test/vsock: MSG_ZEROCOPY flag tests

This adds three tests for MSG_ZEROCOPY feature:
1) SOCK_STREAM tx with different buffers.
2) SOCK_SEQPACKET tx with different buffers.
3) SOCK_STREAM test to read empty error queue of the socket.

Patch also works as preparation for the next patches for tools in this
patchset: vsock_perf and vsock_uring_test:
1) Adds several new functions to util.c - they will be also used by
vsock_uring_test.
2) Adds two new functions for MSG_ZEROCOPY handling to a new source
file - such source will be shared between vsock_test, vsock_perf and
vsock_uring_test, thus avoiding code copy-pasting.

Signed-off-by: Arseniy Krasnov <[e-mail]>
Reviewed-by: Stefano Garzarella <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

tools/testing/vsock/Makefile

···
 # SPDX-License-Identifier: GPL-2.0-only
 all: test vsock_perf
 test: vsock_test vsock_diag_test
-vsock_test: vsock_test.o timeout.o control.o util.o
+vsock_test: vsock_test.o vsock_test_zerocopy.o timeout.o control.o util.o msg_zerocopy_common.o
 vsock_diag_test: vsock_diag_test.o timeout.o control.o util.o
 vsock_perf: vsock_perf.o
 

tools/testing/vsock/msg_zerocopy_common.c

···
+// SPDX-License-Identifier: GPL-2.0-only
+/* Some common code for MSG_ZEROCOPY logic
+ *
+ * Copyright (C) 2023 SberDevices.
+ *
+ * Author: Arseniy Krasnov <[e-mail]>
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <linux/errqueue.h>
+
+#include "msg_zerocopy_common.h"
+
+void enable_so_zerocopy(int fd)
+{
+	int val = 1;
+
+	if (setsockopt(fd, SOL_SOCKET, SO_ZEROCOPY, &val, sizeof(val))) {
+		perror("setsockopt");
+		exit(EXIT_FAILURE);
+	}
+}
+
+void vsock_recv_completion(int fd, const bool *zerocopied)
+{
+	struct sock_extended_err *serr;
+	struct msghdr msg = { 0 };
+	char cmsg_data[128];
+	struct cmsghdr *cm;
+	ssize_t res;
+
+	msg.msg_control = cmsg_data;
+	msg.msg_controllen = sizeof(cmsg_data);
+
+	res = recvmsg(fd, &msg, MSG_ERRQUEUE);
+	if (res) {
+		fprintf(stderr, "failed to read error queue: %zi\n", res);
+		exit(EXIT_FAILURE);
+	}
+
+	cm = CMSG_FIRSTHDR(&msg);
+	if (!cm) {
+		fprintf(stderr, "cmsg: no cmsg\n");
+		exit(EXIT_FAILURE);
+	}
+
+	if (cm->cmsg_level != SOL_VSOCK) {
+		fprintf(stderr, "cmsg: unexpected 'cmsg_level'\n");
+		exit(EXIT_FAILURE);
+	}
+
+	if (cm->cmsg_type != VSOCK_RECVERR) {
+		fprintf(stderr, "cmsg: unexpected 'cmsg_type'\n");
+		exit(EXIT_FAILURE);
+	}
+
+	serr = (void *)CMSG_DATA(cm);
+	if (serr->ee_origin != SO_EE_ORIGIN_ZEROCOPY) {
+		fprintf(stderr, "serr: wrong origin: %u\n", serr->ee_origin);
+		exit(EXIT_FAILURE);
+	}
+
+	if (serr->ee_errno) {
+		fprintf(stderr, "serr: wrong error code: %u\n", serr->ee_errno);
+		exit(EXIT_FAILURE);
+	}
+
+	/* This flag is used for tests, to check that transmission was
+	 * performed as expected: zerocopy or fallback to copy. If NULL
+	 * - don't care.
+	 */
+	if (!zerocopied)
+		return;
+
+	if (*zerocopied && (serr->ee_code & SO_EE_CODE_ZEROCOPY_COPIED)) {
+		fprintf(stderr, "serr: was copy instead of zerocopy\n");
+		exit(EXIT_FAILURE);
+	}
+
+	if (!*zerocopied && !(serr->ee_code & SO_EE_CODE_ZEROCOPY_COPIED)) {
+		fprintf(stderr, "serr: was zerocopy instead of copy\n");
+		exit(EXIT_FAILURE);
+	}
+}

