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/utsname.h>
13#include <linux/cpufeature.h>
14#include <linux/init.h>
15#include <linux/errno.h>
16#include <linux/entry-common.h>
17#include <linux/hardirq.h>
18#include <linux/log2.h>
19#include <linux/kprobes.h>
20#include <linux/kmemleak.h>
21#include <linux/time.h>
22#include <linux/module.h>
23#include <linux/sched/signal.h>
24#include <linux/kvm_host.h>
25#include <asm/lowcore.h>
26#include <asm/ctlreg.h>
27#include <asm/fpu.h>
28#include <asm/smp.h>
29#include <asm/stp.h>
30#include <asm/cputime.h>
31#include <asm/nmi.h>
32#include <asm/crw.h>
33#include <asm/asm-offsets.h>
34#include <asm/pai.h>
35#include <asm/vtime.h>
36
37struct mcck_struct {
38 unsigned int kill_task : 1;
39 unsigned int channel_report : 1;
40 unsigned int warning : 1;
41 unsigned int stp_queue : 1;
42 unsigned long mcck_code;
43};
44
45static DEFINE_PER_CPU(struct mcck_struct, cpu_mcck);
46
47static inline int nmi_needs_mcesa(void)
48{
49 return cpu_has_vx() || cpu_has_gs();
50}
51
52/*
53 * The initial machine check extended save area for the boot CPU.
54 * It will be replaced on the boot CPU reinit with an allocated
55 * structure. The structure is required for machine check happening
56 * early in the boot process.
57 */
58static struct mcesa boot_mcesa __aligned(MCESA_MAX_SIZE);
59
60void __init nmi_alloc_mcesa_early(u64 *mcesad)
61{
62 if (!nmi_needs_mcesa())
63 return;
64 *mcesad = __pa(&boot_mcesa);
65 if (cpu_has_gs())
66 *mcesad |= ilog2(MCESA_MAX_SIZE);
67}
68
69int nmi_alloc_mcesa(u64 *mcesad)
70{
71 unsigned long size;
72 void *origin;
73
74 *mcesad = 0;
75 if (!nmi_needs_mcesa())
76 return 0;
77 size = cpu_has_gs() ? MCESA_MAX_SIZE : MCESA_MIN_SIZE;
78 origin = kmalloc(size, GFP_KERNEL);
79 if (!origin)
80 return -ENOMEM;
81 /* The pointer is stored with mcesa_bits ORed in */
82 kmemleak_not_leak(ptr: origin);
83 *mcesad = __pa(origin);
84 if (cpu_has_gs())
85 *mcesad |= ilog2(MCESA_MAX_SIZE);
86 return 0;
87}
88
89void nmi_free_mcesa(u64 *mcesad)
90{
91 if (!nmi_needs_mcesa())
92 return;
93 kfree(__va(*mcesad & MCESA_ORIGIN_MASK));
94}
95
96static __always_inline char *nmi_puts(char *dest, const char *src)
97{
98 while (*src)
99 *dest++ = *src++;
100 *dest = 0;
101 return dest;
102}
103
104static __always_inline char *u64_to_hex(char *dest, u64 val)
105{
106 int i, num;
107
108 for (i = 1; i <= 16; i++) {
109 num = (val >> (64 - 4 * i)) & 0xf;
110 if (num >= 10)
111 *dest++ = 'A' + num - 10;
112 else
113 *dest++ = '0' + num;
114 }
115 *dest = 0;
116 return dest;
117}
118
119static notrace void nmi_print_info(void)
120{
121 struct lowcore *lc = get_lowcore();
122 char message[100];
123 char *ptr;
124 int i;
125
126 ptr = nmi_puts(dest: message, src: "Unrecoverable machine check, code: ");
127 ptr = u64_to_hex(dest: ptr, val: lc->mcck_interruption_code);
