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 35struct 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 43static DEFINE_PER_CPU(struct mcck_struct, cpu_mcck); 44 45static inline int nmi_needs_mcesa(void) 46{ 47 return cpu_has_vx() || MACHINE_HAS_GS; 48} 49 50/* 51 * The initial machine check extended save area for the boot CPU. 52 * It will be replaced on the boot CPU reinit with an allocated 53 * structure. The structure is required for machine check happening 54 * early in the boot process. 55 */ 56static struct mcesa boot_mcesa __aligned(MCESA_MAX_SIZE); 57 58void __init nmi_alloc_mcesa_early(u64 *mcesad) 59{ 60 if (!nmi_needs_mcesa()) 61 return; 62 *mcesad = __pa(&boot_mcesa); 63 if (MACHINE_HAS_GS) 64 *mcesad |= ilog2(MCESA_MAX_SIZE); 65} 66 67int nmi_alloc_mcesa(u64 *mcesad) 68{ 69 unsigned long size; 70 void *origin; 71 72 *mcesad = 0; 73 if (!nmi_needs_mcesa()) 74 return 0; 75 size = MACHINE_HAS_GS ? MCESA_MAX_SIZE : MCESA_MIN_SIZE; 76 origin = kmalloc(size, GFP_KERNEL); 77 if (!origin) 78 return -ENOMEM; 79 /* The pointer is stored with mcesa_bits ORed in */ 80 kmemleak_not_leak(origin); 81 *mcesad = __pa(origin); 82 if (MACHINE_HAS_GS) 83 *mcesad |= ilog2(MCESA_MAX_SIZE); 84 return 0; 85} 86 87void nmi_free_mcesa(u64 *mcesad) 88{ 89 if (!nmi_needs_mcesa()) 90 return; 91 kfree(__va(*mcesad & MCESA_ORIGIN_MASK)); 92} 93 94static __always_inline char *nmi_puts(char *dest, const char *src) 95{ 96 while (*src) 97 *dest++ = *src++; 98 *dest = 0; 99 return dest; 100} 101 102static __always_inline char *u64_to_hex(char *dest, u64 val) 103{ 104 int i, num; 105 106 for (i = 1; i <= 16; i++) { 107 num = (val >> (64 - 4 * i)) & 0xf; 108 if (num >= 10) 109 *dest++ = 'A' + num - 10; 110 else 111 *dest++ = '0' + num; 112 } 113 *dest = 0; 114 return dest; 115} 116 117static notrace void s390_handle_damage(void) 118{ 119 union ctlreg0 cr0, cr0_new; 120 char message[100]; 121 psw_t psw_save; 122 char *ptr; 123 124 smp_emergency_stop(); 125 diag_amode31_ops.diag308_reset(); 126 ptr = nmi_puts(message, "System stopped due to unrecoverable machine check, code: 0x"); 127 u64_to_hex(ptr, S390_lowcore.mcck_interruption_code); 128 129 /* 130 * Disable low address protection and make machine check new PSW a 131 * disabled wait PSW. Any additional machine check cannot be handled. 132 */ 133 local_ctl_store(0, &cr0.reg); 134 cr0_new = cr0; 135 cr0_new.lap = 0; 136 local_ctl_load(0, &cr0_new.reg); 137 psw_save = S390_lowcore.mcck_new_psw; 138 psw_bits(S390_lowcore.mcck_new_psw).io = 0; 139 psw_bits(S390_lowcore.mcck_new_psw).ext = 0; 140 psw_bits(S390_lowcore.mcck_new_psw).wait = 1; 141 sclp_emergency_printk(message); 142 143 /* 144 * Restore machine check new PSW and control register 0 to original 145 * values. This makes possible system dump analysis easier. 146 */ 147 S390_lowcore.mcck_new_psw = psw_save; 148 local_ctl_load(0, &cr0.reg); 149 disabled_wait(); 150 while (1); 151} 152NOKPROBE_SYMBOL(s390_handle_damage); 153 154/* 155 * Main machine check handler function. Will be called with interrupts disabled 156 * and machine checks enabled. 