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

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * svm_vmcall_test
   4  *
   5  * Copyright © 2021 Amazon.com, Inc. or its affiliates.
   6  *
   7  * Xen shared_info / pvclock testing
   8  */
   9
  10 #include "test_util.h"
  11 #include "kvm_util.h"
  12 #include "processor.h"
  13
  14 #include <stdint.h>
  15 #include <time.h>
  16 #include <sched.h>
  17 #include <signal.h>
  18 #include <pthread.h>
  19
  20 #define NR_TEST_VCPUS 20
  21
  22 static struct kvm_vm *vm;
  23 pthread_spinlock_t create_lock;
  24
  25 #define TEST_TSC_KHZ    2345678UL
  26 #define TEST_TSC_OFFSET 200000000
  27
  28 uint64_t tsc_sync;
  29 static void guest_code(void)
  30 {
  31         uint64_t start_tsc, local_tsc, tmp;
  32
  33         start_tsc = rdtsc();
  34         do {
  35                 tmp = READ_ONCE(tsc_sync);
  36                 local_tsc = rdtsc();
  37                 WRITE_ONCE(tsc_sync, local_tsc);
  38                 if (unlikely(local_tsc < tmp))
  39                         GUEST_SYNC_ARGS(0, local_tsc, tmp, 0, 0);
  40
  41         } while (local_tsc - start_tsc < 5000 * TEST_TSC_KHZ);
  42
  43         GUEST_DONE();
  44 }
  45
  46
  47 static void *run_vcpu(void *_cpu_nr)
  48 {
  49         unsigned long vcpu_id = (unsigned long)_cpu_nr;
  50         unsigned long failures = 0;
  51         static bool first_cpu_done;
  52         struct kvm_vcpu *vcpu;
  53
  54         /* The kernel is fine, but vm_vcpu_add() needs locking */
  55         pthread_spin_lock(&create_lock);
  56
  57         vcpu = vm_vcpu_add(vm, vcpu_id, guest_code);
  58
  59         if (!first_cpu_done) {
  60                 first_cpu_done = true;
  61                 vcpu_set_msr(vcpu, MSR_IA32_TSC, TEST_TSC_OFFSET);
  62         }
  63
  64         pthread_spin_unlock(&create_lock);
  65
  66         for (;;) {
  67                 struct ucall uc;
  68
  69                 vcpu_run(vcpu);
  70                 TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO);
  71
  72                 switch (get_ucall(vcpu, &uc)) {
  73                 case UCALL_DONE:
  74                         goto out;
  75
  76                 case UCALL_SYNC:
  77                         printf("Guest %d sync %lx %lx %ld\n", vcpu->id,
  78                                uc.args[2], uc.args[3], uc.args[2] - uc.args[3]);
  79                         failures++;
  80                         break;
  81
  82                 default:
  83                         TEST_FAIL("Unknown ucall %lu", uc.cmd);
  84                 }
  85         }
  86  out:
  87         return (void *)failures;
  88 }
  89
  90 int main(int argc, char *argv[])
  91 {
  92         TEST_REQUIRE(kvm_has_cap(KVM_CAP_VM_TSC_CONTROL));
  93
  94         vm = vm_create(NR_TEST_VCPUS);
  95         vm_ioctl(vm, KVM_SET_TSC_KHZ, (void *) TEST_TSC_KHZ);
  96
  97         pthread_spin_init(&create_lock, PTHREAD_PROCESS_PRIVATE);
  98         pthread_t cpu_threads[NR_TEST_VCPUS];
  99         unsigned long cpu;
 100         for (cpu = 0; cpu < NR_TEST_VCPUS; cpu++)
 101                 pthread_create(&cpu_threads[cpu], NULL, run_vcpu, (void *)cpu);
 102
 103         unsigned long failures = 0;
 104         for (cpu = 0; cpu < NR_TEST_VCPUS; cpu++) {
 105                 void *this_cpu_failures;
 106                 pthread_join(cpu_threads[cpu], &this_cpu_failures);
 107                 failures += (unsigned long)this_cpu_failures;
 108         }
 109
 110         TEST_ASSERT(!failures, "TSC sync failed");
 111         pthread_spin_destroy(&create_lock);
 112         kvm_vm_free(vm);
 113         return 0;
 114 }