[Devel] [PATCH hci-8.1 v2 2/2] selftests: ve: Test sched_getaffinity in VE
Vladimir Riabchun
vladimir.riabchun at virtuozzo.com
Wed Oct 28 15:46:38 MSK 2026
Add a new selftest that verifies that sched_getaffinity respects both
cgroup cpuset and nr_cpus limits.
https://virtuozzo.atlassian.net/browse/VSTOR-141682
Signed-off-by: Vladimir Riabchun <vladimir.riabchun at virtuozzo.com>
---
tools/testing/selftests/ve/.gitignore | 1 +
tools/testing/selftests/ve/Makefile | 1 +
.../selftests/ve/ve_sched_getaffinity_test.c | 213 +++++++++++++++++++++
3 files changed, 215 insertions(+)
diff --git a/tools/testing/selftests/ve/.gitignore b/tools/testing/selftests/ve/.gitignore
index 8ab1bfe6f5e4..178de0ee1822 100644
--- a/tools/testing/selftests/ve/.gitignore
+++ b/tools/testing/selftests/ve/.gitignore
@@ -3,3 +3,4 @@ ve_perms_test
ve_mount_accounting_test
ve_cpuid_override_test
ve_vtty_stress
+ve_sched_getaffinity_test
diff --git a/tools/testing/selftests/ve/Makefile b/tools/testing/selftests/ve/Makefile
index 51f9316beb99..d53e724205f7 100644
--- a/tools/testing/selftests/ve/Makefile
+++ b/tools/testing/selftests/ve/Makefile
@@ -6,6 +6,7 @@ TEST_GEN_PROGS += ve_ns_owner_test
TEST_GEN_PROGS += ve_perms_test
TEST_GEN_PROGS += ve_mount_accounting_test
TEST_GEN_PROGS += ve_vtty_stress
+TEST_GEN_PROGS += ve_sched_getaffinity_test
# CPUID faulting is x86-64 only. ARCH says "x86" for 32-bit too and lib.mk
# picks the clang target by its emptiness, so decide by the compiler.
diff --git a/tools/testing/selftests/ve/ve_sched_getaffinity_test.c b/tools/testing/selftests/ve/ve_sched_getaffinity_test.c
new file mode 100644
index 000000000000..376b65a215f1
--- /dev/null
+++ b/tools/testing/selftests/ve/ve_sched_getaffinity_test.c
@@ -0,0 +1,213 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ve_mount_accounting selftests
+ *
+ * Tests to check cpuset virtualization.
+ * Not suitable for running inside CT.
+ */
+#define _GNU_SOURCE
+#include <asm/unistd.h>
+#include <linux/sched.h>
+#include <sys/syscall.h>
+#include <sys/stat.h>
+#include <errno.h>
+#include <sched.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+
+#include "../kselftest_harness.h"
+#include "ve_selftest.h"
+
+FIXTURE(ve_getaff_test)
+{
+ int cgv2_fd;
+ int ctid;
+ struct namespace_ctx ns_ctx;
+ cpu_set_t orig_cpuset;
+ int orig_cpucount;
+};
+
+static int __getaffinity_ve(void *cpuset)
+{
+ cpu_set_t *dst = cpuset;
+
+ return sched_getaffinity(getpid(), sizeof(*dst), dst);
+}
+
+static int getaffinity_ve(FIXTURE_DATA(ve_getaff_test) * self, cpu_set_t *dst)
+{
+ int ret = -1;
+ cpu_set_t *tmp = mmap(NULL, sizeof(cpu_set_t),
+ PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS, -1, 0);
+
+ if (tmp == MAP_FAILED) {
+ fprintf(stderr, "Failed to mmap shared region: %s\n", strerror(errno));
+ return -1;
+ }
+ CPU_ZERO(tmp);
+ CPU_ZERO(dst);
+
+ ret = run_in_ve(self->cgv2_fd, self->ctid, &self->ns_ctx,
+ CLONE_NEWVE, __getaffinity_ve, tmp);
+
+ if (!ret)
+ memcpy(dst, tmp, sizeof(cpu_set_t));
+
+ munmap(tmp, sizeof(cpu_set_t));
+ return ret;
+}
+
+static int check_cpumask_is_prefix(cpu_set_t *mask, int expected)
+{
+ int i, count = CPU_COUNT(mask);
+
+ if (expected >= 0 && expected != count) {
+ fprintf(stderr, "cpumask count mismatch: %d != %d\n", expected, count);
+ return 0;
+ }
+ for (i = 0; i < count; i++) {
+ if (!CPU_ISSET(i, mask)) {
+ fprintf(stderr, "cpumask is not a prefix: %d is OFF\n", i);
+ return 0;
+ }
+ }
+ return 1;
+}
+
+static int get_nth_cpu(cpu_set_t *mask, int n)
+{
+ int i;
+
+ for (i = 0; i < sizeof(*mask); i++) {
+ if (!CPU_ISSET(i, mask) || --n)
+ continue;
+
+ return i;
+ }
+ return -1;
+}
+
+FIXTURE_SETUP(ve_getaff_test)
+{
+ self->cgv2_fd = mount_cg2_fd();
+ ASSERT_GE(self->cgv2_fd, 0);
+
+ ASSERT_EQ(write_file_at(self->cgv2_fd, "cgroup.subtree_control",
+ VE_CONTROLLERS), 0);
