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/hardirq.h>
15 #include <linux/log2.h>
16 #include <linux/kprobes.h>
17 #include <linux/kmemleak.h>
18 #include <linux/time.h>
19 #include <linux/module.h>
20 #include <linux/sched/signal.h>
21
22 #include <linux/export.h>
23 #include <asm/lowcore.h>
24 #include <asm/smp.h>
25 #include <asm/stp.h>
26 #include <asm/cputime.h>
27 #include <asm/nmi.h>
28 #include <asm/crw.h>
29 #include <asm/switch_to.h>
30 #include <asm/ctl_reg.h>
31 #include <asm/asm-offsets.h>
32 #include <asm/pai.h>
33
34 #include <linux/kvm_host.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 static struct kmem_cache *mcesa_cache;
46 static unsigned long mcesa_origin_lc;
47
nmi_needs_mcesa(void)48 static inline int nmi_needs_mcesa(void)
49 {
50 return MACHINE_HAS_VX || MACHINE_HAS_GS;
51 }
52
nmi_get_mcesa_size(void)53 static inline unsigned long nmi_get_mcesa_size(void)
54 {
55 if (MACHINE_HAS_GS)
56 return MCESA_MAX_SIZE;
57 return MCESA_MIN_SIZE;
58 }
59
60 /*
61 * The initial machine check extended save area for the boot CPU.
62 * It will be replaced on the boot CPU reinit with an allocated
63 * structure. The structure is required for machine check happening
64 * early in the boot process.
65 */
66 static struct mcesa boot_mcesa __aligned(MCESA_MAX_SIZE);
67
nmi_alloc_mcesa_early(u64 * mcesad)68 void __init nmi_alloc_mcesa_early(u64 *mcesad)
69 {
70 if (!nmi_needs_mcesa())
71 return;
72 *mcesad = __pa(&boot_mcesa);
73 if (MACHINE_HAS_GS)
74 *mcesad |= ilog2(MCESA_MAX_SIZE);
75 }
76
nmi_alloc_cache(void)77 static void __init nmi_alloc_cache(void)
78 {
79 unsigned long size;
80
81 if (!nmi_needs_mcesa())
82 return;
83 size = nmi_get_mcesa_size();
84 if (size > MCESA_MIN_SIZE)
85 mcesa_origin_lc = ilog2(size);
86 /* create slab cache for the machine-check-extended-save-areas */
87 mcesa_cache = kmem_cache_create("nmi_save_areas", size, size, 0, NULL);
88 if (!mcesa_cache)
89 panic("Couldn't create nmi save area cache");
90 }
91
nmi_alloc_mcesa(u64 * mcesad)92 int __ref nmi_alloc_mcesa(u64 *mcesad)
93 {
94 unsigned long origin;
95
96 *mcesad = 0;
97 if (!nmi_needs_mcesa())
98 return 0;
99 if (!mcesa_cache)
100 nmi_alloc_cache();
101 origin = (unsigned long) kmem_cache_alloc(mcesa_cache, GFP_KERNEL);
102 if (!origin)
103 return -ENOMEM;
104 /* The pointer is stored with mcesa_bits ORed in */
105 kmemleak_not_leak((void *) origin);
106 *mcesad = __pa(origin) | mcesa_origin_lc;
107 return 0;
108 }
109
nmi_free_mcesa(u64 * mcesad)110 void nmi_free_mcesa(u64 *mcesad)
111 {
112 if (!nmi_needs_mcesa())
113 return;
114 kmem_cache_free(mcesa_cache, __va(*mcesad & MCESA_ORIGIN_MASK));
115 }
116
s390_handle_damage(void)117 static notrace void s390_handle_damage(void)
118 {
119 smp_emergency_stop();
120 disabled_wait();
121 while (1);
122 }
123 NOKPROBE_SYMBOL(s390_handle_damage);
124
125 /*
126 * Main machine check handler function. Will be called with interrupts disabled
127 * and machine checks enabled.
128 */
__s390_handle_mcck(void)129 void __s390_handle_mcck(void)
130 {
131 struct mcck_struct mcck;
132
133 /*
134 * Disable machine checks and get the current state of accumulated
135 * machine checks. Afterwards delete the old state and enable machine
136 * checks again.
137 */
138 local_mcck_disable();
139 mcck = *this_cpu_ptr(&cpu_mcck);
140 memset(this_cpu_ptr(&cpu_mcck), 0, sizeof(mcck));
141 local_mcck_enable();
142
143 if (mcck.channel_report)
144 crw_handle_channel_report();
145 /*
146 * A warning may remain for a prolonged period on the bare iron.
147 * (actually until the machine is powered off, or the problem is gone)
148 * So we just stop listening for the WARNING MCH and avoid continuously
149 * being interrupted. One caveat is however, that we must do this per
150 * processor and cannot use the smp version of ctl_clear_bit().
