1 files changed, 528 insertions, 0 deletions

diff --git a/arch/s390/kernel/nmi.c b/arch/s390/kernel/nmi.c
new file mode 100644
index 000000000..31cb9b00a
--- /dev/null
+++ b/arch/s390/kernel/nmi.c
@@ -0,0 +1,528 @@
+// 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/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 <asm/pai.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 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);
+}
+
+static void __init nmi_alloc_cache(void)
+{
+	unsigned long size;
+
+	if (!nmi_needs_mcesa())
+		return;
+	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");
+}
+
+int __ref nmi_alloc_mcesa(u64 *mcesad)
+{
+	unsigned long origin;
+
+	*mcesad = 0;
+	if (!nmi_needs_mcesa())
+		return 0;
+	if (!mcesa_cache)
+		nmi_alloc_cache();
+	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);
+	*mcesad = __pa(origin) | mcesa_origin_lc;
+	return 0;
+}
+
+void nmi_free_mcesa(u64 *mcesad)
+{
+	if (!nmi_needs_mcesa())
+		return;
+	kmem_cache_free(mcesa_cache, __va(*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 disabled
+ * and machine checks enabled.
+ */
+void __s390_handle_mcck(void)
+{
+	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_mcck_disable();
+	mcck = *this_cpu_ptr(&cpu_mcck);
+	memset(this_cpu_ptr(&cpu_mcck), 0, sizeof(mcck));
+	local_mcck_enable();
+
+	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);
+	}
+}
+
+void noinstr s390_handle_mcck(struct pt_regs *regs)
+{
+	trace_hardirqs_off();
+	pai_kernel_enter(regs);
+	__s390_handle_mcck();
+	pai_kernel_exit(regs);
+	trace_hardirqs_on();
+}
+/*
+ * returns 0 if all required registers are available
+ * returns 1 otherwise
+ */
+static int notrace s390_validate_registers(union mci mci, int umode)
+{
+	struct mcesa *mcesa;
+	void *fpt_save_area;
+	union ctlreg2 cr2;
+	int kill_task;
+	u64 zero;
+
+	kill_task = 0;
+	zero = 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;
+	}
+	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;
+	}
+	fpt_save_area = &S390_lowcore.floating_pt_save_area;
+	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. Otherwise the
+		 * FPC is just validated.
+		 */
+		if (S390_lowcore.fpu_flags & KERNEL_FPC)
+			s390_handle_damage();
+		asm volatile(
+			"	lfpc	%0\n"
+			:
+			: "Q" (zero));
+		if (!test_cpu_flag(CIF_FPU))
+			kill_task = 1;
+	} else {
+		asm volatile(
+			"	lfpc	%0\n"
+			:
+			: "Q" (S390_lowcore.fpt_creg_save_area));
+	}
+
+	mcesa = __va(S390_lowcore.mcesad & MCESA_ORIGIN_MASK);
+	if (!MACHINE_HAS_VX) {
+		/* Validate floating point registers */
+		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)
+			: "memory");
+	} else {
+		/* Validate vector registers */
+		union ctlreg0 cr0;
+
+		/*
+		 * 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)) {
+			/*
+			 * 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. Otherwise just validate
+			 * the registers.
+			 */
+			if (S390_lowcore.fpu_flags & KERNEL_VXR)
+				s390_handle_damage();
+			if (!test_cpu_flag(CIF_FPU))
+				kill_task = 1;
+		}
+		cr0.val = S390_lowcore.cregs_save_area[0];
+		cr0.afp = cr0.vx = 1;
+		__ctl_load(cr0.val, 0, 0);
+		asm volatile(
+			"	la	1,%0\n"
+			"	.word	0xe70f,0x1000,0x0036\n" /* vlm 0,15,0(1) */
+			"	.word	0xe70f,0x1100,0x0c36\n" /* vlm 16,31,256(1) */
+			:
+			: "Q" (*(struct vx_array *)mcesa->vector_save_area)
+			: "1");
+		__ctl_load(S390_lowcore.cregs_save_area[0], 0, 0);
+	}
+	/* Validate access registers */
+	asm volatile(
+		"	lam	0,15,0(%0)\n"
+		:
+		: "a" (&S390_lowcore.access_regs_save_area)
+		: "memory");
+	if (!mci.ar) {
+		/*
+		 * Access registers have unknown contents.
+		 * Terminating task.
+		 */
+		kill_task = 1;
+	}
+	/* Validate guarded storage registers */
+	cr2.val = S390_lowcore.cregs_save_area[2];
+	if (cr2.gse) {
+		if (!mci.gs) {
+			/*
+			 * 2 cases:
+			 * - 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.
+			 */
+			if (!test_cpu_flag(CIF_MCCK_GUEST))
+				kill_task = 1;
+		} else {
+			load_gs_cb((struct gs_cb *)mcesa->guarded_storage_save_area);
+		}
+	}
+	/*
+	 * The getcpu vdso syscall reads 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());
+	/* Validate clock comparator register */
+	set_clock_comparator(S390_lowcore.clock_comparator);
+
+	if (!mci.ms || !mci.pm || !mci.ia)
+		kill_task = 1;
+
+	return kill_task;
+}
+NOKPROBE_SYMBOL(s390_validate_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;
+	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 (s390_validate_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;
+	}
+
+	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) {
+		irqentry_nmi_exit(regs, irq_state);
+		return 1;
+	}
+
+	if (mcck_pending)
+		schedule_mcck_handler();
+
+	irqentry_nmi_exit(regs, irq_state);
+	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);