1 files changed, 364 insertions, 230 deletions

diff --git a/arch/s390/kernel/nmi.c b/arch/s390/kernel/nmi.c
index 504175ebf8b0..a55abbf65333 100644
--- a/arch/s390/kernel/nmi.c
+++ b/arch/s390/kernel/nmi.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  *   Machine check handler
  *
@@ -5,59 +6,235 @@
  *    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/utsname.h>
+#include <linux/cpufeature.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 <asm/lowcore.h>
+#include <asm/ctlreg.h>
+#include <asm/fpu.h>
 #include <asm/smp.h>
-#include <asm/etr.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>
+#include <asm/vtime.h>
 
 struct mcck_struct {
-	int kill_task;
-	int channel_report;
-	int warning;
-	unsigned long long mcck_code;
+	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 void s390_handle_damage(char *msg)
+static inline int nmi_needs_mcesa(void)
 {
-	smp_send_stop();
-	disabled_wait((unsigned long) __builtin_return_address(0));
-	while (1);
+	return cpu_has_vx() || cpu_has_gs();
 }
 
 /*
- * Main machine check handler function. Will be called with interrupts enabled
- * or disabled and machine checks enabled or disabled.
+ * 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 (cpu_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 = cpu_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 (cpu_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 nmi_print_info(void)
+{
+	struct lowcore *lc = get_lowcore();
+	char message[100];
+	char *ptr;
+	int i;
+
+	ptr = nmi_puts(message, "Unrecoverable machine check, code: ");
+	ptr = u64_to_hex(ptr, lc->mcck_interruption_code);
+	ptr = nmi_puts(ptr, "\n");
+	sclp_emergency_printk(message);
+
+	ptr = nmi_puts(message, init_utsname()->release);
+	ptr = nmi_puts(ptr, "\n");
+	sclp_emergency_printk(message);
+
+	ptr = nmi_puts(message, arch_hw_string);
+	ptr = nmi_puts(ptr, "\n");
+	sclp_emergency_printk(message);
+
+	ptr = nmi_puts(message, "PSW: ");
+	ptr = u64_to_hex(ptr, lc->mcck_old_psw.mask);
+	ptr = nmi_puts(ptr, " ");
+	ptr = u64_to_hex(ptr, lc->mcck_old_psw.addr);
+	ptr = nmi_puts(ptr, " PFX: ");
+	ptr = u64_to_hex(ptr, (u64)get_lowcore());
+	ptr = nmi_puts(ptr, "\n");
+	sclp_emergency_printk(message);
+
+	ptr = nmi_puts(message, "LBA: ");
+	ptr = u64_to_hex(ptr, lc->last_break_save_area);
+	ptr = nmi_puts(ptr, " EDC: ");
+	ptr = u64_to_hex(ptr, lc->external_damage_code);
+	ptr = nmi_puts(ptr, " FSA: ");
+	ptr = u64_to_hex(ptr, lc->failing_storage_address);
+	ptr = nmi_puts(ptr, "\n");
+	sclp_emergency_printk(message);
+
+	ptr = nmi_puts(message, "CRS:\n");
+	sclp_emergency_printk(message);
+	ptr = message;
+	for (i = 0; i < 16; i++) {
+		ptr = u64_to_hex(ptr, lc->cregs_save_area[i].val);
+		ptr = nmi_puts(ptr, " ");
+		if ((i + 1) % 4 == 0) {
+			ptr = nmi_puts(ptr, "\n");
+			sclp_emergency_printk(message);
+			ptr = message;
+		}
+	}
+
+	ptr = nmi_puts(message, "GPRS:\n");
+	sclp_emergency_printk(message);
+	ptr = message;
+	for (i = 0; i < 16; i++) {
+		ptr = u64_to_hex(ptr, lc->gpregs_save_area[i]);
+		ptr = nmi_puts(ptr, " ");
+		if ((i + 1) % 4 == 0) {
+			ptr = nmi_puts(ptr, "\n");
+			sclp_emergency_printk(message);
+			ptr = message;
+		}
+	}
+
+	ptr = nmi_puts(message, "System stopped\n");
+	sclp_emergency_printk(message);
+}
+
+static notrace void __noreturn s390_handle_damage(void)
+{
+	struct lowcore *lc = get_lowcore();
+	union ctlreg0 cr0, cr0_new;
+	psw_t psw_save;
+
+	smp_emergency_stop();
+	diag_amode31_ops.diag308_reset();
+
+	/*
+	 * 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 = lc->mcck_new_psw;
+	psw_bits(lc->mcck_new_psw).io = 0;
+	psw_bits(lc->mcck_new_psw).ext = 0;
+	psw_bits(lc->mcck_new_psw).wait = 1;
+	nmi_print_info();
+
+	/*
+	 * Restore machine check new PSW and control register 0 to original
+	 * values. This makes possible system dump analysis easier.
+	 */
+	lc->mcck_new_psw = psw_save;
+	local_ctl_load(0, &cr0.reg);
+	disabled_wait();
+}
+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)
 {
-	unsigned long flags;
 	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_irq_save(flags);
-	local_mcck_disable();
-	mcck = __get_cpu_var(cpu_mcck);
-	memset(&__get_cpu_var(cpu_mcck), 0, sizeof(struct mcck_struct));
-	clear_thread_flag(TIF_MCCK_PENDING);
-	local_mcck_enable();
-	local_irq_restore(flags);
+	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();
@@ -74,171 +251,112 @@ void s390_handle_mcck(void)
 		static int mchchk_wng_posted = 0;
 
