[PATCH v9 3/4] iommu/arm-smmu-v3: Standardize ATS enablement failure reporting

[Pranjal Shrivastava]

Update arm_smmu_enable_ats() to wrap the pci_enable_ats() call in a
WARN(). Since probe-time checks now preclude configuration errors
any failure during hardware enablement is considered a kernel bug.

Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
Reviewed-by: Nicolin Chen <nicolinc@xxxxxxxxxx>
Reviewed-by: Samiullah Khawaja <skhawaja@xxxxxxxxxx>
Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
Signed-off-by: Pranjal Shrivastava <praan@xxxxxxxxxx>
---
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 9 +++++++--
 1 file changed, 7 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 a10affb483a4..57b750ebcd3d 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -2956,8 +2956,13 @@ static void arm_smmu_enable_ats(struct arm_smmu_master *master)
 	 * ATC invalidation of PASID 0 causes the entire ATC to be flushed.
 	 */
 	arm_smmu_atc_inv_master(master, IOMMU_NO_PASID);
-	if (pci_enable_ats(pdev, stu))
-		dev_err(master->dev, "Failed to enable ATS (STU %zu)\n", stu);
+
+	 /*
+	  * Since pci_prepare_ats() has already verified the HW capability
+	  * and programmed the STE, pci_enable_ats() should not fail here.
+	  */
+	WARN(pci_enable_ats(pdev, stu),
+	     "%s: Failed to enable ATS (STU %zu)\n", dev_name(master->dev), stu);
 }
 
 static int arm_smmu_enable_pasid(struct arm_smmu_master *master)
-- 
2.54.0.1136.gdb2ca164c4-goog