tools/testing/selftests/kvm/x86_64/tsc_scaling_sync.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright © 2021 Amazon.com, Inc. or its affiliates.
   4  */
   5
   6 #include "test_util.h"
   7 #include "kvm_util.h"
   8 #include "processor.h"
   9
  10 #include <stdint.h>
  11 #include <time.h>
  12 #include <sched.h>
  13 #include <signal.h>
  14 #include <pthread.h>
  15
  16 #define NR_TEST_VCPUS 20
  17
  18 static struct kvm_vm *vm;
  19 pthread_spinlock_t create_lock;
  20
  21 #define TEST_TSC_KHZ    2345678UL
  22 #define TEST_TSC_OFFSET 200000000
  23
  24 uint64_t tsc_sync;
  25 static void guest_code(void)
  26 {
  27         uint64_t start_tsc, local_tsc, tmp;
  28
  29         start_tsc = rdtsc();
  30         do {
  31                 tmp = READ_ONCE(tsc_sync);
  32                 local_tsc = rdtsc();
  33                 WRITE_ONCE(tsc_sync, local_tsc);
  34                 if (unlikely(local_tsc < tmp))
  35                         GUEST_SYNC_ARGS(0, local_tsc, tmp, 0, 0);
  36
  37         } while (local_tsc - start_tsc < 5000 * TEST_TSC_KHZ);
  38
  39         GUEST_DONE();
  40 }
  41
  42
  43 static void *run_vcpu(void *_cpu_nr)
  44 {
  45         unsigned long vcpu_id = (unsigned long)_cpu_nr;
  46         unsigned long failures = 0;
  47         static bool first_cpu_done;
  48         struct kvm_vcpu *vcpu;
  49
  50         /* The kernel is fine, but vm_vcpu_add() needs locking */
  51         pthread_spin_lock(&create_lock);
  52
  53         vcpu = vm_vcpu_add(vm, vcpu_id, guest_code);
  54
  55         if (!first_cpu_done) {
  56                 first_cpu_done = true;
  57                 vcpu_set_msr(vcpu, MSR_IA32_TSC, TEST_TSC_OFFSET);
  58         }
  59
  60         pthread_spin_unlock(&create_lock);
  61
  62         for (;;) {
  63                 struct ucall uc;
  64
  65                 vcpu_run(vcpu);
  66                 TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO);
  67
  68                 switch (get_ucall(vcpu, &uc)) {
  69                 case UCALL_DONE:
  70                         goto out;
  71
  72                 case UCALL_SYNC:
  73                         printf("Guest %d sync %lx %lx %ld\n", vcpu->id,
  74                                uc.args[2], uc.args[3], uc.args[2] - uc.args[3]);
  75                         failures++;
  76                         break;
  77
  78                 default:
  79                         TEST_FAIL("Unknown ucall %lu", uc.cmd);
  80                 }
  81         }
  82  out:
  83         return (void *)failures;
  84 }
  85
  86 int main(int argc, char *argv[])
  87 {
  88         TEST_REQUIRE(kvm_has_cap(KVM_CAP_VM_TSC_CONTROL));
  89
  90         vm = vm_create(NR_TEST_VCPUS);
  91         vm_ioctl(vm, KVM_SET_TSC_KHZ, (void *) TEST_TSC_KHZ);
  92
  93         pthread_spin_init(&create_lock, PTHREAD_PROCESS_PRIVATE);
  94         pthread_t cpu_threads[NR_TEST_VCPUS];
  95         unsigned long cpu;
  96         for (cpu = 0; cpu < NR_TEST_VCPUS; cpu++)
  97                 pthread_create(&cpu_threads[cpu], NULL, run_vcpu, (void *)cpu);
  98
  99         unsigned long failures = 0;
 100         for (cpu = 0; cpu < NR_TEST_VCPUS; cpu++) {
 101                 void *this_cpu_failures;
 102                 pthread_join(cpu_threads[cpu], &this_cpu_failures);
 103                 failures += (unsigned long)this_cpu_failures;
 104         }
 105
 106         TEST_ASSERT(!failures, "TSC sync failed");
 107         pthread_spin_destroy(&create_lock);
 108         kvm_vm_free(vm);
 109         return 0;
 110 }