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 enabled 135 * or disabled and machine checks enabled or disabled. 136 */ 137 void s390_handle_mcck(void) 138 { 139 unsigned long flags; 140 struct mcck_struct mcck; 141 142 /* 143 * Disable machine checks and get the current state of accumulated 144 * machine checks. Afterwards delete the old state and enable machine 145 * checks again. 146 */ 147 local_irq_save(flags); 148 local_mcck_disable(); 149 mcck = *this_cpu_ptr(&cpu_mcck); 150 memset(this_cpu_ptr(&cpu_mcck), 0, sizeof(mcck)); 151 clear_cpu_flag(CIF_MCCK_PENDING); 152 local_mcck_enable(); 153 local_irq_restore(flags); 154 155 if (mcck.channel_report) 156 crw_handle_channel_report(); 157 /* 158 * A warning may remain for a prolonged period on the bare iron. 159 * (actually until the machine is powered off, or the problem is gone) 160 * So we just stop listening for the WARNING MCH and avoid continuously 161 * being interrupted. One caveat is however, that we must do this per 162 * processor and cannot use the smp version of ctl_clear_bit(). 163 * On VM we only get one interrupt per virtally presented machinecheck. 164 * Though one suffices, we may get one interrupt per (virtual) cpu. 165 */ 166 if (mcck.warning) { /* WARNING pending ? */ 167 static int mchchk_wng_posted = 0; 168 169 /* Use single cpu clear, as we cannot handle smp here. */ 170 __ctl_clear_bit(14, 24); /* Disable WARNING MCH */ 171 if (xchg(&mchchk_wng_posted, 1) == 0) 172 kill_cad_pid(SIGPWR, 1); 173 } 174 if (mcck.stp_queue) 175 stp_queue_work(); 176 if (mcck.kill_task) { 177 local_irq_enable(); 178 printk(KERN_EMERG "mcck: Terminating task because of machine " 179 "malfunction (code 0x%016lx).\n", mcck.mcck_code); 180 printk(KERN_EMERG "mcck: task: %s, pid: %d.\n", 181 current->comm, current->pid); 182 do_exit(SIGSEGV); 183 } 184 } 185 EXPORT_SYMBOL_GPL(s390_handle_mcck); 186 187 /* 188 * returns 0 if all required registers are available 189 * returns 1 otherwise 190 */ 191 static int notrace s390_check_registers(union mci mci, int umode) 192 { 193 union ctlreg2 cr2; 194 int kill_task; 195 196 kill_task = 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 /* Check control registers */ 208 if (!mci.cr) { 209 /* 210 * Control registers have unknown contents. 211 * Can't recover and therefore stopping machine. 212 */ 213 s390_handle_damage(); 214 } 215 if (!mci.fp) { 216 /* 217 * Floating point registers can't be restored. If the 218 * kernel currently uses floating point registers the 219 * system is stopped. If the process has its floating 220 * pointer registers loaded it is terminated. 221 */ 222 if (S390_lowcore.fpu_flags & KERNEL_VXR_V0V7) 223 s390_handle_damage(); 224 if (!test_cpu_flag(CIF_FPU)) 225 kill_task = 1; 226 } 227 if (!mci.fc) { 228 /* 229 * Floating point control register can't be restored. 230 * If the kernel currently uses the floating pointer 231 * registers and needs the FPC register the system is 232 * stopped. If the process has its floating pointer 233 * registers loaded it is terminated. 234 */ 235 if (S390_lowcore.fpu_flags & KERNEL_FPC) 236 s390_handle_damage(); 237 if (!test_cpu_flag(CIF_FPU)) 238 kill_task = 1; 239 } 240 241 if (MACHINE_HAS_VX) { 242 if (!mci.vr) { 243 /* 244 * Vector registers can't be restored. If the kernel 245 * currently uses vector registers the system is 246 * stopped. If the process has its vector registers 247 * loaded it is terminated. 