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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/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 <asm/pai.h>
34#include <asm/vx-insn.h>
35
36struct 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
44static DEFINE_PER_CPU(struct mcck_struct, cpu_mcck);
45
46static inline int nmi_needs_mcesa(void)
47{
48 return MACHINE_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 */
57static struct mcesa boot_mcesa __aligned(MCESA_MAX_SIZE);
58
59void __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
68int 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
88void nmi_free_mcesa(u64 *mcesad)
89{
90 if (!nmi_needs_mcesa())
91 return;
92 kfree(__va(*mcesad & MCESA_ORIGIN_MASK));
93}
94
95static __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
103static __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
118static notrace void s390_handle_damage(void)
119{
120 union ctlreg0 cr0, cr0_new;
121 char message[100];
122 psw_t psw_save;
123 char *ptr;
124
125 smp_emergency_stop();
126 diag_amode31_ops.diag308_reset();
127 ptr = nmi_puts(message, "System stopped due to unrecoverable machine check, code: 0x");
128 u64_to_hex(ptr, S390_lowcore.mcck_interruption_code);
129
130 /*
131 * Disable low address protection and make machine check new PSW a
132 * disabled wait PSW. Any additional machine check cannot be handled.
133 */
134 __ctl_store(cr0.val, 0, 0);
135 cr0_new = cr0;
136 cr0_new.lap = 0;
137 __ctl_load(cr0_new.val, 0, 0);
138 psw_save = S390_lowcore.mcck_new_psw;
139 psw_bits(S390_lowcore.mcck_new_psw).io = 0;
140 psw_bits(S390_lowcore.mcck_new_psw).ext = 0;
141 psw_bits(S390_lowcore.mcck_new_psw).wait = 1;
142 sclp_emergency_printk(message);
143
144 /*
145 * Restore machine check new PSW and control register 0 to original
146 * values. This makes possible system dump analysis easier.
147 */
148 S390_lowcore.mcck_new_psw = psw_save;
149 __ctl_load(cr0.val, 0, 0);
150 disabled_wait();
151 while (1);
152}
153NOKPROBE_SYMBOL(s390_handle_damage);
154
155/*
156 * Main machine check handler function. Will be called with interrupts disabled
157 * and machine checks enabled.
158 */
159void __s390_handle_mcck(void)
160{
161 struct mcck_struct mcck;
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_disable();
169 mcck = *this_cpu_ptr(&cpu_mcck);
170 memset(this_cpu_ptr(&cpu_mcck), 0, sizeof(mcck));
171 local_mcck_enable();
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 __ctl_clear_bit(14, 24); /* Disable WARNING MCH */
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 local_irq_enable();
196 printk(KERN_EMERG "mcck: Terminating task because of machine "
197 "malfunction (code 0x%016lx).\n", mcck.mcck_code);
198 printk(KERN_EMERG "mcck: task: %s, pid: %d.\n",
199 current->comm, current->pid);
200 make_task_dead(SIGSEGV);
201 }
202}
203
204void noinstr s390_handle_mcck(struct pt_regs *regs)
205{
206 trace_hardirqs_off();
207 pai_kernel_enter(regs);
208 __s390_handle_mcck();
209 pai_kernel_exit(regs);
210 trace_hardirqs_on();
211}
212/*
213 * returns 0 if register contents could be validated
214 * returns 1 otherwise
215 */
216static int notrace s390_validate_registers(union mci mci)
217{
218 struct mcesa *mcesa;
219 void *fpt_save_area;
220 union ctlreg2 cr2;
221 int kill_task;
222 u64 zero;
223
224 kill_task = 0;
225 zero = 0;
226
227 if (!mci.gr || !mci.fp)
228 kill_task = 1;
229 fpt_save_area = &S390_lowcore.floating_pt_save_area;
230 if (!mci.fc) {
231 kill_task = 1;
232 asm volatile(
233 " lfpc %0\n"
234 :
235 : "Q" (zero));
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 kill_task = 1;
279 cr0.val = S390_lowcore.cregs_save_area[0];
280 cr0.afp = cr0.vx = 1;
281 __ctl_load(cr0.val, 0, 0);
282 asm volatile(
283 " la 1,%0\n"
284 " VLM 0,15,0,1\n"
285 " VLM 16,31,256,1\n"
286 :
287 : "Q" (*(struct vx_array *)mcesa->vector_save_area)
288 : "1");
289 __ctl_load(S390_lowcore.cregs_save_area[0], 0, 0);
290 }
291 /* Validate access registers */
292 asm volatile(
293 " lam 0,15,0(%0)\n"
294 :
295 : "a" (&S390_lowcore.access_regs_save_area)
296 : "memory");
297 if (!mci.ar)
298 kill_task = 1;
299 /* Validate guarded storage registers */
300 cr2.val = S390_lowcore.cregs_save_area[2];
301 if (cr2.gse) {
302 if (!mci.gs) {
303 /*
304 * 2 cases:
305 * - machine check in kernel or userspace
306 * - machine check while running SIE (KVM guest)
307 * For kernel or userspace the userspace values of
308 * guarded storage control can not be recreated, the
309 * process must be terminated.
