linux-kernel - [PATCH v2 04/13] iommu/arm: Constrain return value of ->attach

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Message-ID: <20220914051257.10093-1-nicolinc@nvidia.com>
Date:   Tue, 13 Sep 2022 22:12:57 -0700
From:   Nicolin Chen <nicolinc@...dia.com>
To:     <will@...nel.org>, <robin.murphy@....com>, <joro@...tes.org>,
        <robdclark@...il.com>
CC:     <jgg@...dia.com>, <kevin.tian@...el.com>,
        <baolu.lu@...ux.intel.com>, <tglx@...utronix.de>,
        <shameerali.kolothum.thodi@...wei.com>,
        <christophe.jaillet@...adoo.fr>, <thunder.leizhen@...wei.com>,
        <quic_saipraka@...cinc.com>, <yangyingliang@...wei.com>,
        <jon@...id-run.com>, <linux-arm-kernel@...ts.infradead.org>,
        <iommu@...ts.linux.dev>, <linux-kernel@...r.kernel.org>,
        <linux-arm-msm@...r.kernel.org>
Subject: [PATCH v2 04/13] iommu/arm: Constrain return value of ->attach_dev()

Ensure attach_dev() callback functions only return errno values expected
from the attach_dev() op. In particular, only return -EINVAL when we are
sure that the device is incompatible with the domain.

Also drop any dev_err next to -EINVAL, following the attach_dev op kdocs.

Signed-off-by: Nicolin Chen <nicolinc@...dia.com>
---
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 13 ++-----------
 drivers/iommu/arm/arm-smmu/arm-smmu.c       |  7 ++-----
 drivers/iommu/arm/arm-smmu/qcom_iommu.c     |  9 ++-------
 3 files changed, 6 insertions(+), 23 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 d32b02336411..8b5a2e8de7e2 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -2402,7 +2402,7 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
 	struct arm_smmu_master *master;
 
 	if (!fwspec)
-		return -ENOENT;
+		return -ENODEV;
 
 	master = dev_iommu_priv_get(dev);
 	smmu = master->smmu;
@@ -2429,23 +2429,14 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
 			goto out_unlock;
 		}
 	} else if (smmu_domain->smmu != smmu) {
-		dev_err(dev,
-			"cannot attach to SMMU %s (upstream of %s)\n",
-			dev_name(smmu_domain->smmu->dev),
-			dev_name(smmu->dev));
-		ret = -ENXIO;
+		ret = -EINVAL;
 		goto out_unlock;
 	} else if (smmu_domain->stage == ARM_SMMU_DOMAIN_S1 &&
 		   master->ssid_bits != smmu_domain->s1_cfg.s1cdmax) {
-		dev_err(dev,
-			"cannot attach to incompatible domain (%u SSID bits != %u)\n",
-			smmu_domain->s1_cfg.s1cdmax, master->ssid_bits);
 		ret = -EINVAL;
 		goto out_unlock;
 	} else if (smmu_domain->stage == ARM_SMMU_DOMAIN_S1 &&
 		   smmu_domain->stall_enabled != master->stall_enabled) {
-		dev_err(dev, "cannot attach to stall-%s domain\n",
-			smmu_domain->stall_enabled ? "enabled" : "disabled");
 		ret = -EINVAL;
 		goto out_unlock;
 	}
diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c b/drivers/iommu/arm/arm-smmu/arm-smmu.c
index dfa82df00342..63a488f2f16c 100644
--- a/drivers/iommu/arm/arm-smmu/arm-smmu.c
+++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c
@@ -1137,7 +1137,7 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
 
 	if (!fwspec || fwspec->ops != &arm_smmu_ops) {
 		dev_err(dev, "cannot attach to SMMU, is it on the same bus?\n");
-		return -ENXIO;
+		return -ENODEV;
 	}
 
 	/*
@@ -1155,7 +1155,7 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
 
 	ret = arm_smmu_rpm_get(smmu);
 	if (ret < 0)
-		return ret;
+		return -ENODEV;
 
 	/* Ensure that the domain is finalised */
 	ret = arm_smmu_init_domain_context(domain, smmu, dev);
@@ -1167,9 +1167,6 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
 	 * different SMMUs.
 	 */
 	if (smmu_domain->smmu != smmu) {
-		dev_err(dev,
-			"cannot attach to SMMU %s whilst already attached to domain on SMMU %s\n",
-			dev_name(smmu_domain->smmu->dev), dev_name(smmu->dev));
 		ret = -EINVAL;
 		goto rpm_put;
 	}
diff --git a/drivers/iommu/arm/arm-smmu/qcom_iommu.c b/drivers/iommu/arm/arm-smmu/qcom_iommu.c
index 17235116d3bb..542fa8c4b6cb 100644
--- a/drivers/iommu/arm/arm-smmu/qcom_iommu.c
+++ b/drivers/iommu/arm/arm-smmu/qcom_iommu.c
@@ -367,7 +367,7 @@ static int qcom_iommu_attach_dev(struct iommu_domain *domain, struct device *dev
 
 	if (!qcom_iommu) {
 		dev_err(dev, "cannot attach to IOMMU, is it on the same bus?\n");
-		return -ENXIO;
+		return -ENODEV;
 	}
 
 	/* Ensure that the domain is finalized */
@@ -381,13 +381,8 @@ static int qcom_iommu_attach_dev(struct iommu_domain *domain, struct device *dev
 	 * Sanity check the domain. We don't support domains across
 	 * different IOMMUs.
 	 */
-	if (qcom_domain->iommu != qcom_iommu) {
-		dev_err(dev, "cannot attach to IOMMU %s while already "
-			"attached to domain on IOMMU %s\n",
-			dev_name(qcom_domain->iommu->dev),
-			dev_name(qcom_iommu->dev));
+	if (qcom_domain->iommu != qcom_iommu)
 		return -EINVAL;
-	}
 
 	return 0;
 }
-- 
2.17.1