/*
* 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>,
* Heiko Carstens <heiko.carstens@de.ibm.com>,
*/
#include <linux/kernel_stat.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/hardirq.h>
#include <linux/log2.h>
#include <linux/kprobes.h>
#include <linux/slab.h>
#include <linux/time.h>
#include <linux/module.h>
#include <linux/sched/signal.h>
#include <linux/export.h>
#include <asm/lowcore.h>
#include <asm/smp.h>
#include <asm/stp.h>
#include <asm/cputime.h>
#include <asm/nmi.h>
#include <asm/crw.h>
#include <asm/switch_to.h>
#include <asm/ctl_reg.h>
#include <asm/asm-offsets.h>
#include <linux/kvm_host.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 struct kmem_cache *mcesa_cache;
static unsigned long mcesa_origin_lc;
static inline int nmi_needs_mcesa(void)
{
return MACHINE_HAS_VX || MACHINE_HAS_GS;
}
static inline unsigned long nmi_get_mcesa_size(void)
{
if (MACHINE_HAS_GS)
return MCESA_MAX_SIZE;
return MCESA_MIN_SIZE;
}
/*
* The initial machine check extended save area for the boot CPU.
* It will be replaced by nmi_init() with an allocated structure.
* The structure is required for machine check happening early in
* the boot process.
*/
static struct mcesa boot_mcesa __initdata __aligned(MCESA_MAX_SIZE);
void __init nmi_alloc_boot_cpu(struct lowcore *lc)
{
if (!nmi_needs_mcesa())
return;
lc->mcesad = (unsigned long) &boot_mcesa;
if (MACHINE_HAS_GS)
lc->mcesad |= ilog2(MCESA_MAX_SIZE);
}
static int __init nmi_init(void)
{
unsigned long origin, cr0, size;
if (!nmi_needs_mcesa())
return 0;
size = nmi_get_mcesa_size();
if (size > MCESA_MIN_SIZE)
mcesa_origin_lc = ilog2(size);
/* create slab cache for the machine-check-extended-save-areas */
mcesa_cache = kmem_cache_create("nmi_save_areas", size, size, 0, NULL);
if (!mcesa_cache)
panic("Couldn't create nmi save area cache");
origin = (unsigned long) kmem_cache_alloc(mcesa_cache, GFP_KERNEL);
if (!origin)
panic("Couldn't allocate nmi save area");
/* The pointer is stored with mcesa_bits ORed in */
kmemleak_not_leak((void *) origin);
__ctl_store(cr0, 0, 0);
__ctl_clear_bit(0, 28); /* disable lowcore protection */
/* Replace boot_mcesa on the boot CPU */
S390_lowcore.mcesad = origin | mcesa_origin_lc;
__ctl_load(cr0, 0, 0);
return 0;
}
early_initcall(nmi_init);
int nmi_alloc_per_cpu(struct lowcore *lc)
{
unsigned long origin;
if (!nmi_needs_mcesa())
return 0;
origin = (unsigned long) kmem_cache_alloc(mcesa_cache, GFP_KERNEL);
if (!origin)
return -ENOMEM;
/* The pointer is stored with mcesa_bits ORed in */
kmemleak_not_leak((void *) origin);
lc->mcesad = origin | mcesa_origin_lc;
return 0;
}
void nmi_free_per_cpu(struct lowcore *lc)
{
if (!nmi_needs_mcesa())
return;
kmem_cache_free(mcesa_cache, (void *)(lc->mcesad & MCESA_ORIGIN_MASK));
}
static notrace void s390_handle_damage(void)
{
smp_emergency_stop();
disabled_wait((unsigned long) __builtin_return_address(0));
while (1);
}
NOKPROBE_SYMBOL(s390_handle_damage);
/*
* Main machine check handler function. Will be called with interrupts enabled
* or disabled and machine checks enabled or disabled.
*/
void s390_handle_mcck(void)
{
unsigned long flags;
struct mcck_struct mcck;
/*
* Disable machine checks and get the current state of accumulated
* machine checks. Afterwards delete the old state and enable machine
* checks again.
*/
local_irq_save(flags);
local_mcck_disable();
mcck = *this_cpu_ptr(&cpu_mcck);
memset(this_cpu_ptr(&cpu_mcck), 0, sizeof(mcck));
clear_cpu_flag(CIF_MCCK_PENDING);
local_mcck_enable();
local_irq_restore(flags);
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. */
__ctl_clear_bit(14, 24); /* Disable WARNING MCH */
if (xchg(&mchchk_wng_posted, 1) == 0)
kill_cad_pid(SIGPWR, 1);
}
if (mcck.stp_queue)
stp_queue_work();
if (mcck.kill_task) {
local_irq_enable();
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);
do_exit(SIGSEGV);
}
}
EXPORT_SYMBOL_GPL(s390_handle_mcck);
/*
* returns 0 if all required registers are available
* returns 1 otherwise
*/
static int notrace s390_check_registers(union mci mci, int umode)
{
union ctlreg2 cr2;
int kill_task;
kill_task = 0;
if (!mci.gr) {
/*
* General purpose registers couldn't be restored and have
* unknown contents. Stop system or terminate process.
