diff --git a/tools/testing/selftests/arm64/fp/.gitignore b/tools/testing/selftests/arm64/fp/.gitignore
index 6b53a7b60fee..b67395903b9b 100644
--- a/tools/testing/selftests/arm64/fp/.gitignore
+++ b/tools/testing/selftests/arm64/fp/.gitignore
@@ -3,4 +3,5 @@ rdvl-sve
 sve-probe-vls
 sve-ptrace
 sve-test
+vec-syscfg
 vlset
diff --git a/tools/testing/selftests/arm64/fp/Makefile b/tools/testing/selftests/arm64/fp/Makefile
index fa3a0167db2d..f2abdd6ba12e 100644
--- a/tools/testing/selftests/arm64/fp/Makefile
+++ b/tools/testing/selftests/arm64/fp/Makefile
@@ -1,7 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0
 
 CFLAGS += -I../../../../../usr/include/
-TEST_GEN_PROGS := sve-ptrace sve-probe-vls
+TEST_GEN_PROGS := sve-ptrace sve-probe-vls vec-syscfg
 TEST_PROGS_EXTENDED := fpsimd-test fpsimd-stress \
 	rdvl-sve \
 	sve-test sve-stress \
@@ -16,6 +16,7 @@ sve-ptrace: sve-ptrace.o sve-ptrace-asm.o
 sve-probe-vls: sve-probe-vls.o rdvl.o
 sve-test: sve-test.o
 	$(CC) -nostdlib $^ -o $@
+vec-syscfg: vec-syscfg.o rdvl.o
 vlset: vlset.o
 
 include ../../lib.mk
diff --git a/tools/testing/selftests/arm64/fp/vec-syscfg.c b/tools/testing/selftests/arm64/fp/vec-syscfg.c
new file mode 100644
index 000000000000..c02071dcb563
--- /dev/null
+++ b/tools/testing/selftests/arm64/fp/vec-syscfg.c
@@ -0,0 +1,593 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2021 ARM Limited.
+ * Original author: Mark Brown <broonie@kernel.org>
+ */
+#include <assert.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/auxv.h>
+#include <sys/prctl.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <asm/sigcontext.h>
+#include <asm/hwcap.h>
+
+#include "../../kselftest.h"
+#include "rdvl.h"
+
+#define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
+
+#define ARCH_MIN_VL SVE_VL_MIN
+
+struct vec_data {
+	const char *name;
+	unsigned long hwcap_type;
+	unsigned long hwcap;
+	const char *rdvl_binary;
+	int (*rdvl)(void);
+
+	int prctl_get;
+	int prctl_set;
+	const char *default_vl_file;
+
+	int default_vl;
+	int min_vl;
+	int max_vl;
+};
+
+
+static struct vec_data vec_data[] = {
+	{
+		.name = "SVE",
+		.hwcap_type = AT_HWCAP,
+		.hwcap = HWCAP_SVE,
+		.rdvl = rdvl_sve,
+		.rdvl_binary = "./rdvl-sve",
+		.prctl_get = PR_SVE_GET_VL,
+		.prctl_set = PR_SVE_SET_VL,
+		.default_vl_file = "/proc/sys/abi/sve_default_vector_length",
+	},
+};
+
+static int stdio_read_integer(FILE *f, const char *what, int *val)
+{
+	int n = 0;
+	int ret;
+
+	ret = fscanf(f, "%d%*1[\n]%n", val, &n);
+	if (ret < 1 || n < 1) {
+		ksft_print_msg("failed to parse integer from %s\n", what);
+		return -1;
+	}
+
+	return 0;
+}
+
+/* Start a new process and return the vector length it sees */
+static int get_child_rdvl(struct vec_data *data)
+{
+	FILE *out;
+	int pipefd[2];
+	pid_t pid, child;
+	int read_vl, ret;
+
+	ret = pipe(pipefd);
+	if (ret == -1) {
+		ksft_print_msg("pipe() failed: %d (%s)\n",
+			       errno, strerror(errno));
+		return -1;
+	}
+
+	fflush(stdout);
+
+	child = fork();
+	if (child == -1) {
+		ksft_print_msg("fork() failed: %d (%s)\n",
+			       errno, strerror(errno));
+		close(pipefd[0]);
+		close(pipefd[1]);
+		return -1;
+	}
+
+	/* Child: put vector length on the pipe */
+	if (child == 0) {
+		/*
+		 * Replace stdout with the pipe, errors to stderr from
+		 * here as kselftest prints to stdout.
