iommu/arm-smmu: Allow using a threaded handler for context interrupts

Threaded IRQ handlers run in a less critical context compared to normal
IRQs, so they can perform more complex and time-consuming operations
without causing significant delays in other parts of the kernel.
During a context fault, it might be needed to do more processing and
gather debug information from TBUs in the handler. These operations may
sleep, so add an option to use a threaded IRQ handler in these cases.

Signed-off-by: Georgi Djakov <quic_c_gdjako@quicinc.com>
Link: https://lore.kernel.org/r/20240417133731.2055383-4-quic_c_gdjako@quicinc.com
Signed-off-by: Will Deacon <will@kernel.org>

drivers/iommu/arm/arm-smmu/arm-smmu.c

@@ -806,8 +806,16 @@ static int arm_smmu_init_domain_context(struct arm_smmu_domain *smmu_domain,
 	else
 		context_fault = arm_smmu_context_fault;
 
-	ret = devm_request_irq(smmu->dev, irq, context_fault, IRQF_SHARED,
-			       "arm-smmu-context-fault", smmu_domain);
+	if (smmu->impl && smmu->impl->context_fault_needs_threaded_irq)
+		ret = devm_request_threaded_irq(smmu->dev, irq, NULL,
+						context_fault,
+						IRQF_ONESHOT | IRQF_SHARED,
+						"arm-smmu-context-fault",
+						smmu_domain);
+	else
+		ret = devm_request_irq(smmu->dev, irq, context_fault, IRQF_SHARED,
+				       "arm-smmu-context-fault", smmu_domain);
+
 	if (ret < 0) {
 		dev_err(smmu->dev, "failed to request context IRQ %d (%u)\n",
 			cfg->irptndx, irq);

drivers/iommu/arm/arm-smmu/arm-smmu.h

@@ -438,6 +438,7 @@ struct arm_smmu_impl {
 	int (*def_domain_type)(struct device *dev);
 	irqreturn_t (*global_fault)(int irq, void *dev);
 	irqreturn_t (*context_fault)(int irq, void *dev);
+	bool context_fault_needs_threaded_irq;
 	int (*alloc_context_bank)(struct arm_smmu_domain *smmu_domain,
 				  struct arm_smmu_device *smmu,
 				  struct device *dev, int start);