tools/testing/selftests/kvm/x86/sync_regs_test.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Test for x86 KVM_CAP_SYNC_REGS
   4  *
   5  * Copyright (C) 2018, Google LLC.
   6  *
   7  * Verifies expected behavior of x86 KVM_CAP_SYNC_REGS functionality,
   8  * including requesting an invalid register set, updates to/from values
   9  * in kvm_run.s.regs when kvm_valid_regs and kvm_dirty_regs are toggled.
  10  */
  11 #include <fcntl.h>
  12 #include <stdio.h>
  13 #include <stdlib.h>
  14 #include <string.h>
  15 #include <sys/ioctl.h>
  16 #include <pthread.h>
  17
  18 #include "kvm_test_harness.h"
  19 #include "test_util.h"
  20 #include "kvm_util.h"
  21 #include "processor.h"
  22
  23 #define UCALL_PIO_PORT ((uint16_t)0x1000)
  24
  25 struct ucall uc_none = {
  26         .cmd = UCALL_NONE,
  27 };
  28
  29 /*
  30  * ucall is embedded here to protect against compiler reshuffling registers
  31  * before calling a function. In this test we only need to get KVM_EXIT_IO
  32  * vmexit and preserve RBX, no additional information is needed.
  33  */
  34 void guest_code(void)
  35 {
  36         asm volatile("1: in %[port], %%al\n"
  37                      "add $0x1, %%rbx\n"
  38                      "jmp 1b"
  39                      : : [port] "d" (UCALL_PIO_PORT), "D" (&uc_none)
  40                      : "rax", "rbx");
  41 }
  42
  43 KVM_ONE_VCPU_TEST_SUITE(sync_regs_test);
  44
  45 static void compare_regs(struct kvm_regs *left, struct kvm_regs *right)
  46 {
  47 #define REG_COMPARE(reg) \
  48         TEST_ASSERT(left->reg == right->reg, \
  49                     "Register " #reg \
  50                     " values did not match: 0x%llx, 0x%llx", \
  51                     left->reg, right->reg)
  52         REG_COMPARE(rax);
  53         REG_COMPARE(rbx);
  54         REG_COMPARE(rcx);
  55         REG_COMPARE(rdx);
  56         REG_COMPARE(rsi);
  57         REG_COMPARE(rdi);
  58         REG_COMPARE(rsp);
  59         REG_COMPARE(rbp);
  60         REG_COMPARE(r8);
  61         REG_COMPARE(r9);
  62         REG_COMPARE(r10);
  63         REG_COMPARE(r11);
  64         REG_COMPARE(r12);
  65         REG_COMPARE(r13);
  66         REG_COMPARE(r14);
  67         REG_COMPARE(r15);
  68         REG_COMPARE(rip);
  69         REG_COMPARE(rflags);
  70 #undef REG_COMPARE
  71 }
  72
  73 static void compare_sregs(struct kvm_sregs *left, struct kvm_sregs *right)
  74 {
  75 }
  76
  77 static void compare_vcpu_events(struct kvm_vcpu_events *left,
  78                                 struct kvm_vcpu_events *right)
  79 {
  80 }
  81
  82 #define TEST_SYNC_FIELDS   (KVM_SYNC_X86_REGS|KVM_SYNC_X86_SREGS|KVM_SYNC_X86_EVENTS)
  83 #define INVALID_SYNC_FIELD 0x80000000
  84
  85 /*
  86  * Set an exception as pending *and* injected while KVM is processing events.
  87  * KVM is supposed to ignore/drop pending exceptions if userspace is also
  88  * requesting that an exception be injected.
  89  */
  90 static void *race_events_inj_pen(void *arg)
  91 {
  92         struct kvm_run *run = (struct kvm_run *)arg;
  93         struct kvm_vcpu_events *events = &run->s.regs.events;
  94
  95         WRITE_ONCE(events->exception.nr, UD_VECTOR);
  96
  97         for (;;) {
  98                 WRITE_ONCE(run->kvm_dirty_regs, KVM_SYNC_X86_EVENTS);
  99                 WRITE_ONCE(events->flags, 0);
 100                 WRITE_ONCE(events->exception.injected, 1);
 101                 WRITE_ONCE(events->exception.pending, 1);
 102
 103                 pthread_testcancel();
 104         }
 105
 106         return NULL;
 107 }
 108
 109 /*
 110  * Set an invalid exception vector while KVM is processing events.  KVM is
 111  * supposed to reject any vector >= 32, as well as NMIs (vector 2).
