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 <avkrasnov@salutedevices.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 87 insertions, 0 deletions

diff --git a/tools/testing/vsock/msg_zerocopy_common.c b/tools/testing/vsock/msg_zerocopy_common.c
new file mode 100644
index 000000000000..5a4bdf7b5132
--- /dev/null
+++ b/tools/testing/vsock/msg_zerocopy_common.c
@@ -0,0 +1,87 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Some common code for MSG_ZEROCOPY logic
+ *
+ * Copyright (C) 2023 SberDevices.
+ *
+ * Author: Arseniy Krasnov <avkrasnov@salutedevices.com>
+ */
+
+#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);
+	}
+}