128 ptr = nmi_puts(dest: ptr, src: "\n");
129 sclp_emergency_printk(message);
130
131 ptr = nmi_puts(dest: message, src: init_utsname()->release);
132 ptr = nmi_puts(dest: ptr, src: "\n");
133 sclp_emergency_printk(message);
134
135 ptr = nmi_puts(dest: message, src: arch_hw_string);
136 ptr = nmi_puts(dest: ptr, src: "\n");
137 sclp_emergency_printk(message);
138
139 ptr = nmi_puts(dest: message, src: "PSW: ");
140 ptr = u64_to_hex(dest: ptr, val: lc->mcck_old_psw.mask);
141 ptr = nmi_puts(dest: ptr, src: " ");
142 ptr = u64_to_hex(dest: ptr, val: lc->mcck_old_psw.addr);
143 ptr = nmi_puts(dest: ptr, src: " PFX: ");
144 ptr = u64_to_hex(dest: ptr, val: (u64)get_lowcore());
145 ptr = nmi_puts(dest: ptr, src: "\n");
146 sclp_emergency_printk(message);
147
148 ptr = nmi_puts(dest: message, src: "LBA: ");
149 ptr = u64_to_hex(dest: ptr, val: lc->last_break_save_area);
150 ptr = nmi_puts(dest: ptr, src: " EDC: ");
151 ptr = u64_to_hex(dest: ptr, val: lc->external_damage_code);
152 ptr = nmi_puts(dest: ptr, src: " FSA: ");
153 ptr = u64_to_hex(dest: ptr, val: lc->failing_storage_address);
154 ptr = nmi_puts(dest: ptr, src: "\n");
155 sclp_emergency_printk(message);
156
157 ptr = nmi_puts(dest: message, src: "CRS:\n");
158 sclp_emergency_printk(message);
159 ptr = message;
160 for (i = 0; i < 16; i++) {
161 ptr = u64_to_hex(dest: ptr, val: lc->cregs_save_area[i].val);
162 ptr = nmi_puts(dest: ptr, src: " ");
163 if ((i + 1) % 4 == 0) {
164 ptr = nmi_puts(dest: ptr, src: "\n");
165 sclp_emergency_printk(message);
166 ptr = message;
167 }
168 }
169
170 ptr = nmi_puts(dest: message, src: "GPRS:\n");
171 sclp_emergency_printk(message);
172 ptr = message;
173 for (i = 0; i < 16; i++) {
174 ptr = u64_to_hex(dest: ptr, val: lc->gpregs_save_area[i]);
175 ptr = nmi_puts(dest: ptr, src: " ");
176 if ((i + 1) % 4 == 0) {
177 ptr = nmi_puts(dest: ptr, src: "\n");
178 sclp_emergency_printk(message);
179 ptr = message;
180 }
181 }
182
183 ptr = nmi_puts(dest: message, src: "System stopped\n");
184 sclp_emergency_printk(message);
185}
186
187static notrace void __noreturn s390_handle_damage(void)
188{
189 struct lowcore *lc = get_lowcore();
190 union ctlreg0 cr0, cr0_new;
191 psw_t psw_save;
192
193 smp_emergency_stop();
194 diag_amode31_ops.diag308_reset();
195
196 /*
197 * Disable low address protection and make machine check new PSW a
198 * disabled wait PSW. Any additional machine check cannot be handled.
199 */
200 local_ctl_store(0, &cr0.reg);
201 cr0_new = cr0;
202 cr0_new.lap = 0;
203 local_ctl_load(0, &cr0_new.reg);
204 psw_save = lc->mcck_new_psw;
205 psw_bits(lc->mcck_new_psw).io = 0;
206 psw_bits(lc->mcck_new_psw).ext = 0;
207 psw_bits(lc->mcck_new_psw).wait = 1;
208 nmi_print_info();
209
210 /*
211 * Restore machine check new PSW and control register 0 to original
212 * values. This makes possible system dump analysis easier.
