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 #include <linux/kvm_host.h> 23 #include <linux/export.h> 24 #include <asm/lowcore.h> 25 #include <asm/ctlreg.h> 26 #include <asm/fpu.h> 27 #include <asm/smp.h> 28 #include <asm/stp.h> 29 #include <asm/cputime.h> 30 #include <asm/nmi.h> 31 #include <asm/crw.h> 32 #include <asm/asm-offsets.h> 33 #include <asm/pai.h> 34 #include <asm/vtime.h> 35 36 struct mcck_struct { 37 unsigned int kill_task : 1; 38 unsigned int channel_report : 1; 39 unsigned int warning : 1; 40 unsigned int stp_queue : 1; 41 unsigned long mcck_code; 42 }; 43 44 static DEFINE_PER_CPU(struct mcck_struct, cpu_mcck); 45 46 static inline int nmi_needs_mcesa(void) 47 { 48 return cpu_has_vx() || MACHINE_HAS_GS; 49 } 50 51 /* 52 * The initial machine check extended save area for the boot CPU. 53 * It will be replaced on the boot CPU reinit with an allocated 54 * structure. The structure is required for machine check happening 55 * early in the boot process. 56 */ 57 static struct mcesa boot_mcesa __aligned(MCESA_MAX_SIZE); 58 59 void __init nmi_alloc_mcesa_early(u64 *mcesad) 60 { 61 if (!nmi_needs_mcesa()) 62 return; 63 *mcesad = __pa(&boot_mcesa); 64 if (MACHINE_HAS_GS) 65 *mcesad |= ilog2(MCESA_MAX_SIZE); 66 } 67 68 int nmi_alloc_mcesa(u64 *mcesad) 69 { 70 unsigned long size; 71 void *origin; 72 73 *mcesad = 0; 74 if (!nmi_needs_mcesa()) 75 return 0; 76 size = MACHINE_HAS_GS ? MCESA_MAX_SIZE : MCESA_MIN_SIZE; 77 origin = kmalloc(size, GFP_KERNEL); 78 if (!origin) 79 return -ENOMEM; 80 /* The pointer is stored with mcesa_bits ORed in */ 81 kmemleak_not_leak(origin); 82 *mcesad = __pa(origin); 83 if (MACHINE_HAS_GS) 84 *mcesad |= ilog2(MCESA_MAX_SIZE); 85 return 0; 86 } 87 88 void nmi_free_mcesa(u64 *mcesad) 89 { 90 if (!nmi_needs_mcesa()) 91 return; 92 kfree(__va(*mcesad & MCESA_ORIGIN_MASK)); 93 } 94 95 static __always_inline char *nmi_puts(char *dest, const char *src) 96 { 97 while (*src) 98 *dest++ = *src++; 99 *dest = 0; 100 return dest; 101 } 102 103 static __always_inline char *u64_to_hex(char *dest, u64 val) 104 { 105 int i, num; 106 107 for (i = 1; i <= 16; i++) { 108 num = (val >> (64 - 4 * i)) & 0xf; 109 if (num >= 10) 110 *dest++ = 'A' + num - 10; 111 else 112 *dest++ = '0' + num; 113 } 114 *dest = 0; 115 return dest; 116 } 117 118 static notrace void s390_handle_damage(void) 119 { 120 struct lowcore *lc = get_lowcore(); 121 union ctlreg0 cr0, cr0_new; 122 char message[100]; 123 psw_t psw_save; 124 char *ptr; 125 126 smp_emergency_stop(); 127 diag_amode31_ops.diag308_reset(); 128 ptr = nmi_puts(message, "System stopped due to unrecoverable machine check, code: 0x"); 129 u64_to_hex(ptr, lc->mcck_interruption_code); 130 131 /* 132 * Disable low address protection and make machine check new PSW a 133 * disabled wait PSW. Any additional machine check cannot be handled. 134 */ 135 local_ctl_store(0, &cr0.reg); 136 cr0_new = cr0; 137 cr0_new.lap = 0; 138 local_ctl_load(0, &cr0_new.reg); 139 psw_save = lc->mcck_new_psw; 140 psw_bits(lc->mcck_new_psw).io = 0; 141 psw_bits(lc->mcck_new_psw).ext = 0; 142 psw_bits(lc->mcck_new_psw).wait = 1; 143 sclp_emergency_printk(message); 144 145 /* 146 * Restore machine check new PSW and control register 0 to original 147 * values. This makes possible system dump analysis easier. 