 		/* Use single cpu clear, as we cannot handle smp here. */
-		__ctl_clear_bit(14, 24);	/* Disable WARNING MCH */
+		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) {
-		local_irq_enable();
 		printk(KERN_EMERG "mcck: Terminating task because of machine "
-		       "malfunction (code 0x%016llx).\n", mcck.mcck_code);
+		       "malfunction (code 0x%016lx).\n", mcck.mcck_code);
 		printk(KERN_EMERG "mcck: task: %s, pid: %d.\n",
 		       current->comm, current->pid);
-		do_exit(SIGSEGV);
+		if (is_global_init(current))
+			panic("mcck: Attempting to kill init!\n");
+		do_send_sig_info(SIGKILL, SEND_SIG_PRIV, current, PIDTYPE_PID);
 	}
 }
-EXPORT_SYMBOL_GPL(s390_handle_mcck);
 
-/*
- * returns 0 if all registers could be validated
- * returns 1 otherwise
+/**
+ * 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 int notrace s390_revalidate_registers(struct mci *mci)
+static bool notrace nmi_registers_valid(union mci mci)
 {
-	int kill_task;
-	u64 zero;
-	void *fpt_save_area, *fpt_creg_save_area;
-
-	kill_task = 0;
-	zero = 0;
+	union ctlreg2 cr2;
 
