_MAX)
+				error(1, ERANGE,
+				      "ifindex must be < ULONG_MAX");
+			break;
+		}
+	}
+
+	if (!cfg_ifindex)
+		usage(argv[0]);
+
+	if (optind != argc)
+		usage(argv[0]);
+}
+
+static void epoll_ctl_add(int epfd, int fd, uint32_t events)
+{
+	struct epoll_event ev;
+
+	ev.events = events;
+	ev.data.fd = fd;
+	if (epoll_ctl(epfd, EPOLL_CTL_ADD, fd, &ev) == -1)
+		error(1, errno, "epoll_ctl add fd: %d", fd);
+}
+
+static void setnonblock(int sockfd)
+{
+	int flags;
+
+	flags = fcntl(sockfd, F_GETFL, 0);
+
+	if (fcntl(sockfd, F_SETFL, flags | O_NONBLOCK) == -1)
+		error(1, errno, "unable to set socket to nonblocking mode");
+}
+
+static void write_chunk(int fd, char *buf, ssize_t buflen)
+{
+	ssize_t remaining = buflen;
+	char *buf_offset = buf;
+	ssize_t writelen = 0;
+	ssize_t write_result;
+
+	while (writelen < buflen) {
+		write_result = write(fd, buf_offset, remaining);
+		if (write_result == -1)
+			error(1, errno, "unable to write data to outfile");
+
+		writelen += write_result;
+		remaining -= write_result;
+		buf_offset += write_result;
+	}
+}
+
+static void setup_queue(void)
+{
+	struct netdev_napi_get_list *napi_list = NULL;
+	struct netdev_napi_get_req_dump *req = NULL;
+	struct netdev_napi_set_req *set_req = NULL;
+	struct ynl_sock *ys;
+	struct ynl_error yerr;
+	uint32_t napi_id;
+
+	ys = ynl_sock_create(&ynl_netdev_family, &yerr);
+	if (!ys)
+		error(1, 0, "YNL: %s", yerr.msg);
+
+	req = netdev_napi_get_req_dump_alloc();
+	netdev_napi_get_req_dump_set_ifindex(req, cfg_ifindex);
+	napi_list = netdev_napi_get_dump(ys, req);
+
+	/* assume there is 1 NAPI configured and take the first */
+	if (napi_list->obj._present.id)
+		napi_id = napi_list->obj.id;
+	else
+		error(1, 0, "napi ID not present?");
+
+	set_req = netdev_napi_set_req_alloc();
+	netdev_napi_set_req_set_id(set_req, napi_id);
+	netdev_napi_set_req_set_defer_hard_irqs(set_req, cfg_defer_hard_irqs);
+	netdev_napi_set_req_set_gro_flush_timeout(set_req,
+						  cfg_gro_flush_timeout);
+	netdev_napi_set_req_set_irq_suspend_timeout(set_req,
+						    cfg_irq_suspend_timeout);
+
+	if (netdev_napi_set(ys, set_req))
+		error(1, 0, "can't set NAPI params: %s\n", yerr.msg);
+
+	netdev_napi_get_list_free(napi_list);
+	netdev_napi_get_req_dump_free(req);
+	netdev_napi_set_req_free(set_req);
+	ynl_sock_destroy(ys);
+}
+
+static void run_poller(void)
+{
+	struct epoll_event events[cfg_max_events];
+	struct epoll_params epoll_params = {0};
+	struct sockaddr_in server_addr;
+	int i, epfd, nfds;
+	ssize_t readlen;
+	int outfile_fd;
+	char buf[1024];
+	int sockfd;
+	int conn;
+	int val;
+
+	outfile_fd = open(cfg_outfile, O_WRONLY | O_CREAT, 0644);
+	if (outfile_fd == -1)
+		error(1, errno, "unable to open outfile: %s", cfg_outfile);
+
+	sockfd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
+	if (sockfd == -1)
+		error(1, errno, "unable to create listen socket");
+
+	server_addr.sin_family = AF_INET;
+	server_addr.sin_port = htons(cfg_port);
+	server_addr.sin_addr = cfg_bind_addr;
+
+	/* these values are range checked during parse_opts, so casting is safe
+	 * here
+	 */
+	epoll_params.busy_poll_usecs = cfg_busy_poll_usecs;
+	epoll_params.busy_poll_budget = (uint16_t)cfg_busy_poll_budget;
+	epoll_params.prefer_busy_poll = (uint8_t)cfg_prefer_busy_poll;
+	epoll_params.__pad = 0;
+
+	val = 1;
+	if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &val, sizeof(val)))
+		error(1, errno, "poller setsockopt reuseaddr");
+
+	setnonblock(sockfd);
+
+	if (bind(sockfd, (struct sockaddr *)&server_addr,
+		 sizeof(struct sockaddr_in)))
+		error(0, errno, "poller bind to port: %d\n", cfg_port);
+
+	if (listen(sockfd, 1))
+		error(1, errno, "poller listen");
+
+	epfd = epoll_create1(0);
+	if (ioctl(epfd, EPIOCSPARAMS, &epoll_params) == -1)
+		error(1, errno, "unable to set busy poll params");
+
+	epoll_ctl_add(epfd, sockfd, EPOLLIN | EPOLLOUT | EPOLLET);
+
+	for (;;) {
+		nfds = epoll_wait(epfd, events, cfg_max_events, -1);
+		for (i = 0; i < nfds; i++) {
+			if (events[i].data.fd == sockfd) {
+				conn = accept(sockfd, NULL, NULL);
+				if (conn == -1)
+					error(1, errno,
+					      "accepting incoming connection failed");
+
+				setnonblock(conn);
+				epoll_ctl_add(epfd, conn,
+					      EPOLLIN | EPOLLET | EPOLLRDHUP |
+					      EPOLLHUP);
+			} else if (events[i].events & EPOLLIN) {
+				for (;;) {
+					readlen = read(events[i].data.fd, buf,
+						       sizeof(buf));
+					if (readlen > 0)
+						write_chunk(outfile_fd, buf,
+							    readlen);
+					else
+						break;
+				}
+			} else {
+				/* spurious event ? */
+			}
+			if (events[i].events & (EPOLLRDHUP | EPOLLHUP)) {
+				epoll_ctl(epfd, EPOLL_CTL_DEL,
+					  events[i].data.fd, NULL);
+				close(events[i].data.fd);
+				close(outfile_fd);
+				return;
+			}
+		}
+	}
+}
+
+int main(int argc, char *argv[])
+{
+	parse_opts(argc, argv);
+	setup_queue();
+	run_poller();
+	return 0;
+}