tools/testing/vsock/msg_zerocopy_common.h

···
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef MSG_ZEROCOPY_COMMON_H
+#define MSG_ZEROCOPY_COMMON_H
+
+#include <stdbool.h>
+
+#ifndef SOL_VSOCK
+#define SOL_VSOCK	287
+#endif
+
+#ifndef VSOCK_RECVERR
+#define VSOCK_RECVERR	1
+#endif
+
+void enable_so_zerocopy(int fd);
+void vsock_recv_completion(int fd, const bool *zerocopied);
+
+#endif /* MSG_ZEROCOPY_COMMON_H */

tools/testing/vsock/util.c

···
 #include <stdio.h>
 #include <stdint.h>
 #include <stdlib.h>
+#include <string.h>
 #include <signal.h>
 #include <unistd.h>
 #include <assert.h>
 #include <sys/epoll.h>
+#include <sys/mman.h>
 
 #include "timeout.h"
 #include "control.h"
···
 	}
 
 	return hash;
+}
+
+size_t iovec_bytes(const struct iovec *iov, size_t iovnum)
+{
+	size_t bytes;
+	int i;
+
+	for (bytes = 0, i = 0; i < iovnum; i++)
+		bytes += iov[i].iov_len;
+
+	return bytes;
+}
+
+unsigned long iovec_hash_djb2(const struct iovec *iov, size_t iovnum)
+{
+	unsigned long hash;
+	size_t iov_bytes;
+	size_t offs;
+	void *tmp;
+	int i;
+
+	iov_bytes = iovec_bytes(iov, iovnum);
+
+	tmp = malloc(iov_bytes);
+	if (!tmp) {
+		perror("malloc");
+		exit(EXIT_FAILURE);
+	}
+
+	for (offs = 0, i = 0; i < iovnum; i++) {
+		memcpy(tmp + offs, iov[i].iov_base, iov[i].iov_len);
+		offs += iov[i].iov_len;
+	}
+
+	hash = hash_djb2(tmp, iov_bytes);
+	free(tmp);
+
+	return hash;
+}
+
+/* Allocates and returns new 'struct iovec *' according pattern
+ * in the 'test_iovec'. For each element in the 'test_iovec' it
+ * allocates new element in the resulting 'iovec'. 'iov_len'
+ * of the new element is copied from 'test_iovec'. 'iov_base' is
+ * allocated depending on the 'iov_base' of 'test_iovec':
+ *
+ * 'iov_base' == NULL -> valid buf: mmap('iov_len').
+ *
+ * 'iov_base' == MAP_FAILED -> invalid buf:
+ *               mmap('iov_len'), then munmap('iov_len').
+ *               'iov_base' still contains result of
+ *               mmap().
+ *
+ * 'iov_base' == number -> unaligned valid buf:
+ *               mmap('iov_len') + number.
+ *
+ * 'iovnum' is number of elements in 'test_iovec'.
+ *
+ * Returns new 'iovec' or calls 'exit()' on error.
+ */
+struct iovec *alloc_test_iovec(const struct iovec *test_iovec, int iovnum)
+{
+	struct iovec *iovec;
+	int i;
+
+	iovec = malloc(sizeof(*iovec) * iovnum);
+	if (!iovec) {
+		perror("malloc");
+		exit(EXIT_FAILURE);
+	}
+
+	for (i = 0; i < iovnum; i++) {
+		iovec[i].iov_len = test_iovec[i].iov_len;
+
+		iovec[i].iov_base = mmap(NULL, iovec[i].iov_len,
+					 PROT_READ | PROT_WRITE,
+					 MAP_PRIVATE | MAP_ANONYMOUS | MAP_POPULATE,
+					 -1, 0);
+		if (iovec[i].iov_base == MAP_FAILED) {
+			perror("mmap");
+			exit(EXIT_FAILURE);
+		}
+
+		if (test_iovec[i].iov_base != MAP_FAILED)
+			iovec[i].iov_base += (uintptr_t)test_iovec[i].iov_base;
+	}
+
+	/* Unmap "invalid" elements. */
+	for (i = 0; i < iovnum; i++) {
+		if (test_iovec[i].iov_base == MAP_FAILED) {
+			if (munmap(iovec[i].iov_base, iovec[i].iov_len)) {
+				perror("munmap");
+				exit(EXIT_FAILURE);
+			}
+		}
+	}
+
+	for (i = 0; i < iovnum; i++) {
+		int j;
+
+		if (test_iovec[i].iov_base == MAP_FAILED)
+			continue;
+
+		for (j = 0; j < iovec[i].iov_len; j++)
+			((uint8_t *)iovec[i].iov_base)[j] = rand() & 0xff;
+	}
+
+	return iovec;
+}
+
+/* Frees 'iovec *', previously allocated by 'alloc_test_iovec()'.
+ * On error calls 'exit()'.
+ */
+void free_test_iovec(const struct iovec *test_iovec,
+		     struct iovec *iovec, int iovnum)
+{
+	int i;
+
+	for (i = 0; i < iovnum; i++) {
+		if (test_iovec[i].iov_base != MAP_FAILED) {
+			if (test_iovec[i].iov_base)
+				iovec[i].iov_base -= (uintptr_t)test_iovec[i].iov_base;
+
+			if (munmap(iovec[i].iov_base, iovec[i].iov_len)) {
+				perror("munmap");
+				exit(EXIT_FAILURE);
+			}
+		}
+	}
+
+	free(iovec);
 }