157 */ 158void s390_handle_mcck(void) 159{ 160 struct mcck_struct mcck; 161 unsigned long mflags; 162 163 /* 164 * Disable machine checks and get the current state of accumulated 165 * machine checks. Afterwards delete the old state and enable machine 166 * checks again. 167 */ 168 local_mcck_save(mflags); 169 mcck = *this_cpu_ptr(&cpu_mcck); 170 memset(this_cpu_ptr(&cpu_mcck), 0, sizeof(mcck)); 171 local_mcck_restore(mflags); 172 173 if (mcck.channel_report) 174 crw_handle_channel_report(); 175 /* 176 * A warning may remain for a prolonged period on the bare iron. 177 * (actually until the machine is powered off, or the problem is gone) 178 * So we just stop listening for the WARNING MCH and avoid continuously 179 * being interrupted. One caveat is however, that we must do this per 180 * processor and cannot use the smp version of ctl_clear_bit(). 181 * On VM we only get one interrupt per virtally presented machinecheck. 182 * Though one suffices, we may get one interrupt per (virtual) cpu. 183 */ 184 if (mcck.warning) { /* WARNING pending ? */ 185 static int mchchk_wng_posted = 0; 186 187 /* Use single cpu clear, as we cannot handle smp here. */ 188 local_ctl_clear_bit(14, CR14_WARNING_SUBMASK_BIT); 189 if (xchg(&mchchk_wng_posted, 1) == 0) 190 kill_cad_pid(SIGPWR, 1); 191 } 192 if (mcck.stp_queue) 193 stp_queue_work(); 194 if (mcck.kill_task) { 195 printk(KERN_EMERG "mcck: Terminating task because of machine " 196 "malfunction (code 0x%016lx).\n", mcck.mcck_code); 197 printk(KERN_EMERG "mcck: task: %s, pid: %d.\n", 198 current->comm, current->pid); 199 if (is_global_init(current)) 200 panic("mcck: Attempting to kill init!\n"); 201 do_send_sig_info(SIGKILL, SEND_SIG_PRIV, current, PIDTYPE_PID); 202 } 203} 204 205/** 206 * nmi_registers_valid - verify if registers are valid 207 * @mci: machine check interruption code 208 * 209 * Inspect a machine check interruption code and verify if all required 210 * registers are valid. For some registers the corresponding validity bit is 211 * ignored and the registers are set to the expected value. 212 * Returns true if all registers are valid, otherwise false. 213 */ 214static bool notrace nmi_registers_valid(union mci mci) 215{ 216 union ctlreg2 cr2; 217 218 /* 219 * The getcpu vdso syscall reads the CPU number from the programmable 220 * field of the TOD clock. Disregard the TOD programmable register 221 * validity bit and load the CPU number into the TOD programmable field 222 * unconditionally. 223 */ 224 set_tod_programmable_field(raw_smp_processor_id()); 225 /* 226 * Set the clock comparator register to the next expected value. 227 */ 228 set_clock_comparator(S390_lowcore.clock_comparator); 229 if (!mci.gr || !mci.fp || !mci.fc) 230 return false; 231 /* 232 * The vector validity must only be checked if not running a 233 * KVM guest. For KVM guests the machine check is forwarded by 234 * KVM and it is the responsibility of the guest to take 235 * appropriate actions. The host vector or FPU values have been 236 * saved by KVM and will be restored by KVM. 237 */ 238 if (!mci.vr && !test_cpu_flag(CIF_MCCK_GUEST)) 239 return false; 240 if (!mci.ar) 241 return false; 242 /* 243 * Two cases for guarded storage registers: 244 * - machine check in kernel or userspace 245 * - machine check while running SIE (KVM guest) 246 * For kernel or userspace the userspace values of guarded storage 247 * control can not be recreated, the process must be terminated. 