248 */ 249 if (S390_lowcore.fpu_flags & KERNEL_VXR) 250 s390_handle_damage(); 251 if (!test_cpu_flag(CIF_FPU)) 252 kill_task = 1; 253 } 254 } 255 /* Check if access registers are valid */ 256 if (!mci.ar) { 257 /* 258 * Access registers have unknown contents. 259 * Terminating task. 260 */ 261 kill_task = 1; 262 } 263 /* Check guarded storage registers */ 264 cr2.val = S390_lowcore.cregs_save_area[2]; 265 if (cr2.gse) { 266 if (!mci.gs) { 267 /* 268 * Guarded storage register can't be restored and 269 * the current processes uses guarded storage. 270 * It has to be terminated. 271 */ 272 kill_task = 1; 273 } 274 } 275 /* Check if old PSW is valid */ 276 if (!mci.wp) { 277 /* 278 * Can't tell if we come from user or kernel mode 279 * -> stopping machine. 280 */ 281 s390_handle_damage(); 282 } 283 /* Check for invalid kernel instruction address */ 284 if (!mci.ia && !umode) { 285 /* 286 * The instruction address got lost while running 287 * in the kernel -> stopping machine. 288 */ 289 s390_handle_damage(); 290 } 291 292 if (!mci.ms || !mci.pm || !mci.ia) 293 kill_task = 1; 294 295 return kill_task; 296 } 297 NOKPROBE_SYMBOL(s390_check_registers); 298 299 /* 300 * Backup the guest's machine check info to its description block 301 */ 302 static void notrace s390_backup_mcck_info(struct pt_regs *regs) 303 { 304 struct mcck_volatile_info *mcck_backup; 305 struct sie_page *sie_page; 306 307 /* r14 contains the sie block, which was set in sie64a */ 308 struct kvm_s390_sie_block *sie_block = 309 (struct kvm_s390_sie_block *) regs->gprs[14]; 310 311 if (sie_block == NULL) 312 /* Something's seriously wrong, stop system. */ 313 s390_handle_damage(); 314 315 sie_page = container_of(sie_block, struct sie_page, sie_block); 316 mcck_backup = &sie_page->mcck_info; 317 mcck_backup->mcic = S390_lowcore.mcck_interruption_code & 318 ~(MCCK_CODE_CP | MCCK_CODE_EXT_DAMAGE); 319 mcck_backup->ext_damage_code = S390_lowcore.external_damage_code; 320 mcck_backup->failing_storage_address 321 = S390_lowcore.failing_storage_address; 322 } 323 NOKPROBE_SYMBOL(s390_backup_mcck_info); 324 325 #define MAX_IPD_COUNT 29 326 #define MAX_IPD_TIME (5 * 60 * USEC_PER_SEC) /* 5 minutes */ 327 328 #define ED_STP_ISLAND 6 /* External damage STP island check */ 329 #define ED_STP_SYNC 7 /* External damage STP sync check */ 330 331 #define MCCK_CODE_NO_GUEST (MCCK_CODE_CP | MCCK_CODE_EXT_DAMAGE) 332 333 /* 334 * machine check handler. 335 */ 336 void notrace s390_do_machine_check(struct pt_regs *regs) 337 { 338 static int ipd_count; 339 static DEFINE_SPINLOCK(ipd_lock); 340 static unsigned long long last_ipd; 341 struct mcck_struct *mcck; 342 unsigned long long tmp; 343 union mci mci; 344 unsigned long mcck_dam_code; 345 346 nmi_enter(); 347 inc_irq_stat(NMI_NMI); 348 mci.val = S390_lowcore.mcck_interruption_code; 349 mcck = this_cpu_ptr(&cpu_mcck); 350 351 if (mci.sd) { 352 /* System damage -> stopping machine */ 353 s390_handle_damage(); 354 } 355 356 /* 357 * Reinject the instruction processing damages' machine checks 358 * including Delayed Access Exception into the guest 359 * instead of damaging the host if they happen in the guest. 