// SPDX-License-Identifier: GPL-2.0 /* * Machine check handler * * Copyright IBM Corp. 2000, 2009 * Author(s): Ingo Adlung , * Martin Schwidefsky , * Cornelia Huck , */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include struct mcck_struct { unsigned int kill_task : 1; unsigned int channel_report : 1; unsigned int warning : 1; unsigned int stp_queue : 1; unsigned long mcck_code; }; static DEFINE_PER_CPU(struct mcck_struct, cpu_mcck); static inline int nmi_needs_mcesa(void) { return cpu_has_vx() || MACHINE_HAS_GS; } /* * The initial machine check extended save area for the boot CPU. * It will be replaced on the boot CPU reinit with an allocated * structure. The structure is required for machine check happening * early in the boot process. */ static struct mcesa boot_mcesa __aligned(MCESA_MAX_SIZE); void __init nmi_alloc_mcesa_early(u64 *mcesad) { if (!nmi_needs_mcesa()) return; *mcesad = __pa(&boot_mcesa); if (MACHINE_HAS_GS) *mcesad |= ilog2(MCESA_MAX_SIZE); } int nmi_alloc_mcesa(u64 *mcesad) { unsigned long size; void *origin; *mcesad = 0; if (!nmi_needs_mcesa()) return 0; size = MACHINE_HAS_GS ? MCESA_MAX_SIZE : MCESA_MIN_SIZE; origin = kmalloc(size, GFP_KERNEL); if (!origin) return -ENOMEM; /* The pointer is stored with mcesa_bits ORed in */ kmemleak_not_leak(origin); *mcesad = __pa(origin); if (MACHINE_HAS_GS) *mcesad |= ilog2(MCESA_MAX_SIZE); return 0; } void nmi_free_mcesa(u64 *mcesad) { if (!nmi_needs_mcesa()) return; kfree(__va(*mcesad & MCESA_ORIGIN_MASK)); } static __always_inline char *nmi_puts(char *dest, const char *src) { while (*src) *dest++ = *src++; *dest = 0; return dest; } static __always_inline char *u64_to_hex(char *dest, u64 val) { int i, num; for (i = 1; i <= 16; i++) { num = (val >> (64 - 4 * i)) & 0xf; if (num >= 10) *dest++ = 'A' + num - 10; else *dest++ = '0' + num; } *dest = 0; return dest; } static notrace void s390_handle_damage(void) { union ctlreg0 cr0, cr0_new; char message[100]; psw_t psw_save; char *ptr; smp_emergency_stop(); diag_amode31_ops.diag308_reset(); ptr = nmi_puts(message, "System stopped due to unrecoverable machine check, code: 0x"); u64_to_hex(ptr, S390_lowcore.mcck_interruption_code); /* * Disable low address protection and make machine check new PSW a * disabled wait PSW. Any additional machine check cannot be handled. */ local_ctl_store(0, &cr0.reg); cr0_new = cr0; cr0_new.lap = 0; local_ctl_load(0, &cr0_new.reg); psw_save = S390_lowcore.mcck_new_psw; psw_bits(S390_lowcore.mcck_new_psw).io = 0; psw_bits(S390_lowcore.mcck_new_psw).ext = 0; psw_bits(S390_lowcore.mcck_new_psw).wait = 1; sclp_emergency_printk(message); /* * Restore machine check new PSW and control register 0 to original * values. This makes possible system dump analysis easier. */ S390_lowcore.mcck_new_psw = psw_save; local_ctl_load(0, &cr0.reg); disabled_wait(); while (1); } NOKPROBE_SYMBOL(s390_handle_damage); /* * Main machine check handler function. Will be called with interrupts disabled * and machine checks enabled. */ void s390_handle_mcck(void) { struct mcck_struct mcck; unsigned long mflags; /* * Disable machine checks and get the current state of accumulated * machine checks. Afterwards delete the old state and enable machine * checks again. */ local_mcck_save(mflags); mcck = *this_cpu_ptr(&cpu_mcck); memset(this_cpu_ptr(&cpu_mcck), 0, sizeof(mcck)); local_mcck_restore(mflags); if (mcck.channel_report) crw_handle_channel_report(); /* * A warning may remain for a prolonged period on the bare iron. * (actually until the machine is powered off, or the problem is gone) * So we just stop listening for the WARNING MCH and avoid continuously * being interrupted. One caveat is however, that we must do this per * processor and cannot use the smp version of ctl_clear_bit(). * On VM we only get one interrupt per virtally presented machinecheck. * Though one suffices, we may get one interrupt per (virtual) cpu. */ if (mcck.warning) { /* WARNING pending ? */ static int mchchk_wng_posted = 0; /* Use single cpu clear, as we cannot handle smp here. */ local_ctl_clear_bit(14, CR14_WARNING_SUBMASK_BIT); if (xchg(&mchchk_wng_posted, 1) == 0) kill_cad_pid(SIGPWR, 1); } if (mcck.stp_queue) stp_queue_work(); if (mcck.kill_task) { printk(KERN_EMERG "mcck: Terminating task because of machine " "malfunction (code 0x%016lx).