xref: /openbmc/linux/arch/s390/kernel/nmi.c (revision 680ef72a)
1 /*
2  *   Machine check handler
3  *
4  *    Copyright IBM Corp. 2000, 2009
5  *    Author(s): Ingo Adlung <adlung@de.ibm.com>,
6  *		 Martin Schwidefsky <schwidefsky@de.ibm.com>,
7  *		 Cornelia Huck <cornelia.huck@de.ibm.com>,
8  *		 Heiko Carstens <heiko.carstens@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/slab.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 <linux/kvm_host.h>
33 
34 struct mcck_struct {
35 	unsigned int kill_task : 1;
36 	unsigned int channel_report : 1;
37 	unsigned int warning : 1;
38 	unsigned int stp_queue : 1;
39 	unsigned long mcck_code;
40 };
41 
42 static DEFINE_PER_CPU(struct mcck_struct, cpu_mcck);
43 static struct kmem_cache *mcesa_cache;
44 static unsigned long mcesa_origin_lc;
45 
46 static inline int nmi_needs_mcesa(void)
47 {
48 	return MACHINE_HAS_VX || MACHINE_HAS_GS;
49 }
50 
51 static inline unsigned long nmi_get_mcesa_size(void)
52 {
53 	if (MACHINE_HAS_GS)
54 		return MCESA_MAX_SIZE;
55 	return MCESA_MIN_SIZE;
56 }
57 
58 /*
59  * The initial machine check extended save area for the boot CPU.
60  * It will be replaced by nmi_init() with an allocated structure.
61  * The structure is required for machine check happening early in
62  * the boot process.
63  */
64 static struct mcesa boot_mcesa __initdata __aligned(MCESA_MAX_SIZE);
65 
66 void __init nmi_alloc_boot_cpu(struct lowcore *lc)
67 {
68 	if (!nmi_needs_mcesa())
69 		return;
70 	lc->mcesad = (unsigned long) &boot_mcesa;
71 	if (MACHINE_HAS_GS)
72 		lc->mcesad |= ilog2(MCESA_MAX_SIZE);
73 }
74 
75 static int __init nmi_init(void)
76 {
77 	unsigned long origin, cr0, size;
78 
79 	if (!nmi_needs_mcesa())
80 		return 0;
81 	size = nmi_get_mcesa_size();
82 	if (size > MCESA_MIN_SIZE)
83 		mcesa_origin_lc = ilog2(size);
84 	/* create slab cache for the machine-check-extended-save-areas */
85 	mcesa_cache = kmem_cache_create("nmi_save_areas", size, size, 0, NULL);
86 	if (!mcesa_cache)
87 		panic("Couldn't create nmi save area cache");
88 	origin = (unsigned long) kmem_cache_alloc(mcesa_cache, GFP_KERNEL);
89 	if (!origin)
90 		panic("Couldn't allocate nmi save area");
91 	/* The pointer is stored with mcesa_bits ORed in */
92 	kmemleak_not_leak((void *) origin);
93 	__ctl_store(cr0, 0, 0);
94 	__ctl_clear_bit(0, 28); /* disable lowcore protection */
95 	/* Replace boot_mcesa on the boot CPU */
96 	S390_lowcore.mcesad = origin | mcesa_origin_lc;
97 	__ctl_load(cr0, 0, 0);
98 	return 0;
99 }
100 early_initcall(nmi_init);
101 
102 int nmi_alloc_per_cpu(struct lowcore *lc)
103 {
104 	unsigned long origin;
105 
106 	if (!nmi_needs_mcesa())
107 		return 0;
108 	origin = (unsigned long) kmem_cache_alloc(mcesa_cache, GFP_KERNEL);
109 	if (!origin)
110 		return -ENOMEM;
111 	/* The pointer is stored with mcesa_bits ORed in */
112 	kmemleak_not_leak((void *) origin);
113 	lc->mcesad = origin | mcesa_origin_lc;
114 	return 0;
115 }
116 
117 void nmi_free_per_cpu(struct lowcore *lc)
118 {
119 	if (!nmi_needs_mcesa())
120 		return;
121 	kmem_cache_free(mcesa_cache, (void *)(lc->mcesad & MCESA_ORIGIN_MASK));
122 }
123 
124 static notrace void s390_handle_damage(void)
125 {
126 	smp_emergency_stop();
127 	disabled_wait((unsigned long) __builtin_return_address(0));
128 	while (1);
129 }
130 NOKPROBE_SYMBOL(s390_handle_damage);
131 
132 /*
133  * Main machine check handler function. Will be called with interrupts enabled
134  * or disabled and machine checks enabled or disabled.
