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 #ifndef MSR_IA32_TSC_ADJUST
  32 #define MSR_IA32_TSC_ADJUST 0x3b
  33 #endif
  34
  35 #define PAGE_SIZE       4096
  36 #define VCPU_ID         5
  37
  38 #define TSC_ADJUST_VALUE (1ll << 32)
  39 #define TSC_OFFSET_VALUE -(1ll << 48)
  40
  41 enum {
  42         PORT_ABORT = 0x1000,
  43         PORT_REPORT,
  44         PORT_DONE,
  45 };
  46
  47 struct vmx_page {
  48         vm_vaddr_t virt;
  49         vm_paddr_t phys;
  50 };
  51
  52 enum {
  53         VMXON_PAGE = 0,
  54         VMCS_PAGE,
  55         MSR_BITMAP_PAGE,
  56
  57         NUM_VMX_PAGES,
  58 };
  59
  60 struct kvm_single_msr {
  61         struct kvm_msrs header;
  62         struct kvm_msr_entry entry;
  63 } __attribute__((packed));
  64
  65 /* The virtual machine object. */
  66 static struct kvm_vm *vm;
  67
  68 /* Array of vmx_page descriptors that is shared with the guest. */
  69 struct vmx_page *vmx_pages;
  70
  71 #define exit_to_l0(_port, _arg) do_exit_to_l0(_port, (unsigned long) (_arg))
  72 static void do_exit_to_l0(uint16_t port, unsigned long arg)
  73 {
  74         __asm__ __volatile__("in %[port], %%al"
  75                 :
  76                 : [port]"d"(port), "D"(arg)
  77                 : "rax");
  78 }
  79
  80
  81 #define GUEST_ASSERT(_condition) do {                                        \
  82         if (!(_condition))                                                   \
  83                 exit_to_l0(PORT_ABORT, "Failed guest assert: " #_condition); \
  84 } while (0)
  85
  86 static void check_ia32_tsc_adjust(int64_t max)
  87 {
  88         int64_t adjust;
  89
  90         adjust = rdmsr(MSR_IA32_TSC_ADJUST);
  91         exit_to_l0(PORT_REPORT, adjust);
  92         GUEST_ASSERT(adjust <= max);
  93 }
  94
  95 static void l2_guest_code(void)
  96 {
  97         uint64_t l1_tsc = rdtsc() - TSC_OFFSET_VALUE;
  98
  99         wrmsr(MSR_IA32_TSC, l1_tsc - TSC_ADJUST_VALUE);
 100         check_ia32_tsc_adjust(-2 * TSC_ADJUST_VALUE);
 101
 102         /* Exit to L1 */
 103         __asm__ __volatile__("vmcall");
 104 }
 105
 106 static void l1_guest_code(struct vmx_page *vmx_pages)
 107 {
 108 #define L2_GUEST_STACK_SIZE 64
 109         unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE];
 110         uint32_t control;
 111         uintptr_t save_cr3;
 112
 113         GUEST_ASSERT(rdtsc() < TSC_ADJUST_VALUE);
 114         wrmsr(MSR_IA32_TSC, rdtsc() - TSC_ADJUST_VALUE);
 115         check_ia32_tsc_adjust(-1 * TSC_ADJUST_VALUE);
 116
 117         prepare_for_vmx_operation();
 118
 119         /* Enter VMX root operation. */
 120         *(uint32_t *)vmx_pages[VMXON_PAGE].virt = vmcs_revision();
 121         GUEST_ASSERT(!vmxon(vmx_pages[VMXON_PAGE].phys));
 122
 123         /* Load a VMCS. */
 124         *(uint32_t *)vmx_pages[VMCS_PAGE].virt = vmcs_revision();
 125         GUEST_ASSERT(!vmclear(vmx_pages[VMCS_PAGE].phys));
 126         GUEST_ASSERT(!vmptrld(vmx_pages[VMCS_PAGE].phys));
 127
 128         /* Prepare the VMCS for L2 execution. */
 129         prepare_vmcs(l2_guest_code, &l2_guest_stack[L2_GUEST_STACK_SIZE]);
 130         control = vmreadz(CPU_BASED_VM_EXEC_CONTROL);
 131         control |= CPU_BASED_USE_MSR_BITMAPS | CPU_BASED_USE_TSC_OFFSETING;
 132         vmwrite(CPU_BASED_VM_EXEC_CONTROL, control);
 133         vmwrite(MSR_BITMAP, vmx_pages[MSR_BITMAP_PAGE].phys);
 134         vmwrite(TSC_OFFSET, TSC_OFFSET_VALUE);
