4 files changed, 64 insertions, 12 deletions

diff --git a/arch/powerpc/include/asm/hw_irq.h b/arch/powerpc/include/asm/hw_irq.h
index 6eb75b80488c..92224b7fd702 100644
--- a/arch/powerpc/include/asm/hw_irq.h
+++ b/arch/powerpc/include/asm/hw_irq.h
@@ -125,6 +125,8 @@ static inline bool arch_irq_disabled_regs(struct pt_regs *regs)
         return !regs->softe;
 }
 
+extern bool prep_irq_for_idle(void);
+
 #else /* CONFIG_PPC64 */
 
 #define SET_MSR_EE(x)   mtmsr(x)
diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
index 1b415027ec0e..9270a399c9d6 100644
--- a/arch/powerpc/kernel/irq.c
+++ b/arch/powerpc/kernel/irq.c
@@ -286,6 +286,52 @@ void notrace restore_interrupts(void)
                 __hard_irq_enable();
 }
 
+/*
+ * This is a helper to use when about to go into idle low-power
+ * when the latter has the side effect of re-enabling interrupts
+ * (such as calling H_CEDE under pHyp).
+ *
+ * You call this function with interrupts soft-disabled (this is
+ * already the case when ppc_md.power_save is called). The function
+ * will return whether to enter power save or just return.
+ *
+ * In the former case, it will have notified lockdep of interrupts
+ * being re-enabled and generally sanitized the lazy irq state,
+ * and in the latter case it will leave with interrupts hard
+ * disabled and marked as such, so the local_irq_enable() call
+ * in cpu_idle() will properly re-enable everything.
+ */
+bool prep_irq_for_idle(void)
+{
+        /*
+         * First we need to hard disable to ensure no interrupt
+         * occurs before we effectively enter the low power state
+         */
+        hard_irq_disable();
+
+        /*
+         * If anything happened while we were soft-disabled,
+         * we return now and do not enter the low power state.
+         */
+        if (lazy_irq_pending())
+                return false;
+
+        /* Tell lockdep we are about to re-enable */
+        trace_hardirqs_on();
+
+        /*
+         * Mark interrupts as soft-enabled and clear the
+         * PACA_IRQ_HARD_DIS from the pending mask since we
+         * are about to hard enable as well as a side effect
+         * of entering the low power state.
+         */
+        local_paca->irq_happened &= ~PACA_IRQ_HARD_DIS;
+        local_paca->soft_enabled = 1;
+
+        /* Tell the caller to enter the low power state */
+        return true;
+}
+
 #endif /* CONFIG_PPC64 */
 
 int arch_show_interrupts(struct seq_file *p, int prec)
diff --git a/arch/powerpc/platforms/cell/pervasive.c b/arch/powerpc/platforms/cell/pervasive.c
index efdacc829576..d17e98bc0c10 100644
--- a/arch/powerpc/platforms/cell/pervasive.c
+++ b/arch/powerpc/platforms/cell/pervasive.c
@@ -42,11 +42,9 @@ static void cbe_power_save(void)
 {
         unsigned long ctrl, thread_switch_control;
 
-        /*
-         * We need to hard disable interrupts, the local_irq_enable() done by
-         * our caller upon return will hard re-enable.
-         */
-        hard_irq_disable();
+        /* Ensure our interrupt state is properly tracked */
+        if (!prep_irq_for_idle())
+                return;
 
         ctrl = mfspr(SPRN_CTRLF);
 
@@ -81,6 +79,9 @@ static void cbe_power_save(void)
          */
         ctrl &= ~(CTRL_RUNLATCH | CTRL_TE);
         mtspr(SPRN_CTRLT, ctrl);
+
+        /* Re-enable interrupts in MSR */
+        __hard_irq_enable();
 }
 
 static int cbe_system_reset_exception(struct pt_regs *regs)
diff --git a/arch/powerpc/platforms/pseries/processor_idle.c b/arch/powerpc/platforms/pseries/processor_idle.c
index e61483e8e960..c71be66bd5dc 100644
--- a/arch/powerpc/platforms/pseries/processor_idle.c
+++ b/arch/powerpc/platforms/pseries/processor_idle.c
@@ -99,15 +99,18 @@ out:
 static void check_and_cede_processor(void)
 {
         /*
-         * Interrupts are soft-disabled at this point,
-         * but not hard disabled. So an interrupt might have
-         * occurred before entering NAP, and would be potentially
-         * lost (edge events, decrementer events, etc...) unless
-         * we first hard disable then check.
+         * Ensure our interrupt state is properly tracked,
+         * also checks if no interrupt has occurred while we
+         * were soft-disabled
          */
-        hard_irq_disable();
-        if (!lazy_irq_pending())
+        if (prep_irq_for_idle()) {
                 cede_processor();
+#ifdef CONFIG_TRACE_IRQFLAGS
+                /* Ensure that H_CEDE returns with IRQs on */
+                if (WARN_ON(!(mfmsr() & MSR_EE)))
+                        __hard_irq_enable();
+#endif
+        }
 }
 
 static int dedicated_cede_loop(struct cpuidle_device *dev,