1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Machine check handler 4 * 5 * Copyright IBM Corp. 2000, 2009 6 * Author(s): Ingo Adlung <adlung@de.ibm.com>, 7 * Martin Schwidefsky <schwidefsky@de.ibm.com>, 8 * Cornelia Huck <cornelia.huck@de.ibm.com>, 9 */ 10 11 #include <linux/kernel_stat.h> 12 #include <linux/init.h> 13 #include <linux/errno.h> 14 #include <linux/entry-common.h> 15 #include <linux/hardirq.h> 16 #include <linux/log2.h> 17 #include <linux/kprobes.h> 18 #include <linux/kmemleak.h> 19 #include <linux/time.h> 20 #include <linux/module.h> 21 #include <linux/sched/signal.h> 22 23 #include <linux/export.h> 24 #include <asm/lowcore.h> 25 #include <asm/smp.h> 26 #include <asm/stp.h> 27 #include <asm/cputime.h> 28 #include <asm/nmi.h> 29 #include <asm/crw.h> 30 #include <asm/switch_to.h> 31 #include <asm/ctl_reg.h> 32 #include <asm/asm-offsets.h> 33 #include <asm/pai.h> 34 35 #include <linux/kvm_host.h> 36 37 struct mcck_struct { 38 unsigned int kill_task : 1; 39 unsigned int channel_report : 1; 40 unsigned int warning : 1; 41 unsigned int stp_queue : 1; 42 unsigned long mcck_code; 43 }; 44 45 static DEFINE_PER_CPU(struct mcck_struct, cpu_mcck); 46 static struct kmem_cache *mcesa_cache; 47 static unsigned long mcesa_origin_lc; 48 49 static inline int nmi_needs_mcesa(void) 50 { 51 return MACHINE_HAS_VX || MACHINE_HAS_GS; 52 } 53 54 static inline unsigned long nmi_get_mcesa_size(void) 55 { 56 if (MACHINE_HAS_GS) 57 return MCESA_MAX_SIZE; 58 return MCESA_MIN_SIZE; 59 } 60 61 /* 62 * The initial machine check extended save area for the boot CPU. 63 * It will be replaced on the boot CPU reinit with an allocated 64 * structure. The structure is required for machine check happening 65 * early in the boot process. 66 */ 67 static struct mcesa boot_mcesa __initdata __aligned(MCESA_MAX_SIZE); 68 69 void __init nmi_alloc_mcesa_early(u64 *mcesad) 70 { 71 if (!nmi_needs_mcesa()) 72 return; 73 *mcesad = __pa(&boot_mcesa); 74 if (MACHINE_HAS_GS) 75 *mcesad |= ilog2(MCESA_MAX_SIZE); 76 } 77 78 static void __init nmi_alloc_cache(void) 79 { 80 unsigned long size; 81 82 if (!nmi_needs_mcesa()) 83 return; 84 size = nmi_get_mcesa_size(); 85 if (size > MCESA_MIN_SIZE) 86 mcesa_origin_lc = ilog2(size); 87 /* create slab cache for the machine-check-extended-save-areas */ 88 mcesa_cache = kmem_cache_create("nmi_save_areas", size, size, 0, NULL); 89 if (!mcesa_cache) 90 panic("Couldn't create nmi save area cache"); 91 } 92 93 int __ref nmi_alloc_mcesa(u64 *mcesad) 94 { 95 unsigned long origin; 96 97 *mcesad = 0; 98 if (!nmi_needs_mcesa()) 99 return 0; 100 if (!mcesa_cache) 101 nmi_alloc_cache(); 102 origin = (unsigned long) kmem_cache_alloc(mcesa_cache, GFP_KERNEL); 103 if (!origin) 104 return -ENOMEM; 105 /* The pointer is stored with mcesa_bits ORed in */ 106 kmemleak_not_leak((void *) origin); 107 *mcesad = __pa(origin) | mcesa_origin_lc; 108 return 0; 109 } 110 111 void nmi_free_mcesa(u64 *mcesad) 112 { 113 if (!nmi_needs_mcesa()) 114 return; 115 kmem_cache_free(mcesa_cache, __va(*mcesad & MCESA_ORIGIN_MASK)); 116 } 117 118 static notrace void s390_handle_damage(void) 119 { 120 smp_emergency_stop(); 121 disabled_wait(); 122 while (1); 123 } 124 NOKPROBE_SYMBOL(s390_handle_damage); 125 126 /* 127 * Main machine check handler function. Will be called with interrupts disabled 128 * and machine checks enabled. 