248 * For SIE the guest values of guarded storage can not be recreated. 249 * This is either due to a bug or due to GS being disabled in the 250 * guest. The guest will be notified by KVM code and the guests machine 251 * check handling must take care of this. The host values are saved by 252 * KVM and are not affected. 253 */ 254 cr2.reg = S390_lowcore.cregs_save_area[2]; 255 if (cr2.gse && !mci.gs && !test_cpu_flag(CIF_MCCK_GUEST)) 256 return false; 257 if (!mci.ms || !mci.pm || !mci.ia) 258 return false; 259 return true; 260} 261NOKPROBE_SYMBOL(nmi_registers_valid); 262 263/* 264 * Backup the guest's machine check info to its description block 265 */ 266static void notrace s390_backup_mcck_info(struct pt_regs *regs) 267{ 268 struct mcck_volatile_info *mcck_backup; 269 struct sie_page *sie_page; 270 271 /* r14 contains the sie block, which was set in sie64a */ 272 struct kvm_s390_sie_block *sie_block = phys_to_virt(regs->gprs[14]); 273 274 if (sie_block == NULL) 275 /* Something's seriously wrong, stop system. */ 276 s390_handle_damage(); 277 278 sie_page = container_of(sie_block, struct sie_page, sie_block); 279 mcck_backup = &sie_page->mcck_info; 280 mcck_backup->mcic = S390_lowcore.mcck_interruption_code & 281 ~(MCCK_CODE_CP | MCCK_CODE_EXT_DAMAGE); 282 mcck_backup->ext_damage_code = S390_lowcore.external_damage_code; 283 mcck_backup->failing_storage_address 284 = S390_lowcore.failing_storage_address; 285} 286NOKPROBE_SYMBOL(s390_backup_mcck_info); 287 288#define MAX_IPD_COUNT 29 289#define MAX_IPD_TIME (5 * 60 * USEC_PER_SEC) /* 5 minutes */ 290 291#define ED_STP_ISLAND 6 /* External damage STP island check */ 292#define ED_STP_SYNC 7 /* External damage STP sync check */ 293 294#define MCCK_CODE_NO_GUEST (MCCK_CODE_CP | MCCK_CODE_EXT_DAMAGE) 295 296/* 297 * machine check handler. 298 */ 299void notrace s390_do_machine_check(struct pt_regs *regs) 300{ 301 static int ipd_count; 302 static DEFINE_SPINLOCK(ipd_lock); 303 static unsigned long long last_ipd; 304 struct mcck_struct *mcck; 305 unsigned long long tmp; 306 irqentry_state_t irq_state; 307 union mci mci; 308 unsigned long mcck_dam_code; 309 int mcck_pending = 0; 310 311 irq_state = irqentry_nmi_enter(regs); 312 313 if (user_mode(regs)) 314 update_timer_mcck(); 315 inc_irq_stat(NMI_NMI); 316 mci.val = S390_lowcore.mcck_interruption_code; 317 mcck = this_cpu_ptr(&cpu_mcck); 318 319 /* 320 * Reinject the instruction processing damages' machine checks 321 * including Delayed Access Exception into the guest 322 * instead of damaging the host if they happen in the guest. 