\n", mcck.mcck_code); printk(KERN_EMERG "mcck: task: %s, pid: %d.\n", current->comm, current->pid); if (is_global_init(current)) panic("mcck: Attempting to kill init!\n"); do_send_sig_info(SIGKILL, SEND_SIG_PRIV, current, PIDTYPE_PID); } } /** * nmi_registers_valid - verify if registers are valid * @mci: machine check interruption code * * Inspect a machine check interruption code and verify if all required * registers are valid. For some registers the corresponding validity bit is * ignored and the registers are set to the expected value. * Returns true if all registers are valid, otherwise false. */ static bool notrace nmi_registers_valid(union mci mci) { union ctlreg2 cr2; /* * The getcpu vdso syscall reads the CPU number from the programmable * field of the TOD clock. Disregard the TOD programmable register * validity bit and load the CPU number into the TOD programmable field * unconditionally. */ set_tod_programmable_field(raw_smp_processor_id()); /* * Set the clock comparator register to the next expected value. */ set_clock_comparator(S390_lowcore.clock_comparator); if (!mci.gr || !mci.fp || !mci.fc) return false; /* * The vector validity must only be checked if not running a * KVM guest. For KVM guests the machine check is forwarded by * KVM and it is the responsibility of the guest to take * appropriate actions. The host vector or FPU values have been * saved by KVM and will be restored by KVM. */ if (!mci.vr && !test_cpu_flag(CIF_MCCK_GUEST)) return false; if (!mci.ar) return false; /* * Two cases for guarded storage registers: * - machine check in kernel or userspace * - machine check while running SIE (KVM guest) * For kernel or userspace the userspace values of guarded storage * control can not be recreated, the process must be terminated. * For SIE the guest values of guarded storage can not be recreated. * This is either due to a bug or due to GS being disabled in the * guest. The guest will be notified by KVM code and the guests machine * check handling must take care of this. The host values are saved by * KVM and are not affected. */ cr2.reg = S390_lowcore.cregs_save_area[2]; if (cr2.gse && !mci.gs && !test_cpu_flag(CIF_MCCK_GUEST)) return false; if (!mci.ms || !mci.pm || !mci.ia) return false; return true; } NOKPROBE_SYMBOL(nmi_registers_valid); /* * Backup the guest's machine check info to its description block */ static void notrace s390_backup_mcck_info(struct pt_regs *regs) { struct mcck_volatile_info *mcck_backup; struct sie_page *sie_page; /* r14 contains the sie block, which was set in sie64a */ struct kvm_s390_sie_block *sie_block = phys_to_virt(regs->gprs[14]); if (sie_block == NULL) /* Something's seriously wrong, stop system. */ s390_handle_damage(); sie_page = container_of(sie_block, struct sie_page, sie_block); mcck_backup = &sie_page->mcck_info; mcck_backup->mcic = S390_lowcore.mcck_interruption_code & ~(MCCK_CODE_CP | MCCK_CODE_EXT_DAMAGE); mcck_backup->ext_damage_code = S390_lowcore.external_damage_code; mcck_backup->failing_storage_address = S390_lowcore.failing_storage_address; } NOKPROBE_SYMBOL(s390_backup_mcck_info); #define MAX_IPD_COUNT 29 #define MAX_IPD_TIME (5 * 60 * USEC_PER_SEC) /* 5 minutes */ #define ED_STP_ISLAND 