213 */
214 lc->mcck_new_psw = psw_save;
215 local_ctl_load(0, &cr0.reg);
216 disabled_wait();
217}
218NOKPROBE_SYMBOL(s390_handle_damage);
219
220/*
221 * Main machine check handler function. Will be called with interrupts disabled
222 * and machine checks enabled.
223 */
224void s390_handle_mcck(void)
225{
226 struct mcck_struct mcck;
227 unsigned long mflags;
228
229 /*
230 * Disable machine checks and get the current state of accumulated
231 * machine checks. Afterwards delete the old state and enable machine
232 * checks again.
233 */
234 local_mcck_save(mflags);
235 mcck = *this_cpu_ptr(&cpu_mcck);
236 memset(this_cpu_ptr(&cpu_mcck), 0, sizeof(mcck));
237 local_mcck_restore(mflags);
238
239 if (mcck.channel_report)
240 crw_handle_channel_report();
241 /*
242 * A warning may remain for a prolonged period on the bare iron.
243 * (actually until the machine is powered off, or the problem is gone)
244 * So we just stop listening for the WARNING MCH and avoid continuously
245 * being interrupted. One caveat is however, that we must do this per
246 * processor and cannot use the smp version of ctl_clear_bit().
247 * On VM we only get one interrupt per virtally presented machinecheck.
248 * Though one suffices, we may get one interrupt per (virtual) cpu.
249 */
250 if (mcck.warning) { /* WARNING pending ? */
251 static int mchchk_wng_posted = 0;
252
253 /* Use single cpu clear, as we cannot handle smp here. */
254 local_ctl_clear_bit(14, CR14_WARNING_SUBMASK_BIT);
255 if (xchg(&mchchk_wng_posted, 1) == 0)
256 kill_cad_pid(SIGPWR, priv: 1);
257 }
258 if (mcck.stp_queue)
259 stp_queue_work();
260 if (mcck.kill_task) {
261 printk(KERN_EMERG "mcck: Terminating task because of machine "
262 "malfunction (code 0x%016lx).\n", mcck.mcck_code);
263 printk(KERN_EMERG "mcck: task: %s, pid: %d.\n",
264 current->comm, current->pid);
265 if (is_global_init(current))
266 panic(fmt: "mcck: Attempting to kill init!\n");
267 do_send_sig_info(SIGKILL, SEND_SIG_PRIV, current, type: PIDTYPE_PID);
268 }
269}
270
271/**
272 * nmi_registers_valid - verify if registers are valid
273 * @mci: machine check interruption code
274 *
275 * Inspect a machine check interruption code and verify if all required
276 * registers are valid. For some registers the corresponding validity bit is
277 * ignored and the registers are set to the expected value.
278 * Returns true if all registers are valid, otherwise false.
279 */
280static bool notrace nmi_registers_valid(union mci mci)
281{
282 union ctlreg2 cr2;
283
284 /*
285 * The getcpu vdso syscall reads the CPU number from the programmable
286 * field of the TOD clock. Disregard the TOD programmable register
287 * validity bit and load the CPU number into the TOD programmable field
288 * unconditionally.
289 */
290 set_tod_programmable_field(raw_smp_processor_id());
291 /*
292 * Set the clock comparator register to the next expected value.
293 */
294 set_clock_comparator(get_lowcore()->clock_comparator);
295 if (!mci.gr || !mci.fp || !mci.fc)
296 return false;
297 /*
298 * The vector validity must only be checked if not running a
299 * KVM guest. For KVM guests the machine check is forwarded by
300 * KVM and it is the responsibility of the guest to take
301 * appropriate actions. The host vector or FPU values have been
302 * saved by KVM and will be restored by KVM.
303 */
304 if (!mci.vr && !test_cpu_flag(CIF_MCCK_GUEST))
305 return false;
306 if (!mci.ar)
307 return false;
308 /*
309 * Two cases for guarded storage registers:
310 * - machine check in kernel or userspace
311 * - machine check while running SIE (KVM guest)
312 * For kernel or userspace the userspace values of guarded storage
313 * control can not be recreated, the process must be terminated.
