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-rw-r--r--arch/s390/kernel/nmi.c485
1 files changed, 485 insertions, 0 deletions
diff --git a/arch/s390/kernel/nmi.c b/arch/s390/kernel/nmi.c
new file mode 100644
index 000000000..0102376ec
--- /dev/null
+++ b/arch/s390/kernel/nmi.c
@@ -0,0 +1,485 @@
+// 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>,
+ * 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/kmemleak.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();
+ 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));
+ 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);
+ make_task_dead(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.
+ */
+int 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;
+ int mcck_pending = 0;
+
+ 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;
+ 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)) {
+ 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;
+ 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 (user_mode(regs) && mcck_pending) {
+ nmi_exit();
+ return 1;
+ }
+
+ if (mcck_pending)
+ schedule_mcck_handler();
+
+ nmi_exit();
+ return 0;
+}
+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);
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