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 ((u16)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 kvm_pthread_create(&thread, NULL, racer, (void *)run); 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 kvm_pthread_cancel_join(thread); 203 204 kvm_x86_state_cleanup(state); 205 } 206 207 KVM_ONE_VCPU_TEST(sync_regs_test, read_invalid, guest_code) 208 { 209 struct kvm_run *run = vcpu->run; 210 int rv; 211 212 /* Request reading invalid register set from VCPU. */ 213 run->kvm_valid_regs = INVALID_SYNC_FIELD; 214 rv = _vcpu_run(vcpu); 215 TEST_ASSERT(rv < 0 && errno == EINVAL, 216 "Invalid kvm_valid_regs did not cause expected KVM_RUN error: %d", 217 rv); 218 run->kvm_valid_regs = 0; 219 220 run->kvm_valid_regs = INVALID_SYNC_FIELD | TEST_SYNC_FIELDS; 221 rv = _vcpu_run(vcpu); 222 TEST_ASSERT(rv < 0 && errno == EINVAL, 223 "Invalid kvm_valid_regs did not cause expected KVM_RUN error: %d", 224 rv); 225 run->kvm_valid_regs = 0; 226 } 227 228 KVM_ONE_VCPU_TEST(sync_regs_test, set_invalid, guest_code) 229 { 230 struct kvm_run *run = vcpu->run; 231 int rv; 232 233 /* Request setting invalid register set into VCPU. */ 234 run->kvm_dirty_regs = INVALID_SYNC_FIELD; 235 rv = _vcpu_run(vcpu); 236 TEST_ASSERT(rv < 0 && errno == EINVAL, 237 "Invalid kvm_dirty_regs did not cause expected KVM_RUN error: %d", 238 rv); 239 run->kvm_dirty_regs = 0; 240 241 run->kvm_dirty_regs = INVALID_SYNC_FIELD | TEST_SYNC_FIELDS; 242 rv = _vcpu_run(vcpu); 243 TEST_ASSERT(rv < 0 && errno == EINVAL, 244 "Invalid kvm_dirty_regs did not cause expected KVM_RUN error: %d", 245 rv); 246 run->kvm_dirty_regs = 0; 247 } 248 249 KVM_ONE_VCPU_TEST(sync_regs_test, req_and_verify_all_valid, guest_code) 250 { 251 struct kvm_run *run = vcpu->run; 252 struct kvm_vcpu_events events; 253 struct kvm_sregs sregs; 254 struct kvm_regs regs; 255 256 /* Request and verify all valid register sets. */ 257 run->kvm_valid_regs = TEST_SYNC_FIELDS; 258 vcpu_run(vcpu); 259 TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO); 260 261 vcpu_regs_get(vcpu, ®s); 262 compare_regs(®s, &run->s.regs.regs); 263 264 vcpu_sregs_get(vcpu, &sregs); 265 compare_sregs(&sregs, &run->s.regs.sregs); 266 267 vcpu_events_get(vcpu, &events); 268 compare_vcpu_events(&events, &run->s.regs.events); 269 } 270 271 KVM_ONE_VCPU_TEST(sync_regs_test, set_and_verify_various, guest_code) 272 { 273 struct kvm_run *run = vcpu->run; 274 struct kvm_vcpu_events events; 275 struct kvm_sregs sregs; 276 struct kvm_regs regs; 277 278 /* Run once to get register set */ 279 run->kvm_valid_regs = TEST_SYNC_FIELDS; 280 vcpu_run(vcpu); 281 TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO); 282 283 /* Set and verify various register values. */ 284 run->s.regs.regs.rbx = 0xBAD1DEA; 285 run->s.regs.sregs.apic_base = 1 << 11; 286 /* TODO run->s.regs.events.XYZ = ABC; */ 287 288 run->kvm_valid_regs = TEST_SYNC_FIELDS; 289 run->kvm_dirty_regs = KVM_SYNC_X86_REGS | KVM_SYNC_X86_SREGS; 290 vcpu_run(vcpu); 291 TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO); 292 TEST_ASSERT(run->s.regs.regs.rbx == 0xBAD1DEA + 1, 293 "rbx sync regs value incorrect 0x%llx.", 294 run->s.regs.regs.rbx); 295 TEST_ASSERT(run->s.regs.sregs.apic_base == 1 << 11, 296 "apic_base sync regs value incorrect 0x%llx.", 297 run->s.regs.sregs.apic_base); 298 299 vcpu_regs_get(vcpu, ®s); 300 compare_regs(®s, &run->s.regs.regs); 301 302 vcpu_sregs_get(vcpu, &sregs); 303 compare_sregs(&sregs, &run->s.regs.sregs); 304 305 vcpu_events_get(vcpu, &events); 306 compare_vcpu_events(&events, &run->s.regs.events); 307 } 308 309 KVM_ONE_VCPU_TEST(sync_regs_test, clear_kvm_dirty_regs_bits, guest_code) 310 { 311 struct kvm_run *run = vcpu->run; 312 313 /* Clear kvm_dirty_regs bits, verify new s.regs values are 314 * overwritten with existing guest values. 