129 */ 130 void __s390_handle_mcck(void) 131 { 132 struct mcck_struct mcck; 133 134 /* 135 * Disable machine checks and get the current state of accumulated 136 * machine checks. Afterwards delete the old state and enable machine 137 * checks again. 138 */ 139 local_mcck_disable(); 140 mcck = *this_cpu_ptr(&cpu_mcck); 141 memset(this_cpu_ptr(&cpu_mcck), 0, sizeof(mcck)); 142 local_mcck_enable(); 143 144 if (mcck.channel_report) 145 crw_handle_channel_report(); 146 /* 147 * A warning may remain for a prolonged period on the bare iron. 148 * (actually until the machine is powered off, or the problem is gone) 149 * So we just stop listening for the WARNING MCH and avoid continuously 150 * being interrupted. One caveat is however, that we must do this per 151 * processor and cannot use the smp version of ctl_clear_bit(). 152 * On VM we only get one interrupt per virtally presented machinecheck. 153 * Though one suffices, we may get one interrupt per (virtual) cpu. 154 */ 155 if (mcck.warning) { /* WARNING pending ? */ 156 static int mchchk_wng_posted = 0; 157 158 /* Use single cpu clear, as we cannot handle smp here. */ 159 __ctl_clear_bit(14, 24); /* Disable WARNING MCH */ 160 if (xchg(&mchchk_wng_posted, 1) == 0) 161 kill_cad_pid(SIGPWR, 1); 162 } 163 if (mcck.stp_queue) 164 stp_queue_work(); 165 if (mcck.kill_task) { 166 local_irq_enable(); 167 printk(KERN_EMERG "mcck: Terminating task because of machine " 168 "malfunction (code 0x%016lx).\n", mcck.mcck_code); 169 printk(KERN_EMERG "mcck: task: %s, pid: %d.\n", 170 current->comm, current->pid); 171 make_task_dead(SIGSEGV); 172 } 173 } 174 175 void noinstr s390_handle_mcck(struct pt_regs *regs) 176 { 177 trace_hardirqs_off(); 178 pai_kernel_enter(regs); 179 __s390_handle_mcck(); 180 pai_kernel_exit(regs); 181 trace_hardirqs_on(); 182 } 183 /* 184 * returns 0 if all required registers are available 185 * returns 1 otherwise 186 */ 187 static int notrace s390_validate_registers(union mci mci, int umode) 188 { 189 struct mcesa *mcesa; 190 void *fpt_save_area; 191 union ctlreg2 cr2; 192 int kill_task; 193 u64 zero; 194 195 kill_task = 0; 196 zero = 0; 197 198 if (!mci.gr) { 199 /* 200 * General purpose registers couldn't be restored and have 201 * unknown contents. Stop system or terminate process. 202 */ 203 if (!umode) 204 s390_handle_damage(); 205 kill_task = 1; 206 } 207 if (!mci.fp) { 208 /* 209 * Floating point registers can't be restored. If the 210 * kernel currently uses floating point registers the 211 * system is stopped. If the process has its floating 212 * pointer registers loaded it is terminated. 213 */ 214 if (S390_lowcore.fpu_flags & KERNEL_VXR_V0V7) 215 s390_handle_damage(); 216 if (!test_cpu_flag(CIF_FPU)) 217 kill_task = 1; 218 } 219 fpt_save_area = &S390_lowcore.floating_pt_save_area; 220 if (!mci.fc) { 221 /* 222 * Floating point control register can't be restored. 