This moves the common NMI entry and exit code into the interrupt handler
wrappers.

This changes the behaviour of soft-NMI (watchdog) and HMI interrupts, and
also MCE interrupts on 64e, by adding missing parts of the NMI entry to
them.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
  arch/powerpc/include/asm/interrupt.h | 24 ++++++++++++++++
  arch/powerpc/kernel/mce.c            | 11 --------
  arch/powerpc/kernel/traps.c          | 42 +++++-----------------------
  arch/powerpc/kernel/watchdog.c       | 10 +++----
  4 files changed, 35 insertions(+), 52 deletions(-)

diff --git a/arch/powerpc/include/asm/interrupt.h b/arch/powerpc/include/asm/interrupt.h
index e278dffe7657..01192e213f9a 100644
--- a/arch/powerpc/include/asm/interrupt.h
+++ b/arch/powerpc/include/asm/interrupt.h

@@ -95,14 +95,38 @@ static inline void interrupt_async_exit_prepare(struct pt_regs *regs, struct int
  }
  
  struct interrupt_nmi_state {
+#ifdef CONFIG_PPC64
+	u8 ftrace_enabled;
+#endif
  };
  
  static inline void interrupt_nmi_enter_prepare(struct pt_regs *regs, struct interrupt_nmi_state *state)
  {
+#ifdef CONFIG_PPC64
+	state->ftrace_enabled = this_cpu_get_ftrace_enabled();
+	this_cpu_set_ftrace_enabled(0);
+#endif
+
+	/*
+	 * Do not use nmi_enter() for pseries hash guest taking a real-mode
+	 * NMI because not everything it touches is within the RMA limit.
+	 */
+	if (!IS_ENABLED(CONFIG_PPC_BOOK3S_64) ||
+			!firmware_has_feature(FW_FEATURE_LPAR) ||
+			radix_enabled() || (mfmsr() & MSR_DR))
+		nmi_enter();
  }
  
  static inline void interrupt_nmi_exit_prepare(struct pt_regs *regs, struct interrupt_nmi_state *state)
  {
+	if (!IS_ENABLED(CONFIG_PPC_BOOK3S_64) ||
+			!firmware_has_feature(FW_FEATURE_LPAR) ||
+			radix_enabled() || (mfmsr() & MSR_DR))
+		nmi_exit();
+
+#ifdef CONFIG_PPC64
+	this_cpu_set_ftrace_enabled(state->ftrace_enabled);
+#endif
  }
  
  /**

diff --git a/arch/powerpc/kernel/mce.c b/arch/powerpc/kernel/mce.c
index 54269947113d..51456217ec40 100644
--- a/arch/powerpc/kernel/mce.c
+++ b/arch/powerpc/kernel/mce.c

@@ -592,12 +592,6 @@ EXPORT_SYMBOL_GPL(machine_check_print_event_info);
  DEFINE_INTERRUPT_HANDLER_NMI(machine_check_early)
  {
  	long handled = 0;
-	u8 ftrace_enabled = this_cpu_get_ftrace_enabled();
-
-	this_cpu_set_ftrace_enabled(0);
-	/* Do not use nmi_enter/exit for pseries hpte guest */
-	if (radix_enabled() || !firmware_has_feature(FW_FEATURE_LPAR))
-		nmi_enter();
  
  	hv_nmi_check_nonrecoverable(regs);
  

@@ -607,11 +601,6 @@ DEFINE_INTERRUPT_HANDLER_NMI(machine_check_early)
  	if (ppc_md.machine_check_early)
  		handled = ppc_md.machine_check_early(regs);
  
-	if (radix_enabled() || !firmware_has_feature(FW_FEATURE_LPAR))
-		nmi_exit();
-
-	this_cpu_set_ftrace_enabled(ftrace_enabled);
-
  	return handled;
  }
  

diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index b4f23e871a68..43d23232ef5c 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c

@@ -435,11 +435,6 @@ DEFINE_INTERRUPT_HANDLER_NMI(system_reset_exception)
  {
  	unsigned long hsrr0, hsrr1;
  	bool saved_hsrrs = false;
-	u8 ftrace_enabled = this_cpu_get_ftrace_enabled();
-
-	this_cpu_set_ftrace_enabled(0);
-
-	nmi_enter();
  
  	/*
  	 * System reset can interrupt code where HSRRs are live and MSR[RI]=1.