tools/testing/vsock/util.h

···
 void skip_test(struct test_case *test_cases, size_t test_cases_len,
 	       const char *test_id_str);
 unsigned long hash_djb2(const void *data, size_t len);
+size_t iovec_bytes(const struct iovec *iov, size_t iovnum);
+unsigned long iovec_hash_djb2(const struct iovec *iov, size_t iovnum);
+struct iovec *alloc_test_iovec(const struct iovec *test_iovec, int iovnum);
+void free_test_iovec(const struct iovec *test_iovec,
+		     struct iovec *iovec, int iovnum);
 #endif /* UTIL_H */

tools/testing/vsock/vsock_test.c

···
 #include <poll.h>
 #include <signal.h>
 
+#include "vsock_test_zerocopy.h"
 #include "timeout.h"
 #include "control.h"
 #include "util.h"
···
 		.name = "SOCK_STREAM SHUT_RD",
 		.run_client = test_stream_shutrd_client,
 		.run_server = test_stream_shutrd_server,
+	},
+	{
+		.name = "SOCK_STREAM MSG_ZEROCOPY",
+		.run_client = test_stream_msgzcopy_client,
+		.run_server = test_stream_msgzcopy_server,
+	},
+	{
+		.name = "SOCK_SEQPACKET MSG_ZEROCOPY",
+		.run_client = test_seqpacket_msgzcopy_client,
+		.run_server = test_seqpacket_msgzcopy_server,
+	},
+	{
+		.name = "SOCK_STREAM MSG_ZEROCOPY empty MSG_ERRQUEUE",
+		.run_client = test_stream_msgzcopy_empty_errq_client,
+		.run_server = test_stream_msgzcopy_empty_errq_server,
 	},
 	{},
 };