-	if (!mci->gr) {
-		/*
-		 * General purpose registers couldn't be restored and have
-		 * unknown contents. Process needs to be terminated.
-		 */
-		kill_task = 1;
-	}
-	if (!mci->fp) {
-		/*
-		 * Floating point registers can't be restored and
-		 * therefore the process needs to be terminated.
-		 */
-		kill_task = 1;
-	}
-#ifndef CONFIG_64BIT
-	asm volatile(
-		"	ld	0,0(%0)\n"
-		"	ld	2,8(%0)\n"
-		"	ld	4,16(%0)\n"
-		"	ld	6,24(%0)"
-		: : "a" (&S390_lowcore.floating_pt_save_area));
-#endif
-
-	if (MACHINE_HAS_IEEE) {
-#ifdef CONFIG_64BIT
-		fpt_save_area = &S390_lowcore.floating_pt_save_area;
-		fpt_creg_save_area = &S390_lowcore.fpt_creg_save_area;
-#else
-		fpt_save_area = (void *) S390_lowcore.extended_save_area_addr;
-		fpt_creg_save_area = fpt_save_area + 128;
-#endif
-		if (!mci->fc) {
-			/*
-			 * Floating point control register can't be restored.
-			 * Task will be terminated.
-			 */
-			asm volatile("lfpc 0(%0)" : : "a" (&zero), "m" (zero));
-			kill_task = 1;
-
-		} else
-			asm volatile("lfpc 0(%0)" : : "a" (fpt_creg_save_area));
-
-		asm volatile(
-			"	ld	0,0(%0)\n"
-			"	ld	1,8(%0)\n"
-			"	ld	2,16(%0)\n"
-			"	ld	3,24(%0)\n"
-			"	ld	4,32(%0)\n"
-			"	ld	5,40(%0)\n"
-			"	ld	6,48(%0)\n"
-			"	ld	7,56(%0)\n"
-			"	ld	8,64(%0)\n"
-			"	ld	9,72(%0)\n"
-			"	ld	10,80(%0)\n"
-			"	ld	11,88(%0)\n"
-			"	ld	12,96(%0)\n"
-			"	ld	13,104(%0)\n"
-			"	ld	14,112(%0)\n"
-			"	ld	15,120(%0)\n"
-			: : "a" (fpt_save_area));
-	}
-	/* Revalidate access registers */
-	asm volatile(
-		"	lam	0,15,0(%0)"
-		: : "a" (&S390_lowcore.access_regs_save_area));
-	if (!mci->ar) {
-		/*
-		 * Access registers have unknown contents.
-		 * Terminating task.
-		 */
-		kill_task = 1;
-	}
-	/* Revalidate control registers */
-	if (!mci->cr) {
-		/*
-		 * Control registers have unknown contents.
-		 * Can't recover and therefore stopping machine.
-		 */
-		s390_handle_damage("invalid control registers.");
-	} else {
-#ifdef CONFIG_64BIT
-		asm volatile(
-			"	lctlg	0,15,0(%0)"
-			: : "a" (&S390_lowcore.cregs_save_area));
-#else
-		asm volatile(
-			"	lctl	0,15,0(%0)"
-			: : "a" (&S390_lowcore.cregs_save_area));
-#endif
-	}
 	/*
-	 * We don't even try to revalidate the TOD register, since we simply
-	 * can't write something sensible into that register.
+	 * 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.
 	 */
-#ifdef CONFIG_64BIT
+	set_tod_programmable_field(raw_smp_processor_id());
 	/*
-	 * See if we can revalidate the TOD programmable register with its
-	 * old contents (should be zero) otherwise set it to zero.
+	 * Set the clock comparator register to the next expected value.
 	 */
-	if (!mci->pr)
-		asm volatile(
-			"	sr	0,0\n"
-			"	sckpf"
-			: : : "0", "cc");
-	else
-		asm volatile(
-			"	l	0,0(%0)\n"
-			"	sckpf"
-			: : "a" (&S390_lowcore.tod_progreg_save_area)
-			: "0", "cc");
-#endif
-	/* Revalidate clock comparator register */
-	if (S390_lowcore.clock_comparator == -1)
-		set_clock_comparator(S390_lowcore.mcck_clock);
-	else
-		set_clock_comparator(S390_lowcore.clock_comparator);
-	/* 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("old psw invalid.");
+	set_clock_comparator(get_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 = get_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);
 
-	if (!mci->ms || !mci->pm || !mci->ia)
-		kill_task = 1;
+/*
+ * 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]);
 
-	return kill_task;
+	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 = get_lowcore()->mcck_interruption_code &
+				~(MCCK_CODE_CP | MCCK_CODE_EXT_DAMAGE);
+	mcck_backup->ext_damage_code = get_lowcore()->external_damage_code;
+	mcck_backup->failing_storage_address = get_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 ED_ETR_SYNC	12	/* External damage ETR sync check */
-#define ED_ETR_SWITCH	13	/* External damage ETR switch to local */
+
+#define MCCK_CODE_NO_GUEST	(MCCK_CODE_CP | MCCK_CODE_EXT_DAMAGE)
 
 /*
  * machine check handler.
@@ -248,44 +366,41 @@ 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 lowcore *lc = get_lowcore();
 	struct mcck_struct *mcck;
 	unsigned long long tmp;
-	struct mci *mci;
-	int umode;
+	irqentry_state_t irq_state;
+	union mci mci;
+	unsigned long mcck_dam_code;
+	int mcck_pending = 0;
+
+	irq_state = irqentry_nmi_enter(regs);
 
-	nmi_enter();
+	if (user_mode(regs))
+		update_timer_mcck();
 	inc_irq_stat(NMI_NMI);
-	mci = (struct mci *) &S390_lowcore.mcck_interruption_code;
-	mcck = &__get_cpu_var(cpu_mcck);
-	umode = user_mode(regs);
+	mci.val = lc->mcck_interruption_code;
+	mcck = this_cpu_ptr(&cpu_mcck);
 