+
+ self->ctid = make_ve(self->cgv2_fd, CTID_MIN);
+ ASSERT_GE(self->ctid, 0);
+
+ ASSERT_EQ(prepare_namespaces(&self->ns_ctx, CLONE_NEWVE,
+ self->cgv2_fd, self->ctid), 0);
+
+
+ ASSERT_EQ(sched_getaffinity(getpid(), sizeof(cpu_set_t), &self->orig_cpuset), 0);
+ if (CPU_COUNT(&self->orig_cpuset) < 2)
+ SKIP(return, "Not enough CPUs available");
+
+ self->orig_cpucount = CPU_COUNT(&self->orig_cpuset);
+};
+
+FIXTURE_TEARDOWN(ve_getaff_test)
+{
+ close_namespace_fds(&self->ns_ctx);
+ destroy_ve(self->cgv2_fd, self->ctid);
+ close(self->cgv2_fd);
+}
+
+/* Test correct processing of cpuset.cpus updates */
+TEST_F(ve_getaff_test, update_cg_cpuset)
+{
+ char path[PATH_MAX];
+ int cpu_leave;
+ cpu_set_t in_ve;
+
+ snprintf(path, sizeof(path), "%d/cpuset.cpus", self->ctid);
+ if (faccessat(self->cgv2_fd, path, F_OK, 0))
+ SKIP(return, "CT cgroup doesn't have cpuset.cpus entry");
+
+ ASSERT_EQ(getaffinity_ve(self, &in_ve), 0);
+ ASSERT_TRUE(check_cpumask_is_prefix(&in_ve, self->orig_cpucount));
+
+ /* Find two CPUs and leave the second via cgroup interface */
+ cpu_leave = get_nth_cpu(&self->orig_cpuset, 2);
+ ASSERT_GE(cpu_leave, 0);
+ ASSERT_EQ(write_u64_at(self->cgv2_fd, path, cpu_leave), 0);
+
+ /* Verify sched_getaffinity sees 1 CPU, that is the first one */
+ ASSERT_EQ(getaffinity_ve(self, &in_ve), 0);
+ ASSERT_TRUE(check_cpumask_is_prefix(&in_ve, 1));
+}
+
+/* Test correct processing of cpu.nr_cpus updates */
+TEST_F(ve_getaff_test, nr_proc_bound)
+{
+ char path[PATH_MAX];
+ cpu_set_t in_ve;
+
+ snprintf(path, sizeof(path), "%d/cpu.nr_cpus", self->ctid);
+ if (faccessat(self->cgv2_fd, path, F_OK, 0))
+ SKIP(return, "CT cgroup doesn't have cpu.nr_cpus entry");
+
+ /* We expect here CPU_COUNT >= 2 */
+ ASSERT_EQ(getaffinity_ve(self, &in_ve), 0);
+ ASSERT_TRUE(check_cpumask_is_prefix(&in_ve, self->orig_cpucount));
+
+ /* Leave one vCPU */
+ ASSERT_EQ(write_u64_at(self->cgv2_fd, path, 1), 0);
+
+ /* Verify sched_getaffinity sees only one vCPU */
+ ASSERT_EQ(getaffinity_ve(self, &in_ve), 0);
+ ASSERT_TRUE(check_cpumask_is_prefix(&in_ve, 1));
+}
+
+/* Test correct interaction of cpu.nr_cpus and cpuset.cpus */
+TEST_F(ve_getaff_test, limits_interaction)
+{
+ char path_nr[PATH_MAX], path_set[PATH_MAX], tmp[128];
+ int c1, c3;
+ cpu_set_t in_ve;
+
+ snprintf(path_nr, sizeof(path_nr), "%d/cpu.nr_cpus", self->ctid);
+ if (faccessat(self->cgv2_fd, path_nr, F_OK, 0))
+ SKIP(return, "CT cgroup doesn't have cpu.nr_cpus entry");
+
+ snprintf(path_set, sizeof(path_set), "%d/cpuset.cpus", self->ctid);
+ if (faccessat(self->cgv2_fd, path_set, F_OK, 0))
+ SKIP(return, "CT cgroup doesn't have cpuset.cpus entry");
+
+ if (self->orig_cpucount < 3)
+ SKIP(return, "This test requires at least 3 CPUs");
+
+ /* We expect here CPU_COUNT >= 3 */
+ ASSERT_EQ(getaffinity_ve(self, &in_ve), 0);
+ ASSERT_TRUE(check_cpumask_is_prefix(&in_ve, self->orig_cpucount));
+
+ /* Leave two CPUs in cpuset */
+ c1 = get_nth_cpu(&self->orig_cpuset, 1);
+ c3 = get_nth_cpu(&self->orig_cpuset, 3);
+ ASSERT_TRUE(c1 >= 0 && c3 >= 0);
+
+ snprintf(tmp, sizeof(tmp), "%d,%d", c1, c3);
+ ASSERT_EQ(write_file_at(self->cgv2_fd, path_set, tmp), 0);
+
+ /* Verify sched_getaffinity sees two vCPU */
+ ASSERT_EQ(getaffinity_ve(self, &in_ve), 0);
+ ASSERT_TRUE(check_cpumask_is_prefix(&in_ve, 2));
+
+ /* Set vCPU limit to 2 and check that we still have two vCPUs */
+ ASSERT_EQ(write_u64_at(self->cgv2_fd, path_nr, 2), 0);
+ ASSERT_EQ(getaffinity_ve(self, &in_ve), 0);
+ ASSERT_TRUE(check_cpumask_is_prefix(&in_ve, 2));
+
+ /* Set vCPU limit to 1 and check that we have one vCPU only */
+ ASSERT_EQ(write_u64_at(self->cgv2_fd, path_nr, 1), 0);
+ ASSERT_EQ(getaffinity_ve(self, &in_ve), 0);
+ ASSERT_TRUE(check_cpumask_is_prefix(&in_ve, 1));
+
+}
+
+TEST_HARNESS_MAIN
--
2.52.0
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