310 * For SIE the guest values of guarded storage can not
311 * be recreated. This is either due to a bug or due to
312 * GS being disabled in the guest. The guest will be
313 * notified by KVM code and the guests machine check
314 * handling must take care of this. The host values
315 * are saved by KVM and are not affected.
316 */
317 if (!test_cpu_flag(CIF_MCCK_GUEST))
318 kill_task = 1;
319 } else {
320 load_gs_cb((struct gs_cb *)mcesa->guarded_storage_save_area);
321 }
322 }
323 /*
324 * The getcpu vdso syscall reads CPU number from the programmable
325 * field of the TOD clock. Disregard the TOD programmable register
326 * validity bit and load the CPU number into the TOD programmable
327 * field unconditionally.
328 */
329 set_tod_programmable_field(raw_smp_processor_id());
330 /* Validate clock comparator register */
331 set_clock_comparator(S390_lowcore.clock_comparator);
332
333 if (!mci.ms || !mci.pm || !mci.ia)
334 kill_task = 1;
335
336 return kill_task;
337}
338NOKPROBE_SYMBOL(s390_validate_registers);
339
340/*
341 * Backup the guest's machine check info to its description block
342 */
343static void notrace s390_backup_mcck_info(struct pt_regs *regs)
344{
345 struct mcck_volatile_info *mcck_backup;
346 struct sie_page *sie_page;
347
348 /* r14 contains the sie block, which was set in sie64a */
349 struct kvm_s390_sie_block *sie_block =
350 (struct kvm_s390_sie_block *) regs->gprs[14];
351
352 if (sie_block == NULL)
353 /* Something's seriously wrong, stop system. */
354 s390_handle_damage();
355
356 sie_page = container_of(sie_block, struct sie_page, sie_block);
357 mcck_backup = &sie_page->mcck_info;
358 mcck_backup->mcic = S390_lowcore.mcck_interruption_code &
359 ~(MCCK_CODE_CP | MCCK_CODE_EXT_DAMAGE);
360 mcck_backup->ext_damage_code = S390_lowcore.external_damage_code;
361 mcck_backup->failing_storage_address
362 = S390_lowcore.failing_storage_address;
363}
364NOKPROBE_SYMBOL(s390_backup_mcck_info);
365
366#define MAX_IPD_COUNT 29
367#define MAX_IPD_TIME (5 * 60 * USEC_PER_SEC) /* 5 minutes */
368
369#define ED_STP_ISLAND 6 /* External damage STP island check */
370#define ED_STP_SYNC 7 /* External damage STP sync check */
371
372#define MCCK_CODE_NO_GUEST (MCCK_CODE_CP | MCCK_CODE_EXT_DAMAGE)
373
374/*
375 * machine check handler.
376 */
377int notrace s390_do_machine_check(struct pt_regs *regs)
378{
379 static int ipd_count;
380 static DEFINE_SPINLOCK(ipd_lock);
381 static unsigned long long last_ipd;
382 struct mcck_struct *mcck;
383 unsigned long long tmp;
384 irqentry_state_t irq_state;
385 union mci mci;
386 unsigned long mcck_dam_code;
387 int mcck_pending = 0;
388
389 irq_state = irqentry_nmi_enter(regs);
390
391 if (user_mode(regs))
392 update_timer_mcck();
393 inc_irq_stat(NMI_NMI);
394 mci.val = S390_lowcore.mcck_interruption_code;
395 mcck = this_cpu_ptr(&cpu_mcck);
396
397 /*
398 * Reinject the instruction processing damages' machine checks
399 * including Delayed Access Exception into the guest
400 * instead of damaging the host if they happen in the guest.