 112  */
 113 static void *race_events_exc(void *arg)
 114 {
 115         struct kvm_run *run = (struct kvm_run *)arg;
 116         struct kvm_vcpu_events *events = &run->s.regs.events;
 117
 118         for (;;) {
 119                 WRITE_ONCE(run->kvm_dirty_regs, KVM_SYNC_X86_EVENTS);
 120                 WRITE_ONCE(events->flags, 0);
 121                 WRITE_ONCE(events->exception.nr, UD_VECTOR);
 122                 WRITE_ONCE(events->exception.pending, 1);
 123                 WRITE_ONCE(events->exception.nr, 255);
 124
 125                 pthread_testcancel();
 126         }
 127
 128         return NULL;
 129 }
 130
 131 /*
 132  * Toggle CR4.PAE while KVM is processing SREGS, EFER.LME=1 with CR4.PAE=0 is
 133  * illegal, and KVM's MMU heavily relies on vCPU state being valid.
 134  */
 135 static noinline void *race_sregs_cr4(void *arg)
 136 {
 137         struct kvm_run *run = (struct kvm_run *)arg;
 138         __u64 *cr4 = &run->s.regs.sregs.cr4;
 139         __u64 pae_enabled = *cr4;
 140         __u64 pae_disabled = *cr4 & ~X86_CR4_PAE;
 141
 142         for (;;) {
 143                 WRITE_ONCE(run->kvm_dirty_regs, KVM_SYNC_X86_SREGS);
 144                 WRITE_ONCE(*cr4, pae_enabled);
 145                 asm volatile(".rept 512\n\t"
 146                              "nop\n\t"
 147                              ".endr");
 148                 WRITE_ONCE(*cr4, pae_disabled);
 149
 150                 pthread_testcancel();
 151         }
 152
 153         return NULL;
 154 }
 155
 156 static void race_sync_regs(struct kvm_vcpu *vcpu, void *racer)
 157 {
 158         const time_t TIMEOUT = 2; /* seconds, roughly */
 159         struct kvm_x86_state *state;
 160         struct kvm_translation tr;
 161         struct kvm_run *run;
 162         pthread_t thread;
 163         time_t t;
 164
 165         run = vcpu->run;
 166
 167         run->kvm_valid_regs = KVM_SYNC_X86_SREGS;
 168         vcpu_run(vcpu);
 169         run->kvm_valid_regs = 0;
 170
 171         /* Save state *before* spawning the thread that mucks with vCPU state. */
 172         state = vcpu_save_state(vcpu);
 173
 174         /*
 175          * Selftests run 64-bit guests by default, both EFER.LME and CR4.PAE
 176          * should already be set in guest state.
 177          */
 178         TEST_ASSERT((run->s.regs.sregs.cr4 & X86_CR4_PAE) &&
 179                     (run->s.regs.sregs.efer & EFER_LME),
 180                     "vCPU should be in long mode, CR4.PAE=%d, EFER.LME=%d",
 181                     !!(run->s.regs.sregs.cr4 & X86_CR4_PAE),
 182                     !!(run->s.regs.sregs.efer & EFER_LME));
 183
 184         TEST_ASSERT_EQ(pthread_create(&thread, NULL, racer, (void *)run), 0);
 185
 186         for (t = time(NULL) + TIMEOUT; time(NULL) < t;) {
 187                 /*
 188                  * Reload known good state if the vCPU triple faults, e.g. due
 189                  * to the unhandled #GPs being injected.  VMX preserves state
 190                  * on shutdown, but SVM synthesizes an INIT as the VMCB state
 191                  * is architecturally undefined on triple fault.
