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