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 #include <asm/vtime.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
nmi_needs_mcesa(void)46 static inline int nmi_needs_mcesa(void)
47 {
48 return cpu_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 */
57 static struct mcesa boot_mcesa __aligned(MCESA_MAX_SIZE);
58
nmi_alloc_mcesa_early(u64 * mcesad)59 void __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
nmi_alloc_mcesa(u64 * mcesad)68 int 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
nmi_free_mcesa(u64 * mcesad)88 void nmi_free_mcesa(u64 *mcesad)
89 {
90 if (!nmi_needs_mcesa())
91 return;
92 kfree(__va(*mcesad & MCESA_ORIGIN_MASK));
93 }
94
nmi_puts(char * dest,const char * src)95 static __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
u64_to_hex(char * dest,u64 val)103 static __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
s390_handle_damage(void)118 static 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 local_ctl_store(0, &cr0.reg);
135 cr0_new = cr0;
136 cr0_new.lap = 0;
137 local_ctl_load(0, &cr0_new.reg);
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 local_ctl_load(0, &cr0.reg);
150 disabled_wait();
151 while (1);
152 }
153 NOKPROBE_SYMBOL(s390_handle_damage);
154
155 /*
156 * Main machine check handler function. Will be called with interrupts disabled
157 * and machine checks enabled.
158 */
s390_handle_mcck(void)159 void s390_handle_mcck(void)
160 {
161 struct mcck_struct mcck;
162 unsigned long mflags;
163
164 /*
165 * Disable machine checks and get the current state of accumulated
166 * machine checks. Afterwards delete the old state and enable machine
167 * checks again.
168 */
169 local_mcck_save(mflags);
170 mcck = *this_cpu_ptr(&cpu_mcck);
171 memset(this_cpu_ptr(&cpu_mcck), 0, sizeof(mcck));
172 local_mcck_restore(mflags);
173
174 if (mcck.channel_report)
175 crw_handle_channel_report();
176 /*
177 * A warning may remain for a prolonged period on the bare iron.
178 * (actually until the machine is powered off, or the problem is gone)
179 * So we just stop listening for the WARNING MCH and avoid continuously
180 * being interrupted. One caveat is however, that we must do this per
181 * processor and cannot use the smp version of ctl_clear_bit().
182 * On VM we only get one interrupt per virtally presented machinecheck.
183 * Though one suffices, we may get one interrupt per (virtual) cpu.
184 */
185 if (mcck.warning) { /* WARNING pending ? */
186 static int mchchk_wng_posted = 0;
187
188 /* Use single cpu clear, as we cannot handle smp here. */
189 local_ctl_clear_bit(14, CR14_WARNING_SUBMASK_BIT);
190 if (xchg(&mchchk_wng_posted, 1) == 0)
191 kill_cad_pid(SIGPWR, 1);
192 }
193 if (mcck.stp_queue)
194 stp_queue_work();
195 if (mcck.kill_task) {
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 if (is_global_init(current))
201 panic("mcck: Attempting to kill init!\n");
202 do_send_sig_info(SIGKILL, SEND_SIG_PRIV, current, PIDTYPE_PID);
203 }
204 }
205
206 /**
207 * nmi_registers_valid - verify if registers are valid
208 * @mci: machine check interruption code
209 *
210 * Inspect a machine check interruption code and verify if all required
211 * registers are valid. For some registers the corresponding validity bit is
212 * ignored and the registers are set to the expected value.
213 * Returns true if all registers are valid, otherwise false.
214 */
nmi_registers_valid(union mci mci)215 static bool notrace nmi_registers_valid(union mci mci)
216 {
217 union ctlreg2 cr2;
218
219 /*
220 * The getcpu vdso syscall reads the CPU number from the programmable
221 * field of the TOD clock. Disregard the TOD programmable register
222 * validity bit and load the CPU number into the TOD programmable field
223 * unconditionally.
224 */
225 set_tod_programmable_field(raw_smp_processor_id());
226 /*
227 * Set the clock comparator register to the next expected value.
228 */
229 set_clock_comparator(S390_lowcore.clock_comparator);
230 if (!mci.gr || !mci.fp || !mci.fc)
231 return false;
232 /*
233 * The vector validity must only be checked if not running a
234 * KVM guest. For KVM guests the machine check is forwarded by
235 * KVM and it is the responsibility of the guest to take
236 * appropriate actions. The host vector or FPU values have been
237 * saved by KVM and will be restored by KVM.