223 * If the kernel currently uses the floating pointer 224 * registers and needs the FPC register the system is 225 * stopped. If the process has its floating pointer 226 * registers loaded it is terminated. Otherwise the 227 * FPC is just validated. 228 */ 229 if (S390_lowcore.fpu_flags & KERNEL_FPC) 230 s390_handle_damage(); 231 asm volatile( 232 " lfpc %0\n" 233 : 234 : "Q" (zero)); 235 if (!test_cpu_flag(CIF_FPU)) 236 kill_task = 1; 237 } else { 238 asm volatile( 239 " lfpc %0\n" 240 : 241 : "Q" (S390_lowcore.fpt_creg_save_area)); 242 } 243 244 mcesa = __va(S390_lowcore.mcesad & MCESA_ORIGIN_MASK); 245 if (!MACHINE_HAS_VX) { 246 /* Validate floating point registers */ 247 asm volatile( 248 " ld 0,0(%0)\n" 249 " ld 1,8(%0)\n" 250 " ld 2,16(%0)\n" 251 " ld 3,24(%0)\n" 252 " ld 4,32(%0)\n" 253 " ld 5,40(%0)\n" 254 " ld 6,48(%0)\n" 255 " ld 7,56(%0)\n" 256 " ld 8,64(%0)\n" 257 " ld 9,72(%0)\n" 258 " ld 10,80(%0)\n" 259 " ld 11,88(%0)\n" 260 " ld 12,96(%0)\n" 261 " ld 13,104(%0)\n" 262 " ld 14,112(%0)\n" 263 " ld 15,120(%0)\n" 264 : 265 : "a" (fpt_save_area) 266 : "memory"); 267 } else { 268 /* Validate vector registers */ 269 union ctlreg0 cr0; 270 271 /* 272 * The vector validity must only be checked if not running a 273 * KVM guest. For KVM guests the machine check is forwarded by 274 * KVM and it is the responsibility of the guest to take 275 * appropriate actions. The host vector or FPU values have been 276 * saved by KVM and will be restored by KVM. 277 */ 278 if (!mci.vr && !test_cpu_flag(CIF_MCCK_GUEST)) { 279 /* 280 * Vector registers can't be restored. If the kernel 281 * currently uses vector registers the system is 282 * stopped. If the process has its vector registers 283 * loaded it is terminated. Otherwise just validate 284 * the registers. 285 */ 286 if (S390_lowcore.fpu_flags & KERNEL_VXR) 287 s390_handle_damage(); 288 if (!test_cpu_flag(CIF_FPU)) 289 kill_task = 1; 290 } 291 cr0.val = S390_lowcore.cregs_save_area[0]; 292 cr0.afp = cr0.vx = 1; 293 __ctl_load(cr0.val, 0, 0); 294 asm volatile( 295 " la 1,%0\n" 296 " .word 0xe70f,0x1000,0x0036\n" /* vlm 0,15,0(1) */ 297 " .word 0xe70f,0x1100,0x0c36\n" /* vlm 16,31,256(1) */ 298 : 299 : "Q" (*(struct vx_array *)mcesa->vector_save_area) 300 : "1"); 301 __ctl_load(S390_lowcore.cregs_save_area[0], 0, 0); 302 } 303 /* Validate access registers */ 304 asm volatile( 305 " lam 0,15,0(%0)\n" 306 : 307 : "a" (&S390_lowcore.access_regs_save_area) 308 : "memory"); 309 if (!mci.ar) { 310 /* 311 * Access registers have unknown contents. 312 * Terminating task. 313 */ 314 kill_task = 1; 315 } 316 /* Validate guarded storage registers */ 317 cr2.val = S390_lowcore.cregs_save_area[2]; 318 if (cr2.gse) { 319 if (!mci.gs) { 320 /* 321 * 2 cases: 322 * - machine check in kernel or userspace 323 * - machine check while running SIE (KVM guest) 324 * For kernel or userspace the userspace values of 325 * guarded storage control can not be recreated, the 326 * process must be terminated. 