[PATCH v5 3/6] iommu/arm-smmu-v3: Suppress EVTQ/PRIQ events in kdump kernel

[Nicolin Chen <nicolinc@nvidia.com>]

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(), and guard the
thread functions against being entered via a combined-IRQ delivery while
the queue is disabled.

Fixes: b63b3439b856 ("iommu/arm-smmu-v3: Abort all transactions if SMMU is enabled in kdump kernel")
Cc: stable@vger.kernel.org # v6.12+
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 23 +++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 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 579c8af82d6b6..ebb0826d74541 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -2364,6 +2364,14 @@ static irqreturn_t arm_smmu_evtq_thread(int irq, void *dev)
 	static DEFINE_RATELIMIT_STATE(rs, DEFAULT_RATELIMIT_INTERVAL,
 				      DEFAULT_RATELIMIT_BURST);
 
+	/*
+	 * A combined IRQ might call into this function with the queue disabled.
+	 * E.g. kdump, where stale HW PROD vs SW CONS would drive a bogus drain
+	 * and a CONS write to a disabled queue.
+	 */
+	if (!(readl_relaxed(smmu->base + ARM_SMMU_CR0) & CR0_EVTQEN))
+		return IRQ_NONE;
+
 	do {
 		while (!queue_remove_raw(q, evt)) {
 			arm_smmu_decode_event(smmu, evt, &event);
@@ -2432,6 +2440,14 @@ static irqreturn_t arm_smmu_priq_thread(int irq, void *dev)
 	struct arm_smmu_ll_queue *llq = &q->llq;
 	u64 evt[PRIQ_ENT_DWORDS];
 
+	/*
+	 * A combined IRQ might call into this function with the queue disabled.
+	 * E.g. kdump, where stale HW PROD vs SW CONS would drive a bogus drain
+	 * and a CONS write to a disabled queue.
+	 */
+	if (!(readl_relaxed(smmu->base + ARM_SMMU_CR0) & CR0_PRIQEN))
+		return IRQ_NONE;
+
 	do {
 		while (!queue_remove_raw(q, evt))
 			arm_smmu_handle_ppr(smmu, evt);
@@ -5056,7 +5072,10 @@ 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;
+
+	if (!is_kdump_kernel())
+		irqen_flags |= IRQ_CTRL_EVTQ_IRQEN;
 
 	/* Disable IRQs first */
 	ret = arm_smmu_write_reg_sync(smmu, 0, ARM_SMMU_IRQ_CTRL,
@@ -5082,7 +5101,7 @@ static int arm_smmu_setup_irqs(struct arm_smmu_device *smmu)
 	} else
 		arm_smmu_setup_unique_irqs(smmu);
 
-	if (smmu->features & ARM_SMMU_FEAT_PRI)
+	if (!is_kdump_kernel() && (smmu->features & ARM_SMMU_FEAT_PRI))
 		irqen_flags |= IRQ_CTRL_PRIQ_IRQEN;
 
 	/* Enable interrupt generation on the SMMU */
-- 
2.43.0