linux-kernel - [PATCH 3/3] irqchip/irq-sifive-plic: Fixup set

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Date:   Fri, 23 Oct 2020 10:17:25 +0000
From:   guoren@...nel.org
To:     palmerdabbelt@...gle.com, paul.walmsley@...ive.com,
        anup@...infault.org, greentime.hu@...ive.com, zong.li@...ive.com,
        atish.patra@....com, tglx@...utronix.de, jason@...edaemon.net,
        maz@...nel.org, wesley@...ive.com, yash.shah@...ive.com, hch@....de
Cc:     linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
        guoren@...nel.org, Guo Ren <guoren@...ux.alibaba.com>
Subject: [PATCH 3/3] irqchip/irq-sifive-plic: Fixup set_affinity enable irq unexpected

From: Guo Ren <guoren@...ux.alibaba.com>

For PLIC, we only have enable registers to control per hart's irq
affinity and irq_set_affinity would call plic_irq_toggle to enable
the IRQ's routing. So we can't enable irq in irq_domain_map before
request_irq, it'll let uninitialized devices' irq exception.

The solution is to check the irq has been enabled, just like what
irq-gic-v3 has done in gic_set_affinity.

Signed-off-by: Guo Ren <guoren@...ux.alibaba.com>
---
 drivers/irqchip/irq-sifive-plic.c | 45 ++++++++++++++++++++++++++++++++++++---
 1 file changed, 42 insertions(+), 3 deletions(-)

diff --git a/drivers/irqchip/irq-sifive-plic.c b/drivers/irqchip/irq-sifive-plic.c
index 0003322..1a63859 100644
--- a/drivers/irqchip/irq-sifive-plic.c
+++ b/drivers/irqchip/irq-sifive-plic.c
@@ -130,6 +130,36 @@ static void plic_irq_mask(struct irq_data *d)
 }
 
 #ifdef CONFIG_SMP
+static inline bool plic_toggle_is_enabled(struct plic_handler *handler,
+						int hwirq)
+{
+	u32 __iomem *reg = handler->enable_base + (hwirq / 32) * sizeof(u32);
+	u32 hwirq_mask = 1 << (hwirq % 32);
+
+	if (readl(reg) & hwirq_mask)
+		return true;
+	else
+		return false;
+}
+
+static inline bool plic_irq_is_enabled(const struct cpumask *mask,
+				   struct irq_data *d)
+{
+	int cpu;
+
+	for_each_cpu(cpu, mask) {
+		struct plic_handler *handler = per_cpu_ptr(&plic_handlers, cpu);
+
+		if (!handler->present)
+			continue;
+
+		if (plic_toggle_is_enabled(handler, d->hwirq))
+			return true;
+	}
+
+	return false;
+}
+
 static int plic_set_affinity(struct irq_data *d,
 			     const struct cpumask *mask_val, bool force)
 {
@@ -141,8 +171,10 @@ static int plic_set_affinity(struct irq_data *d,
 
 	irq_data_update_effective_affinity(d, &amask);
 
-	plic_irq_toggle(&priv->lmask, d, 0);
-	plic_irq_toggle(&amask, d, 1);
+	if (plic_irq_is_enabled(&priv->lmask, d)) {
+		plic_irq_toggle(&priv->lmask, d, 0);
+		plic_irq_toggle(&amask, d, 1);
+	}
 
 	return IRQ_SET_MASK_OK_DONE;
 }
@@ -168,12 +200,19 @@ static struct irq_chip plic_chip = {
 static int plic_irqdomain_map(struct irq_domain *d, unsigned int irq,
 			      irq_hw_number_t hwirq)
 {
+	unsigned int cpu;
 	struct plic_priv *priv = d->host_data;
 
 	irq_domain_set_info(d, irq, hwirq, &plic_chip, d->host_data,
 			    handle_fasteoi_irq, NULL, NULL);
 	irq_set_noprobe(irq);
-	irq_set_affinity(irq, &priv->lmask);
+
+	cpu = cpumask_any_and(&priv->lmask, cpu_online_mask);
+	if (WARN_ON_ONCE(cpu >= nr_cpu_ids))
+		return -EINVAL;
+
+	irq_set_affinity(irq, cpumask_of(cpu));
+
 	return 0;
 }
 
-- 
2.7.4