[PATCH 1/2] irqchip/sifive-plic: Fix PLIC crash on touching offline CPU context

[guoren at kernel.org]

From: Guo Ren <guoren at linux.alibaba.com>

The current plic driver would touch offline CPU context and cause
bus error in some chip when in CPU hotplug scenario.

This patch fixes up the problem and prevents plic access offline
CPU context in plic_init() & plic_set_affinity().

Signed-off-by: Guo Ren <guoren at linux.alibaba.com>
Cc: Anup Patel <anup at brainfault.org>
Cc: Atish Patra <atish.patra at wdc.com>
Cc: Greentime Hu <greentime.hu at sifive.com>
Cc: Marc Zyngier <maz at kernel.org>
---
 drivers/irqchip/irq-sifive-plic.c | 26 +++++++++++++++++---------
 1 file changed, 17 insertions(+), 9 deletions(-)

diff --git a/drivers/irqchip/irq-sifive-plic.c b/drivers/irqchip/irq-sifive-plic.c
index cf74cfa..9c9bb20 100644
--- a/drivers/irqchip/irq-sifive-plic.c
+++ b/drivers/irqchip/irq-sifive-plic.c
@@ -64,6 +64,7 @@ struct plic_priv {
 	struct cpumask lmask;
 	struct irq_domain *irqdomain;
 	void __iomem *regs;
+	unsigned int nr_irqs;
 };
 
 struct plic_handler {
@@ -150,7 +151,7 @@ static int plic_set_affinity(struct irq_data *d,
 	if (cpu >= nr_cpu_ids)
 		return -EINVAL;
 
-	plic_irq_toggle(&priv->lmask, d, 0);
+	plic_irq_toggle(cpu_online_mask, d, 0);
 	plic_irq_toggle(cpumask_of(cpu), d, !irqd_irq_masked(d));
 
 	irq_data_update_effective_affinity(d, cpumask_of(cpu));
@@ -251,15 +252,25 @@ static void plic_set_threshold(struct plic_handler *handler, u32 threshold)
 
 static int plic_dying_cpu(unsigned int cpu)
 {
+	struct plic_handler *handler = this_cpu_ptr(&plic_handlers);
+
 	if (plic_parent_irq)
 		disable_percpu_irq(plic_parent_irq);
 
+	handler->present = false;
+
 	return 0;
 }
 
 static int plic_starting_cpu(unsigned int cpu)
 {
 	struct plic_handler *handler = this_cpu_ptr(&plic_handlers);
+	irq_hw_number_t hwirq;
+
+	handler->present = true;
+
+	for (hwirq = 1; hwirq <= handler->priv->nr_irqs; hwirq++)
+		plic_toggle(handler, hwirq, 0);
 
 	if (plic_parent_irq)
 		enable_percpu_irq(plic_parent_irq,
@@ -275,7 +286,6 @@ static int __init plic_init(struct device_node *node,
 		struct device_node *parent)
 {
 	int error = 0, nr_contexts, nr_handlers = 0, i;
-	u32 nr_irqs;
 	struct plic_priv *priv;
 	struct plic_handler *handler;
 
@@ -290,8 +300,8 @@ static int __init plic_init(struct device_node *node,
 	}
 
 	error = -EINVAL;
-	of_property_read_u32(node, "riscv,ndev", &nr_irqs);
-	if (WARN_ON(!nr_irqs))
+	of_property_read_u32(node, "riscv,ndev", &priv->nr_irqs);
+	if (WARN_ON(!priv->nr_irqs))
 		goto out_iounmap;
 
 	nr_contexts = of_irq_count(node);
@@ -299,14 +309,13 @@ static int __init plic_init(struct device_node *node,
 		goto out_iounmap;
 
 	error = -ENOMEM;
-	priv->irqdomain = irq_domain_add_linear(node, nr_irqs + 1,
+	priv->irqdomain = irq_domain_add_linear(node, priv->nr_irqs + 1,
 			&plic_irqdomain_ops, priv);
 	if (WARN_ON(!priv->irqdomain))
 		goto out_iounmap;
 
 	for (i = 0; i < nr_contexts; i++) {
 		struct of_phandle_args parent;
-		irq_hw_number_t hwirq;
 		int cpu, hartid;
 
 		if (of_irq_parse_one(node, i, &parent)) {
@@ -354,7 +363,8 @@ static int __init plic_init(struct device_node *node,
 		}
 
 		cpumask_set_cpu(cpu, &priv->lmask);
-		handler->present = true;
+		if (cpu == smp_processor_id())
+			handler->present = true;
 		handler->hart_base =
 			priv->regs + CONTEXT_BASE + i * CONTEXT_PER_HART;
 		raw_spin_lock_init(&handler->enable_lock);
@@ -362,8 +372,6 @@ static int __init plic_init(struct device_node *node,
 			priv->regs + ENABLE_BASE + i * ENABLE_PER_HART;
 		handler->priv = priv;
 done:
-		for (hwirq = 1; hwirq <= nr_irqs; hwirq++)
-			plic_toggle(handler, hwirq, 0);
 		nr_handlers++;
 	}
 
-- 
2.7.4