323 */ 324 if (mci.pd && !test_cpu_flag(CIF_MCCK_GUEST)) { 325 if (mci.b) { 326 /* Processing backup -> verify if we can survive this */ 327 u64 z_mcic, o_mcic, t_mcic; 328 z_mcic = (1ULL<<63 | 1ULL<<59 | 1ULL<<29); 329 o_mcic = (1ULL<<43 | 1ULL<<42 | 1ULL<<41 | 1ULL<<40 | 330 1ULL<<36 | 1ULL<<35 | 1ULL<<34 | 1ULL<<32 | 331 1ULL<<30 | 1ULL<<21 | 1ULL<<20 | 1ULL<<17 | 332 1ULL<<16); 333 t_mcic = mci.val; 334 335 if (((t_mcic & z_mcic) != 0) || 336 ((t_mcic & o_mcic) != o_mcic)) { 337 s390_handle_damage(); 338 } 339 340 /* 341 * Nullifying exigent condition, therefore we might 342 * retry this instruction. 343 */ 344 spin_lock(&ipd_lock); 345 tmp = get_tod_clock(); 346 if (((tmp - last_ipd) >> 12) < MAX_IPD_TIME) 347 ipd_count++; 348 else 349 ipd_count = 1; 350 last_ipd = tmp; 351 if (ipd_count == MAX_IPD_COUNT) 352 s390_handle_damage(); 353 spin_unlock(&ipd_lock); 354 } else { 355 /* Processing damage -> stopping machine */ 356 s390_handle_damage(); 357 } 358 } 359 if (!nmi_registers_valid(mci)) { 360 if (!user_mode(regs)) 361 s390_handle_damage(); 362 /* 363 * Couldn't restore all register contents for the 364 * user space process -> mark task for termination. 365 */ 366 mcck->kill_task = 1; 367 mcck->mcck_code = mci.val; 368 mcck_pending = 1; 369 } 370 371 /* 372 * Backup the machine check's info if it happens when the guest 373 * is running. 374 */ 375 if (test_cpu_flag(CIF_MCCK_GUEST)) 376 s390_backup_mcck_info(regs); 377 378 if (mci.cd) { 379 /* Timing facility damage */ 380 s390_handle_damage(); 381 } 382 if (mci.ed && mci.ec) { 383 /* External damage */ 384 if (S390_lowcore.external_damage_code & (1U << ED_STP_SYNC)) 385 mcck->stp_queue |= stp_sync_check(); 386 if (S390_lowcore.external_damage_code & (1U << ED_STP_ISLAND)) 387 mcck->stp_queue |= stp_island_check(); 388 mcck_pending = 1; 389 } 390 /* 391 * Reinject storage related machine checks into the guest if they 392 * happen when the guest is running. 393 */ 394 if (!test_cpu_flag(CIF_MCCK_GUEST)) { 395 /* Storage error uncorrected */ 396 if (mci.se) 397 s390_handle_damage(); 398 /* Storage key-error uncorrected */ 399 if (mci.ke) 400 s390_handle_damage(); 401 /* Storage degradation */ 402 if (mci.ds && mci.fa) 403 s390_handle_damage(); 404 } 405 if (mci.cp) { 406 /* Channel report word pending */ 407 mcck->channel_report = 1; 408 mcck_pending = 1; 409 } 410 if (mci.w) { 411 /* Warning pending */ 412 mcck->warning = 1; 413 mcck_pending = 1; 414 } 415 416 /* 417 * If there are only Channel Report Pending and External Damage 418 * machine checks, they will not be reinjected into the guest 419 * because they refer to host conditions only. 420 */ 421 mcck_dam_code = (mci.val & MCIC_SUBCLASS_MASK); 422 if (test_cpu_flag(CIF_MCCK_GUEST) && 423 (mcck_dam_code & MCCK_CODE_NO_GUEST) != mcck_dam_code) { 424 /* Set exit reason code for host's later handling */ 425 *((long *)(regs->gprs[15] + __SF_SIE_REASON)) = -EINTR; 426 } 427 clear_cpu_flag(CIF_MCCK_GUEST); 428 429 if (mcck_pending) 430 schedule_mcck_handler(); 431 432 irqentry_nmi_exit(regs, irq_state); 433} 434NOKPROBE_SYMBOL(s390_do_machine_check); 435 436static int __init machine_check_init(void) 437{ 438 system_ctl_set_bit(14, CR14_EXTERNAL_DAMAGE_SUBMASK_BIT); 439 system_ctl_set_bit(14, CR14_RECOVERY_SUBMASK_BIT); 440 system_ctl_set_bit(14, CR14_WARNING_SUBMASK_BIT); 441 return 0; 442} 443early_initcall(machine_check_init); 444