401 */
402 if (mci.pd && !test_cpu_flag(CIF_MCCK_GUEST)) {
403 if (mci.b) {
404 /* Processing backup -> verify if we can survive this */
405 u64 z_mcic, o_mcic, t_mcic;
406 z_mcic = (1ULL<<63 | 1ULL<<59 | 1ULL<<29);
407 o_mcic = (1ULL<<43 | 1ULL<<42 | 1ULL<<41 | 1ULL<<40 |
408 1ULL<<36 | 1ULL<<35 | 1ULL<<34 | 1ULL<<32 |
409 1ULL<<30 | 1ULL<<21 | 1ULL<<20 | 1ULL<<17 |
410 1ULL<<16);
411 t_mcic = mci.val;
412
413 if (((t_mcic & z_mcic) != 0) ||
414 ((t_mcic & o_mcic) != o_mcic)) {
415 s390_handle_damage();
416 }
417
418 /*
419 * Nullifying exigent condition, therefore we might
420 * retry this instruction.
421 */
422 spin_lock(&ipd_lock);
423 tmp = get_tod_clock();
424 if (((tmp - last_ipd) >> 12) < MAX_IPD_TIME)
425 ipd_count++;
426 else
427 ipd_count = 1;
428 last_ipd = tmp;
429 if (ipd_count == MAX_IPD_COUNT)
430 s390_handle_damage();
431 spin_unlock(&ipd_lock);
432 } else {
433 /* Processing damage -> stopping machine */
434 s390_handle_damage();
435 }
436 }
437 if (s390_validate_registers(mci)) {
438 if (!user_mode(regs))
439 s390_handle_damage();
440 /*
441 * Couldn't restore all register contents for the
442 * user space process -> mark task for termination.
443 */
444 mcck->kill_task = 1;
445 mcck->mcck_code = mci.val;
446 mcck_pending = 1;
447 }
448
449 /*
450 * Backup the machine check's info if it happens when the guest
451 * is running.
452 */
453 if (test_cpu_flag(CIF_MCCK_GUEST))
454 s390_backup_mcck_info(regs);
455
456 if (mci.cd) {
457 /* Timing facility damage */
458 s390_handle_damage();
459 }
460 if (mci.ed && mci.ec) {
461 /* External damage */
462 if (S390_lowcore.external_damage_code & (1U << ED_STP_SYNC))
463 mcck->stp_queue |= stp_sync_check();
464 if (S390_lowcore.external_damage_code & (1U << ED_STP_ISLAND))
465 mcck->stp_queue |= stp_island_check();
466 mcck_pending = 1;
467 }
468 /*
469 * Reinject storage related machine checks into the guest if they
470 * happen when the guest is running.
471 */
472 if (!test_cpu_flag(CIF_MCCK_GUEST)) {
473 /* Storage error uncorrected */
474 if (mci.se)
475 s390_handle_damage();
476 /* Storage key-error uncorrected */
477 if (mci.ke)
478 s390_handle_damage();
479 /* Storage degradation */
480 if (mci.ds && mci.fa)
481 s390_handle_damage();
482 }
483 if (mci.cp) {
484 /* Channel report word pending */
485 mcck->channel_report = 1;
486 mcck_pending = 1;
487 }
488 if (mci.w) {
489 /* Warning pending */
490 mcck->warning = 1;
491 mcck_pending = 1;
492 }
493
494 /*
495 * If there are only Channel Report Pending and External Damage
496 * machine checks, they will not be reinjected into the guest
497 * because they refer to host conditions only.