151 * On VM we only get one interrupt per virtally presented machinecheck.
152 * Though one suffices, we may get one interrupt per (virtual) cpu.
153 */
154 if (mcck.warning) { /* WARNING pending ? */
155 static int mchchk_wng_posted = 0;
156
157 /* Use single cpu clear, as we cannot handle smp here. */
158 __ctl_clear_bit(14, 24); /* Disable WARNING MCH */
159 if (xchg(&mchchk_wng_posted, 1) == 0)
160 kill_cad_pid(SIGPWR, 1);
161 }
162 if (mcck.stp_queue)
163 stp_queue_work();
164 if (mcck.kill_task) {
165 local_irq_enable();
166 printk(KERN_EMERG "mcck: Terminating task because of machine "
167 "malfunction (code 0x%016lx).\n", mcck.mcck_code);
168 printk(KERN_EMERG "mcck: task: %s, pid: %d.\n",
169 current->comm, current->pid);
170 make_task_dead(SIGSEGV);
171 }
172 }
173
s390_handle_mcck(struct pt_regs * regs)174 void noinstr s390_handle_mcck(struct pt_regs *regs)
175 {
176 trace_hardirqs_off();
177 pai_kernel_enter(regs);
178 __s390_handle_mcck();
179 pai_kernel_exit(regs);
180 trace_hardirqs_on();
181 }
182 /*
183 * returns 0 if all required registers are available
184 * returns 1 otherwise
185 */
s390_validate_registers(union mci mci,int umode)186 static int notrace s390_validate_registers(union mci mci, int umode)
187 {
188 struct mcesa *mcesa;
189 void *fpt_save_area;
190 union ctlreg2 cr2;
191 int kill_task;
192 u64 zero;
193
194 kill_task = 0;
195 zero = 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 if (!mci.fp) {
207 /*
208 * Floating point registers can't be restored. If the
209 * kernel currently uses floating point registers the
210 * system is stopped. If the process has its floating
211 * pointer registers loaded it is terminated.
212 */
213 if (S390_lowcore.fpu_flags & KERNEL_VXR_V0V7)
214 s390_handle_damage();
215 if (!test_cpu_flag(CIF_FPU))
216 kill_task = 1;
217 }
218 fpt_save_area = &S390_lowcore.floating_pt_save_area;
219 if (!mci.fc) {
220 /*
221 * Floating point control register can't be restored.
222 * If the kernel currently uses the floating pointer
223 * registers and needs the FPC register the system is
224 * stopped. If the process has its floating pointer
225 * registers loaded it is terminated. Otherwise the
226 * FPC is just validated.
227 */
228 if (S390_lowcore.fpu_flags & KERNEL_FPC)
229 s390_handle_damage();
230 asm volatile(
231 " lfpc %0\n"
232 :
233 : "Q" (zero));
234 if (!test_cpu_flag(CIF_FPU))
235 kill_task = 1;
236 } else {
237 asm volatile(
238 " lfpc %0\n"
239 :
240 : "Q" (S390_lowcore.fpt_creg_save_area));
241 }
242
243 mcesa = __va(S390_lowcore.mcesad & MCESA_ORIGIN_MASK);
244 if (!MACHINE_HAS_VX) {
245 /* Validate floating point registers */
246 asm volatile(
247 " ld 0,0(%0)\n"
248 " ld 1,8(%0)\n"
249 " ld 2,16(%0)\n"
250 " ld 3,24(%0)\n"
251 " ld 4,32(%0)\n"
252 " ld 5,40(%0)\n"
253 " ld 6,48(%0)\n"
254 " ld 7,56(%0)\n"
255 " ld 8,64(%0)\n"
256 " ld 9,72(%0)\n"
257 " ld 10,80(%0)\n"
258 " ld 11,88(%0)\n"
259 " ld 12,96(%0)\n"
260 " ld 13,104(%0)\n"
261 " ld 14,112(%0)\n"
262 " ld 15,120(%0)\n"
263 :
264 : "a" (fpt_save_area)
265 : "memory");
266 } else {
267 /* Validate vector registers */
268 union ctlreg0 cr0;
269
270 /*
271 * The vector validity must only be checked if not running a
272 * KVM guest. For KVM guests the machine check is forwarded by
273 * KVM and it is the responsibility of the guest to take
274 * appropriate actions. The host vector or FPU values have been
275 * saved by KVM and will be restored by KVM.
276 */
277 if (!mci.vr && !test_cpu_flag(CIF_MCCK_GUEST)) {
278 /*
279 * Vector registers can't be restored. If the kernel
280 * currently uses vector registers the system is
281 * stopped. If the process has its vector registers
282 * loaded it is terminated. Otherwise just validate
283 * the registers.
