Add a helper function pin_task_to_random_cpu() to randomly select a CPU from a given cpu_set_t and pin the specified task to it. This helper will be used in a future change in the KVM IRQ test to migrate vCPU threads. Suggested-by: Sean Christopherson Signed-off-by: Josh Hilke --- .../testing/selftests/kvm/include/kvm_util.h | 2 ++ tools/testing/selftests/kvm/lib/kvm_util.c | 21 +++++++++++++++++++ 2 files changed, 23 insertions(+) diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h index 499e695f1fc4..f725ab0ed4f9 100644 --- a/tools/testing/selftests/kvm/include/kvm_util.h +++ b/tools/testing/selftests/kvm/include/kvm_util.h @@ -1096,6 +1096,8 @@ static inline void pin_task_to_cpu(pthread_t task, int cpu) TEST_ASSERT(!r, "Failed to set thread affinity to pCPU '%u'", cpu); } +void pin_task_to_random_cpu(pthread_t task, cpu_set_t *possible_cpus); + static inline int pin_task_to_any_cpu(pthread_t task) { int cpu = sched_getcpu(); diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c index ebd04cf1847b..29cd649a54d5 100644 --- a/tools/testing/selftests/kvm/lib/kvm_util.c +++ b/tools/testing/selftests/kvm/lib/kvm_util.c @@ -662,6 +662,27 @@ void kvm_print_vcpu_pinning_help(void) " (default: no pinning)\n", name, name); } +void pin_task_to_random_cpu(pthread_t task, cpu_set_t *possible_cpus) +{ + int target_idx; + int nr_cpus; + int cpu; + + nr_cpus = CPU_COUNT(possible_cpus); + TEST_ASSERT(nr_cpus > 0, "No CPUs available in possible_cpus"); + + target_idx = kvm_random_u64(&kvm_rng) % nr_cpus; + + for (cpu = 0; cpu < CPU_SETSIZE; cpu++) { + if (CPU_ISSET(cpu, possible_cpus) && target_idx-- == 0) { + pin_task_to_cpu(task, cpu); + return; + } + } + + TEST_FAIL("Failed to find random CPU in possible_cpus"); +} + void kvm_parse_vcpu_pinning(const char *pcpus_string, uint32_t vcpu_to_pcpu[], int nr_vcpus) { -- 2.54.0.929.g9b7fa37559-goog