arch/s390/kernel/nmi.c

   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         local_mcck_enable();
 152         local_irq_restore(flags);
 153
 154         if (mcck.channel_report)
 155                 crw_handle_channel_report();
 156         /*
 157          * A warning may remain for a prolonged period on the bare iron.
 158          * (actually until the machine is powered off, or the problem is gone)
 159          * So we just stop listening for the WARNING MCH and avoid continuously
 160          * being interrupted.  One caveat is however, that we must do this per
 161          * processor and cannot use the smp version of ctl_clear_bit().
 162          * On VM we only get one interrupt per virtally presented machinecheck.
 163          * Though one suffices, we may get one interrupt per (virtual) cpu.
 164          */
 165         if (mcck.warning) {     /* WARNING pending ? */
 166                 static int mchchk_wng_posted = 0;
 167
 168                 /* Use single cpu clear, as we cannot handle smp here. */
 169                 __ctl_clear_bit(14, 24);        /* Disable WARNING MCH */
 170                 if (xchg(&mchchk_wng_posted, 1) == 0)
 171                         kill_cad_pid(SIGPWR, 1);
 172         }
 173         if (mcck.stp_queue)
 174                 stp_queue_work();
 175         if (mcck.kill_task) {
 176                 local_irq_enable();
 177                 printk(KERN_EMERG "mcck: Terminating task because of machine "
 178                        "malfunction (code 0x%016lx).\n", mcck.mcck_code);
 179                 printk(KERN_EMERG "mcck: task: %s, pid: %d.\n",
 180                        current->comm, current->pid);
 181                 do_exit(SIGSEGV);
 182         }
 183 }
 184 EXPORT_SYMBOL_GPL(s390_handle_mcck);
 185
 186 /*
 187  * returns 0 if all required registers are available
 188  * returns 1 otherwise
 189  */
 190 static int notrace s390_check_registers(union mci mci, int umode)
 191 {
 192         union ctlreg2 cr2;
 193         int kill_task;
 194
 195         kill_task = 0;
 196
 197         if (!mci.gr) {
 198                 /*
 199                  * General purpose registers couldn't be restored and have
 200                  * unknown contents. Stop system or terminate process.
 201                  */
 202                 if (!umode)
 203                         s390_handle_damage();
 204                 kill_task = 1;
 205         }
 206         /* Check control registers */
 207         if (!mci.cr) {
 208                 /*
 209                  * Control registers have unknown contents.
 210                  * Can't recover and therefore stopping machine.
 211                  */
 212                 s390_handle_damage();
 213         }
 214         if (!mci.fp) {
 215                 /*
 216                  * Floating point registers can't be restored. If the
 217                  * kernel currently uses floating point registers the
 218                  * system is stopped. If the process has its floating
 219                  * pointer registers loaded it is terminated.
 220                  */
 221                 if (S390_lowcore.fpu_flags & KERNEL_VXR_V0V7)
 222                         s390_handle_damage();
 223                 if (!test_cpu_flag(CIF_FPU))
 224                         kill_task = 1;
 225         }
 226         if (!mci.fc) {
 227                 /*
 228                  * Floating point control register can't be restored.
 229                  * If the kernel currently uses the floating pointer
 230                  * registers and needs the FPC register the system is
 231                  * stopped. If the process has its floating pointer
 232                  * registers loaded it is terminated.
 233                  */
 234                 if (S390_lowcore.fpu_flags & KERNEL_FPC)
 235                         s390_handle_damage();
 236                 if (!test_cpu_flag(CIF_FPU))
 237                         kill_task = 1;
 238         }
 239
 240         if (MACHINE_HAS_VX) {
 241                 if (!mci.vr) {
 242                         /*
 243                          * Vector registers can't be restored. If the kernel
 244                          * currently uses vector registers the system is
 245                          * stopped. If the process has its vector registers
 246                          * loaded it is terminated.
 247                          */
 248                         if (S390_lowcore.fpu_flags & KERNEL_VXR)
 249                                 s390_handle_damage();
 250                         if (!test_cpu_flag(CIF_FPU))
 251                                 kill_task = 1;
 252                 }
 253         }
 254         /* Check if access registers are valid */
 255         if (!mci.ar) {
 256                 /*
 257                  * Access registers have unknown contents.
 258                  * Terminating task.
 259                  */
 260                 kill_task = 1;
 261         }
 262         /* Check guarded storage registers */
 263         cr2.val = S390_lowcore.cregs_save_area[2];
 264         if (cr2.gse) {
 265                 if (!mci.gs) {
 266                         /*
 267                          * Guarded storage register can't be restored and
 268                          * the current processes uses guarded storage.
 269                          * It has to be terminated.
 270                          */
 271                         kill_task = 1;
 272                 }
 273         }
 274         /* Check if old PSW is valid */
 275         if (!mci.wp) {
 276                 /*
 277                  * Can't tell if we come from user or kernel mode
 278                  * -> stopping machine.