-	if (mci->sd) {
-		/* System damage -> stopping machine */
-		s390_handle_damage("received system damage machine check.");
-	}
-	if (mci->pd) {
-		if (mci->b) {
+	/*
+	 * 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;
-#ifdef CONFIG_64BIT
 			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);
-#else
-			z_mcic = (1ULL<<63 | 1ULL<<59 | 1ULL<<57 | 1ULL<<50 |
-				  1ULL<<29);
-			o_mcic = (1ULL<<43 | 1ULL<<42 | 1ULL<<41 | 1ULL<<40 |
-				  1ULL<<36 | 1ULL<<35 | 1ULL<<34 | 1ULL<<32 |
-				  1ULL<<30 | 1ULL<<20 | 1ULL<<17 | 1ULL<<16);
-#endif
-			t_mcic = *(u64 *)mci;
+			t_mcic = mci.val;
 
 			if (((t_mcic & z_mcic) != 0) ||
 			    ((t_mcic & o_mcic) != o_mcic)) {
-				s390_handle_damage("processing backup machine "
-						   "check with damage.");
+				s390_handle_damage();
 			}
 
 			/*
@@ -300,76 +415,95 @@ void notrace s390_do_machine_check(struct pt_regs *regs)
 				ipd_count = 1;
 			last_ipd = tmp;
 			if (ipd_count == MAX_IPD_COUNT)
-				s390_handle_damage("too many ipd retries.");
+				s390_handle_damage();
 			spin_unlock(&ipd_lock);
 		} else {
 			/* Processing damage -> stopping machine */
-			s390_handle_damage("received instruction processing "
-					   "damage machine check.");
+			s390_handle_damage();
 		}
 	}
-	if (s390_revalidate_registers(mci)) {
-		if (umode) {
-			/*
-			 * Couldn't restore all register contents while in
-			 * user mode -> mark task for termination.
-			 */
-			mcck->kill_task = 1;
-			mcck->mcck_code = *(unsigned long long *) mci;
-			set_thread_flag(TIF_MCCK_PENDING);
-		} else {
-			/*
-			 * Couldn't restore all register contents while in
-			 * kernel mode -> stopping machine.
-			 */
-			s390_handle_damage("unable to revalidate registers.");
-		}
+	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;
 	}
-	if (mci->cd) {
+
+	/*
+	 * 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("TOD clock damaged");
+		s390_handle_damage();
 	}
-	if (mci->ed && mci->ec) {
+	if (mci.ed && mci.ec) {
 		/* External damage */
-		if (S390_lowcore.external_damage_code & (1U << ED_ETR_SYNC))
-			etr_sync_check();
-		if (S390_lowcore.external_damage_code & (1U << ED_ETR_SWITCH))
-			etr_switch_to_local();
-		if (S390_lowcore.external_damage_code & (1U << ED_STP_SYNC))
-			stp_sync_check();
-		if (S390_lowcore.external_damage_code & (1U << ED_STP_ISLAND))
-			stp_island_check();
+		if (lc->external_damage_code & (1U << ED_STP_SYNC))
+			mcck->stp_queue |= stp_sync_check();
+		if (lc->external_damage_code & (1U << ED_STP_ISLAND))
+			mcck->stp_queue |= stp_island_check();
+		mcck_pending = 1;
 	}
-	if (mci->se)
+	/*
+	 * 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 */
-		s390_handle_damage("received storage error uncorrected "
-				   "machine check.");
-	if (mci->ke)
+		if (mci.se)
+			s390_handle_damage();
 		/* Storage key-error uncorrected */
-		s390_handle_damage("received storage key-error uncorrected "
-				   "machine check.");
-	if (mci->ds && mci->fa)
+		if (mci.ke)
+			s390_handle_damage();
 		/* Storage degradation */
-		s390_handle_damage("received storage degradation machine "
-				   "check.");
-	if (mci->cp) {
+		if (mci.ds && mci.fa)
+			s390_handle_damage();
+	}
+	if (mci.cp) {
 		/* Channel report word pending */
 		mcck->channel_report = 1;
-		set_thread_flag(TIF_MCCK_PENDING);
+		mcck_pending = 1;
 	}
-	if (mci->w) {
+	if (mci.w) {
 		/* Warning pending */
 		mcck->warning = 1;
-		set_thread_flag(TIF_MCCK_PENDING);
+		mcck_pending = 1;
 	}
-	nmi_exit();
+
+	/*
+	 * 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)
 {
-	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 */
+	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;
 }
-arch_initcall(machine_check_init);
+early_initcall(machine_check_init);