+		 */
+		ret = dup2(pipefd[1], 1);
+		if (ret == -1) {
+			fprintf(stderr, "dup2() %d\n", errno);
+			exit(EXIT_FAILURE);
+		}
+
+		/* exec() a new binary which puts the VL on stdout */
+		ret = execl(data->rdvl_binary, data->rdvl_binary, NULL);
+		fprintf(stderr, "execl(%s) failed: %d\n",
+			data->rdvl_binary, errno, strerror(errno));
+
+		exit(EXIT_FAILURE);
+	}
+
+	close(pipefd[1]);
+
+	/* Parent; wait for the exit status from the child & verify it */
+	do {
+		pid = wait(&ret);
+		if (pid == -1) {
+			ksft_print_msg("wait() failed: %d (%s)\n",
+				       errno, strerror(errno));
+			close(pipefd[0]);
+			return -1;
+		}
+	} while (pid != child);
+
+	assert(pid == child);
+
+	if (!WIFEXITED(ret)) {
+		ksft_print_msg("child exited abnormally\n");
+		close(pipefd[0]);
+		return -1;
+	}
+
+	if (WEXITSTATUS(ret) != 0) {
+		ksft_print_msg("child returned error %d\n",
+			       WEXITSTATUS(ret));
+		close(pipefd[0]);
+		return -1;
+	}
+
+	out = fdopen(pipefd[0], "r");
+	if (!out) {
+		ksft_print_msg("failed to open child stdout\n");
+		close(pipefd[0]);
+		return -1;
+	}
+
+	ret = stdio_read_integer(out, "child", &read_vl);
+	fclose(out);
+	if (ret != 0)
+		return ret;
+
+	return read_vl;
+}
+
+static int file_read_integer(const char *name, int *val)
+{
+	FILE *f;
+	int ret;
+
+	f = fopen(name, "r");
+	if (!f) {
+		ksft_test_result_fail("Unable to open %s: %d (%s)\n",
+				      name, errno,
+				      strerror(errno));
+		return -1;
+	}
+
+	ret = stdio_read_integer(f, name, val);
+	fclose(f);
+
+	return ret;
+}
+
+static int file_write_integer(const char *name, int val)
+{
+	FILE *f;
+	int ret;
+
+	f = fopen(name, "w");
+	if (!f) {
+		ksft_test_result_fail("Unable to open %s: %d (%s)\n",
+				      name, errno,
+				      strerror(errno));
+		return -1;
+	}
+
+	fprintf(f, "%d", val);
+	fclose(f);
+	if (ret < 0) {
+		ksft_test_result_fail("Error writing %d to %s\n",
+				      val, name);
+		return -1;
+	}
+
+	return 0;
+}
+
+/*
+ * Verify that we can read the default VL via proc, checking that it
+ * is set in a freshly spawned child.