148 */ 149 lc->mcck_new_psw = psw_save; 150 local_ctl_load(0, &cr0.reg); 151 disabled_wait(); 152 while (1); 153 } 154 NOKPROBE_SYMBOL(s390_handle_damage); 155 156 /* 157 * Main machine check handler function. Will be called with interrupts disabled 158 * and machine checks enabled. 159 */ 160 void s390_handle_mcck(void) 161 { 162 struct mcck_struct mcck; 163 unsigned long mflags; 164 165 /* 166 * Disable machine checks and get the current state of accumulated 167 * machine checks. Afterwards delete the old state and enable machine 168 * checks again. 169 */ 170 local_mcck_save(mflags); 171 mcck = *this_cpu_ptr(&cpu_mcck); 172 memset(this_cpu_ptr(&cpu_mcck), 0, sizeof(mcck)); 173 local_mcck_restore(mflags); 174 175 if (mcck.channel_report) 176 crw_handle_channel_report(); 177 /* 178 * A warning may remain for a prolonged period on the bare iron. 179 * (actually until the machine is powered off, or the problem is gone) 180 * So we just stop listening for the WARNING MCH and avoid continuously 181 * being interrupted. One caveat is however, that we must do this per 182 * processor and cannot use the smp version of ctl_clear_bit(). 183 * On VM we only get one interrupt per virtally presented machinecheck. 184 * Though one suffices, we may get one interrupt per (virtual) cpu. 185 */ 186 if (mcck.warning) { /* WARNING pending ? */ 187 static int mchchk_wng_posted = 0; 188 189 /* Use single cpu clear, as we cannot handle smp here. */ 190 local_ctl_clear_bit(14, CR14_WARNING_SUBMASK_BIT); 191 if (xchg(&mchchk_wng_posted, 1) == 0) 192 kill_cad_pid(SIGPWR, 1); 193 } 194 if (mcck.stp_queue) 195 stp_queue_work(); 196 if (mcck.kill_task) { 197 printk(KERN_EMERG "mcck: Terminating task because of machine " 198 "malfunction (code 0x%016lx).\n", mcck.mcck_code); 199 printk(KERN_EMERG "mcck: task: %s, pid: %d.\n", 200 current->comm, current->pid); 201 if (is_global_init(current)) 202 panic("mcck: Attempting to kill init!\n"); 203 do_send_sig_info(SIGKILL, SEND_SIG_PRIV, current, PIDTYPE_PID); 204 } 205 } 206 207 /** 208 * nmi_registers_valid - verify if registers are valid 209 * @mci: machine check interruption code 210 * 211 * Inspect a machine check interruption code and verify if all required 212 * registers are valid. For some registers the corresponding validity bit is 213 * ignored and the registers are set to the expected value. 214 * Returns true if all registers are valid, otherwise false. 215 */ 216 static bool notrace nmi_registers_valid(union mci mci) 217 { 218 union ctlreg2 cr2; 219 220 /* 221 * The getcpu vdso syscall reads the CPU number from the programmable 222 * field of the TOD clock. Disregard the TOD programmable register 223 * validity bit and load the CPU number into the TOD programmable field 224 * unconditionally. 225 */ 226 set_tod_programmable_field(raw_smp_processor_id()); 227 /* 228 * Set the clock comparator register to the next expected value. 