[PATCH v2 00/12] powerpc/64: machine check and system reset fixes

@@ -1335,6 +1335,10 @@ END_FTR_SECTION_IFSET(CPU_FTR_HVMODE)
 	andc	r10,r10,r3
 	mtmsrd	r10
 
+	lhz	r12,PACA_IN_MCE(r13)
+	subi	r12,r12,1
+	sth	r12,PACA_IN_MCE(r13)
+
 	/* Invoke machine_check_exception to print MCE event and panic. */
 	addi	r3,r1,STACK_FRAME_OVERHEAD
 	bl	machine_check_exception

@@ -1011,13 +1011,13 @@ EXC_COMMON_BEGIN(system_reset_common)
 	 * the right thing. We do not want to reconcile because that goes
 	 * through irq tracing which we don't want in NMI.
 	 *
-	 * Save PACAIRQHAPPENED to _DAR (otherwise unused), and set HARD_DIS
+	 * Save PACAIRQHAPPENED to RESULT (otherwise unused), and set HARD_DIS
 	 * as we are running with MSR[EE]=0.
 	 */
 	li	r10,IRQS_ALL_DISABLED
 	stb	r10,PACAIRQSOFTMASK(r13)
 	lbz	r10,PACAIRQHAPPENED(r13)
-	std	r10,_DAR(r1)
+	std	r10,RESULT(r1)
 	ori	r10,r10,PACA_IRQ_HARD_DIS
 	stb	r10,PACAIRQHAPPENED(r13)
 

@@ -1038,7 +1038,7 @@ EXC_COMMON_BEGIN(system_reset_common)
 	/*
 	 * Restore soft mask settings.
 	 */
-	ld	r10,_DAR(r1)
+	ld	r10,RESULT(r1)
 	stb	r10,PACAIRQHAPPENED(r13)
 	ld	r10,SOFTE(r1)
 	stb	r10,PACAIRQSOFTMASK(r13)

@@ -2809,7 +2809,7 @@ EXC_COMMON_BEGIN(soft_nmi_common)
 	li	r10,IRQS_ALL_DISABLED
 	stb	r10,PACAIRQSOFTMASK(r13)
 	lbz	r10,PACAIRQHAPPENED(r13)
-	std	r10,_DAR(r1)
+	std	r10,RESULT(r1)
 	ori	r10,r10,PACA_IRQ_HARD_DIS
 	stb	r10,PACAIRQHAPPENED(r13)
 

@@ -2823,7 +2823,7 @@ EXC_COMMON_BEGIN(soft_nmi_common)
 	/*
 	 * Restore soft mask settings.
 	 */
-	ld	r10,_DAR(r1)
+	ld	r10,RESULT(r1)
 	stb	r10,PACAIRQHAPPENED(r13)
 	ld	r10,SOFTE(r1)
 	stb	r10,PACAIRQSOFTMASK(r13)

@@ -1186,11 +1186,30 @@ END_FTR_SECTION_IFSET(CPU_FTR_HVMODE)
 	li	r10,MSR_RI
 	mtmsrd	r10,1
 
+	/*
+	 * Set IRQS_ALL_DISABLED and save PACAIRQHAPPENED (see
+	 * system_reset_common)
+	 */
+	li	r10,IRQS_ALL_DISABLED
+	stb	r10,PACAIRQSOFTMASK(r13)
+	lbz	r10,PACAIRQHAPPENED(r13)
+	std	r10,RESULT(r1)
+	ori	r10,r10,PACA_IRQ_HARD_DIS
+	stb	r10,PACAIRQHAPPENED(r13)
+
 	addi	r3,r1,STACK_FRAME_OVERHEAD
 	bl	machine_check_early
 	std	r3,RESULT(r1)	/* Save result */
 	ld	r12,_MSR(r1)
 
+	/*
+	 * Restore soft mask settings.
+	 */
+	ld	r10,RESULT(r1)
+	stb	r10,PACAIRQHAPPENED(r13)
+	ld	r10,SOFTE(r1)
+	stb	r10,PACAIRQSOFTMASK(r13)
+
 #ifdef CONFIG_PPC_P7_NAP
 	/*
 	 * Check if thread was in power saving mode. We come here when any

@@ -128,6 +128,7 @@ extern void machine_check_fwnmi(void);
 
 /* This is true if we are using the firmware NMI handler (typically LPAR) */
 extern int fwnmi_active;
+extern int ibm_nmi_interlock_token;
 
 extern unsigned int __start___fw_ftr_fixup, __stop___fw_ftr_fixup;
 