314 * For SIE the guest values of guarded storage can not be recreated.
315 * This is either due to a bug or due to GS being disabled in the
316 * guest. The guest will be notified by KVM code and the guests machine
317 * check handling must take care of this. The host values are saved by
318 * KVM and are not affected.
319 */
320 cr2.reg = get_lowcore()->cregs_save_area[2];
321 if (cr2.gse && !mci.gs && !test_cpu_flag(CIF_MCCK_GUEST))
322 return false;
323 if (!mci.ms || !mci.pm || !mci.ia)
324 return false;
325 return true;
326}
327NOKPROBE_SYMBOL(nmi_registers_valid);
328
329/*
330 * Backup the guest's machine check info to its description block
331 */
332static void notrace s390_backup_mcck_info(struct pt_regs *regs)
333{
334 struct mcck_volatile_info *mcck_backup;
335 struct sie_page *sie_page;
336
337 /* r14 contains the sie block, which was set in sie64a */
338 struct kvm_s390_sie_block *sie_block = phys_to_virt(address: regs->gprs[14]);
339
340 if (sie_block == NULL)
341 /* Something's seriously wrong, stop system. */
342 s390_handle_damage();
343
344 sie_page = container_of(sie_block, struct sie_page, sie_block);
345 mcck_backup = &sie_page->mcck_info;
346 mcck_backup->mcic = get_lowcore()->mcck_interruption_code &
347 ~(MCCK_CODE_CP | MCCK_CODE_EXT_DAMAGE);
348 mcck_backup->ext_damage_code = get_lowcore()->external_damage_code;
349 mcck_backup->failing_storage_address = get_lowcore()->failing_storage_address;
350}
351NOKPROBE_SYMBOL(s390_backup_mcck_info);
352
353#define MAX_IPD_COUNT 29
354#define MAX_IPD_TIME (5 * 60 * USEC_PER_SEC) /* 5 minutes */
355
356#define ED_STP_ISLAND 6 /* External damage STP island check */
357#define ED_STP_SYNC 7 /* External damage STP sync check */
358
359#define MCCK_CODE_NO_GUEST (MCCK_CODE_CP | MCCK_CODE_EXT_DAMAGE)
360
361/*
362 * machine check handler.
363 */
364void notrace s390_do_machine_check(struct pt_regs *regs)
365{
366 static int ipd_count;
367 static DEFINE_SPINLOCK(ipd_lock);
368 static unsigned long long last_ipd;
369 struct lowcore *lc = get_lowcore();
370 struct mcck_struct *mcck;
371 unsigned long long tmp;
372 irqentry_state_t irq_state;
373 union mci mci;
374 unsigned long mcck_dam_code;
375 int mcck_pending = 0;
376
377 irq_state = irqentry_nmi_enter(regs);
378
379 if (user_mode(regs))
380 update_timer_mcck();
381 inc_irq_stat(NMI_NMI);
382 mci.val = lc->mcck_interruption_code;
383 mcck = this_cpu_ptr(&cpu_mcck);
384
385 /*
386 * Reinject the instruction processing damages' machine checks
387 * including Delayed Access Exception into the guest
388 * instead of damaging the host if they happen in the guest.
389 */
390 if (mci.pd && !test_cpu_flag(CIF_MCCK_GUEST)) {
391 if (mci.b) {
392 /* Processing backup -> verify if we can survive this */
393 u64 z_mcic, o_mcic, t_mcic;
394 z_mcic = (1ULL<<63 | 1ULL<<59 | 1ULL<<29);
395 o_mcic = (1ULL<<43 | 1ULL<<42 | 1ULL<<41 | 1ULL<<40 |
396 1ULL<<36 | 1ULL<<35 | 1ULL<<34 | 1ULL<<32 |
397 1ULL<<30 | 1ULL<<21 | 1ULL<<20 | 1ULL<<17 |
398 1ULL<<16);
399 t_mcic = mci.val;
400
401 if (((t_mcic & z_mcic) != 0) ||
402 ((t_mcic & o_mcic) != o_mcic)) {
403 s390_handle_damage();
404 }
405
406 /*
407 * Nullifying exigent condition, therefore we might
408 * retry this instruction.