tools/testing/vsock/vsock_test_zerocopy.c

···
+// SPDX-License-Identifier: GPL-2.0-only
+/* MSG_ZEROCOPY feature tests for vsock
+ *
+ * Copyright (C) 2023 SberDevices.
+ *
+ * Author: Arseniy Krasnov <[e-mail]>
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <unistd.h>
+#include <poll.h>
+#include <linux/errqueue.h>
+#include <linux/kernel.h>
+#include <errno.h>
+
+#include "control.h"
+#include "vsock_test_zerocopy.h"
+#include "msg_zerocopy_common.h"
+
+#ifndef PAGE_SIZE
+#define PAGE_SIZE		4096
+#endif
+
+#define VSOCK_TEST_DATA_MAX_IOV 3
+
+struct vsock_test_data {
+	/* This test case if for SOCK_STREAM only. */
+	bool stream_only;
+	/* Data must be zerocopied. This field is checked against
+	 * field 'ee_code' of the 'struct sock_extended_err', which
+	 * contains bit to detect that zerocopy transmission was
+	 * fallbacked to copy mode.
+	 */
+	bool zerocopied;
+	/* Enable SO_ZEROCOPY option on the socket. Without enabled
+	 * SO_ZEROCOPY, every MSG_ZEROCOPY transmission will behave
+	 * like without MSG_ZEROCOPY flag.
+	 */
+	bool so_zerocopy;
+	/* 'errno' after 'sendmsg()' call. */
+	int sendmsg_errno;
+	/* Number of valid elements in 'vecs'. */
+	int vecs_cnt;
+	struct iovec vecs[VSOCK_TEST_DATA_MAX_IOV];
+};
+
+static struct vsock_test_data test_data_array[] = {
+	/* Last element has non-page aligned size. */
+	{
+		.zerocopied = true,
+		.so_zerocopy = true,
+		.sendmsg_errno = 0,
+		.vecs_cnt = 3,
+		{
+			{ NULL, PAGE_SIZE },
+			{ NULL, PAGE_SIZE },
+			{ NULL, 200 }
+		}
+	},
+	/* All elements have page aligned base and size. */
+	{
+		.zerocopied = true,
+		.so_zerocopy = true,
+		.sendmsg_errno = 0,
+		.vecs_cnt = 3,
+		{
+			{ NULL, PAGE_SIZE },
+			{ NULL, PAGE_SIZE * 2 },
+			{ NULL, PAGE_SIZE * 3 }
+		}
+	},
+	/* All elements have page aligned base and size. But
+	 * data length is bigger than 64Kb.
+	 */
+	{
+		.zerocopied = true,
+		.so_zerocopy = true,
+		.sendmsg_errno = 0,
+		.vecs_cnt = 3,
+		{
+			{ NULL, PAGE_SIZE * 16 },
+			{ NULL, PAGE_SIZE * 16 },
+			{ NULL, PAGE_SIZE * 16 }
+		}
+	},
+	/* Middle element has both non-page aligned base and size. */
+	{
+		.zerocopied = true,
+		.so_zerocopy = true,
+		.sendmsg_errno = 0,
+		.vecs_cnt = 3,
+		{
+			{ NULL, PAGE_SIZE },
+			{ (void *)1, 100 },
+			{ NULL, PAGE_SIZE }
+		}
+	},
+	/* Middle element is unmapped. */
+	{
+		.zerocopied = false,
+		.so_zerocopy = true,
+		.sendmsg_errno = ENOMEM,
+		.vecs_cnt = 3,
+		{
+			{ NULL, PAGE_SIZE },
+			{ MAP_FAILED, PAGE_SIZE },
+			{ NULL, PAGE_SIZE }
+		}
+	},
+	/* Valid data, but SO_ZEROCOPY is off. This
+	 * will trigger fallback to copy.
+	 */
+	{
+		.zerocopied = false,
+		.so_zerocopy = false,
+		.sendmsg_errno = 0,
+		.vecs_cnt = 1,
+		{
+			{ NULL, PAGE_SIZE }
+		}
+	},
+	/* Valid data, but message is bigger than peer's
+	 * buffer, so this will trigger fallback to copy.
