tools/testing/selftests/kvm/vmx_tsc_adjust_test.c

   1 /*
   2  * gtests/tests/vmx_tsc_adjust_test.c
   3  *
   4  * Copyright (C) 2018, Google LLC.
   5  *
   6  * This work is licensed under the terms of the GNU GPL, version 2.
   7  *
   8  *
   9  * IA32_TSC_ADJUST test
  10  *
  11  * According to the SDM, "if an execution of WRMSR to the
  12  * IA32_TIME_STAMP_COUNTER MSR adds (or subtracts) value X from the TSC,
  13  * the logical processor also adds (or subtracts) value X from the
  14  * IA32_TSC_ADJUST MSR.
  15  *
  16  * Note that when L1 doesn't intercept writes to IA32_TSC, a
  17  * WRMSR(IA32_TSC) from L2 sets L1's TSC value, not L2's perceived TSC
  18  * value.
  19  *
  20  * This test verifies that this unusual case is handled correctly.
  21  */
  22
  23 #include "test_util.h"
  24 #include "kvm_util.h"
  25 #include "x86.h"
  26 #include "vmx.h"
  27
  28 #include <string.h>
  29 #include <sys/ioctl.h>
  30
  31 #include "../kselftest.h"
  32
  33 #ifndef MSR_IA32_TSC_ADJUST
  34 #define MSR_IA32_TSC_ADJUST 0x3b
  35 #endif
  36
  37 #define PAGE_SIZE       4096
  38 #define VCPU_ID         5
  39
  40 #define TSC_ADJUST_VALUE (1ll << 32)
  41 #define TSC_OFFSET_VALUE -(1ll << 48)
  42
  43 enum {
  44         PORT_ABORT = 0x1000,
  45         PORT_REPORT,
  46         PORT_DONE,
  47 };
  48
  49 enum {
  50         VMXON_PAGE = 0,
  51         VMCS_PAGE,
  52         MSR_BITMAP_PAGE,
  53
  54         NUM_VMX_PAGES,
  55 };
  56
  57 struct kvm_single_msr {
  58         struct kvm_msrs header;
  59         struct kvm_msr_entry entry;
  60 } __attribute__((packed));
  61
  62 /* The virtual machine object. */
  63 static struct kvm_vm *vm;
  64
  65 static void check_ia32_tsc_adjust(int64_t max)
  66 {
  67         int64_t adjust;
  68
  69         adjust = rdmsr(MSR_IA32_TSC_ADJUST);
  70         GUEST_SYNC(adjust);
  71         GUEST_ASSERT(adjust <= max);
  72 }
  73
  74 static void l2_guest_code(void)
  75 {
  76         uint64_t l1_tsc = rdtsc() - TSC_OFFSET_VALUE;
  77
  78         wrmsr(MSR_IA32_TSC, l1_tsc - TSC_ADJUST_VALUE);
  79         check_ia32_tsc_adjust(-2 * TSC_ADJUST_VALUE);
  80
  81         /* Exit to L1 */
  82         __asm__ __volatile__("vmcall");
  83 }
  84
  85 static void l1_guest_code(struct vmx_pages *vmx_pages)
  86 {
  87 #define L2_GUEST_STACK_SIZE 64
  88         unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE];
  89         uint32_t control;
  90         uintptr_t save_cr3;
  91
  92         GUEST_ASSERT(rdtsc() < TSC_ADJUST_VALUE);
  93         wrmsr(MSR_IA32_TSC, rdtsc() - TSC_ADJUST_VALUE);
  94         check_ia32_tsc_adjust(-1 * TSC_ADJUST_VALUE);
  95
  96         GUEST_ASSERT(prepare_for_vmx_operation(vmx_pages));
  97
  98         /* Prepare the VMCS for L2 execution. */
  99         prepare_vmcs(vmx_pages, l2_guest_code,
 100                      &l2_guest_stack[L2_GUEST_STACK_SIZE]);
 101         control = vmreadz(CPU_BASED_VM_EXEC_CONTROL);
 102         control |= CPU_BASED_USE_MSR_BITMAPS | CPU_BASED_USE_TSC_OFFSETING;
 103         vmwrite(CPU_BASED_VM_EXEC_CONTROL, control);
 104         vmwrite(TSC_OFFSET, TSC_OFFSET_VALUE);
 105
 106         /* Jump into L2.  First, test failure to load guest CR3.  */
 107         save_cr3 = vmreadz(GUEST_CR3);
 108         vmwrite(GUEST_CR3, -1ull);
 109         GUEST_ASSERT(!vmlaunch());
 110         GUEST_ASSERT(vmreadz(VM_EXIT_REASON) ==
 111                      (EXIT_REASON_FAILED_VMENTRY | EXIT_REASON_INVALID_STATE));
 112         check_ia32_tsc_adjust(-1 * TSC_ADJUST_VALUE);
 113         vmwrite(GUEST_CR3, save_cr3);
 114
 115         GUEST_ASSERT(!vmlaunch());
 116         GUEST_ASSERT(vmreadz(VM_EXIT_REASON) == EXIT_REASON_VMCALL);
 117
 118         check_ia32_tsc_adjust(-2 * TSC_ADJUST_VALUE);
 119
 120         GUEST_DONE();
 121 }
 122
 123 void report(int64_t val)
 124 {
 125         printf("IA32_TSC_ADJUST is %ld (%lld * TSC_ADJUST_VALUE + %lld).\n",
 126                val, val / TSC_ADJUST_VALUE, val % TSC_ADJUST_VALUE);
 127 }
 128
 129 int main(int argc, char *argv[])
 130 {
 131         struct vmx_pages *vmx_pages;
 132         vm_vaddr_t vmx_pages_gva;
 133         struct kvm_cpuid_entry2 *entry = kvm_get_supported_cpuid_entry(1);
 134
 135         if (!(entry->ecx & CPUID_VMX)) {
 136                 fprintf(stderr, "nested VMX not enabled, skipping test\n");
 137                 exit(KSFT_SKIP);
 138         }
 139
 140         vm = vm_create_default(VCPU_ID, 0, (void *) l1_guest_code);
 141         vcpu_set_cpuid(vm, VCPU_ID, kvm_get_supported_cpuid());
 142
 143         /* Allocate VMX pages and shared descriptors (vmx_pages). */
 144         vmx_pages = vcpu_alloc_vmx(vm, &vmx_pages_gva);
 145         vcpu_args_set(vm, VCPU_ID, 1, vmx_pages_gva);
 146
 147         for (;;) {
 148                 volatile struct kvm_run *run = vcpu_state(vm, VCPU_ID);
 149                 struct guest_args args;
 150
 151                 vcpu_run(vm, VCPU_ID);
 152                 guest_args_read(vm, VCPU_ID, &args);
 153                 TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
 154                             "Got exit_reason other than KVM_EXIT_IO: %u (%s)\n",
 155                             run->exit_reason,
 156                             exit_reason_str(run->exit_reason));
 157
 158                 switch (args.port) {
 159                 case GUEST_PORT_ABORT:
 160                         TEST_ASSERT(false, "%s", (const char *) args.arg0);
 161                         /* NOT REACHED */
 162                 case GUEST_PORT_SYNC:
 163                         report(args.arg1);
 164                         break;
 165                 case GUEST_PORT_DONE:
 166                         goto done;
 167                 default:
 168                         TEST_ASSERT(false, "Unknown port 0x%x.", args.port);
 169                 }
 170         }
 171
 172         kvm_vm_free(vm);
 173 done:
 174         return 0;
 175 }