229 */ 230 set_clock_comparator(get_lowcore()->clock_comparator); 231 if (!mci.gr || !mci.fp || !mci.fc) 232 return false; 233 /* 234 * The vector validity must only be checked if not running a 235 * KVM guest. For KVM guests the machine check is forwarded by 236 * KVM and it is the responsibility of the guest to take 237 * appropriate actions. The host vector or FPU values have been 238 * saved by KVM and will be restored by KVM. 239 */ 240 if (!mci.vr && !test_cpu_flag(CIF_MCCK_GUEST)) 241 return false; 242 if (!mci.ar) 243 return false; 244 /* 245 * Two cases for guarded storage registers: 246 * - machine check in kernel or userspace 247 * - machine check while running SIE (KVM guest) 248 * For kernel or userspace the userspace values of guarded storage 249 * control can not be recreated, the process must be terminated. 250 * For SIE the guest values of guarded storage can not be recreated. 251 * This is either due to a bug or due to GS being disabled in the 252 * guest. The guest will be notified by KVM code and the guests machine 253 * check handling must take care of this. The host values are saved by 254 * KVM and are not affected. 255 */ 256 cr2.reg = get_lowcore()->cregs_save_area[2]; 257 if (cr2.gse && !mci.gs && !test_cpu_flag(CIF_MCCK_GUEST)) 258 return false; 259 if (!mci.ms || !mci.pm || !mci.ia) 260 return false; 261 return true; 262 } 263 NOKPROBE_SYMBOL(nmi_registers_valid); 264 265 /* 266 * Backup the guest's machine check info to its description block 267 */ 268 static void notrace s390_backup_mcck_info(struct pt_regs *regs) 269 { 270 struct mcck_volatile_info *mcck_backup; 271 struct sie_page *sie_page; 272 273 /* r14 contains the sie block, which was set in sie64a */ 274 struct kvm_s390_sie_block *sie_block = phys_to_virt(regs->gprs[14]); 275 276 if (sie_block == NULL) 277 /* Something's seriously wrong, stop system. */ 278 s390_handle_damage(); 279 280 sie_page = container_of(sie_block, struct sie_page, sie_block); 281 mcck_backup = &sie_page->mcck_info; 282 mcck_backup->mcic = get_lowcore()->mcck_interruption_code & 283 ~(MCCK_CODE_CP | MCCK_CODE_EXT_DAMAGE); 284 mcck_backup->ext_damage_code = get_lowcore()->external_damage_code; 285 mcck_backup->failing_storage_address = get_lowcore()->failing_storage_address; 286 } 287 NOKPROBE_SYMBOL(s390_backup_mcck_info); 288 289 #define MAX_IPD_COUNT 29 290 #define MAX_IPD_TIME (5 * 60 * USEC_PER_SEC) /* 5 minutes */ 291 292 #define ED_STP_ISLAND 6 /* External damage STP island check */ 293 #define ED_STP_SYNC 7 /* External damage STP sync check */ 294 295 #define MCCK_CODE_NO_GUEST (MCCK_CODE_CP | MCCK_CODE_EXT_DAMAGE) 296 297 /* 298 * machine check handler. 299 */ 300 void notrace s390_do_machine_check(struct pt_regs *regs) 301 { 302 static int ipd_count; 303 static DEFINE_SPINLOCK(ipd_lock); 304 static unsigned long long last_ipd; 305 struct lowcore *lc = get_lowcore(); 306 struct mcck_struct *mcck; 307 unsigned long long tmp; 308 irqentry_state_t irq_state; 309 union mci mci; 310 unsigned long mcck_dam_code; 311 int mcck_pending = 0; 312 313 irq_state = irqentry_nmi_enter(regs); 314 315 if (user_mode(regs)) 316 update_timer_mcck(); 317 inc_irq_stat(NMI_NMI); 318 mci.val = lc->mcck_interruption_code; 319 mcck = this_cpu_ptr(&cpu_mcck); 320 321 /* 322 * Reinject the instruction processing damages' machine checks 323 * including Delayed Access Exception into the guest 324 * instead of damaging the host if they happen in the guest. 