498 */
499 mcck_dam_code = (mci.val & MCIC_SUBCLASS_MASK);
500 if (test_cpu_flag(CIF_MCCK_GUEST) &&
501 (mcck_dam_code & MCCK_CODE_NO_GUEST) != mcck_dam_code) {
502 /* Set exit reason code for host's later handling */
503 *((long *)(regs->gprs[15] + __SF_SIE_REASON)) = -EINTR;
504 }
505 clear_cpu_flag(CIF_MCCK_GUEST);
506
507 if (user_mode(regs) && mcck_pending) {
508 irqentry_nmi_exit(regs, irq_state);
509 return 1;
510 }
511
512 if (mcck_pending)
513 schedule_mcck_handler();
514
515 irqentry_nmi_exit(regs, irq_state);
516 return 0;
517}
518NOKPROBE_SYMBOL(s390_do_machine_check);
519
520static int __init machine_check_init(void)
521{
522 ctl_set_bit(14, 25); /* enable external damage MCH */
523 ctl_set_bit(14, 27); /* enable system recovery MCH */
524 ctl_set_bit(14, 24); /* enable warning MCH */
525 return 0;
526}
527early_initcall(machine_check_init);
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/smp.h>
27#include <asm/stp.h>
28#include <asm/cputime.h>
29#include <asm/nmi.h>
30#include <asm/crw.h>
31#include <asm/switch_to.h>
32#include <asm/asm-offsets.h>
33#include <asm/pai.h>
34#include <asm/vx-insn.h>
35#include <asm/fpu/api.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() || MACHINE_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 (MACHINE_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 = MACHINE_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(origin);
83 *mcesad = __pa(origin);
84 if (MACHINE_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 s390_handle_damage(void)
120{
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, S390_lowcore.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 = S390_lowcore.mcck_new_psw;
140 psw_bits(S390_lowcore.mcck_new_psw).io = 0;
141 psw_bits(S390_lowcore.mcck_new_psw).ext = 0;
142 psw_bits(S390_lowcore.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 S390_lowcore.mcck_new_psw = psw_save;
150 local_ctl_load(0, &cr0.reg);
151 disabled_wait();
152 while (1);
153}
154NOKPROBE_SYMBOL(s390_handle_damage);
155
156/*
157 * Main machine check handler function. Will be called with interrupts disabled
158 * and machine checks enabled.
159 */
160void 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 * returns 0 if register contents could be validated
209 * returns 1 otherwise
210 */
211static int notrace s390_validate_registers(union mci mci)
212{
213 struct mcesa *mcesa;
214 void *fpt_save_area;
215 union ctlreg2 cr2;
216 int kill_task;
217 u64 zero;
218
219 kill_task = 0;
220 zero = 0;
221
222 if (!mci.gr || !mci.fp)
223 kill_task = 1;
224 fpt_save_area = &S390_lowcore.floating_pt_save_area;
225 if (!mci.fc) {
226 kill_task = 1;
227 asm volatile(
228 " lfpc %0\n"
229 :
230 : "Q" (zero));
231 } else {
232 asm volatile(
233 " lfpc %0\n"
234 :
235 : "Q" (S390_lowcore.fpt_creg_save_area));
236 }
237
238 mcesa = __va(S390_lowcore.mcesad & MCESA_ORIGIN_MASK);
239 if (!cpu_has_vx()) {
240 /* Validate floating point registers */
241 asm volatile(
242 " ld 0,0(%0)\n"
243 " ld 1,8(%0)\n"
244 " ld 2,16(%0)\n"
245 " ld 3,24(%0)\n"
246 " ld 4,32(%0)\n"
247 " ld 5,40(%0)\n"
248 " ld 6,48(%0)\n"
249 " ld 7,56(%0)\n"
250 " ld 8,64(%0)\n"
251 " ld 9,72(%0)\n"
252 " ld 10,80(%0)\n"
253 " ld 11,88(%0)\n"
254 " ld 12,96(%0)\n"
255 " ld 13,104(%0)\n"
256 " ld 14,112(%0)\n"
257 " ld 15,120(%0)\n"
258 :
259 : "a" (fpt_save_area)
260 : "memory");
261 } else {
262 /* Validate vector registers */
263 union ctlreg0 cr0;
264
265 /*
266 * The vector validity must only be checked if not running a
267 * KVM guest. For KVM guests the machine check is forwarded by
268 * KVM and it is the responsibility of the guest to take
269 * appropriate actions. The host vector or FPU values have been
270 * saved by KVM and will be restored by KVM.
271 */
272 if (!mci.vr && !test_cpu_flag(CIF_MCCK_GUEST))
273 kill_task = 1;
274 cr0.reg = S390_lowcore.cregs_save_area[0];
275 cr0.afp = cr0.vx = 1;
276 local_ctl_load(0, &cr0.reg);
277 asm volatile(
278 " la 1,%0\n"
279 " VLM 0,15,0,1\n"
280 " VLM 16,31,256,1\n"
281 :
282 : "Q" (*(struct vx_array *)mcesa->vector_save_area)
283 : "1");
284 local_ctl_load(0, &S390_lowcore.cregs_save_area[0]);
285 }
286 /* Validate access registers */
287 asm volatile(
288 " lam 0,15,0(%0)\n"
289 :
290 : "a" (&S390_lowcore.access_regs_save_area)
291 : "memory");
292 if (!mci.ar)
293 kill_task = 1;
294 /* Validate guarded storage registers */
295 cr2.reg = S390_lowcore.cregs_save_area[2];
296 if (cr2.gse) {
297 if (!mci.gs) {
298 /*
299 * 2 cases:
300 * - machine check in kernel or userspace
301 * - machine check while running SIE (KVM guest)
302 * For kernel or userspace the userspace values of
303 * guarded storage control can not be recreated, the
304 * process must be terminated.
