1 files changed, 46 insertions, 0 deletions

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)