@@ -458,7 +458,7 @@ static struct rtas_error_log *fwnmi_get_errinfo(struct pt_regs *regs)
  */
 static void fwnmi_release_errinfo(void)
 {
-	int ret = rtas_call(rtas_token("ibm,nmi-interlock"), 0, 1, NULL);
+	int ret = rtas_call(ibm_nmi_interlock_token, 0, 1, NULL);
 	if (ret != 0)
 		printk(KERN_ERR "FWNMI: nmi-interlock failed: %d\n", ret);
 }

@@ -83,6 +83,7 @@ unsigned long CMO_PageSize = (ASM_CONST(1) << IOMMU_PAGE_SHIFT_4K);
 EXPORT_SYMBOL(CMO_PageSize);
 
 int fwnmi_active;  /* TRUE if an FWNMI handler is present */
+int ibm_nmi_interlock_token;
 
 static void pSeries_show_cpuinfo(struct seq_file *m)
 {

@@ -113,9 +114,14 @@ static void __init fwnmi_init(void)
 	struct slb_entry *slb_ptr;
 	size_t size;
 #endif
+	int ibm_nmi_register_token;
 
-	int ibm_nmi_register = rtas_token("ibm,nmi-register");
-	if (ibm_nmi_register == RTAS_UNKNOWN_SERVICE)
+	ibm_nmi_register_token = rtas_token("ibm,nmi-register");
+	if (ibm_nmi_register_token == RTAS_UNKNOWN_SERVICE)
+		return;
+
+	ibm_nmi_interlock_token = rtas_token("ibm,nmi-interlock");
+	if (WARN_ON(ibm_nmi_interlock_token == RTAS_UNKNOWN_SERVICE))
 		return;
 
 	/* If the kernel's not linked at zero we point the firmware at low

@@ -123,7 +129,8 @@ static void __init fwnmi_init(void)
 	system_reset_addr  = __pa(system_reset_fwnmi) - PHYSICAL_START;
 	machine_check_addr = __pa(machine_check_fwnmi) - PHYSICAL_START;
 
-	if (0 == rtas_call(ibm_nmi_register, 2, 1, NULL, system_reset_addr,
+	if (0 == rtas_call(ibm_nmi_register_token, 2, 1, NULL,
+				system_reset_addr,
 				machine_check_addr))
 		fwnmi_active = 1;
 

@@ -395,10 +395,11 @@ static irqreturn_t ras_error_interrupt(int irq, void *dev_id)
 /*
  * Some versions of FWNMI place the buffer inside the 4kB page starting at
  * 0x7000. Other versions place it inside the rtas buffer. We check both.
+ * Minimum size of the buffer is 16 bytes.
  */
 #define VALID_FWNMI_BUFFER(A) \
-	((((A) >= 0x7000) && ((A) < 0x7ff0)) || \
-	(((A) >= rtas.base) && ((A) < (rtas.base + rtas.size - 16))))
+	((((A) >= 0x7000) && ((A) <= 0x8000 - 16)) || \
+	(((A) >= rtas.base) && ((A) <= (rtas.base + rtas.size - 16))))
 
 static inline struct rtas_error_log *fwnmi_get_errlog(void)
 {

@@ -423,18 +423,19 @@ static inline struct rtas_error_log *fwnmi_get_errlog(void)
  */
 static struct rtas_error_log *fwnmi_get_errinfo(struct pt_regs *regs)
 {
+	unsigned long savep_ra;
 	unsigned long *savep;
 	struct rtas_error_log *h;
 
 	/* Mask top two bits */
-	regs->gpr[3] &= ~(0x3UL << 62);
+	savep_ra = regs->gpr[3] & ~(0x3UL << 62);
 
-	if (!VALID_FWNMI_BUFFER(regs->gpr[3])) {
+	if (!VALID_FWNMI_BUFFER(savep_ra)) {
 		printk(KERN_ERR "FWNMI: corrupt r3 0x%016lx\n", regs->gpr[3]);
 		return NULL;
 	}
 
-	savep = __va(regs->gpr[3]);
+	savep = __va(savep_ra);
 	regs->gpr[3] = be64_to_cpu(savep[0]);	/* restore original r3 */
 
 	h = (struct rtas_error_log *)&savep[1];

@@ -406,6 +406,20 @@ static inline struct rtas_error_log *fwnmi_get_errlog(void)
 	return (struct rtas_error_log *)local_paca->mce_data_buf;
 }
 