305 * For SIE the guest values of guarded storage can not
306 * be recreated. This is either due to a bug or due to
307 * GS being disabled in the guest. The guest will be
308 * notified by KVM code and the guests machine check
309 * handling must take care of this. The host values
310 * are saved by KVM and are not affected.
311 */
312 if (!test_cpu_flag(CIF_MCCK_GUEST))
313 kill_task = 1;
314 } else {
315 load_gs_cb((struct gs_cb *)mcesa->guarded_storage_save_area);
316 }
317 }
318 /*
319 * The getcpu vdso syscall reads CPU number from the programmable
320 * field of the TOD clock. Disregard the TOD programmable register
321 * validity bit and load the CPU number into the TOD programmable
322 * field unconditionally.
323 */
324 set_tod_programmable_field(raw_smp_processor_id());
325 /* Validate clock comparator register */
326 set_clock_comparator(S390_lowcore.clock_comparator);
327
328 if (!mci.ms || !mci.pm || !mci.ia)
329 kill_task = 1;
330
331 return kill_task;
332}
333NOKPROBE_SYMBOL(s390_validate_registers);
334
335/*
336 * Backup the guest's machine check info to its description block
337 */
338static void notrace s390_backup_mcck_info(struct pt_regs *regs)
339{
340 struct mcck_volatile_info *mcck_backup;
341 struct sie_page *sie_page;
342
343 /* r14 contains the sie block, which was set in sie64a */
344 struct kvm_s390_sie_block *sie_block = phys_to_virt(regs->gprs[14]);
345
346 if (sie_block == NULL)
347 /* Something's seriously wrong, stop system. */
348 s390_handle_damage();
349
350 sie_page = container_of(sie_block, struct sie_page, sie_block);
351 mcck_backup = &sie_page->mcck_info;
352 mcck_backup->mcic = S390_lowcore.mcck_interruption_code &
353 ~(MCCK_CODE_CP | MCCK_CODE_EXT_DAMAGE);
354 mcck_backup->ext_damage_code = S390_lowcore.external_damage_code;
355 mcck_backup->failing_storage_address
356 = S390_lowcore.failing_storage_address;
357}
358NOKPROBE_SYMBOL(s390_backup_mcck_info);
359
360#define MAX_IPD_COUNT 29
361#define MAX_IPD_TIME (5 * 60 * USEC_PER_SEC) /* 5 minutes */
362
363#define ED_STP_ISLAND 6 /* External damage STP island check */
364#define ED_STP_SYNC 7 /* External damage STP sync check */
365
366#define MCCK_CODE_NO_GUEST (MCCK_CODE_CP | MCCK_CODE_EXT_DAMAGE)
367
368/*
369 * machine check handler.
370 */
371void notrace s390_do_machine_check(struct pt_regs *regs)
372{
373 static int ipd_count;
374 static DEFINE_SPINLOCK(ipd_lock);
375 static unsigned long long last_ipd;
376 struct mcck_struct *mcck;
377 unsigned long long tmp;
378 irqentry_state_t irq_state;
379 union mci mci;
380 unsigned long mcck_dam_code;
381 int mcck_pending = 0;
382
383 irq_state = irqentry_nmi_enter(regs);
384
385 if (user_mode(regs))
386 update_timer_mcck();
387 inc_irq_stat(NMI_NMI);
388 mci.val = S390_lowcore.mcck_interruption_code;
389 mcck = this_cpu_ptr(&cpu_mcck);
390
391 /*
392 * Reinject the instruction processing damages' machine checks
393 * including Delayed Access Exception into the guest
394 * instead of damaging the host if they happen in the guest.
