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KVM: selftests: Expand set of APIs for pinning tasks to a single CPU

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Expand kvm_pin_this_task_to_pcpu() into a set of APIs to allow pinning a
task (or self) to a CPU (any or specific).  This will allow deduplicating
code throughout a variety of selftests.

Opportunistically use "self" instead of "this_task" as it is both more
concise and less ambiguous.

Link: https://lore.kernel.org/r/20250626001225.744268-4-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Sean Christopherson 2025-06-25 17:12:23 -07:00
parent a7cec20845
commit e83ee6f76c
3 changed files with 38 additions and 10 deletions
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31
tools/testing/selftests/kvm/include/kvm_util.h
View File

@ -20,6 +20,8 @@
#include <sys/ioctl.h>
#include <pthread.h>
#include "kvm_util_arch.h"
#include "kvm_util_types.h"
#include "sparsebit.h"
@ -1013,7 +1015,34 @@ struct kvm_vcpu *vm_recreate_with_one_vcpu(struct kvm_vm *vm);
void kvm_set_files_rlimit(uint32_t nr_vcpus);
void kvm_pin_this_task_to_pcpu(uint32_t pcpu);
int __pin_task_to_cpu(pthread_t task, int cpu);
static inline void pin_task_to_cpu(pthread_t task, int cpu)
{
int r;
r = __pin_task_to_cpu(task, cpu);
TEST_ASSERT(!r, "Failed to set thread affinity to pCPU '%u'", cpu);
}
static inline int pin_task_to_any_cpu(pthread_t task)
{
int cpu = sched_getcpu();
pin_task_to_cpu(task, cpu);
return cpu;
}
static inline void pin_self_to_cpu(int cpu)
{
pin_task_to_cpu(pthread_self(), cpu);
}
static inline int pin_self_to_any_cpu(void)
{
return pin_task_to_any_cpu(pthread_self());
}
void kvm_print_vcpu_pinning_help(void);
void kvm_parse_vcpu_pinning(const char *pcpus_string, uint32_t vcpu_to_pcpu[],
int nr_vcpus);

15
tools/testing/selftests/kvm/lib/kvm_util.c
View File

@ -605,15 +605,14 @@ struct kvm_vcpu *vm_recreate_with_one_vcpu(struct kvm_vm *vm)
return vm_vcpu_recreate(vm, 0);
}
void kvm_pin_this_task_to_pcpu(uint32_t pcpu)
int __pin_task_to_cpu(pthread_t task, int cpu)
{
cpu_set_t mask;
int r;
cpu_set_t cpuset;
CPU_ZERO(&mask);
CPU_SET(pcpu, &mask);
r = sched_setaffinity(0, sizeof(mask), &mask);
TEST_ASSERT(!r, "sched_setaffinity() failed for pCPU '%u'.", pcpu);
CPU_ZERO(&cpuset);
CPU_SET(cpu, &cpuset);
return pthread_setaffinity_np(task, sizeof(cpuset), &cpuset);
}
static uint32_t parse_pcpu(const char *cpu_str, const cpu_set_t *allowed_mask)
@ -667,7 +666,7 @@ void kvm_parse_vcpu_pinning(const char *pcpus_string, uint32_t vcpu_to_pcpu[],
/* 2. Check if the main worker needs to be pinned. */
if (cpu) {
kvm_pin_this_task_to_pcpu(parse_pcpu(cpu, &allowed_mask));
pin_self_to_cpu(parse_pcpu(cpu, &allowed_mask));
cpu = strtok(NULL, delim);
}

2
tools/testing/selftests/kvm/lib/memstress.c
View File

@ -265,7 +265,7 @@ static void *vcpu_thread_main(void *data)
int vcpu_idx = vcpu->vcpu_idx;
if (memstress_args.pin_vcpus)
kvm_pin_this_task_to_pcpu(memstress_args.vcpu_to_pcpu[vcpu_idx]);
pin_self_to_cpu(memstress_args.vcpu_to_pcpu[vcpu_idx]);
WRITE_ONCE(vcpu->running, true);