 192                  */
 193                 if (!__vcpu_run(vcpu) && run->exit_reason == KVM_EXIT_SHUTDOWN)
 194                         vcpu_load_state(vcpu, state);
 195
 196                 if (racer == race_sregs_cr4) {
 197                         tr = (struct kvm_translation) { .linear_address = 0 };
 198                         __vcpu_ioctl(vcpu, KVM_TRANSLATE, &tr);
 199                 }
 200         }
 201
 202         TEST_ASSERT_EQ(pthread_cancel(thread), 0);
 203         TEST_ASSERT_EQ(pthread_join(thread, NULL), 0);
 204
 205         kvm_x86_state_cleanup(state);
 206 }
 207
 208 KVM_ONE_VCPU_TEST(sync_regs_test, read_invalid, guest_code)
 209 {
 210         struct kvm_run *run = vcpu->run;
 211         int rv;
 212
 213         /* Request reading invalid register set from VCPU. */
 214         run->kvm_valid_regs = INVALID_SYNC_FIELD;
 215         rv = _vcpu_run(vcpu);
 216         TEST_ASSERT(rv < 0 && errno == EINVAL,
 217                     "Invalid kvm_valid_regs did not cause expected KVM_RUN error: %d",
 218                     rv);
 219         run->kvm_valid_regs = 0;
 220
 221         run->kvm_valid_regs = INVALID_SYNC_FIELD | TEST_SYNC_FIELDS;
 222         rv = _vcpu_run(vcpu);
 223         TEST_ASSERT(rv < 0 && errno == EINVAL,
 224                     "Invalid kvm_valid_regs did not cause expected KVM_RUN error: %d",
 225                     rv);
 226         run->kvm_valid_regs = 0;
 227 }
 228
 229 KVM_ONE_VCPU_TEST(sync_regs_test, set_invalid, guest_code)
 230 {
 231         struct kvm_run *run = vcpu->run;
 232         int rv;
 233
 234         /* Request setting invalid register set into VCPU. */
 235         run->kvm_dirty_regs = INVALID_SYNC_FIELD;
 236         rv = _vcpu_run(vcpu);
 237         TEST_ASSERT(rv < 0 && errno == EINVAL,
 238                     "Invalid kvm_dirty_regs did not cause expected KVM_RUN error: %d",
 239                     rv);
 240         run->kvm_dirty_regs = 0;
 241
 242         run->kvm_dirty_regs = INVALID_SYNC_FIELD | TEST_SYNC_FIELDS;
 243         rv = _vcpu_run(vcpu);
 244         TEST_ASSERT(rv < 0 && errno == EINVAL,
 245                     "Invalid kvm_dirty_regs did not cause expected KVM_RUN error: %d",
 246                     rv);
 247         run->kvm_dirty_regs = 0;
 248 }
 249
 250 KVM_ONE_VCPU_TEST(sync_regs_test, req_and_verify_all_valid, guest_code)
 251 {
 252         struct kvm_run *run = vcpu->run;
 253         struct kvm_vcpu_events events;
 254         struct kvm_sregs sregs;
 255         struct kvm_regs regs;
 256
 257         /* Request and verify all valid register sets. */
 258         /* TODO: BUILD TIME CHECK: TEST_ASSERT(KVM_SYNC_X86_NUM_FIELDS != 3); */
 259         run->kvm_valid_regs = TEST_SYNC_FIELDS;
 260         vcpu_run(vcpu);
 261         TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO);
 262
 263         vcpu_regs_get(vcpu, &regs);
 264         compare_regs(&regs, &run->s.regs.regs);
 265
 266         vcpu_sregs_get(vcpu, &sregs);
 267         compare_sregs(&sregs, &run->s.regs.sregs);
 268
 269         vcpu_events_get(vcpu, &events);
 270         compare_vcpu_events(&events, &run->s.regs.events);
 271 }
 272
 273 KVM_ONE_VCPU_TEST(sync_regs_test, set_and_verify_various, guest_code)
 274 {
 275         struct kvm_run *run = vcpu->run;
 276         struct kvm_vcpu_events events;
 277         struct kvm_sregs sregs;
 278         struct kvm_regs regs;
 279
 280         /* Run once to get register set */
 281         run->kvm_valid_regs = TEST_SYNC_FIELDS;
 282         vcpu_run(vcpu);
 283         TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO);
 284
 285         /* Set and verify various register values. */
 286         run->s.regs.regs.rbx = 0xBAD1DEA;
 287         run->s.regs.sregs.apic_base = 1 << 11;
 288         /* TODO run->s.regs.events.XYZ = ABC; */
 289
 290         run->kvm_valid_regs = TEST_SYNC_FIELDS;
 291         run->kvm_dirty_regs = KVM_SYNC_X86_REGS | KVM_SYNC_X86_SREGS;
 292         vcpu_run(vcpu);
 293         TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO);
 294         TEST_ASSERT(run->s.regs.regs.rbx == 0xBAD1DEA + 1,
 295                     "rbx sync regs value incorrect 0x%llx.",
 296                     run->s.regs.regs.rbx);
 297         TEST_ASSERT(run->s.regs.sregs.apic_base == 1 << 11,
 298                     "apic_base sync regs value incorrect 0x%llx.",
 299                     run->s.regs.sregs.apic_base);
 300
 301         vcpu_regs_get(vcpu, &regs);
 302         compare_regs(&regs, &run->s.regs.regs);
 303
 304         vcpu_sregs_get(vcpu, &sregs);
 305         compare_sregs(&sregs, &run->s.regs.sregs);
 306
 307         vcpu_events_get(vcpu, &events);
 308         compare_vcpu_events(&events, &run->s.regs.events);
 309 }
 310
 311 KVM_ONE_VCPU_TEST(sync_regs_test, clear_kvm_dirty_regs_bits, guest_code)
 312 {
 313         struct kvm_run *run = vcpu->run;
 314
 315         /* Clear kvm_dirty_regs bits, verify new s.regs values are
 316          * overwritten with existing guest values.
