[PATCH v9 01/12] iommu/arm-smmu-v3: Do not enable EVTQ/PRIQ interrupts in kdump kernel

In kdump cases, the crashed kernel's CDs and page tables can be corrupted,
which could trigger event spamming. Also, we cannot serve page requests.

Skip the IRQ setup for EVTQ/PRIQ in arm_smmu_setup_irqs().

Skip their IRQ handler registration in unique-IRQ and combined-IRQ cases.

Note that arm_smmu_device_reset() at this point still enables EVTQEN/PRIQEN
transiently before clearing them. A following change will skip the entire
queue setup, removing that transient enable window.

Reviewed-by: Kevin Tian <[email protected]>
Reviewed-by: Pranjal Shrivastava <[email protected]>
Signed-off-by: Nicolin Chen <[email protected]>
---
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 58 ++++++++++++++-------
 1 file changed, 39 insertions(+), 19 deletions(-)

diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
index a10affb483a4f..404790d2c7210 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -2294,7 +2294,11 @@ static irqreturn_t arm_smmu_combined_irq_thread(int irq, void *dev)
 
 static irqreturn_t arm_smmu_combined_irq_handler(int irq, void *dev)
 {
-	arm_smmu_gerror_handler(irq, dev);
+	irqreturn_t ret = arm_smmu_gerror_handler(irq, dev);
+
+	/* In kdump, EVTQ/PRIQ are disabled and there is no thread to wake */
+	if (is_kdump_kernel())
+		return ret;
 	return IRQ_WAKE_THREAD;
 }
 
@@ -4625,6 +4629,21 @@ static void arm_smmu_setup_unique_irqs(struct arm_smmu_device *smmu)
 	arm_smmu_setup_msis(smmu);
 
 	/* Request interrupt lines */
+	irq = smmu->gerr_irq;
+	if (irq) {
+		ret = devm_request_irq(smmu->dev, irq, arm_smmu_gerror_handler,
+				       0, "arm-smmu-v3-gerror", smmu);
+		if (ret < 0)
+			dev_warn(smmu->dev, "failed to enable gerror irq\n");
+	} else {
+		dev_warn(smmu->dev,
+			 "no gerr irq - errors will not be reported!\n");
+	}
+
+	/* No EVTQ/PRIQ interrupts in kdump -- queues are disabled */
+	if (is_kdump_kernel())
+		return;
+
 	irq = smmu->evtq.q.irq;
 	if (irq) {
 		ret = devm_request_threaded_irq(smmu->dev, irq, NULL,
@@ -4637,16 +4656,6 @@ static void arm_smmu_setup_unique_irqs(struct arm_smmu_device *smmu)
 		dev_warn(smmu->dev, "no evtq irq - events will not be reported!\n");
 	}
 
-	irq = smmu->gerr_irq;
-	if (irq) {
-		ret = devm_request_irq(smmu->dev, irq, arm_smmu_gerror_handler,
-				       0, "arm-smmu-v3-gerror", smmu);
-		if (ret < 0)
-			dev_warn(smmu->dev, "failed to enable gerror irq\n");
-	} else {
-		dev_warn(smmu->dev, "no gerr irq - errors will not be reported!\n");
-	}
-
 	if (smmu->features & ARM_SMMU_FEAT_PRI) {
 		irq = smmu->priq.q.irq;
 		if (irq) {
@@ -4667,7 +4676,7 @@ static void arm_smmu_setup_unique_irqs(struct arm_smmu_device *smmu)
 static int arm_smmu_setup_irqs(struct arm_smmu_device *smmu)
 {
 	int ret, irq;
-	u32 irqen_flags = IRQ_CTRL_EVTQ_IRQEN | IRQ_CTRL_GERROR_IRQEN;
+	u32 irqen_flags = IRQ_CTRL_GERROR_IRQEN;
 
 	/* Disable IRQs first */
 	ret = arm_smmu_write_reg_sync(smmu, 0, ARM_SMMU_IRQ_CTRL,
@@ -4682,19 +4691,30 @@ static int arm_smmu_setup_irqs(struct arm_smmu_device *smmu)
 		/*
 		 * Cavium ThunderX2 implementation doesn't support unique irq
 		 * lines. Use a single irq line for all the SMMUv3 interrupts.
+		 *
+		 * In kdump, EVTQ/PRIQ are disabled, so no threaded handling.
 		 */
-		ret = devm_request_threaded_irq(smmu->dev, irq,
-					arm_smmu_combined_irq_handler,
-					arm_smmu_combined_irq_thread,
-					IRQF_ONESHOT,
-					"arm-smmu-v3-combined-irq", smmu);
+		if (is_kdump_kernel())
+			ret = devm_request_irq(smmu->dev, irq,
+					       arm_smmu_combined_irq_handler, 0,
+					       "arm-smmu-v3-combined-irq",
+					       smmu);
+		else
+			ret = devm_request_threaded_irq(
+				smmu->dev, irq, arm_smmu_combined_irq_handler,
+				arm_smmu_combined_irq_thread, IRQF_ONESHOT,
+				"arm-smmu-v3-combined-irq", smmu);
 		if (ret < 0)
 			dev_warn(smmu->dev, "failed to enable combined irq\n");
 	} else
 		arm_smmu_setup_unique_irqs(smmu);
 
-	if (smmu->features & ARM_SMMU_FEAT_PRI)
-		irqen_flags |= IRQ_CTRL_PRIQ_IRQEN;
+	/* No EVTQ/PRIQ IRQ generation in kdump -- queues are disabled */
+	if (!is_kdump_kernel()) {
+		irqen_flags |= IRQ_CTRL_EVTQ_IRQEN;
+		if (smmu->features & ARM_SMMU_FEAT_PRI)
+			irqen_flags |= IRQ_CTRL_PRIQ_IRQEN;
+	}
 
 	/* Enable interrupt generation on the SMMU */
 	ret = arm_smmu_write_reg_sync(smmu, irqen_flags,
-- 
2.43.0