+ */
+static void proc_read_default(struct vec_data *data)
+{
+	int default_vl, child_vl, ret;
+
+	ret = file_read_integer(data->default_vl_file, &default_vl);
+	if (ret != 0)
+		return;
+
+	/* Is this the actual default seen by new processes? */
+	child_vl = get_child_rdvl(data);
+	if (child_vl != default_vl) {
+		ksft_test_result_fail("%s is %d but child VL is %d\n",
+				      data->default_vl_file,
+				      default_vl, child_vl);
+		return;
+	}
+
+	ksft_test_result_pass("%s default vector length %d\n", data->name,
+			      default_vl);
+	data->default_vl = default_vl;
+}
+
+/* Verify that we can write a minimum value and have it take effect */
+static void proc_write_min(struct vec_data *data)
+{
+	int ret, new_default, child_vl;
+
+	if (geteuid() != 0) {
+		ksft_test_result_skip("Need to be root to write to /proc\n");
+		return;
+	}
+
+	ret = file_write_integer(data->default_vl_file, ARCH_MIN_VL);
+	if (ret != 0)
+		return;
+
+	/* What was the new value? */
+	ret = file_read_integer(data->default_vl_file, &new_default);
+	if (ret != 0)
+		return;
+
+	/* Did it take effect in a new process? */
+	child_vl = get_child_rdvl(data);
+	if (child_vl != new_default) {
+		ksft_test_result_fail("%s is %d but child VL is %d\n",
+				      data->default_vl_file,
+				      new_default, child_vl);
+		return;
+	}
+
+	ksft_test_result_pass("%s minimum vector length %d\n", data->name,
+			      new_default);
+	data->min_vl = new_default;
+
+	file_write_integer(data->default_vl_file, data->default_vl);
+}
+
+/* Verify that we can write a maximum value and have it take effect */
+static void proc_write_max(struct vec_data *data)
+{
+	int ret, new_default, child_vl;
+
+	if (geteuid() != 0) {
+		ksft_test_result_skip("Need to be root to write to /proc\n");
+		return;
+	}
+
+	/* -1 is accepted by the /proc interface as the maximum VL */
+	ret = file_write_integer(data->default_vl_file, -1);
+	if (ret != 0)
+		return;
+
+	/* What was the new value? */
+	ret = file_read_integer(data->default_vl_file, &new_default);
+	if (ret != 0)
+		return;
+
+	/* Did it take effect in a new process? */
+	child_vl = get_child_rdvl(data);
+	if (child_vl != new_default) {
+		ksft_test_result_fail("%s is %d but child VL is %d\n",
+				      data->default_vl_file,
+				      new_default, child_vl);
+		return;
+	}
+
+	ksft_test_result_pass("%s maximum vector length %d\n", data->name,
+			      new_default);
+	data->max_vl = new_default;
+
+	file_write_integer(data->default_vl_file, data->default_vl);
+}
+
+/* Can we read back a VL from prctl? */
+static void prctl_get(struct vec_data *data)
+{
+	int ret;
+
+	ret = prctl(data->prctl_get);
+	if (ret == -1) {
+		ksft_test_result_fail("%s prctl() read failed: %d (%s)\n",
+				      data->name, errno, strerror(errno));
+		return;
+	}
+
+	/* Mask out any flags */
+	ret &= PR_SVE_VL_LEN_MASK;
+
+	/* Is that what we can read back directly? */
+	if (ret == data->rdvl())
+		ksft_test_result_pass("%s current VL is %d\n",
+				      data->name, ret);
+	else
+		ksft_test_result_fail("%s prctl() VL %d but RDVL is %d\n",
+				      data->name, ret, data->rdvl());
+}
+
+/* Does the prctl let us set the VL we already have? */
+static void prctl_set_same(struct vec_data *data)
+{
+	int cur_vl = data->rdvl();
+	int ret;
+
+	ret = prctl(data->prctl_set, cur_vl);
+	if (ret < 0) {
+		ksft_test_result_fail("%s prctl set failed: %d (%s)\n",
+				      data->name, errno, strerror(errno));