238 */
239 if (!mci.vr && !test_cpu_flag(CIF_MCCK_GUEST))
240 return false;
241 if (!mci.ar)
242 return false;
243 /*
244 * Two cases for guarded storage registers:
245 * - machine check in kernel or userspace
246 * - machine check while running SIE (KVM guest)
247 * For kernel or userspace the userspace values of guarded storage
248 * control can not be recreated, the process must be terminated.
249 * For SIE the guest values of guarded storage can not be recreated.
250 * This is either due to a bug or due to GS being disabled in the
251 * guest. The guest will be notified by KVM code and the guests machine
252 * check handling must take care of this. The host values are saved by
253 * KVM and are not affected.
254 */
255 cr2.reg = S390_lowcore.cregs_save_area[2];
256 if (cr2.gse && !mci.gs && !test_cpu_flag(CIF_MCCK_GUEST))
257 return false;
258 if (!mci.ms || !mci.pm || !mci.ia)
259 return false;
260 return true;
261 }
262 NOKPROBE_SYMBOL(nmi_registers_valid);
263
264 /*
265 * Backup the guest's machine check info to its description block
266 */
s390_backup_mcck_info(struct pt_regs * regs)267 static void notrace s390_backup_mcck_info(struct pt_regs *regs)
268 {
269 struct mcck_volatile_info *mcck_backup;
270 struct sie_page *sie_page;
271
272 /* r14 contains the sie block, which was set in sie64a */
273 struct kvm_s390_sie_block *sie_block = phys_to_virt(regs->gprs[14]);
274
275 if (sie_block == NULL)
276 /* Something's seriously wrong, stop system. */
277 s390_handle_damage();
278
279 sie_page = container_of(sie_block, struct sie_page, sie_block);
280 mcck_backup = &sie_page->mcck_info;
281 mcck_backup->mcic = S390_lowcore.mcck_interruption_code &
282 ~(MCCK_CODE_CP | MCCK_CODE_EXT_DAMAGE);
283 mcck_backup->ext_damage_code = S390_lowcore.external_damage_code;
284 mcck_backup->failing_storage_address
285 = S390_lowcore.failing_storage_address;
286 }
287 NOKPROBE_SYMBOL(s390_backup_mcck_info);
288
289 #define MAX_IPD_COUNT 29
290 #define MAX_IPD_TIME (5 * 60 * USEC_PER_SEC) /* 5 minutes */
291
292 #define ED_STP_ISLAND 6 /* External damage STP island check */
293 #define ED_STP_SYNC 7 /* External damage STP sync check */
294
295 #define MCCK_CODE_NO_GUEST (MCCK_CODE_CP | MCCK_CODE_EXT_DAMAGE)
296
297 /*
298 * machine check handler.
299 */
s390_do_machine_check(struct pt_regs * regs)300 void notrace s390_do_machine_check(struct pt_regs *regs)
301 {
302 static int ipd_count;
303 static DEFINE_SPINLOCK(ipd_lock);
304 static unsigned long long last_ipd;
305 struct mcck_struct *mcck;
306 unsigned long long tmp;
307 irqentry_state_t irq_state;
308 union mci mci;
309 unsigned long mcck_dam_code;
310 int mcck_pending = 0;
311
312 irq_state = irqentry_nmi_enter(regs);
313
314 if (user_mode(regs))
315 update_timer_mcck();
316 inc_irq_stat(NMI_NMI);
317 mci.val = S390_lowcore.mcck_interruption_code;
318 mcck = this_cpu_ptr(&cpu_mcck);
319
320 /*
321 * Reinject the instruction processing damages' machine checks
322 * including Delayed Access Exception into the guest
323 * instead of damaging the host if they happen in the guest.
