blob: c77382a673257abcdae4c64fe03a94f0aedfb0f0 [file] [log] [blame]
// SPDX-License-Identifier: GPL-2.0
/*
* Machine check handler
*
* Copyright IBM Corp. 2000, 2009
* Author(s): Ingo Adlung <adlung@de.ibm.com>,
* Martin Schwidefsky <schwidefsky@de.ibm.com>,
* Cornelia Huck <cornelia.huck@de.ibm.com>,
*/
#include <linux/kernel_stat.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/entry-common.h>
#include <linux/hardirq.h>
#include <linux/log2.h>
#include <linux/kprobes.h>
#include <linux/kmemleak.h>
#include <linux/time.h>
#include <linux/module.h>
#include <linux/sched/signal.h>
#include <linux/kvm_host.h>
#include <linux/export.h>
#include <asm/lowcore.h>
#include <asm/ctlreg.h>
#include <asm/fpu.h>
#include <asm/smp.h>
#include <asm/stp.h>
#include <asm/cputime.h>
#include <asm/nmi.h>
#include <asm/crw.h>
#include <asm/asm-offsets.h>
#include <asm/pai.h>
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);