+		return;
+	}
+
+	if (cur_vl != data->rdvl())
+		ksft_test_result_pass("%s current VL is %d\n",
+				      data->name, ret);
+	else
+		ksft_test_result_fail("%s prctl() VL %d but RDVL is %d\n",
+				      data->name, ret, data->rdvl());
+}
+
+/* Can we set a new VL for this process? */
+static void prctl_set(struct vec_data *data)
+{
+	int ret;
+
+	if (data->min_vl == data->max_vl) {
+		ksft_test_result_skip("%s only one VL supported\n",
+				      data->name);
+		return;
+	}
+
+	/* Try to set the minimum VL */
+	ret = prctl(data->prctl_set, data->min_vl);
+	if (ret < 0) {
+		ksft_test_result_fail("%s prctl set failed for %d: %d (%s)\n",
+				      data->name, data->min_vl,
+				      errno, strerror(errno));
+		return;
+	}
+
+	if ((ret & PR_SVE_VL_LEN_MASK) != data->min_vl) {
+		ksft_test_result_fail("%s prctl set %d but return value is %d\n",
+				      data->name, data->min_vl, data->rdvl());
+		return;
+	}
+
+	if (data->rdvl() != data->min_vl) {
+		ksft_test_result_fail("%s set %d but RDVL is %d\n",
+				      data->name, data->min_vl, data->rdvl());
+		return;
+	}
+
+	/* Try to set the maximum VL */
+	ret = prctl(data->prctl_set, data->max_vl);
+	if (ret < 0) {
+		ksft_test_result_fail("%s prctl set failed for %d: %d (%s)\n",
+				      data->name, data->max_vl,
+				      errno, strerror(errno));
+		return;
+	}
+
+	if ((ret & PR_SVE_VL_LEN_MASK) != data->max_vl) {
+		ksft_test_result_fail("%s prctl() set %d but return value is %d\n",
+				      data->name, data->max_vl, data->rdvl());
+		return;
+	}
+
+	/* The _INHERIT flag should not be present when we read the VL */
+	ret = prctl(data->prctl_get);
+	if (ret == -1) {
+		ksft_test_result_fail("%s prctl() read failed: %d (%s)\n",
+				      data->name, errno, strerror(errno));
+		return;
+	}
+
+	if (ret & PR_SVE_VL_INHERIT) {
+		ksft_test_result_fail("%s prctl() reports _INHERIT\n",
+				      data->name);
+		return;
+	}
+
+	ksft_test_result_pass("%s prctl() set min/max\n", data->name);
+}
+
+/* If we didn't request it a new VL shouldn't affect the child */
+static void prctl_set_no_child(struct vec_data *data)
+{
+	int ret, child_vl;
+
+	if (data->min_vl == data->max_vl) {
+		ksft_test_result_skip("%s only one VL supported\n",
+				      data->name);
+		return;
+	}
+
+	ret = prctl(data->prctl_set, data->min_vl);
+	if (ret < 0) {
+		ksft_test_result_fail("%s prctl set failed for %d: %d (%s)\n",
+				      data->name, data->min_vl,
+				      errno, strerror(errno));
+		return;
+	}
+
+	/* Ensure the default VL is different */
+	ret = file_write_integer(data->default_vl_file, data->max_vl);
+	if (ret != 0)
+		return;
+
+	/* Check that the child has the default we just set */
+	child_vl = get_child_rdvl(data);
+	if (child_vl != data->max_vl) {
+		ksft_test_result_fail("%s is %d but child VL is %d\n",
+				      data->default_vl_file,
+				      data->max_vl, child_vl);
+		return;
+	}
+
+	ksft_test_result_pass("%s vector length used default\n", data->name);
+
+	file_write_integer(data->default_vl_file, data->default_vl);
+}
+
+/* If we didn't request it a new VL shouldn't affect the child */
+static void prctl_set_for_child(struct vec_data *data)
+{
+	int ret, child_vl;
+
+	if (data->min_vl == data->max_vl) {
+		ksft_test_result_skip("%s only one VL supported\n",
+				      data->name);
+		return;
+	}
+
+	ret = prctl(data->prctl_set, data->min_vl | PR_SVE_VL_INHERIT);
+	if (ret < 0) {