 135
 136         /* Jump into L2.  First, test failure to load guest CR3.  */
 137         save_cr3 = vmreadz(GUEST_CR3);
 138         vmwrite(GUEST_CR3, -1ull);
 139         GUEST_ASSERT(!vmlaunch());
 140         GUEST_ASSERT(vmreadz(VM_EXIT_REASON) ==
 141                      (EXIT_REASON_FAILED_VMENTRY | EXIT_REASON_INVALID_STATE));
 142         check_ia32_tsc_adjust(-1 * TSC_ADJUST_VALUE);
 143         vmwrite(GUEST_CR3, save_cr3);
 144
 145         GUEST_ASSERT(!vmlaunch());
 146         GUEST_ASSERT(vmreadz(VM_EXIT_REASON) == EXIT_REASON_VMCALL);
 147
 148         check_ia32_tsc_adjust(-2 * TSC_ADJUST_VALUE);
 149
 150         exit_to_l0(PORT_DONE, 0);
 151 }
 152
 153 static void allocate_vmx_page(struct vmx_page *page)
 154 {
 155         vm_vaddr_t virt;
 156
 157         virt = vm_vaddr_alloc(vm, PAGE_SIZE, 0, 0, 0);
 158         memset(addr_gva2hva(vm, virt), 0, PAGE_SIZE);
 159
 160         page->virt = virt;
 161         page->phys = addr_gva2gpa(vm, virt);
 162 }
 163
 164 static vm_vaddr_t allocate_vmx_pages(void)
 165 {
 166         vm_vaddr_t vmx_pages_vaddr;
 167         int i;
 168
 169         vmx_pages_vaddr = vm_vaddr_alloc(
 170                 vm, sizeof(struct vmx_page) * NUM_VMX_PAGES, 0, 0, 0);
 171
 172         vmx_pages = (void *) addr_gva2hva(vm, vmx_pages_vaddr);
 173
 174         for (i = 0; i < NUM_VMX_PAGES; i++)
 175                 allocate_vmx_page(&vmx_pages[i]);
 176
 177         return vmx_pages_vaddr;
 178 }
 179
 180 void report(int64_t val)
 181 {
 182         printf("IA32_TSC_ADJUST is %ld (%lld * TSC_ADJUST_VALUE + %lld).\n",
 183                val, val / TSC_ADJUST_VALUE, val % TSC_ADJUST_VALUE);
 184 }
 185
 186 int main(int argc, char *argv[])
 187 {
 188         vm_vaddr_t vmx_pages_vaddr;
 189         struct kvm_cpuid_entry2 *entry = kvm_get_supported_cpuid_entry(1);
 190
 191         if (!(entry->ecx & CPUID_VMX)) {
 192                 printf("nested VMX not enabled, skipping test");
 193                 return 0;
 194         }
 195
 196         vm = vm_create_default_vmx(VCPU_ID, (void *) l1_guest_code);
 197
 198         /* Allocate VMX pages and shared descriptors (vmx_pages). */
 199         vmx_pages_vaddr = allocate_vmx_pages();
 200         vcpu_args_set(vm, VCPU_ID, 1, vmx_pages_vaddr);
 201
 202         for (;;) {
 203                 volatile struct kvm_run *run = vcpu_state(vm, VCPU_ID);
 204                 struct kvm_regs regs;
 205
 206                 vcpu_run(vm, VCPU_ID);
 207                 TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
 208                             "Got exit_reason other than KVM_EXIT_IO: %u (%s),\n",
 209                             run->exit_reason,
 210                             exit_reason_str(run->exit_reason));
 211
 212                 vcpu_regs_get(vm, VCPU_ID, &regs);
 213
 214                 switch (run->io.port) {
 215                 case PORT_ABORT:
 216                         TEST_ASSERT(false, "%s", (const char *) regs.rdi);
 217                         /* NOT REACHED */
 218                 case PORT_REPORT:
 219                         report(regs.rdi);
 220                         break;
 221                 case PORT_DONE:
 222                         goto done;
 223                 default:
 224                         TEST_ASSERT(false, "Unknown port 0x%x.", run->io.port);
 225                 }
 226         }
 227
 228         kvm_vm_free(vm);
 229 done:
 230         return 0;
 231 }