284 */
285 if (S390_lowcore.fpu_flags & KERNEL_VXR)
286 s390_handle_damage();
287 if (!test_cpu_flag(CIF_FPU))
288 kill_task = 1;
289 }
290 cr0.val = S390_lowcore.cregs_save_area[0];
291 cr0.afp = cr0.vx = 1;
292 __ctl_load(cr0.val, 0, 0);
293 asm volatile(
294 " la 1,%0\n"
295 " .word 0xe70f,0x1000,0x0036\n" /* vlm 0,15,0(1) */
296 " .word 0xe70f,0x1100,0x0c36\n" /* vlm 16,31,256(1) */
297 :
298 : "Q" (*(struct vx_array *)mcesa->vector_save_area)
299 : "1");
300 __ctl_load(S390_lowcore.cregs_save_area[0], 0, 0);
301 }
302 /* Validate access registers */
303 asm volatile(
304 " lam 0,15,0(%0)\n"
305 :
306 : "a" (&S390_lowcore.access_regs_save_area)
307 : "memory");
308 if (!mci.ar) {
309 /*
310 * Access registers have unknown contents.
311 * Terminating task.
312 */
313 kill_task = 1;
314 }
315 /* Validate guarded storage registers */
316 cr2.val = S390_lowcore.cregs_save_area[2];
317 if (cr2.gse) {
318 if (!mci.gs) {
319 /*
320 * 2 cases:
321 * - machine check in kernel or userspace
322 * - machine check while running SIE (KVM guest)
323 * For kernel or userspace the userspace values of
324 * guarded storage control can not be recreated, the
325 * process must be terminated.
326 * For SIE the guest values of guarded storage can not
327 * be recreated. This is either due to a bug or due to
328 * GS being disabled in the guest. The guest will be
329 * notified by KVM code and the guests machine check
330 * handling must take care of this. The host values
331 * are saved by KVM and are not affected.
332 */
333 if (!test_cpu_flag(CIF_MCCK_GUEST))
334 kill_task = 1;
335 } else {
336 load_gs_cb((struct gs_cb *)mcesa->guarded_storage_save_area);
337 }
338 }
339 /*
340 * The getcpu vdso syscall reads CPU number from the programmable
341 * field of the TOD clock. Disregard the TOD programmable register
342 * validity bit and load the CPU number into the TOD programmable
343 * field unconditionally.
344 */
345 set_tod_programmable_field(raw_smp_processor_id());
346 /* Validate clock comparator register */
347 set_clock_comparator(S390_lowcore.clock_comparator);
348
349 if (!mci.ms || !mci.pm || !mci.ia)
350 kill_task = 1;
351
352 return kill_task;
353 }
354 NOKPROBE_SYMBOL(s390_validate_registers);
355
356 /*
357 * Backup the guest's machine check info to its description block
358 */
s390_backup_mcck_info(struct pt_regs * regs)359 static void notrace s390_backup_mcck_info(struct pt_regs *regs)
360 {
361 struct mcck_volatile_info *mcck_backup;
362 struct sie_page *sie_page;
363
364 /* r14 contains the sie block, which was set in sie64a */
365 struct kvm_s390_sie_block *sie_block =
366 (struct kvm_s390_sie_block *) regs->gprs[14];
367
368 if (sie_block == NULL)
369 /* Something's seriously wrong, stop system. */
370 s390_handle_damage();
371
372 sie_page = container_of(sie_block, struct sie_page, sie_block);
373 mcck_backup = &sie_page->mcck_info;
374 mcck_backup->mcic = S390_lowcore.mcck_interruption_code &
375 ~(MCCK_CODE_CP | MCCK_CODE_EXT_DAMAGE);
376 mcck_backup->ext_damage_code = S390_lowcore.external_damage_code;
377 mcck_backup->failing_storage_address
378 = S390_lowcore.failing_storage_address;
379 }
380 NOKPROBE_SYMBOL(s390_backup_mcck_info);
381
382 #define MAX_IPD_COUNT 29
383 #define MAX_IPD_TIME (5 * 60 * USEC_PER_SEC) /* 5 minutes */
384
385 #define ED_STP_ISLAND 6 /* External damage STP island check */
386 #define ED_STP_SYNC 7 /* External damage STP sync check */
387
388 #define MCCK_CODE_NO_GUEST (MCCK_CODE_CP | MCCK_CODE_EXT_DAMAGE)
389
390 /*
391 * machine check handler.