324 */
325 if (mci.pd && !test_cpu_flag(CIF_MCCK_GUEST)) {
326 if (mci.b) {
327 /* Processing backup -> verify if we can survive this */
328 u64 z_mcic, o_mcic, t_mcic;
329 z_mcic = (1ULL<<63 | 1ULL<<59 | 1ULL<<29);
330 o_mcic = (1ULL<<43 | 1ULL<<42 | 1ULL<<41 | 1ULL<<40 |
331 1ULL<<36 | 1ULL<<35 | 1ULL<<34 | 1ULL<<32 |
332 1ULL<<30 | 1ULL<<21 | 1ULL<<20 | 1ULL<<17 |
333 1ULL<<16);
334 t_mcic = mci.val;
335
336 if (((t_mcic & z_mcic) != 0) ||
337 ((t_mcic & o_mcic) != o_mcic)) {
338 s390_handle_damage();
339 }
340
341 /*
342 * Nullifying exigent condition, therefore we might
343 * retry this instruction.
344 */
345 spin_lock(&ipd_lock);
346 tmp = get_tod_clock();
347 if (((tmp - last_ipd) >> 12) < MAX_IPD_TIME)
348 ipd_count++;
349 else
350 ipd_count = 1;
351 last_ipd = tmp;
352 if (ipd_count == MAX_IPD_COUNT)
353 s390_handle_damage();
354 spin_unlock(&ipd_lock);
355 } else {
356 /* Processing damage -> stopping machine */
357 s390_handle_damage();
358 }
359 }
360 if (!nmi_registers_valid(mci)) {
361 if (!user_mode(regs))
362 s390_handle_damage();
363 /*
364 * Couldn't restore all register contents for the
365 * user space process -> mark task for termination.
366 */
367 mcck->kill_task = 1;
368 mcck->mcck_code = mci.val;
369 mcck_pending = 1;
370 }
371
372 /*
373 * Backup the machine check's info if it happens when the guest
374 * is running.
375 */
376 if (test_cpu_flag(CIF_MCCK_GUEST))
377 s390_backup_mcck_info(regs);
378
379 if (mci.cd) {
380 /* Timing facility damage */
381 s390_handle_damage();
382 }
383 if (mci.ed && mci.ec) {
384 /* External damage */
385 if (S390_lowcore.external_damage_code & (1U << ED_STP_SYNC))
386 mcck->stp_queue |= stp_sync_check();
387 if (S390_lowcore.external_damage_code & (1U << ED_STP_ISLAND))
388 mcck->stp_queue |= stp_island_check();
389 mcck_pending = 1;
390 }
391 /*
392 * Reinject storage related machine checks into the guest if they
393 * happen when the guest is running.
394 */
395 if (!test_cpu_flag(CIF_MCCK_GUEST)) {
396 /* Storage error uncorrected */
397 if (mci.se)
398 s390_handle_damage();
399 /* Storage key-error uncorrected */
400 if (mci.ke)
401 s390_handle_damage();
402 /* Storage degradation */
403 if (mci.ds && mci.fa)
404 s390_handle_damage();
405 }
406 if (mci.cp) {
407 /* Channel report word pending */
408 mcck->channel_report = 1;
409 mcck_pending = 1;
410 }
411 if (mci.w) {
412 /* Warning pending */
413 mcck->warning = 1;
414 mcck_pending = 1;
415 }
416
417 /*
418 * If there are only Channel Report Pending and External Damage
419 * machine checks, they will not be reinjected into the guest
420 * because they refer to host conditions only.
421 */
422 mcck_dam_code = (mci.val & MCIC_SUBCLASS_MASK);
423 if (test_cpu_flag(CIF_MCCK_GUEST) &&
424 (mcck_dam_code & MCCK_CODE_NO_GUEST) != mcck_dam_code) {
425 /* Set exit reason code for host's later handling */
426 *((long *)(regs->gprs[15] + __SF_SIE_REASON)) = -EINTR;
427 }
428 clear_cpu_flag(CIF_MCCK_GUEST);
429
430 if (mcck_pending)
431 schedule_mcck_handler();
432
433 irqentry_nmi_exit(regs, irq_state);
434 }
435 NOKPROBE_SYMBOL(s390_do_machine_check);
436
machine_check_init(void)437 static int __init machine_check_init(void)
438 {
439 system_ctl_set_bit(14, CR14_EXTERNAL_DAMAGE_SUBMASK_BIT);
440 system_ctl_set_bit(14, CR14_RECOVERY_SUBMASK_BIT);
441 system_ctl_set_bit(14, CR14_WARNING_SUBMASK_BIT);
442 return 0;
443 }
444 early_initcall(machine_check_init);
445