395 */
396 if (mci.pd && !test_cpu_flag(CIF_MCCK_GUEST)) {
397 if (mci.b) {
398 /* Processing backup -> verify if we can survive this */
399 u64 z_mcic, o_mcic, t_mcic;
400 z_mcic = (1ULL<<63 | 1ULL<<59 | 1ULL<<29);
401 o_mcic = (1ULL<<43 | 1ULL<<42 | 1ULL<<41 | 1ULL<<40 |
402 1ULL<<36 | 1ULL<<35 | 1ULL<<34 | 1ULL<<32 |
403 1ULL<<30 | 1ULL<<21 | 1ULL<<20 | 1ULL<<17 |
404 1ULL<<16);
405 t_mcic = mci.val;
406
407 if (((t_mcic & z_mcic) != 0) ||
408 ((t_mcic & o_mcic) != o_mcic)) {
409 s390_handle_damage();
410 }
411
412 /*
413 * Nullifying exigent condition, therefore we might
414 * retry this instruction.
415 */
416 spin_lock(&ipd_lock);
417 tmp = get_tod_clock();
418 if (((tmp - last_ipd) >> 12) < MAX_IPD_TIME)
419 ipd_count++;
420 else
421 ipd_count = 1;
422 last_ipd = tmp;
423 if (ipd_count == MAX_IPD_COUNT)
424 s390_handle_damage();
425 spin_unlock(&ipd_lock);
426 } else {
427 /* Processing damage -> stopping machine */
428 s390_handle_damage();
429 }
430 }
431 if (s390_validate_registers(mci)) {
432 if (!user_mode(regs))
433 s390_handle_damage();
434 /*
435 * Couldn't restore all register contents for the
436 * user space process -> mark task for termination.
437 */
438 mcck->kill_task = 1;
439 mcck->mcck_code = mci.val;
440 mcck_pending = 1;
441 }
442
443 /*
444 * Backup the machine check's info if it happens when the guest
445 * is running.
446 */
447 if (test_cpu_flag(CIF_MCCK_GUEST))
448 s390_backup_mcck_info(regs);
449
450 if (mci.cd) {
451 /* Timing facility damage */
452 s390_handle_damage();
453 }
454 if (mci.ed && mci.ec) {
455 /* External damage */
456 if (S390_lowcore.external_damage_code & (1U << ED_STP_SYNC))
457 mcck->stp_queue |= stp_sync_check();
458 if (S390_lowcore.external_damage_code & (1U << ED_STP_ISLAND))
459 mcck->stp_queue |= stp_island_check();
460 mcck_pending = 1;
461 }
462 /*
463 * Reinject storage related machine checks into the guest if they
464 * happen when the guest is running.
465 */
466 if (!test_cpu_flag(CIF_MCCK_GUEST)) {
467 /* Storage error uncorrected */
468 if (mci.se)
469 s390_handle_damage();
470 /* Storage key-error uncorrected */
471 if (mci.ke)
472 s390_handle_damage();
473 /* Storage degradation */
474 if (mci.ds && mci.fa)
475 s390_handle_damage();
476 }
477 if (mci.cp) {
478 /* Channel report word pending */
479 mcck->channel_report = 1;
480 mcck_pending = 1;
481 }
482 if (mci.w) {
483 /* Warning pending */
484 mcck->warning = 1;
485 mcck_pending = 1;
486 }
487
488 /*
489 * If there are only Channel Report Pending and External Damage
490 * machine checks, they will not be reinjected into the guest
491 * because they refer to host conditions only.
492 */
493 mcck_dam_code = (mci.val & MCIC_SUBCLASS_MASK);
494 if (test_cpu_flag(CIF_MCCK_GUEST) &&
495 (mcck_dam_code & MCCK_CODE_NO_GUEST) != mcck_dam_code) {
496 /* Set exit reason code for host's later handling */
497 *((long *)(regs->gprs[15] + __SF_SIE_REASON)) = -EINTR;
498 }
499 clear_cpu_flag(CIF_MCCK_GUEST);
500
501 if (mcck_pending)
502 schedule_mcck_handler();
503
504 irqentry_nmi_exit(regs, irq_state);
505}
506NOKPROBE_SYMBOL(s390_do_machine_check);
507
508static int __init machine_check_init(void)
509{
510 system_ctl_set_bit(14, CR14_EXTERNAL_DAMAGE_SUBMASK_BIT);
511 system_ctl_set_bit(14, CR14_RECOVERY_SUBMASK_BIT);
512 system_ctl_set_bit(14, CR14_WARNING_SUBMASK_BIT);
513 return 0;
514}
515early_initcall(machine_check_init);