392 */
s390_do_machine_check(struct pt_regs * regs)393 int notrace s390_do_machine_check(struct pt_regs *regs)
394 {
395 static int ipd_count;
396 static DEFINE_SPINLOCK(ipd_lock);
397 static unsigned long long last_ipd;
398 struct mcck_struct *mcck;
399 unsigned long long tmp;
400 union mci mci;
401 unsigned long mcck_dam_code;
402 int mcck_pending = 0;
403
404 nmi_enter();
405
406 if (user_mode(regs))
407 update_timer_mcck();
408 inc_irq_stat(NMI_NMI);
409 mci.val = S390_lowcore.mcck_interruption_code;
410 mcck = this_cpu_ptr(&cpu_mcck);
411
412 /*
413 * Reinject the instruction processing damages' machine checks
414 * including Delayed Access Exception into the guest
415 * instead of damaging the host if they happen in the guest.
416 */
417 if (mci.pd && !test_cpu_flag(CIF_MCCK_GUEST)) {
418 if (mci.b) {
419 /* Processing backup -> verify if we can survive this */
420 u64 z_mcic, o_mcic, t_mcic;
421 z_mcic = (1ULL<<63 | 1ULL<<59 | 1ULL<<29);
422 o_mcic = (1ULL<<43 | 1ULL<<42 | 1ULL<<41 | 1ULL<<40 |
423 1ULL<<36 | 1ULL<<35 | 1ULL<<34 | 1ULL<<32 |
424 1ULL<<30 | 1ULL<<21 | 1ULL<<20 | 1ULL<<17 |
425 1ULL<<16);
426 t_mcic = mci.val;
427
428 if (((t_mcic & z_mcic) != 0) ||
429 ((t_mcic & o_mcic) != o_mcic)) {
430 s390_handle_damage();
431 }
432
433 /*
434 * Nullifying exigent condition, therefore we might
435 * retry this instruction.
436 */
437 spin_lock(&ipd_lock);
438 tmp = get_tod_clock();
439 if (((tmp - last_ipd) >> 12) < MAX_IPD_TIME)
440 ipd_count++;
441 else
442 ipd_count = 1;
443 last_ipd = tmp;
444 if (ipd_count == MAX_IPD_COUNT)
445 s390_handle_damage();
446 spin_unlock(&ipd_lock);
447 } else {
448 /* Processing damage -> stopping machine */
449 s390_handle_damage();
450 }
451 }
452 if (s390_validate_registers(mci, user_mode(regs))) {
453 /*
454 * Couldn't restore all register contents for the
455 * user space process -> mark task for termination.
456 */
457 mcck->kill_task = 1;
458 mcck->mcck_code = mci.val;
459 mcck_pending = 1;
460 }
461
462 /*
463 * Backup the machine check's info if it happens when the guest
464 * is running.
465 */
466 if (test_cpu_flag(CIF_MCCK_GUEST))
467 s390_backup_mcck_info(regs);
468
469 if (mci.cd) {
470 /* Timing facility damage */
471 s390_handle_damage();
472 }
473 if (mci.ed && mci.ec) {
474 /* External damage */
475 if (S390_lowcore.external_damage_code & (1U << ED_STP_SYNC))
476 mcck->stp_queue |= stp_sync_check();
477 if (S390_lowcore.external_damage_code & (1U << ED_STP_ISLAND))
478 mcck->stp_queue |= stp_island_check();
479 mcck_pending = 1;
480 }
481
482 if (mci.cp) {
483 /* Channel report word pending */
484 mcck->channel_report = 1;
485 mcck_pending = 1;
486 }
487 if (mci.w) {
488 /* Warning pending */
489 mcck->warning = 1;
490 mcck_pending = 1;
491 }
492
493 /*
494 * If there are only Channel Report Pending and External Damage
495 * machine checks, they will not be reinjected into the guest
496 * because they refer to host conditions only.
497 */
498 mcck_dam_code = (mci.val & MCIC_SUBCLASS_MASK);
499 if (test_cpu_flag(CIF_MCCK_GUEST) &&
500 (mcck_dam_code & MCCK_CODE_NO_GUEST) != mcck_dam_code) {
501 /* Set exit reason code for host's later handling */
502 *((long *)(regs->gprs[15] + __SF_SIE_REASON)) = -EINTR;
503 }
504 clear_cpu_flag(CIF_MCCK_GUEST);
505
506 if (user_mode(regs) && mcck_pending) {
507 nmi_exit();
508 return 1;
509 }
510
511 if (mcck_pending)
512 schedule_mcck_handler();
513
514 nmi_exit();
515 return 0;
516 }
517 NOKPROBE_SYMBOL(s390_do_machine_check);
518
machine_check_init(void)519 static int __init machine_check_init(void)
520 {
521 ctl_set_bit(14, 25); /* enable external damage MCH */
522 ctl_set_bit(14, 27); /* enable system recovery MCH */
523 ctl_set_bit(14, 24); /* enable warning MCH */
524 return 0;
525 }
526 early_initcall(machine_check_init);
527