+	 * This test is for SOCK_STREAM only, because
+	 * for SOCK_SEQPACKET, 'sendmsg()' returns EMSGSIZE.
+	 */
+	{
+		.stream_only = true,
+		.zerocopied = false,
+		.so_zerocopy = true,
+		.sendmsg_errno = 0,
+		.vecs_cnt = 1,
+		{
+			{ NULL, 100 * PAGE_SIZE }
+		}
+	},
+};
+
+#define POLL_TIMEOUT_MS		100
+
+static void test_client(const struct test_opts *opts,
+			const struct vsock_test_data *test_data,
+			bool sock_seqpacket)
+{
+	struct pollfd fds = { 0 };
+	struct msghdr msg = { 0 };
+	ssize_t sendmsg_res;
+	struct iovec *iovec;
+	int fd;
+
+	if (sock_seqpacket)
+		fd = vsock_seqpacket_connect(opts->peer_cid, 1234);
+	else
+		fd = vsock_stream_connect(opts->peer_cid, 1234);
+
+	if (fd < 0) {
+		perror("connect");
+		exit(EXIT_FAILURE);
+	}
+
+	if (test_data->so_zerocopy)
+		enable_so_zerocopy(fd);
+
+	iovec = alloc_test_iovec(test_data->vecs, test_data->vecs_cnt);
+
+	msg.msg_iov = iovec;
+	msg.msg_iovlen = test_data->vecs_cnt;
+
+	errno = 0;
+
+	sendmsg_res = sendmsg(fd, &msg, MSG_ZEROCOPY);
+	if (errno != test_data->sendmsg_errno) {
+		fprintf(stderr, "expected 'errno' == %i, got %i\n",
+			test_data->sendmsg_errno, errno);
+		exit(EXIT_FAILURE);
+	}
+
+	if (!errno) {
+		if (sendmsg_res != iovec_bytes(iovec, test_data->vecs_cnt)) {
+			fprintf(stderr, "expected 'sendmsg()' == %li, got %li\n",
+				iovec_bytes(iovec, test_data->vecs_cnt),
+				sendmsg_res);
+			exit(EXIT_FAILURE);
+		}
+	}
+
+	fds.fd = fd;
+	fds.events = 0;
+
+	if (poll(&fds, 1, POLL_TIMEOUT_MS) < 0) {
+		perror("poll");
+		exit(EXIT_FAILURE);
+	}
+
+	if (fds.revents & POLLERR) {
+		vsock_recv_completion(fd, &test_data->zerocopied);
+	} else if (test_data->so_zerocopy && !test_data->sendmsg_errno) {
+		/* If we don't have data in the error queue, but
+		 * SO_ZEROCOPY was enabled and 'sendmsg()' was
+		 * successful - this is an error.
+		 */
+		fprintf(stderr, "POLLERR expected\n");
+		exit(EXIT_FAILURE);
+	}
+
+	if (!test_data->sendmsg_errno)
+		control_writeulong(iovec_hash_djb2(iovec, test_data->vecs_cnt));
+	else
+		control_writeulong(0);
+
+	control_writeln("DONE");
+	free_test_iovec(test_data->vecs, iovec, test_data->vecs_cnt);
+	close(fd);
+}
+
+void test_stream_msgzcopy_client(const struct test_opts *opts)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(test_data_array); i++)
+		test_client(opts, &test_data_array[i], false);
+}
+
+void test_seqpacket_msgzcopy_client(const struct test_opts *opts)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(test_data_array); i++) {
+		if (test_data_array[i].stream_only)
+			continue;
+
+		test_client(opts, &test_data_array[i], true);
+	}
+}
+
+static void test_server(const struct test_opts *opts,
+			const struct vsock_test_data *test_data,
+			bool sock_seqpacket)
+{
+	unsigned long remote_hash;
+	unsigned long local_hash;
+	ssize_t total_bytes_rec;
+	unsigned char *data;
+	size_t data_len;
+	int fd;