 279                  */
 280                 s390_handle_damage();
 281         }
 282         /* Check for invalid kernel instruction address */
 283         if (!mci.ia && !umode) {
 284                 /*
 285                  * The instruction address got lost while running
 286                  * in the kernel -> stopping machine.
 287                  */
 288                 s390_handle_damage();
 289         }
 290
 291         if (!mci.ms || !mci.pm || !mci.ia)
 292                 kill_task = 1;
 293
 294         return kill_task;
 295 }
 296 NOKPROBE_SYMBOL(s390_check_registers);
 297
 298 /*
 299  * Backup the guest's machine check info to its description block
 300  */
 301 static void notrace s390_backup_mcck_info(struct pt_regs *regs)
 302 {
 303         struct mcck_volatile_info *mcck_backup;
 304         struct sie_page *sie_page;
 305
 306         /* r14 contains the sie block, which was set in sie64a */
 307         struct kvm_s390_sie_block *sie_block =
 308                         (struct kvm_s390_sie_block *) regs->gprs[14];
 309
 310         if (sie_block == NULL)
 311                 /* Something's seriously wrong, stop system. */
 312                 s390_handle_damage();
 313
 314         sie_page = container_of(sie_block, struct sie_page, sie_block);
 315         mcck_backup = &sie_page->mcck_info;
 316         mcck_backup->mcic = S390_lowcore.mcck_interruption_code &
 317                                 ~(MCCK_CODE_CP | MCCK_CODE_EXT_DAMAGE);
 318         mcck_backup->ext_damage_code = S390_lowcore.external_damage_code;
 319         mcck_backup->failing_storage_address
 320                         = S390_lowcore.failing_storage_address;
 321 }
 322 NOKPROBE_SYMBOL(s390_backup_mcck_info);
 323
 324 #define MAX_IPD_COUNT   29
 325 #define MAX_IPD_TIME    (5 * 60 * USEC_PER_SEC) /* 5 minutes */
 326
 327 #define ED_STP_ISLAND   6       /* External damage STP island check */
 328 #define ED_STP_SYNC     7       /* External damage STP sync check */
 329
 330 #define MCCK_CODE_NO_GUEST      (MCCK_CODE_CP | MCCK_CODE_EXT_DAMAGE)
 331
 332 /*
 333  * machine check handler.
 334  */
 335 int notrace s390_do_machine_check(struct pt_regs *regs)
 336 {
 337         static int ipd_count;
 338         static DEFINE_SPINLOCK(ipd_lock);
 339         static unsigned long long last_ipd;
 340         struct mcck_struct *mcck;
 341         unsigned long long tmp;
 342         union mci mci;
 343         unsigned long mcck_dam_code;
 344         int mcck_pending = 0;
 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                 mcck_pending = 1;
 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                 mcck_pending = 1;
 424         }
 425
 426         /*
 427          * Reinject storage related machine checks into the guest if they
 428          * happen when the guest is running.
 429          */
 430         if (!test_cpu_flag(CIF_MCCK_GUEST)) {
 431                 if (mci.se)
 432                         /* Storage error uncorrected */
 433                         s390_handle_damage();
 434                 if (mci.ke)
 435                         /* Storage key-error uncorrected */
 436                         s390_handle_damage();
 437                 if (mci.ds && mci.fa)
 438                         /* Storage degradation */
 439                         s390_handle_damage();
 440         }
 441         if (mci.cp) {
 442                 /* Channel report word pending */
 443                 mcck->channel_report = 1;
 444                 mcck_pending = 1;
 445         }
 446         if (mci.w) {
 447                 /* Warning pending */
 448                 mcck->warning = 1;
 449                 mcck_pending = 1;
 450         }
 451
 452         /*
 453          * If there are only Channel Report Pending and External Damage
 454          * machine checks, they will not be reinjected into the guest
 455          * because they refer to host conditions only.
 456          */
 457         mcck_dam_code = (mci.val & MCIC_SUBCLASS_MASK);
 458         if (test_cpu_flag(CIF_MCCK_GUEST) &&
 459         (mcck_dam_code & MCCK_CODE_NO_GUEST) != mcck_dam_code) {
 460                 /* Set exit reason code for host's later handling */
 461                 *((long *)(regs->gprs[15] + __SF_SIE_REASON)) = -EINTR;
 462         }
 463         clear_cpu_flag(CIF_MCCK_GUEST);
 464
 465         if (user_mode(regs) && mcck_pending) {
 466                 nmi_exit();
 467                 return 1;
 468         }
 469
 470         if (mcck_pending)
 471                 schedule_mcck_handler();
 472
 473         nmi_exit();
 474         return 0;
 475 }
 476 NOKPROBE_SYMBOL(s390_do_machine_check);
 477
 478 static int __init machine_check_init(void)
 479 {
 480         ctl_set_bit(14, 25);    /* enable external damage MCH */
 481         ctl_set_bit(14, 27);    /* enable system recovery MCH */
 482         ctl_set_bit(14, 24);    /* enable warning MCH */
 483         return 0;
 484 }
 485 early_initcall(machine_check_init);