327 * For SIE the guest values of guarded storage can not 328 * be recreated. This is either due to a bug or due to 329 * GS being disabled in the guest. The guest will be 330 * notified by KVM code and the guests machine check 331 * handling must take care of this. The host values 332 * are saved by KVM and are not affected. 333 */ 334 if (!test_cpu_flag(CIF_MCCK_GUEST)) 335 kill_task = 1; 336 } else { 337 load_gs_cb((struct gs_cb *)mcesa->guarded_storage_save_area); 338 } 339 } 340 /* 341 * The getcpu vdso syscall reads CPU number from the programmable 342 * field of the TOD clock. Disregard the TOD programmable register 343 * validity bit and load the CPU number into the TOD programmable 344 * field unconditionally. 345 */ 346 set_tod_programmable_field(raw_smp_processor_id()); 347 /* Validate clock comparator register */ 348 set_clock_comparator(S390_lowcore.clock_comparator); 349 350 if (!mci.ms || !mci.pm || !mci.ia) 351 kill_task = 1; 352 353 return kill_task; 354 } 355 NOKPROBE_SYMBOL(s390_validate_registers); 356 357 /* 358 * Backup the guest's machine check info to its description block 359 */ 360 static void notrace s390_backup_mcck_info(struct pt_regs *regs) 361 { 362 struct mcck_volatile_info *mcck_backup; 363 struct sie_page *sie_page; 364 365 /* r14 contains the sie block, which was set in sie64a */ 366 struct kvm_s390_sie_block *sie_block = 367 (struct kvm_s390_sie_block *) regs->gprs[14]; 368 369 if (sie_block == NULL) 370 /* Something's seriously wrong, stop system. */ 371 s390_handle_damage(); 372 373 sie_page = container_of(sie_block, struct sie_page, sie_block); 374 mcck_backup = &sie_page->mcck_info; 375 mcck_backup->mcic = S390_lowcore.mcck_interruption_code & 376 ~(MCCK_CODE_CP | MCCK_CODE_EXT_DAMAGE); 377 mcck_backup->ext_damage_code = S390_lowcore.external_damage_code; 378 mcck_backup->failing_storage_address 379 = S390_lowcore.failing_storage_address; 380 } 381 NOKPROBE_SYMBOL(s390_backup_mcck_info); 382 383 #define MAX_IPD_COUNT 29 384 #define MAX_IPD_TIME (5 * 60 * USEC_PER_SEC) /* 5 minutes */ 385 386 #define ED_STP_ISLAND 6 /* External damage STP island check */ 387 #define ED_STP_SYNC 7 /* External damage STP sync check */ 388 389 #define MCCK_CODE_NO_GUEST (MCCK_CODE_CP | MCCK_CODE_EXT_DAMAGE) 390 391 /* 392 * machine check handler. 393 */ 394 int notrace s390_do_machine_check(struct pt_regs *regs) 395 { 396 static int ipd_count; 397 static DEFINE_SPINLOCK(ipd_lock); 398 static unsigned long long last_ipd; 399 struct mcck_struct *mcck; 400 unsigned long long tmp; 401 irqentry_state_t irq_state; 402 union mci mci; 403 unsigned long mcck_dam_code; 404 int mcck_pending = 0; 405 406 irq_state = irqentry_nmi_enter(regs); 407 408 if (user_mode(regs)) 409 update_timer_mcck(); 410 inc_irq_stat(NMI_NMI); 411 mci.val = S390_lowcore.mcck_interruption_code; 412 mcck = this_cpu_ptr(&cpu_mcck); 413 414 /* 415 * Reinject the instruction processing damages' machine checks 416 * including Delayed Access Exception into the guest 417 * instead of damaging the host if they happen in the guest. 