409 */
410 spin_lock(lock: &ipd_lock);
411 tmp = get_tod_clock();
412 if (((tmp - last_ipd) >> 12) < MAX_IPD_TIME)
413 ipd_count++;
414 else
415 ipd_count = 1;
416 last_ipd = tmp;
417 if (ipd_count == MAX_IPD_COUNT)
418 s390_handle_damage();
419 spin_unlock(lock: &ipd_lock);
420 } else {
421 /* Processing damage -> stopping machine */
422 s390_handle_damage();
423 }
424 }
425 if (!nmi_registers_valid(mci: mci)) {
426 if (!user_mode(regs))
427 s390_handle_damage();
428 /*
429 * Couldn't restore all register contents for the
430 * user space process -> mark task for termination.
431 */
432 mcck->kill_task = 1;
433 mcck->mcck_code = mci.val;
434 mcck_pending = 1;
435 }
436
437 /*
438 * Backup the machine check's info if it happens when the guest
439 * is running.
440 */
441 if (test_cpu_flag(CIF_MCCK_GUEST))
442 s390_backup_mcck_info(regs);
443
444 if (mci.cd) {
445 /* Timing facility damage */
446 s390_handle_damage();
447 }
448 if (mci.ed && mci.ec) {
449 /* External damage */
450 if (lc->external_damage_code & (1U << ED_STP_SYNC))
451 mcck->stp_queue |= stp_sync_check();
452 if (lc->external_damage_code & (1U << ED_STP_ISLAND))
453 mcck->stp_queue |= stp_island_check();
454 mcck_pending = 1;
455 }
456 /*
457 * Reinject storage related machine checks into the guest if they
458 * happen when the guest is running.
459 */
460 if (!test_cpu_flag(CIF_MCCK_GUEST)) {
461 /* Storage error uncorrected */
462 if (mci.se)
463 s390_handle_damage();
464 /* Storage key-error uncorrected */
465 if (mci.ke)
466 s390_handle_damage();
467 /* Storage degradation */
468 if (mci.ds && mci.fa)
469 s390_handle_damage();
470 }
471 if (mci.cp) {
472 /* Channel report word pending */
473 mcck->channel_report = 1;
474 mcck_pending = 1;
475 }
476 if (mci.w) {
477 /* Warning pending */
478 mcck->warning = 1;
479 mcck_pending = 1;
480 }
481
482 /*
483 * If there are only Channel Report Pending and External Damage
484 * machine checks, they will not be reinjected into the guest
485 * because they refer to host conditions only.
486 */
487 mcck_dam_code = (mci.val & MCIC_SUBCLASS_MASK);
488 if (test_cpu_flag(CIF_MCCK_GUEST) &&
489 (mcck_dam_code & MCCK_CODE_NO_GUEST) != mcck_dam_code) {
490 /* Set exit reason code for host's later handling */
491 *((long *)(regs->gprs[15] + __SF_SIE_REASON)) = -EINTR;
492 }
493 clear_cpu_flag(CIF_MCCK_GUEST);
494
495 if (mcck_pending)
496 schedule_mcck_handler();
497
498 irqentry_nmi_exit(regs, irq_state);
499}
500NOKPROBE_SYMBOL(s390_do_machine_check);
501
502static int __init machine_check_init(void)
503{
504 system_ctl_set_bit(14, CR14_EXTERNAL_DAMAGE_SUBMASK_BIT);
505 system_ctl_set_bit(14, CR14_RECOVERY_SUBMASK_BIT);
506 system_ctl_set_bit(14, CR14_WARNING_SUBMASK_BIT);
507 return 0;
508}
509early_initcall(machine_check_init);
510

source code of linux/arch/s390/kernel/nmi.c