+static unsigned long *fwnmi_get_savep(struct pt_regs *regs)
+{
+	unsigned long savep_ra;
+
+	/* Mask top two bits */
+	savep_ra = regs->gpr[3] & ~(0x3UL << 62);
+	if (!VALID_FWNMI_BUFFER(savep_ra)) {
+		printk(KERN_ERR "FWNMI: corrupt r3 0x%016lx\n", regs->gpr[3]);
+		return NULL;
+	}
+
+	return __va(savep_ra);
+}
+
 /*
  * Get the error information for errors coming through the
  * FWNMI vectors.  The pt_regs' r3 will be updated to reflect

@@ -423,20 +437,15 @@ static inline struct rtas_error_log *fwnmi_get_errlog(void)
  */
 static struct rtas_error_log *fwnmi_get_errinfo(struct pt_regs *regs)
 {
-	unsigned long savep_ra;
 	unsigned long *savep;
 	struct rtas_error_log *h;
 
-	/* Mask top two bits */
-	savep_ra = regs->gpr[3] & ~(0x3UL << 62);
-
-	if (!VALID_FWNMI_BUFFER(savep_ra)) {
-		printk(KERN_ERR "FWNMI: corrupt r3 0x%016lx\n", regs->gpr[3]);
+	savep = fwnmi_get_savep(regs);
+	if (!savep)
 		return NULL;
-	}
 
-	savep = __va(savep_ra);
-	regs->gpr[3] = be64_to_cpu(savep[0]);	/* restore original r3 */
+	/* restore original r3 */
+	regs->gpr[3] = be64_to_cpu(savep[0]);
 
 	h = (struct rtas_error_log *)&savep[1];
 	/* Use the per cpu buffer from paca to store rtas error log */

@@ -483,11 +492,22 @@ int pSeries_system_reset_exception(struct pt_regs *regs)
 #endif
 
 	if (fwnmi_active) {
-		struct rtas_error_log *errhdr = fwnmi_get_errinfo(regs);
-		if (errhdr) {
-			/* XXX Should look at FWNMI information */
-		}
-		fwnmi_release_errinfo();
+		unsigned long *savep;
+
+		/*
+		 * Firmware (PowerVM and KVM) saves r3 to a save area like
+		 * machine check, which is not exactly what PAPR (2.9)
+		 * suggests but there is no way to detect otherwise, so this
+		 * is the interface now.
+		 *
+		 * System resets do not save any error log or require an
+		 * "ibm,nmi-interlock" rtas call to release.
+		 */
+
+		savep = fwnmi_get_savep(regs);
+		/* restore original r3 */
+		if (savep)
+			regs->gpr[3] = be64_to_cpu(savep[0]);
 	}
 
 	if (smp_handle_nmi_ipi(regs))

@@ -695,6 +695,9 @@ void __init exc_lvl_early_init(void)
 void __init emergency_stack_init(void)
 {
 	u64 limit;
+#ifdef CONFIG_PPC_BOOK3S_64
+	u64 mce_limit;
+#endif
 	unsigned int i;
 
 	/*

@@ -713,6 +716,16 @@ void __init emergency_stack_init(void)
 	 */
 	limit = min(ppc64_bolted_size(), ppc64_rma_size);
 
+	/*
+	 * Machine check on pseries calls rtas, but can't use the static
+	 * rtas_args due to a machine check hitting while the lock is held.
+	 * rtas args have to be under 4GB, so the machine check stack is
+	 * limited to 4GB so args can be put on stack.
+	 */
+	mce_limit = limit;
+	if (firmware_has_feature(FW_FEATURE_LPAR) && mce_limit > 4UL*1024*1024*1024)
+		mce_limit = 4UL*1024*1024*1024;
+
 	for_each_possible_cpu(i) {
 		paca_ptrs[i]->emergency_sp = alloc_stack(limit, i) + THREAD_SIZE;
 

@@ -721,7 +734,7 @@ void __init emergency_stack_init(void)
 		paca_ptrs[i]->nmi_emergency_sp = alloc_stack(limit, i) + THREAD_SIZE;
 
 		/* emergency stack for machine check exception handling. */
-		paca_ptrs[i]->mc_emergency_sp = alloc_stack(limit, i) + THREAD_SIZE;
+		paca_ptrs[i]->mc_emergency_sp = alloc_stack(mce_limit, i) + THREAD_SIZE;
 #endif
 	}
 }