315 */ 316 run->kvm_valid_regs = TEST_SYNC_FIELDS; 317 run->kvm_dirty_regs = 0; 318 run->s.regs.regs.rbx = 0xDEADBEEF; 319 vcpu_run(vcpu); 320 TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO); 321 TEST_ASSERT(run->s.regs.regs.rbx != 0xDEADBEEF, 322 "rbx sync regs value incorrect 0x%llx.", 323 run->s.regs.regs.rbx); 324 } 325 326 KVM_ONE_VCPU_TEST(sync_regs_test, clear_kvm_valid_and_dirty_regs, guest_code) 327 { 328 struct kvm_run *run = vcpu->run; 329 struct kvm_regs regs; 330 331 /* Run once to get register set */ 332 run->kvm_valid_regs = TEST_SYNC_FIELDS; 333 vcpu_run(vcpu); 334 TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO); 335 336 /* Clear kvm_valid_regs bits and kvm_dirty_bits. 337 * Verify s.regs values are not overwritten with existing guest values 338 * and that guest values are not overwritten with kvm_sync_regs values. 339 */ 340 run->kvm_valid_regs = 0; 341 run->kvm_dirty_regs = 0; 342 run->s.regs.regs.rbx = 0xAAAA; 343 vcpu_regs_get(vcpu, ®s); 344 regs.rbx = 0xBAC0; 345 vcpu_regs_set(vcpu, ®s); 346 vcpu_run(vcpu); 347 TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO); 348 TEST_ASSERT(run->s.regs.regs.rbx == 0xAAAA, 349 "rbx sync regs value incorrect 0x%llx.", 350 run->s.regs.regs.rbx); 351 vcpu_regs_get(vcpu, ®s); 352 TEST_ASSERT(regs.rbx == 0xBAC0 + 1, 353 "rbx guest value incorrect 0x%llx.", 354 regs.rbx); 355 } 356 357 KVM_ONE_VCPU_TEST(sync_regs_test, clear_kvm_valid_regs_bits, guest_code) 358 { 359 struct kvm_run *run = vcpu->run; 360 struct kvm_regs regs; 361 362 /* Run once to get register set */ 363 run->kvm_valid_regs = TEST_SYNC_FIELDS; 364 vcpu_run(vcpu); 365 TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO); 366 367 /* Clear kvm_valid_regs bits. Verify s.regs values are not overwritten 368 * with existing guest values but that guest values are overwritten 369 * with kvm_sync_regs values. 370 */ 371 run->kvm_valid_regs = 0; 372 run->kvm_dirty_regs = TEST_SYNC_FIELDS; 373 run->s.regs.regs.rbx = 0xBBBB; 374 vcpu_run(vcpu); 375 TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO); 376 TEST_ASSERT(run->s.regs.regs.rbx == 0xBBBB, 377 "rbx sync regs value incorrect 0x%llx.", 378 run->s.regs.regs.rbx); 379 vcpu_regs_get(vcpu, ®s); 380 TEST_ASSERT(regs.rbx == 0xBBBB + 1, 381 "rbx guest value incorrect 0x%llx.", 382 regs.rbx); 383 } 384 385 KVM_ONE_VCPU_TEST(sync_regs_test, race_cr4, guest_code) 386 { 387 race_sync_regs(vcpu, race_sregs_cr4); 388 } 389 390 KVM_ONE_VCPU_TEST(sync_regs_test, race_exc, guest_code) 391 { 392 race_sync_regs(vcpu, race_events_exc); 393 } 394 395 KVM_ONE_VCPU_TEST(sync_regs_test, race_inj_pen, guest_code) 396 { 397 race_sync_regs(vcpu, race_events_inj_pen); 398 } 399 400 int main(int argc, char *argv[]) 401 { 402 int cap; 403 404 cap = kvm_check_cap(KVM_CAP_SYNC_REGS); 405 TEST_REQUIRE((cap & TEST_SYNC_FIELDS) == TEST_SYNC_FIELDS); 406 TEST_REQUIRE(!(cap & INVALID_SYNC_FIELD)); 407 408 return test_harness_run(argc, argv); 409 } 410