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KVM: selftests: Add a utility to pin a task to a random CPU, given a CPU set

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Add a helper function, pin_task_to_random_cpu(), to pin a task to a random
CPU from a given cpu_set_t.

This helper will be used eventfd IRQ test to migrate vCPUs to random pCPUs,
to stress host-side interrupt routing and delivery.

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Josh Hilke <jrhilke@google.com>
[sean: massage changelog]
Link: https://patch.msgid.link/20260626213534.3866178-18-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Josh Hilke 2026-06-26 14:35:30 -07:00 committed by Sean Christopherson
parent 76703ca0cb
commit 26fd1fb473
2 changed files with 23 additions and 0 deletions
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2
tools/testing/selftests/kvm/include/kvm_util.h
View File

@ -1094,6 +1094,8 @@ 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();

21
tools/testing/selftests/kvm/lib/kvm_util.c
View File

@ -668,6 +668,27 @@ 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, u32 vcpu_to_pcpu[],
int nr_vcpus)
{