@@ -469,7 +469,15 @@ static struct rtas_error_log *fwnmi_get_errinfo(struct pt_regs *regs)
  */
 static void fwnmi_release_errinfo(void)
 {
-	int ret = rtas_call(ibm_nmi_interlock_token, 0, 1, NULL);
+	struct rtas_args rtas_args;
+	int ret;
+
+	/*
+	 * On pseries, the machine check stack is limited to under 4GB, so
+	 * args can be on-stack.
+	 */
+	rtas_call_unlocked(&rtas_args, ibm_nmi_interlock_token, 0, 1, NULL);
+	ret = be32_to_cpu(rtas_args.rets[0]);
 	if (ret != 0)
 		printk(KERN_ERR "FWNMI: nmi-interlock failed: %d\n", ret);
 }

@@ -560,6 +560,9 @@ EXPORT_SYMBOL_GPL(machine_check_print_event_info);
 long machine_check_early(struct pt_regs *regs)
 {
 	long handled = 0;
+	bool nested = in_nmi();
+	if (!nested)
+		nmi_enter();
 
 	hv_nmi_check_nonrecoverable(regs);
 

@@ -568,6 +571,10 @@ long machine_check_early(struct pt_regs *regs)
 	 */
 	if (ppc_md.machine_check_early)
 		handled = ppc_md.machine_check_early(regs);
+
+	if (!nested)
+		nmi_exit();
+
 	return handled;
 }
 

@@ -1421,7 +1421,7 @@ void show_regs(struct pt_regs * regs)
 		pr_cont("DAR: "REG" DSISR: %08lx ", regs->dar, regs->dsisr);
 #endif
 #ifdef CONFIG_PPC64
-	pr_cont("IRQMASK: %lx ", regs->softe);
+	pr_cont("IRQMASK: %lx IN_NMI:%d IN_MCE:%d", regs->softe, (int)get_paca()->in_nmi, (int)get_paca()->in_mce);
 #endif
 #ifdef CONFIG_PPC_TRANSACTIONAL_MEM
 	if (MSR_TM_ACTIVE(regs->msr))

@@ -823,9 +823,6 @@ int machine_check_generic(struct pt_regs *regs)
 void machine_check_exception(struct pt_regs *regs)
 {
 	int recover = 0;
-	bool nested = in_nmi();
-	if (!nested)
-		nmi_enter();
 
 	__this_cpu_inc(irq_stat.mce_exceptions);
 

@@ -851,20 +848,12 @@ void machine_check_exception(struct pt_regs *regs)
 	if (check_io_access(regs))
 		goto bail;
 
-	if (!nested)
-		nmi_exit();
-
 	die("Machine check", regs, SIGBUS);
 
+bail:
 	/* Must die if the interrupt is not recoverable */
 	if (!(regs->msr & MSR_RI))
 		nmi_panic(regs, "Unrecoverable Machine check");
-
-	return;
-
-bail:
-	if (!nested)
-		nmi_exit();
 }
 
 void SMIException(struct pt_regs *regs)

@@ -557,10 +557,13 @@ EXPORT_SYMBOL_GPL(machine_check_print_event_info);
  *
  * regs->nip and regs->msr contains srr0 and ssr1.
  */
-long machine_check_early(struct pt_regs *regs)
+long notrace machine_check_early(struct pt_regs *regs)
 {
 	long handled = 0;
 	bool nested = in_nmi();
+	u8 ftrace_enabled = local_paca->ftrace_enabled;
+
+	local_paca->ftrace_enabled = 0;
 	if (!nested)
 		nmi_enter();
 

@@ -574,6 +577,7 @@ long machine_check_early(struct pt_regs *regs)
 
 	if (!nested)
 		nmi_exit();
+	local_paca->ftrace_enabled = ftrace_enabled;
 
 	return handled;
 }

@@ -443,6 +443,9 @@ void system_reset_exception(struct pt_regs *regs)
 	unsigned long hsrr0, hsrr1;
 	bool nested = in_nmi();
 	bool saved_hsrrs = false;
+	u8 ftrace_enabled = local_paca->ftrace_enabled;
+
+	local_paca->ftrace_enabled = 0;
 
 	/*
 	 * Avoid crashes in case of nested NMI exceptions. Recoverability

@@ -524,6 +527,8 @@ void system_reset_exception(struct pt_regs *regs)
 	if (!nested)
 		nmi_exit();
 
+	local_paca->ftrace_enabled = ftrace_enabled;
+
 	/* What should we do here? We could issue a shutdown or hard reset. */
 }