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 #define exit_to_l0(_port, _arg) do_exit_to_l0(_port, (unsigned long) (_arg))
  66 static void do_exit_to_l0(uint16_t port, unsigned long arg)
  67 {
  68         __asm__ __volatile__("in %[port], %%al"
  69                 :
  70                 : [port]"d"(port), "D"(arg)
  71                 : "rax");
  72 }
  73
  74
  75 #define GUEST_ASSERT(_condition) do {                                        \
  76         if (!(_condition))                                                   \
  77                 exit_to_l0(PORT_ABORT, "Failed guest assert: " #_condition); \
  78 } while (0)
  79
  80 static void check_ia32_tsc_adjust(int64_t max)
  81 {
  82         int64_t adjust;
  83
  84         adjust = rdmsr(MSR_IA32_TSC_ADJUST);
  85         exit_to_l0(PORT_REPORT, adjust);
  86         GUEST_ASSERT(adjust <= max);
  87 }
  88
  89 static void l2_guest_code(void)
  90 {
  91         uint64_t l1_tsc = rdtsc() - TSC_OFFSET_VALUE;
  92
  93         wrmsr(MSR_IA32_TSC, l1_tsc - TSC_ADJUST_VALUE);
  94         check_ia32_tsc_adjust(-2 * TSC_ADJUST_VALUE);
  95
  96         /* Exit to L1 */
  97         __asm__ __volatile__("vmcall");
  98 }
  99
 100 static void l1_guest_code(struct vmx_pages *vmx_pages)
 101 {
 102 #define L2_GUEST_STACK_SIZE 64
 103         unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE];
 104         uint32_t control;
 105         uintptr_t save_cr3;
 106
 107         GUEST_ASSERT(rdtsc() < TSC_ADJUST_VALUE);
 108         wrmsr(MSR_IA32_TSC, rdtsc() - TSC_ADJUST_VALUE);
 109         check_ia32_tsc_adjust(-1 * TSC_ADJUST_VALUE);
 110
 111         GUEST_ASSERT(prepare_for_vmx_operation(vmx_pages));
 112
 113         /* Prepare the VMCS for L2 execution. */
 114         prepare_vmcs(vmx_pages, l2_guest_code,
 115                      &l2_guest_stack[L2_GUEST_STACK_SIZE]);
 116         control = vmreadz(CPU_BASED_VM_EXEC_CONTROL);
 117         control |= CPU_BASED_USE_MSR_BITMAPS | CPU_BASED_USE_TSC_OFFSETING;
 118         vmwrite(CPU_BASED_VM_EXEC_CONTROL, control);
 119         vmwrite(TSC_OFFSET, TSC_OFFSET_VALUE);
 120
 121         /* Jump into L2.  First, test failure to load guest CR3.  */
 122         save_cr3 = vmreadz(GUEST_CR3);
 123         vmwrite(GUEST_CR3, -1ull);
 124         GUEST_ASSERT(!vmlaunch());
 125         GUEST_ASSERT(vmreadz(VM_EXIT_REASON) ==
 126                      (EXIT_REASON_FAILED_VMENTRY | EXIT_REASON_INVALID_STATE));
 127         check_ia32_tsc_adjust(-1 * TSC_ADJUST_VALUE);
 128         vmwrite(GUEST_CR3, save_cr3);
 129
 130         GUEST_ASSERT(!vmlaunch());
 131         GUEST_ASSERT(vmreadz(VM_EXIT_REASON) == EXIT_REASON_VMCALL);
 132
 133         check_ia32_tsc_adjust(-2 * TSC_ADJUST_VALUE);
 134
 135         exit_to_l0(PORT_DONE, 0);
 136 }
 137
 138 void report(int64_t val)
 139 {
 140         printf("IA32_TSC_ADJUST is %ld (%lld * TSC_ADJUST_VALUE + %lld).\n",
 141                val, val / TSC_ADJUST_VALUE, val % TSC_ADJUST_VALUE);
 142 }
 143
 144 int main(int argc, char *argv[])
 145 {
 146         struct vmx_pages *vmx_pages;
 147         vm_vaddr_t vmx_pages_gva;
 148         struct kvm_cpuid_entry2 *entry = kvm_get_supported_cpuid_entry(1);
 149
 150         if (!(entry->ecx & CPUID_VMX)) {
 151                 fprintf(stderr, "nested VMX not enabled, skipping test\n");
 152                 exit(KSFT_SKIP);
 153         }
 154
 155         vm = vm_create_default(VCPU_ID, (void *) l1_guest_code);
 156         vcpu_set_cpuid(vm, VCPU_ID, kvm_get_supported_cpuid());
 157
 158         /* Allocate VMX pages and shared descriptors (vmx_pages). */
 159         vmx_pages = vcpu_alloc_vmx(vm, &vmx_pages_gva);
 160         vcpu_args_set(vm, VCPU_ID, 1, vmx_pages_gva);
 161
 162         for (;;) {
 163                 volatile struct kvm_run *run = vcpu_state(vm, VCPU_ID);
 164                 struct kvm_regs regs;
 165
 166                 vcpu_run(vm, VCPU_ID);
 167                 vcpu_regs_get(vm, VCPU_ID, &regs);
 168                 TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
 169                             "Got exit_reason other than KVM_EXIT_IO: %u (%s), rip=%lx\n",
 170                             run->exit_reason,
 171                             exit_reason_str(run->exit_reason), regs.rip);
 172
 173                 switch (run->io.port) {
 174                 case PORT_ABORT:
 175                         TEST_ASSERT(false, "%s", (const char *) regs.rdi);
 176                         /* NOT REACHED */
 177                 case PORT_REPORT:
 178                         report(regs.rdi);
 179                         break;
 180                 case PORT_DONE:
 181                         goto done;
 182                 default:
 183                         TEST_ASSERT(false, "Unknown port 0x%x.", run->io.port);
 184                 }
 185         }
 186
 187         kvm_vm_free(vm);
 188 done:
 189         return 0;
 190 }