+
+	if (sock_seqpacket)
+		fd = vsock_seqpacket_accept(VMADDR_CID_ANY, 1234, NULL);
+	else
+		fd = vsock_stream_accept(VMADDR_CID_ANY, 1234, NULL);
+
+	if (fd < 0) {
+		perror("accept");
+		exit(EXIT_FAILURE);
+	}
+
+	data_len = iovec_bytes(test_data->vecs, test_data->vecs_cnt);
+
+	data = malloc(data_len);
+	if (!data) {
+		perror("malloc");
+		exit(EXIT_FAILURE);
+	}
+
+	total_bytes_rec = 0;
+
+	while (total_bytes_rec != data_len) {
+		ssize_t bytes_rec;
+
+		bytes_rec = read(fd, data + total_bytes_rec,
+				 data_len - total_bytes_rec);
+		if (bytes_rec <= 0)
+			break;
+
+		total_bytes_rec += bytes_rec;
+	}
+
+	if (test_data->sendmsg_errno == 0)
+		local_hash = hash_djb2(data, data_len);
+	else
+		local_hash = 0;
+
+	free(data);
+
+	/* Waiting for some result. */
+	remote_hash = control_readulong();
+	if (remote_hash != local_hash) {
+		fprintf(stderr, "hash mismatch\n");
+		exit(EXIT_FAILURE);
+	}
+
+	control_expectln("DONE");
+	close(fd);
+}
+
+void test_stream_msgzcopy_server(const struct test_opts *opts)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(test_data_array); i++)
+		test_server(opts, &test_data_array[i], false);
+}
+
+void test_seqpacket_msgzcopy_server(const struct test_opts *opts)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(test_data_array); i++) {
+		if (test_data_array[i].stream_only)
+			continue;
+
+		test_server(opts, &test_data_array[i], true);
+	}
+}
+
+void test_stream_msgzcopy_empty_errq_client(const struct test_opts *opts)
+{
+	struct msghdr msg = { 0 };
+	char cmsg_data[128];
+	ssize_t res;
+	int fd;
+
+	fd = vsock_stream_connect(opts->peer_cid, 1234);
+	if (fd < 0) {
+		perror("connect");
+		exit(EXIT_FAILURE);
+	}
+
+	msg.msg_control = cmsg_data;
+	msg.msg_controllen = sizeof(cmsg_data);
+
+	res = recvmsg(fd, &msg, MSG_ERRQUEUE);
+	if (res != -1) {
+		fprintf(stderr, "expected 'recvmsg(2)' failure, got %zi\n",
+			res);
+		exit(EXIT_FAILURE);
+	}
+
+	control_writeln("DONE");
+	close(fd);
+}
+
+void test_stream_msgzcopy_empty_errq_server(const struct test_opts *opts)
+{
+	int fd;
+
+	fd = vsock_stream_accept(VMADDR_CID_ANY, 1234, NULL);
+	if (fd < 0) {
+		perror("accept");
+		exit(EXIT_FAILURE);
+	}
+
+	control_expectln("DONE");
+	close(fd);
+}

tools/testing/vsock/vsock_test_zerocopy.h

···
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef VSOCK_TEST_ZEROCOPY_H
+#define VSOCK_TEST_ZEROCOPY_H
+#include "util.h"
+
+void test_stream_msgzcopy_client(const struct test_opts *opts);
+void test_stream_msgzcopy_server(const struct test_opts *opts);
+
+void test_seqpacket_msgzcopy_client(const struct test_opts *opts);
+void test_seqpacket_msgzcopy_server(const struct test_opts *opts);
+
+void test_stream_msgzcopy_empty_errq_client(const struct test_opts *opts);
+void test_stream_msgzcopy_empty_errq_server(const struct test_opts *opts);
+
+#endif /* VSOCK_TEST_ZEROCOPY_H */