360 */ 361 if (mci.pd && !test_cpu_flag(CIF_MCCK_GUEST)) { 362 if (mci.b) { 363 /* Processing backup -> verify if we can survive this */ 364 u64 z_mcic, o_mcic, t_mcic; 365 z_mcic = (1ULL<<63 | 1ULL<<59 | 1ULL<<29); 366 o_mcic = (1ULL<<43 | 1ULL<<42 | 1ULL<<41 | 1ULL<<40 | 367 1ULL<<36 | 1ULL<<35 | 1ULL<<34 | 1ULL<<32 | 368 1ULL<<30 | 1ULL<<21 | 1ULL<<20 | 1ULL<<17 | 369 1ULL<<16); 370 t_mcic = mci.val; 371 372 if (((t_mcic & z_mcic) != 0) || 373 ((t_mcic & o_mcic) != o_mcic)) { 374 s390_handle_damage(); 375 } 376 377 /* 378 * Nullifying exigent condition, therefore we might 379 * retry this instruction. 380 */ 381 spin_lock(&ipd_lock); 382 tmp = get_tod_clock(); 383 if (((tmp - last_ipd) >> 12) < MAX_IPD_TIME) 384 ipd_count++; 385 else 386 ipd_count = 1; 387 last_ipd = tmp; 388 if (ipd_count == MAX_IPD_COUNT) 389 s390_handle_damage(); 390 spin_unlock(&ipd_lock); 391 } else { 392 /* Processing damage -> stopping machine */ 393 s390_handle_damage(); 394 } 395 } 396 if (s390_check_registers(mci, user_mode(regs))) { 397 /* 398 * Couldn't restore all register contents for the 399 * user space process -> mark task for termination. 400 */ 401 mcck->kill_task = 1; 402 mcck->mcck_code = mci.val; 403 set_cpu_flag(CIF_MCCK_PENDING); 404 } 405 406 /* 407 * Backup the machine check's info if it happens when the guest 408 * is running. 409 */ 410 if (test_cpu_flag(CIF_MCCK_GUEST)) 411 s390_backup_mcck_info(regs); 412 413 if (mci.cd) { 414 /* Timing facility damage */ 415 s390_handle_damage(); 416 } 417 if (mci.ed && mci.ec) { 418 /* External damage */ 419 if (S390_lowcore.external_damage_code & (1U << ED_STP_SYNC)) 420 mcck->stp_queue |= stp_sync_check(); 421 if (S390_lowcore.external_damage_code & (1U << ED_STP_ISLAND)) 422 mcck->stp_queue |= stp_island_check(); 423 if (mcck->stp_queue) 424 set_cpu_flag(CIF_MCCK_PENDING); 425 } 426 427 /* 428 * Reinject storage related machine checks into the guest if they 429 * happen when the guest is running. 430 */ 431 if (!test_cpu_flag(CIF_MCCK_GUEST)) { 432 if (mci.se) 433 /* Storage error uncorrected */ 434 s390_handle_damage(); 435 if (mci.ke) 436 /* Storage key-error uncorrected */ 437 s390_handle_damage(); 438 if (mci.ds && mci.fa) 439 /* Storage degradation */ 440 s390_handle_damage(); 441 } 442 if (mci.cp) { 443 /* Channel report word pending */ 444 mcck->channel_report = 1; 445 set_cpu_flag(CIF_MCCK_PENDING); 446 } 447 if (mci.w) { 448 /* Warning pending */ 449 mcck->warning = 1; 450 set_cpu_flag(CIF_MCCK_PENDING); 451 } 452 453 /* 454 * If there are only Channel Report Pending and External Damage 455 * machine checks, they will not be reinjected into the guest 456 * because they refer to host conditions only. 457 */ 458 mcck_dam_code = (mci.val & MCIC_SUBCLASS_MASK); 459 if (test_cpu_flag(CIF_MCCK_GUEST) && 460 (mcck_dam_code & MCCK_CODE_NO_GUEST) != mcck_dam_code) { 461 /* Set exit reason code for host's later handling */ 462 *((long *)(regs->gprs[15] + __SF_SIE_REASON)) = -EINTR; 463 } 464 clear_cpu_flag(CIF_MCCK_GUEST); 465 nmi_exit(); 466 } 467 NOKPROBE_SYMBOL(s390_do_machine_check); 468 469 static int __init machine_check_init(void) 470 { 471 ctl_set_bit(14, 25); /* enable external damage MCH */ 472 ctl_set_bit(14, 27); /* enable system recovery MCH */ 473 ctl_set_bit(14, 24); /* enable warning MCH */ 474 return 0; 475 } 476 early_initcall(machine_check_init); 477