6 /* External damage STP island check */ #define ED_STP_SYNC 7 /* External damage STP sync check */ #define MCCK_CODE_NO_GUEST (MCCK_CODE_CP | MCCK_CODE_EXT_DAMAGE) /* * machine check handler. */ void notrace s390_do_machine_check(struct pt_regs *regs) { static int ipd_count; static DEFINE_SPINLOCK(ipd_lock); static unsigned long long last_ipd; struct mcck_struct *mcck; unsigned long long tmp; irqentry_state_t irq_state; union mci mci; unsigned long mcck_dam_code; int mcck_pending = 0; irq_state = irqentry_nmi_enter(regs); if (user_mode(regs)) update_timer_mcck(); inc_irq_stat(NMI_NMI); mci.val = S390_lowcore.mcck_interruption_code; mcck = this_cpu_ptr(&cpu_mcck); /* * Reinject the instruction processing damages' machine checks * including Delayed Access Exception into the guest * instead of damaging the host if they happen in the guest. */ if (mci.pd && !test_cpu_flag(CIF_MCCK_GUEST)) { if (mci.b) { /* Processing backup -> verify if we can survive this */ u64 z_mcic, o_mcic, t_mcic; z_mcic = (1ULL<<63 | 1ULL<<59 | 1ULL<<29); o_mcic = (1ULL<<43 | 1ULL<<42 | 1ULL<<41 | 1ULL<<40 | 1ULL<<36 | 1ULL<<35 | 1ULL<<34 | 1ULL<<32 | 1ULL<<30 | 1ULL<<21 | 1ULL<<20 | 1ULL<<17 | 1ULL<<16); t_mcic = mci.val; if (((t_mcic & z_mcic) != 0) || ((t_mcic & o_mcic) != o_mcic)) { s390_handle_damage(); } /* * Nullifying exigent condition, therefore we might * retry this instruction. */ spin_lock(&ipd_lock); tmp = get_tod_clock(); if (((tmp - last_ipd) >> 12) < MAX_IPD_TIME) ipd_count++; else ipd_count = 1; last_ipd = tmp; if (ipd_count == MAX_IPD_COUNT) s390_handle_damage(); spin_unlock(&ipd_lock); } else { /* Processing damage -> stopping machine */ s390_handle_damage(); } } if (!nmi_registers_valid(mci)) { if (!user_mode(regs)) s390_handle_damage(); /* * Couldn't restore all register contents for the * user space process -> mark task for termination. */ mcck->kill_task = 1; mcck->mcck_code = mci.val; mcck_pending = 1; } /* * Backup the machine check's info if it happens when the guest * is running. */ if (test_cpu_flag(CIF_MCCK_GUEST)) s390_backup_mcck_info(regs); if (mci.cd) { /* Timing facility damage */ s390_handle_damage(); } if (mci.ed && mci.ec) { /* External damage */ if (S390_lowcore.external_damage_code & (1U << ED_STP_SYNC)) mcck->stp_queue |= stp_sync_check(); if (S390_lowcore.external_damage_code & (1U << ED_STP_ISLAND)) mcck->stp_queue |= stp_island_check(); mcck_pending = 1; } /* * Reinject storage related machine checks into the guest if they * happen when the guest is running. */ if (!test_cpu_flag(CIF_MCCK_GUEST)) { /* Storage error uncorrected */ if (mci.se) s390_handle_damage(); /* Storage key-error uncorrected */ if (mci.ke) s390_handle_damage(); /* Storage degradation */ if (mci.ds && mci.fa) s390_handle_damage(); } if (mci.cp) { /* Channel report word pending */ mcck->channel_report = 1; mcck_pending = 1; } if (mci.w) { /* Warning pending */ mcck->warning = 1; mcck_pending = 1; } /* * If there are only Channel Report Pending and External Damage * machine checks, they will not be reinjected into the guest * because they refer to host conditions only. */ mcck_dam_code = (mci.val & MCIC_SUBCLASS_MASK); if (test_cpu_flag(CIF_MCCK_GUEST) && (mcck_dam_code & MCCK_CODE_NO_GUEST) != mcck_dam_code) { /* Set exit reason code for host's later handling */ *((long *)(regs->gprs[15] + __SF_SIE_REASON)) = -EINTR; } clear_cpu_flag(CIF_MCCK_GUEST); if (mcck_pending) schedule_mcck_handler(); irqentry_nmi_exit(regs, irq_state); } NOKPROBE_SYMBOL(s390_do_machine_check); static int __init machine_check_init(void) { system_ctl_set_bit(14, CR14_EXTERNAL_DAMAGE_SUBMASK_BIT); system_ctl_set_bit(14, CR14_RECOVERY_SUBMASK_BIT); system_ctl_set_bit(14, CR14_WARNING_SUBMASK_BIT); return 0; } early_initcall(machine_check_init);