*/
if (!umode)
s390_handle_damage();
kill_task = 1;
}
/* Check control registers */
if (!mci.cr) {
/*
* Control registers have unknown contents.
* Can't recover and therefore stopping machine.
*/
s390_handle_damage();
}
if (!mci.fp) {
/*
* Floating point registers can't be restored. If the
* kernel currently uses floating point registers the
* system is stopped. If the process has its floating
* pointer registers loaded it is terminated.
*/
if (S390_lowcore.fpu_flags & KERNEL_VXR_V0V7)
s390_handle_damage();
if (!test_cpu_flag(CIF_FPU))
kill_task = 1;
}
if (!mci.fc) {
/*
* Floating point control register can't be restored.
* If the kernel currently uses the floating pointer
* registers and needs the FPC register the system is
* stopped. If the process has its floating pointer
* registers loaded it is terminated.
*/
if (S390_lowcore.fpu_flags & KERNEL_FPC)
s390_handle_damage();
if (!test_cpu_flag(CIF_FPU))
kill_task = 1;
}
if (MACHINE_HAS_VX) {
if (!mci.vr) {
/*
* Vector registers can't be restored. If the kernel
* currently uses vector registers the system is
* stopped. If the process has its vector registers
* loaded it is terminated.
*/
if (S390_lowcore.fpu_flags & KERNEL_VXR)
s390_handle_damage();
if (!test_cpu_flag(CIF_FPU))
kill_task = 1;
}
}
/* Check if access registers are valid */
if (!mci.ar) {
/*
* Access registers have unknown contents.
* Terminating task.
*/
kill_task = 1;
}
/* Check guarded storage registers */
cr2.val = S390_lowcore.cregs_save_area[2];
if (cr2.gse) {
if (!mci.gs) {
/*
* Guarded storage register can't be restored and
* the current processes uses guarded storage.
* It has to be terminated.
*/
kill_task = 1;
}
}
/* Check if old PSW is valid */
if (!mci.wp) {
/*
* Can't tell if we come from user or kernel mode
* -> stopping machine.
*/
s390_handle_damage();
}
/* Check for invalid kernel instruction address */
if (!mci.ia && !umode) {
/*
* The instruction address got lost while running
* in the kernel -> stopping machine.
*/
s390_handle_damage();
}
if (!mci.ms || !mci.pm || !mci.ia)
kill_task = 1;
return kill_task;
}
NOKPROBE_SYMBOL(s390_check_registers);
/*
* 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 =
(struct kvm_s390_sie_block *) 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;
union mci mci;
unsigned long mcck_dam_code;
nmi_enter();
inc_irq_stat(NMI_NMI);
mci.val = S390_lowcore.mcck_interruption_code;
mcck = this_cpu_ptr(&cpu_mcck);
if (mci.sd) {
/* System damage -> stopping machine */
s390_handle_damage();
}
/*
* 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 (s390_check_registers(mci, user_mode(regs))) {
/*
* Couldn't restore all register contents for the
* user space process -> mark task for termination.
*/
mcck->kill_task = 1;
mcck->mcck_code = mci.val;
set_cpu_flag(CIF_MCCK_PENDING);
}
/*
* 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();
if (mcck->stp_queue)
set_cpu_flag(CIF_MCCK_PENDING);
}
/*
* Reinject storage related machine checks into the guest if they
* happen when the guest is running.
*/
if (!test_cpu_flag(CIF_MCCK_GUEST)) {
if (mci.se)
/* Storage error uncorrected */
s390_handle_damage();
if (mci.ke)
/* Storage key-error uncorrected */
s390_handle_damage();
if (mci.ds && mci.fa)
/* Storage degradation */
s390_handle_damage();
}
if (mci.cp) {
/* Channel report word pending */
mcck->channel_report = 1;
set_cpu_flag(CIF_MCCK_PENDING);
}
if (mci.w) {
/* Warning pending */
mcck->warning = 1;
set_cpu_flag(CIF_MCCK_PENDING);
}
/*
* 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);
nmi_exit();
}
NOKPROBE_SYMBOL(s390_do_machine_check);
static int __init machine_check_init(void)
{
ctl_set_bit(14, 25); /* enable external damage MCH */
ctl_set_bit(14, 27); /* enable system recovery MCH */
ctl_set_bit(14, 24); /* enable warning MCH */
return 0;
}
early_initcall(machine_check_init);