418 */ 419 if (mci.pd && !test_cpu_flag(CIF_MCCK_GUEST)) { 420 if (mci.b) { 421 /* Processing backup -> verify if we can survive this */ 422 u64 z_mcic, o_mcic, t_mcic; 423 z_mcic = (1ULL<<63 | 1ULL<<59 | 1ULL<<29); 424 o_mcic = (1ULL<<43 | 1ULL<<42 | 1ULL<<41 | 1ULL<<40 | 425 1ULL<<36 | 1ULL<<35 | 1ULL<<34 | 1ULL<<32 | 426 1ULL<<30 | 1ULL<<21 | 1ULL<<20 | 1ULL<<17 | 427 1ULL<<16); 428 t_mcic = mci.val; 429 430 if (((t_mcic & z_mcic) != 0) || 431 ((t_mcic & o_mcic) != o_mcic)) { 432 s390_handle_damage(); 433 } 434 435 /* 436 * Nullifying exigent condition, therefore we might 437 * retry this instruction. 438 */ 439 spin_lock(&ipd_lock); 440 tmp = get_tod_clock(); 441 if (((tmp - last_ipd) >> 12) < MAX_IPD_TIME) 442 ipd_count++; 443 else 444 ipd_count = 1; 445 last_ipd = tmp; 446 if (ipd_count == MAX_IPD_COUNT) 447 s390_handle_damage(); 448 spin_unlock(&ipd_lock); 449 } else { 450 /* Processing damage -> stopping machine */ 451 s390_handle_damage(); 452 } 453 } 454 if (s390_validate_registers(mci, user_mode(regs))) { 455 /* 456 * Couldn't restore all register contents for the 457 * user space process -> mark task for termination. 458 */ 459 mcck->kill_task = 1; 460 mcck->mcck_code = mci.val; 461 mcck_pending = 1; 462 } 463 464 /* 465 * Backup the machine check's info if it happens when the guest 466 * is running. 467 */ 468 if (test_cpu_flag(CIF_MCCK_GUEST)) 469 s390_backup_mcck_info(regs); 470 471 if (mci.cd) { 472 /* Timing facility damage */ 473 s390_handle_damage(); 474 } 475 if (mci.ed && mci.ec) { 476 /* External damage */ 477 if (S390_lowcore.external_damage_code & (1U << ED_STP_SYNC)) 478 mcck->stp_queue |= stp_sync_check(); 479 if (S390_lowcore.external_damage_code & (1U << ED_STP_ISLAND)) 480 mcck->stp_queue |= stp_island_check(); 481 mcck_pending = 1; 482 } 483 484 if (mci.cp) { 485 /* Channel report word pending */ 486 mcck->channel_report = 1; 487 mcck_pending = 1; 488 } 489 if (mci.w) { 490 /* Warning pending */ 491 mcck->warning = 1; 492 mcck_pending = 1; 493 } 494 495 /* 496 * If there are only Channel Report Pending and External Damage 497 * machine checks, they will not be reinjected into the guest 498 * because they refer to host conditions only. 499 */ 500 mcck_dam_code = (mci.val & MCIC_SUBCLASS_MASK); 501 if (test_cpu_flag(CIF_MCCK_GUEST) && 502 (mcck_dam_code & MCCK_CODE_NO_GUEST) != mcck_dam_code) { 503 /* Set exit reason code for host's later handling */ 504 *((long *)(regs->gprs[15] + __SF_SIE_REASON)) = -EINTR; 505 } 506 clear_cpu_flag(CIF_MCCK_GUEST); 507 508 if (user_mode(regs) && mcck_pending) { 509 irqentry_nmi_exit(regs, irq_state); 510 return 1; 511 } 512 513 if (mcck_pending) 514 schedule_mcck_handler(); 515 516 irqentry_nmi_exit(regs, irq_state); 517 return 0; 518 } 519 NOKPROBE_SYMBOL(s390_do_machine_check); 520 521 static int __init machine_check_init(void) 522 { 523 ctl_set_bit(14, 25); /* enable external damage MCH */ 524 ctl_set_bit(14, 27); /* enable system recovery MCH */ 525 ctl_set_bit(14, 24); /* enable warning MCH */ 526 return 0; 527 } 528 early_initcall(machine_check_init); 529