[PATCH v14 05/18] irqchip/sifive-plic: Cleanup PLIC contexts upon irqdomain creation failure

[Anup Patel]

The SiFive PLIC contexts should not be left dangling if irqdomain creation
fails because plic_starting_cpu() can crash accessing unmapped registers.

Signed-off-by: Anup Patel <apatel at ventanamicro.com>
---
 drivers/irqchip/irq-sifive-plic.c | 73 ++++++++++++++++++++++---------
 1 file changed, 53 insertions(+), 20 deletions(-)

diff --git a/drivers/irqchip/irq-sifive-plic.c b/drivers/irqchip/irq-sifive-plic.c
index 615498071b6e..f0df5d0cb76e 100644
--- a/drivers/irqchip/irq-sifive-plic.c
+++ b/drivers/irqchip/irq-sifive-plic.c
@@ -416,17 +416,45 @@ static const struct of_device_id plic_match[] = {
 	{}
 };
 
+static int plic_parse_context_parent(struct platform_device *pdev, u32 context,
+				     u32 *parent_hwirq, int *parent_cpu)
+{
+	struct device *dev = &pdev->dev;
+	struct of_phandle_args parent;
+	unsigned long hartid;
+	int rc;
+
+	/*
+	 * Currently, only OF fwnode is supported so extend this
+	 * function for ACPI support.
+	 */
+	if (!is_of_node(dev->fwnode))
+		return -EINVAL;
+
+	rc = of_irq_parse_one(to_of_node(dev->fwnode), context, &parent);
+	if (rc)
+		return rc;
+
+	rc = riscv_of_parent_hartid(parent.np, &hartid);
+	if (rc)
+		return rc;
+
+	*parent_hwirq = parent.args[0];
+	*parent_cpu = riscv_hartid_to_cpuid(hartid);
+	return 0;
+}
+
 static int plic_probe(struct platform_device *pdev)
 {
-	int error = 0, nr_contexts, nr_handlers = 0, i;
+	int error = 0, nr_contexts, nr_handlers = 0, cpu, i;
 	struct device *dev = &pdev->dev;
 	unsigned long plic_quirks = 0;
 	struct plic_handler *handler;
+	u32 nr_irqs, parent_hwirq;
 	struct irq_domain *domain;
 	struct plic_priv *priv;
+	irq_hw_number_t hwirq;
 	bool cpuhp_setup;
-	unsigned int cpu;
-	u32 nr_irqs;
 
 	if (is_of_node(dev->fwnode)) {
 		const struct of_device_id *id;
@@ -462,13 +490,9 @@ static int plic_probe(struct platform_device *pdev)
 		return -EINVAL;
 
 	for (i = 0; i < nr_contexts; i++) {
-		struct of_phandle_args parent;
-		irq_hw_number_t hwirq;
-		int cpu;
-		unsigned long hartid;
-
-		if (of_irq_parse_one(to_of_node(dev->fwnode), i, &parent)) {
-			dev_err(dev, "failed to parse parent for context %d.\n", i);
+		error = plic_parse_context_parent(pdev, i, &parent_hwirq, &cpu);
+		if (error) {
+			dev_warn(dev, "hwirq for context%d not found\n", i);
 			continue;
 		}
 
@@ -476,7 +500,7 @@ static int plic_probe(struct platform_device *pdev)
 		 * Skip contexts other than external interrupts for our
 		 * privilege level.
 		 */
-		if (parent.args[0] != RV_IRQ_EXT) {
+		if (parent_hwirq != RV_IRQ_EXT) {
 			/* Disable S-mode enable bits if running in M-mode. */
 			if (IS_ENABLED(CONFIG_RISCV_M_MODE)) {
 				void __iomem *enable_base = priv->regs +
@@ -489,13 +513,6 @@ static int plic_probe(struct platform_device *pdev)
 			continue;
 		}
 
-		error = riscv_of_parent_hartid(parent.np, &hartid);
-		if (error < 0) {
-			dev_warn(dev, "failed to parse hart ID for context %d.\n", i);
-			continue;
-		}
-
-		cpu = riscv_hartid_to_cpuid(hartid);
 		if (cpu < 0) {
 			dev_warn(dev, "Invalid cpuid for context %d\n", i);
 			continue;
@@ -534,7 +551,7 @@ static int plic_probe(struct platform_device *pdev)
 		handler->enable_save = devm_kcalloc(dev, DIV_ROUND_UP(nr_irqs, 32),
 						    sizeof(*handler->enable_save), GFP_KERNEL);
 		if (!handler->enable_save)
-			return -ENOMEM;
+			goto fail_cleanup_contexts;
 done:
 		for (hwirq = 1; hwirq <= nr_irqs; hwirq++) {
 			plic_toggle(handler, hwirq, 0);
@@ -547,7 +564,7 @@ static int plic_probe(struct platform_device *pdev)
 	priv->irqdomain = irq_domain_add_linear(to_of_node(dev->fwnode), nr_irqs + 1,
 						&plic_irqdomain_ops, priv);
 	if (WARN_ON(!priv->irqdomain))
-		return -ENOMEM;
+		goto fail_cleanup_contexts;
 
 	/*
 	 * We can have multiple PLIC instances so setup cpuhp state
@@ -575,6 +592,22 @@ static int plic_probe(struct platform_device *pdev)
 	dev_info(dev, "mapped %d interrupts with %d handlers for %d contexts.\n",
 		 nr_irqs, nr_handlers, nr_contexts);
 	return 0;
+
+fail_cleanup_contexts:
+	for (i = 0; i < nr_contexts; i++) {
+		if (plic_parse_context_parent(pdev, i, &parent_hwirq, &cpu))
+			continue;
+		if (parent_hwirq != RV_IRQ_EXT || cpu < 0)
+			continue;
+
+		handler = per_cpu_ptr(&plic_handlers, cpu);
+		handler->present = false;
+		handler->hart_base = NULL;
+		handler->enable_base = NULL;
+		handler->enable_save = NULL;
+		handler->priv = NULL;
+	}
+	return -ENOMEM;
 }
 
 static struct platform_driver plic_driver = {
-- 
2.34.1