135  */
136 void s390_handle_mcck(void)
137 {
138 	unsigned long flags;
139 	struct mcck_struct mcck;
140 
141 	/*
142 	 * Disable machine checks and get the current state of accumulated
143 	 * machine checks. Afterwards delete the old state and enable machine
144 	 * checks again.
145 	 */
146 	local_irq_save(flags);
147 	local_mcck_disable();
148 	mcck = *this_cpu_ptr(&cpu_mcck);
149 	memset(this_cpu_ptr(&cpu_mcck), 0, sizeof(mcck));
150 	clear_cpu_flag(CIF_MCCK_PENDING);
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 void 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 
345 	nmi_enter();
346 	inc_irq_stat(NMI_NMI);
347 	mci.val = S390_lowcore.mcck_interruption_code;
348 	mcck = this_cpu_ptr(&cpu_mcck);
349 
350 	if (mci.sd) {
351 		/* System damage -> stopping machine */
352 		s390_handle_damage();
353 	}
354 
355 	/*
356 	 * Reinject the instruction processing damages' machine checks
357 	 * including Delayed Access Exception into the guest
358 	 * instead of damaging the host if they happen in the guest.
359 	 */
360 	if (mci.pd && !test_cpu_flag(CIF_MCCK_GUEST)) {
361 		if (mci.b) {
362 			/* Processing backup -> verify if we can survive this */
363 			u64 z_mcic, o_mcic, t_mcic;
364 			z_mcic = (1ULL<<63 | 1ULL<<59 | 1ULL<<29);
365 			o_mcic = (1ULL<<43 | 1ULL<<42 | 1ULL<<41 | 1ULL<<40 |
366 				  1ULL<<36 | 1ULL<<35 | 1ULL<<34 | 1ULL<<32 |
367 				  1ULL<<30 | 1ULL<<21 | 1ULL<<20 | 1ULL<<17 |
368 				  1ULL<<16);
369 			t_mcic = mci.val;
370 
371 			if (((t_mcic & z_mcic) != 0) ||
372 			    ((t_mcic & o_mcic) != o_mcic)) {
373 				s390_handle_damage();
374 			}
375 
376 			/*
377 			 * Nullifying exigent condition, therefore we might
378 			 * retry this instruction.
379 			 */
380 			spin_lock(&ipd_lock);
381 			tmp = get_tod_clock();
382 			if (((tmp - last_ipd) >> 12) < MAX_IPD_TIME)
383 				ipd_count++;
384 			else
385 				ipd_count = 1;
386 			last_ipd = tmp;
387 			if (ipd_count == MAX_IPD_COUNT)
388 				s390_handle_damage();
389 			spin_unlock(&ipd_lock);
390 		} else {
391 			/* Processing damage -> stopping machine */
392 			s390_handle_damage();
393 		}
394 	}
395 	if (s390_check_registers(mci, user_mode(regs))) {
396 		/*
397 		 * Couldn't restore all register contents for the
398 		 * user space process -> mark task for termination.
399 		 */
400 		mcck->kill_task = 1;
401 		mcck->mcck_code = mci.val;
402 		set_cpu_flag(CIF_MCCK_PENDING);
403 	}
404 
405 	/*
406 	 * Backup the machine check's info if it happens when the guest
407 	 * is running.
408 	 */
409 	if (test_cpu_flag(CIF_MCCK_GUEST))
410 		s390_backup_mcck_info(regs);
411 
412 	if (mci.cd) {
413 		/* Timing facility damage */
414 		s390_handle_damage();
415 	}
416 	if (mci.ed && mci.ec) {
417 		/* External damage */
418 		if (S390_lowcore.external_damage_code & (1U << ED_STP_SYNC))
419 			mcck->stp_queue |= stp_sync_check();
420 		if (S390_lowcore.external_damage_code & (1U << ED_STP_ISLAND))
421 			mcck->stp_queue |= stp_island_check();
422 		if (mcck->stp_queue)
423 			set_cpu_flag(CIF_MCCK_PENDING);
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 		set_cpu_flag(CIF_MCCK_PENDING);
445 	}
446 	if (mci.w) {
447 		/* Warning pending */
448 		mcck->warning = 1;
449 		set_cpu_flag(CIF_MCCK_PENDING);
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 	nmi_exit();
465 }
466 NOKPROBE_SYMBOL(s390_do_machine_check);
467 
468 static int __init machine_check_init(void)
469 {
470 	ctl_set_bit(14, 25);	/* enable external damage MCH */
471 	ctl_set_bit(14, 27);	/* enable system recovery MCH */
472 	ctl_set_bit(14, 24);	/* enable warning MCH */
473 	return 0;
474 }
475 early_initcall(machine_check_init);
476