1 files changed, 172 insertions, 202 deletions

diff --git a/arch/s390/kernel/nmi.c b/arch/s390/kernel/nmi.c
index 0a487fae763e..3da371c144eb 100644
--- a/arch/s390/kernel/nmi.c
+++ b/arch/s390/kernel/nmi.c
@@ -6,12 +6,13 @@
  *    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/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>
@@ -19,18 +20,19 @@
 #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/switch_to.h>
-#include <asm/ctl_reg.h>
 #include <asm/asm-offsets.h>
-#include <linux/kvm_host.h>
+#include <asm/pai.h>
+#include <asm/vtime.h>
 
 struct mcck_struct {
 	unsigned int kill_task : 1;
@@ -41,116 +43,135 @@ struct mcck_struct {
 };
 
 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;
+	return cpu_has_vx() || cpu_has_gs();
 }
 
 /*
  * 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.
+ * 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 __initdata __aligned(MCESA_MAX_SIZE);
+static struct mcesa boot_mcesa __aligned(MCESA_MAX_SIZE);
 
-void __init nmi_alloc_boot_cpu(struct lowcore *lc)
+void __init nmi_alloc_mcesa_early(u64 *mcesad)
 {
 	if (!nmi_needs_mcesa())
 		return;
-	lc->mcesad = (unsigned long) &boot_mcesa;
-	if (MACHINE_HAS_GS)
-		lc->mcesad |= ilog2(MCESA_MAX_SIZE);
+	*mcesad = __pa(&boot_mcesa);
+	if (cpu_has_gs())
+		*mcesad |= ilog2(MCESA_MAX_SIZE);
 }
 
-static int __init nmi_init(void)
+int nmi_alloc_mcesa(u64 *mcesad)
 {
-	unsigned long origin, cr0, size;
+	unsigned long size;
+	void *origin;
 
+	*mcesad = 0;
 	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);
+	size = cpu_has_gs() ? MCESA_MAX_SIZE : MCESA_MIN_SIZE;
+	origin = kmalloc(size, GFP_KERNEL);
 	if (!origin)
-		panic("Couldn't allocate nmi save area");
+		return -ENOMEM;
 	/* 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);
+	kmemleak_not_leak(origin);
+	*mcesad = __pa(origin);
+	if (cpu_has_gs())
+		*mcesad |= ilog2(MCESA_MAX_SIZE);
 	return 0;
 }
-early_initcall(nmi_init);
 
-int nmi_alloc_per_cpu(struct lowcore *lc)
+void nmi_free_mcesa(u64 *mcesad)
 {
-	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;
+		return;
+	kfree(__va(*mcesad & MCESA_ORIGIN_MASK));
 }
 
-void nmi_free_per_cpu(struct lowcore *lc)
+static __always_inline char *nmi_puts(char *dest, const char *src)
 {
-	if (!nmi_needs_mcesa())
-		return;
-	kmem_cache_free(mcesa_cache, (void *)(lc->mcesad & MCESA_ORIGIN_MASK));
+	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)
 {
+	struct lowcore *lc = get_lowcore();
+	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, lc->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 = 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;
+	sclp_emergency_printk(message);
+
+	/*
+	 * 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();
 	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.
+ * 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();
+	local_mcck_save(mflags);
 	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);
+	local_mcck_restore(mflags);
 
 	if (mcck.channel_report)
 		crw_handle_channel_report();
@@ -167,134 +188,80 @@ 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%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 required registers are available
- * 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_check_registers(union mci mci, int umode)
+static bool notrace nmi_registers_valid(union mci mci)
 {
 	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();
-	}
 
+	/*
+	 * 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(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)
-		kill_task = 1;
-
-	return kill_task;
+		return false;
+	return true;
 }
-NOKPROBE_SYMBOL(s390_check_registers);
+NOKPROBE_SYMBOL(nmi_registers_valid);
 
 /*
  * Backup the guest's machine check info to its description block
@@ -305,8 +272,7 @@ static void notrace s390_backup_mcck_info(struct pt_regs *regs)
 	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];
+	struct kvm_s390_sie_block *sie_block = phys_to_virt(regs->gprs[14]);
 
 	if (sie_block == NULL)
 		/* Something's seriously wrong, stop system. */
@@ -314,11 +280,10 @@ static void notrace s390_backup_mcck_info(struct pt_regs *regs)
 
 	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_backup->mcic = get_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;
+	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);
 
@@ -338,21 +303,22 @@ 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;
+	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.val = S390_lowcore.mcck_interruption_code;
+	mci.val = lc->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
@@ -393,14 +359,16 @@ void notrace s390_do_machine_check(struct pt_regs *regs)
 			s390_handle_damage();
 		}
 	}
-	if (s390_check_registers(mci, user_mode(regs))) {
+	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;
-		set_cpu_flag(CIF_MCCK_PENDING);
+		mcck_pending = 1;
 	}
 
 	/*
@@ -416,38 +384,36 @@ void notrace s390_do_machine_check(struct pt_regs *regs)
 	}
 	if (mci.ed && mci.ec) {
 		/* External damage */
-		if (S390_lowcore.external_damage_code & (1U << ED_STP_SYNC))
+		if (lc->external_damage_code & (1U << ED_STP_SYNC))
 			mcck->stp_queue |= stp_sync_check();
-		if (S390_lowcore.external_damage_code & (1U << ED_STP_ISLAND))
+		if (lc->external_damage_code & (1U << ED_STP_ISLAND))
 			mcck->stp_queue |= stp_island_check();
-		if (mcck->stp_queue)
-			set_cpu_flag(CIF_MCCK_PENDING);
+		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)
-			/* Storage error uncorrected */
 			s390_handle_damage();
+		/* Storage key-error uncorrected */
 		if (mci.ke)
-			/* Storage key-error uncorrected */
 			s390_handle_damage();
+		/* Storage degradation */
 		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);
+		mcck_pending = 1;
 	}
 	if (mci.w) {
 		/* Warning pending */
 		mcck->warning = 1;
-		set_cpu_flag(CIF_MCCK_PENDING);
+		mcck_pending = 1;
 	}
 
 	/*
@@ -462,15 +428,19 @@ void notrace s390_do_machine_check(struct pt_regs *regs)
 		*((long *)(regs->gprs[15] + __SF_SIE_REASON)) = -EINTR;
 	}
 	clear_cpu_flag(CIF_MCCK_GUEST);
-	nmi_exit();
+
+	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;
 }
 early_initcall(machine_check_init);