@@ -511,10 +506,6 @@ DEFINE_INTERRUPT_HANDLER_NMI(system_reset_exception)
  		mtspr(SPRN_HSRR1, hsrr1);
  	}
  
-	nmi_exit();
-
-	this_cpu_set_ftrace_enabled(ftrace_enabled);
-
  	/* What should we do here? We could issue a shutdown or hard reset. */
  
  	return 0;

@@ -792,6 +783,12 @@ int machine_check_generic(struct pt_regs *regs)
  #endif /* everything else */
  
  
+/*
+ * BOOK3S_64 does not call this handler as a non-maskable interrupt
+ * (it uses its own early real-mode handler to handle the MCE proper
+ * and then raises irq_work to call this handler when interrupts are
+ * enabled).
+ */
  #ifdef CONFIG_PPC_BOOK3S_64
  DEFINE_INTERRUPT_HANDLER_ASYNC(machine_check_exception)
  #else

@@ -800,20 +797,6 @@ DEFINE_INTERRUPT_HANDLER_NMI(machine_check_exception)
  {
  	int recover = 0;
  
-	/*
-	 * BOOK3S_64 does not call this handler as a non-maskable interrupt
-	 * (it uses its own early real-mode handler to handle the MCE proper
-	 * and then raises irq_work to call this handler when interrupts are
-	 * enabled).
-	 *
-	 * This is silly. The BOOK3S_64 should just call a different function
-	 * rather than expecting semantics to magically change. Something
-	 * like 'non_nmi_machine_check_exception()', perhaps?
-	 */
-	const bool nmi = !IS_ENABLED(CONFIG_PPC_BOOK3S_64);
-
-	if (nmi) nmi_enter();
-
  	__this_cpu_inc(irq_stat.mce_exceptions);
  
  	add_taint(TAINT_MACHINE_CHECK, LOCKDEP_NOW_UNRELIABLE);

@@ -838,24 +821,17 @@ DEFINE_INTERRUPT_HANDLER_NMI(machine_check_exception)
  	if (check_io_access(regs))
  		goto bail;
  
-	if (nmi) nmi_exit();
-

  	die("Machine check", regs, SIGBUS);
  
  	/* Must die if the interrupt is not recoverable */
  	if (!(regs->msr & MSR_RI))
  		die("Unrecoverable Machine check", regs, SIGBUS);
  
-#ifdef CONFIG_PPC_BOOK3S_64
  bail:
+#ifdef CONFIG_PPC_BOOK3S_64
  	return;
  #else
  	return 0;
-
-bail:
-	if (nmi) nmi_exit();
-
-	return 0;
  #endif
  }
  NOKPROBE_SYMBOL(machine_check_exception);

@@ -1873,14 +1849,10 @@ DEFINE_INTERRUPT_HANDLER(vsx_unavailable_tm)
  #ifdef CONFIG_PPC64
  DEFINE_INTERRUPT_HANDLER_NMI(performance_monitor_exception_nmi)
  {
-	nmi_enter();
-
  	__this_cpu_inc(irq_stat.pmu_irqs);
  
  	perf_irq(regs);
  
-	nmi_exit();
-
  	return 0;
  }
  #endif

diff --git a/arch/powerpc/kernel/watchdog.c b/arch/powerpc/kernel/watchdog.c
index 824b9376ac35..dc39534836a3 100644
--- a/arch/powerpc/kernel/watchdog.c
+++ b/arch/powerpc/kernel/watchdog.c

@@ -254,11 +254,12 @@ DEFINE_INTERRUPT_HANDLER_NMI(soft_nmi_interrupt)
  	int cpu = raw_smp_processor_id();
  	u64 tb;
  
+	/* should only arrive from kernel, with irqs disabled */
+	WARN_ON_ONCE(!arch_irq_disabled_regs(regs));
+
  	if (!cpumask_test_cpu(cpu, &wd_cpus_enabled))
  		return 0;
  
-	nmi_enter();
-
  	__this_cpu_inc(irq_stat.soft_nmi_irqs);
  
  	tb = get_tb();

@@ -266,7 +267,7 @@ DEFINE_INTERRUPT_HANDLER_NMI(soft_nmi_interrupt)
  		wd_smp_lock(&flags);
  		if (cpumask_test_cpu(cpu, &wd_smp_cpus_stuck)) {
  			wd_smp_unlock(&flags);
-			goto out;
+			return 0;
  		}
  		set_cpu_stuck(cpu, tb);
  

@@ -290,9 +291,6 @@ DEFINE_INTERRUPT_HANDLER_NMI(soft_nmi_interrupt)
  	if (wd_panic_timeout_tb < 0x7fffffff)
  		mtspr(SPRN_DEC, wd_panic_timeout_tb);
  
-out:
-	nmi_exit();
-
  	return 0;
  }