325 */ 326 if (mci.pd && !test_cpu_flag(CIF_MCCK_GUEST)) { 327 if (mci.b) { 328 /* Processing backup -> verify if we can survive this */ 329 u64 z_mcic, o_mcic, t_mcic; 330 z_mcic = (1ULL<<63 | 1ULL<<59 | 1ULL<<29); 331 o_mcic = (1ULL<<43 | 1ULL<<42 | 1ULL<<41 | 1ULL<<40 | 332 1ULL<<36 | 1ULL<<35 | 1ULL<<34 | 1ULL<<32 | 333 1ULL<<30 | 1ULL<<21 | 1ULL<<20 | 1ULL<<17 | 334 1ULL<<16); 335 t_mcic = mci.val; 336 337 if (((t_mcic & z_mcic) != 0) || 338 ((t_mcic & o_mcic) != o_mcic)) { 339 s390_handle_damage(); 340 } 341 342 /* 343 * Nullifying exigent condition, therefore we might 344 * retry this instruction. 345 */ 346 spin_lock(&ipd_lock); 347 tmp = get_tod_clock(); 348 if (((tmp - last_ipd) >> 12) < MAX_IPD_TIME) 349 ipd_count++; 350 else 351 ipd_count = 1; 352 last_ipd = tmp; 353 if (ipd_count == MAX_IPD_COUNT) 354 s390_handle_damage(); 355 spin_unlock(&ipd_lock); 356 } else { 357 /* Processing damage -> stopping machine */ 358 s390_handle_damage(); 359 } 360 } 361 if (!nmi_registers_valid(mci)) { 362 if (!user_mode(regs)) 363 s390_handle_damage(); 364 /* 365 * Couldn't restore all register contents for the 366 * user space process -> mark task for termination. 367 */ 368 mcck->kill_task = 1; 369 mcck->mcck_code = mci.val; 370 mcck_pending = 1; 371 } 372 373 /* 374 * Backup the machine check's info if it happens when the guest 375 * is running. 376 */ 377 if (test_cpu_flag(CIF_MCCK_GUEST)) 378 s390_backup_mcck_info(regs); 379 380 if (mci.cd) { 381 /* Timing facility damage */ 382 s390_handle_damage(); 383 } 384 if (mci.ed && mci.ec) { 385 /* External damage */ 386 if (lc->external_damage_code & (1U << ED_STP_SYNC)) 387 mcck->stp_queue |= stp_sync_check(); 388 if (lc->external_damage_code & (1U << ED_STP_ISLAND)) 389 mcck->stp_queue |= stp_island_check(); 390 mcck_pending = 1; 391 } 392 /* 393 * Reinject storage related machine checks into the guest if they 394 * happen when the guest is running. 395 */ 396 if (!test_cpu_flag(CIF_MCCK_GUEST)) { 397 /* Storage error uncorrected */ 398 if (mci.se) 399 s390_handle_damage(); 400 /* Storage key-error uncorrected */ 401 if (mci.ke) 402 s390_handle_damage(); 403 /* Storage degradation */ 404 if (mci.ds && mci.fa) 405 s390_handle_damage(); 406 } 407 if (mci.cp) { 408 /* Channel report word pending */ 409 mcck->channel_report = 1; 410 mcck_pending = 1; 411 } 412 if (mci.w) { 413 /* Warning pending */ 414 mcck->warning = 1; 415 mcck_pending = 1; 416 } 417 418 /* 419 * If there are only Channel Report Pending and External Damage 420 * machine checks, they will not be reinjected into the guest 421 * because they refer to host conditions only. 422 */ 423 mcck_dam_code = (mci.val & MCIC_SUBCLASS_MASK); 424 if (test_cpu_flag(CIF_MCCK_GUEST) && 425 (mcck_dam_code & MCCK_CODE_NO_GUEST) != mcck_dam_code) { 426 /* Set exit reason code for host's later handling */ 427 *((long *)(regs->gprs[15] + __SF_SIE_REASON)) = -EINTR; 428 } 429 clear_cpu_flag(CIF_MCCK_GUEST); 430 431 if (mcck_pending) 432 schedule_mcck_handler(); 433 434 irqentry_nmi_exit(regs, irq_state); 435 } 436 NOKPROBE_SYMBOL(s390_do_machine_check); 437 438 static int __init machine_check_init(void) 439 { 440 system_ctl_set_bit(14, CR14_EXTERNAL_DAMAGE_SUBMASK_BIT); 441 system_ctl_set_bit(14, CR14_RECOVERY_SUBMASK_BIT); 442 system_ctl_set_bit(14, CR14_WARNING_SUBMASK_BIT); 443 return 0; 444 } 445 early_initcall(machine_check_init); 446