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

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Date:   Tue, 13 Sep 2022 22:15:28 -0700
From:   Nicolin Chen <nicolinc@...dia.com>
To:     <jean-philippe@...aro.org>, <joro@...tes.org>, <will@...nel.org>,
        <robin.murphy@....com>
CC:     <jgg@...dia.com>, <kevin.tian@...el.com>,
        <virtualization@...ts.linux-foundation.org>,
        <iommu@...ts.linux.dev>, <linux-kernel@...r.kernel.org>
Subject: [PATCH v2 13/13] iommu/virtio: Constrain return value of ->attach_dev()

From: Jean-Philippe Brucker <jean-philippe@...aro.org>

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: Jean-Philippe Brucker <jean-philippe@...aro.org>
Signed-off-by: Nicolin Chen <nicolinc@...dia.com>
---
 drivers/iommu/virtio-iommu.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/drivers/iommu/virtio-iommu.c b/drivers/iommu/virtio-iommu.c
index 80151176ba12..168cd9c1f7e1 100644
--- a/drivers/iommu/virtio-iommu.c
+++ b/drivers/iommu/virtio-iommu.c
@@ -669,13 +669,13 @@ static int viommu_domain_finalise(struct viommu_endpoint *vdev,
 		dev_err(vdev->dev,
 			"granule 0x%lx larger than system page size 0x%lx\n",
 			viommu_page_size, PAGE_SIZE);
-		return -EINVAL;
+		return -ENODEV;
 	}
 
 	ret = ida_alloc_range(&viommu->domain_ids, viommu->first_domain,
 			      viommu->last_domain, GFP_KERNEL);
 	if (ret < 0)
-		return ret;
+		return -ENOMEM;
 
 	vdomain->id		= (unsigned int)ret;
 
@@ -696,7 +696,7 @@ static int viommu_domain_finalise(struct viommu_endpoint *vdev,
 		if (ret) {
 			ida_free(&viommu->domain_ids, vdomain->id);
 			vdomain->viommu = NULL;
-			return -EOPNOTSUPP;
+			return -ENODEV;
 		}
 	}
 
@@ -733,8 +733,7 @@ static int viommu_attach_dev(struct iommu_domain *domain, struct device *dev)
 		 */
 		ret = viommu_domain_finalise(vdev, domain);
 	} else if (vdomain->viommu != vdev->viommu) {
-		dev_err(dev, "cannot attach to foreign vIOMMU\n");
-		ret = -EXDEV;
+		ret = -EINVAL;
 	}
 	mutex_unlock(&vdomain->mutex);
 
@@ -769,7 +768,7 @@ static int viommu_attach_dev(struct iommu_domain *domain, struct device *dev)
 
 		ret = viommu_send_req_sync(vdomain->viommu, &req, sizeof(req));
 		if (ret)
-			return ret;
+			return -ENODEV;
 	}
 
 	if (!vdomain->nr_endpoints) {
@@ -779,7 +778,7 @@ static int viommu_attach_dev(struct iommu_domain *domain, struct device *dev)
 		 */
 		ret = viommu_replay_mappings(vdomain);
 		if (ret)
-			return ret;
+			return -ENODEV;
 	}
 
 	vdomain->nr_endpoints++;
-- 
2.17.1