[PATCH] iommu/arm-smmu-v3: Disable PRI when no priq IRQ is available

[Breno Leitao <leitao@debian.org>]

When platform firmware advertises an SMMU as PRI-capable in IDR0.PRI
but does not assign a GSIV for its priq, arm_smmu_setup_unique_irqs()
warns and continues. ARM_SMMU_FEAT_PRI remains set, so the driver
still allocates the PRI queue, programs PRIQ_BASE/PROD/CONS, enables
IRQ_CTRL_PRIQ_IRQEN, and lets IOMMU_DEV_FEAT_IOPF be advertised to
upper layers. Page Request messages from devices land in a queue no
one drains, and SVA binds appear to succeed while silently dropping
every page fault.

Clear ARM_SMMU_FEAT_PRI in the missing-IRQ path so every PRI-gated
site in the driver consistently treats the SMMU as PRI-less, instead of
the half-baked stated.

Signed-off-by: Breno Leitao <leitao@debian.org>
---
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

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..44bafbb38e242 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -4659,7 +4659,8 @@ static void arm_smmu_setup_unique_irqs(struct arm_smmu_device *smmu)
 				dev_warn(smmu->dev,
 					 "failed to enable priq irq\n");
 		} else {
-			dev_warn(smmu->dev, "no priq irq - PRI will be broken\n");
+			dev_warn(smmu->dev, "no priq irq - disabling PRI\n");
+			smmu->features &= ~ARM_SMMU_FEAT_PRI;
 		}
 	}
 }

---
base-commit: 948efecf22e49aa4bf55bb73ec79a0ddcfd38571
change-id: 20260622-smmu_pri-a33326900c33

Best regards,
-- 
Breno Leitao <leitao@debian.org>