 317          */
 318         run->kvm_valid_regs = TEST_SYNC_FIELDS;
 319         run->kvm_dirty_regs = 0;
 320         run->s.regs.regs.rbx = 0xDEADBEEF;
 321         vcpu_run(vcpu);
 322         TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO);
 323         TEST_ASSERT(run->s.regs.regs.rbx != 0xDEADBEEF,
 324                     "rbx sync regs value incorrect 0x%llx.",
 325                     run->s.regs.regs.rbx);
 326 }
 327
 328 KVM_ONE_VCPU_TEST(sync_regs_test, clear_kvm_valid_and_dirty_regs, guest_code)
 329 {
 330         struct kvm_run *run = vcpu->run;
 331         struct kvm_regs regs;
 332
 333         /* Run once to get register set */
 334         run->kvm_valid_regs = TEST_SYNC_FIELDS;
 335         vcpu_run(vcpu);
 336         TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO);
 337
 338         /* Clear kvm_valid_regs bits and kvm_dirty_bits.
 339          * Verify s.regs values are not overwritten with existing guest values
 340          * and that guest values are not overwritten with kvm_sync_regs values.
 341          */
 342         run->kvm_valid_regs = 0;
 343         run->kvm_dirty_regs = 0;
 344         run->s.regs.regs.rbx = 0xAAAA;
 345         vcpu_regs_get(vcpu, &regs);
 346         regs.rbx = 0xBAC0;
 347         vcpu_regs_set(vcpu, &regs);
 348         vcpu_run(vcpu);
 349         TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO);
 350         TEST_ASSERT(run->s.regs.regs.rbx == 0xAAAA,
 351                     "rbx sync regs value incorrect 0x%llx.",
 352                     run->s.regs.regs.rbx);
 353         vcpu_regs_get(vcpu, &regs);
 354         TEST_ASSERT(regs.rbx == 0xBAC0 + 1,
 355                     "rbx guest value incorrect 0x%llx.",
 356                     regs.rbx);
 357 }
 358
 359 KVM_ONE_VCPU_TEST(sync_regs_test, clear_kvm_valid_regs_bits, guest_code)
 360 {
 361         struct kvm_run *run = vcpu->run;
 362         struct kvm_regs regs;
 363
 364         /* Run once to get register set */
 365         run->kvm_valid_regs = TEST_SYNC_FIELDS;
 366         vcpu_run(vcpu);
 367         TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO);
 368
 369         /* Clear kvm_valid_regs bits. Verify s.regs values are not overwritten
 370          * with existing guest values but that guest values are overwritten
 371          * with kvm_sync_regs values.
 372          */
 373         run->kvm_valid_regs = 0;
 374         run->kvm_dirty_regs = TEST_SYNC_FIELDS;
 375         run->s.regs.regs.rbx = 0xBBBB;
 376         vcpu_run(vcpu);
 377         TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO);
 378         TEST_ASSERT(run->s.regs.regs.rbx == 0xBBBB,
 379                     "rbx sync regs value incorrect 0x%llx.",
 380                     run->s.regs.regs.rbx);
 381         vcpu_regs_get(vcpu, &regs);
 382         TEST_ASSERT(regs.rbx == 0xBBBB + 1,
 383                     "rbx guest value incorrect 0x%llx.",
 384                     regs.rbx);
 385 }
 386
 387 KVM_ONE_VCPU_TEST(sync_regs_test, race_cr4, guest_code)
 388 {
 389         race_sync_regs(vcpu, race_sregs_cr4);
 390 }
 391
 392 KVM_ONE_VCPU_TEST(sync_regs_test, race_exc, guest_code)
 393 {
 394         race_sync_regs(vcpu, race_events_exc);
 395 }
 396
 397 KVM_ONE_VCPU_TEST(sync_regs_test, race_inj_pen, guest_code)
 398 {
 399         race_sync_regs(vcpu, race_events_inj_pen);
 400 }
 401
 402 int main(int argc, char *argv[])
 403 {
 404         int cap;
 405
 406         cap = kvm_check_cap(KVM_CAP_SYNC_REGS);
 407         TEST_REQUIRE((cap & TEST_SYNC_FIELDS) == TEST_SYNC_FIELDS);
 408         TEST_REQUIRE(!(cap & INVALID_SYNC_FIELD));
 409
 410         return test_harness_run(argc, argv);
 411 }