1 files changed, 33 insertions, 10 deletions

diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
index 7305d84f2df5..0cbc4e25c48d 100644
--- a/drivers/irqchip/irq-gic-v3.c
+++ b/drivers/irqchip/irq-gic-v3.c
@@ -556,7 +556,8 @@ static void gic_irq_nmi_teardown(struct irq_data *d)
 
 static void gic_eoi_irq(struct irq_data *d)
 {
-	gic_write_eoir(gic_irq(d));
+	write_gicreg(gic_irq(d), ICC_EOIR1_EL1);
+	isb();
 }
 
 static void gic_eoimode1_eoi_irq(struct irq_data *d)
@@ -640,10 +641,38 @@ static void gic_deactivate_unhandled(u32 irqnr)
 		if (irqnr < 8192)
 			gic_write_dir(irqnr);
 	} else {
-		gic_write_eoir(irqnr);
+		write_gicreg(irqnr, ICC_EOIR1_EL1);
+		isb();
 	}
 }
 
+/*
+ * Follow a read of the IAR with any HW maintenance that needs to happen prior
+ * to invoking the relevant IRQ handler. We must do two things:
+ *
+ * (1) Ensure instruction ordering between a read of IAR and subsequent
+ *     instructions in the IRQ handler using an ISB.
+ *
+ *     It is possible for the IAR to report an IRQ which was signalled *after*
+ *     the CPU took an IRQ exception as multiple interrupts can race to be
+ *     recognized by the GIC, earlier interrupts could be withdrawn, and/or
+ *     later interrupts could be prioritized by the GIC.
+ *
+ *     For devices which are tightly coupled to the CPU, such as PMUs, a
+ *     context synchronization event is necessary to ensure that system
+ *     register state is not stale, as these may have been indirectly written
+ *     *after* exception entry.
+ *
+ * (2) Deactivate the interrupt when EOI mode 1 is in use.
+ */
+static inline void gic_complete_ack(u32 irqnr)
+{
+	if (static_branch_likely(&supports_deactivate_key))
+		write_gicreg(irqnr, ICC_EOIR1_EL1);
+
+	isb();
+}
+
 static inline void gic_handle_nmi(u32 irqnr, struct pt_regs *regs)
 {
 	bool irqs_enabled = interrupts_enabled(regs);
@@ -652,10 +681,7 @@ static inline void gic_handle_nmi(u32 irqnr, struct pt_regs *regs)
 	if (irqs_enabled)
 		nmi_enter();
 
-	if (static_branch_likely(&supports_deactivate_key))
-		gic_write_eoir(irqnr);
-	else
-		isb()
+	gic_complete_ack(irqnr);
 
 	/*
 	 * Leave the PSR.I bit set to prevent other NMIs to be
@@ -726,10 +752,7 @@ static asmlinkage void __exception_irq_entry gic_handle_irq(struct pt_regs *regs
 		gic_arch_enable_irqs();
 	}
 
-	if (static_branch_likely(&supports_deactivate_key))
-		gic_write_eoir(irqnr);
-	else
-		isb();
+	gic_complete_ack(irqnr);
 
 	if (generic_handle_domain_irq(gic_data.domain, irqnr)) {
 		WARN_ONCE(true, "Unexpected interrupt received!\n");