+		ksft_test_result_fail("%s prctl set failed for %d: %d (%s)\n",
+				      data->name, data->min_vl,
+				      errno, strerror(errno));
+		return;
+	}
+
+	/* The _INHERIT flag should be present when we read the VL */
+	ret = prctl(data->prctl_get);
+	if (ret == -1) {
+		ksft_test_result_fail("%s prctl() read failed: %d (%s)\n",
+				      data->name, errno, strerror(errno));
+		return;
+	}
+	if (!(ret & PR_SVE_VL_INHERIT)) {
+		ksft_test_result_fail("%s prctl() does not report _INHERIT\n",
+				      data->name);
+		return;
+	}
+
+	/* Ensure the default VL is different */
+	ret = file_write_integer(data->default_vl_file, data->max_vl);
+	if (ret != 0)
+		return;
+
+	/* Check that the child inherited our VL */
+	child_vl = get_child_rdvl(data);
+	if (child_vl != data->min_vl) {
+		ksft_test_result_fail("%s is %d but child VL is %d\n",
+				      data->default_vl_file,
+				      data->min_vl, child_vl);
+		return;
+	}
+
+	ksft_test_result_pass("%s vector length was inherited\n", data->name);
+
+	file_write_integer(data->default_vl_file, data->default_vl);
+}
+
+/* _ONEXEC takes effect only in the child process */
+static void prctl_set_onexec(struct vec_data *data)
+{
+	int ret, child_vl;
+
+	if (data->min_vl == data->max_vl) {
+		ksft_test_result_skip("%s only one VL supported\n",
+				      data->name);
+		return;
+	}
+
+	/* Set a known value for the default and our current VL */
+	ret = file_write_integer(data->default_vl_file, data->max_vl);
+	if (ret != 0)
+		return;
+
+	ret = prctl(data->prctl_set, data->max_vl);
+	if (ret < 0) {
+		ksft_test_result_fail("%s prctl set failed for %d: %d (%s)\n",
+				      data->name, data->min_vl,
+				      errno, strerror(errno));
+		return;
+	}
+
+	/* Set a different value for the child to have on exec */
+	ret = prctl(data->prctl_set, data->min_vl | PR_SVE_SET_VL_ONEXEC);
+	if (ret < 0) {
+		ksft_test_result_fail("%s prctl set failed for %d: %d (%s)\n",
+				      data->name, data->min_vl,
+				      errno, strerror(errno));
+		return;
+	}
+
+	/* Our current VL should stay the same */
+	if (data->rdvl() != data->max_vl) {
+		ksft_test_result_fail("%s VL changed by _ONEXEC prctl()\n",
+				      data->name);
+		return;
+	}
+
+	/* Check that the child inherited our VL */
+	child_vl = get_child_rdvl(data);
+	if (child_vl != data->min_vl) {
+		ksft_test_result_fail("Set %d _ONEXEC but child VL is %d\n",
+				      data->min_vl, child_vl);
+		return;
+	}
+
+	ksft_test_result_pass("%s vector length set on exec\n", data->name);
+
+	file_write_integer(data->default_vl_file, data->default_vl);
+}
+
+typedef void (*test_type)(struct vec_data *);
+
+static const test_type tests[] = {
+	/*
+	 * The default/min/max tests must be first and in this order
+	 * to provide data for other tests.
+	 */
+	proc_read_default,
+	proc_write_min,
+	proc_write_max,
+
+	prctl_get,
+	prctl_set,
+	prctl_set_no_child,
+	prctl_set_for_child,
+	prctl_set_onexec,
+};
+
+int main(void)
+{
+	int i, j;
+
+	ksft_print_header();
+	ksft_set_plan(ARRAY_SIZE(tests) * ARRAY_SIZE(vec_data));
+
+	for (i = 0; i < ARRAY_SIZE(vec_data); i++) {
+		struct vec_data *data = &vec_data[i];
+		unsigned long supported;
+
+		supported = getauxval(data->hwcap_type) & data->hwcap;
+
+		for (j = 0; j < ARRAY_SIZE(tests); j++) {
+			if (supported)
+				tests[j](data);
+			else
+				ksft_test_result_skip("%s not supported\n",
+						      data->name);
+		}
+	}
+
+	ksft_exit_pass();
+}