[PATCH v2 8/8] iommu: Clean up open-coded ownership checks

Robin Murphy
2023-01-26T18:27:04Z

Some drivers already implement their own defence against the possibility
of being given someone else's device. Since this is now taken care of by
the core code (and via a slightly different path from the original
fwspec-based idea), let's clean them up.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
---

v2: No change, but I'll note here that it's really about the fwspec->ops
checks; the !fwspec clauses are just going along for the ride where
that's clearly impossible as well. I plan to sweep for other
redundant checks in future when looking at the relevant flows.

drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 3 ---
drivers/iommu/arm/arm-smmu/arm-smmu.c | 9 +--------
drivers/iommu/arm/arm-smmu/qcom_iommu.c | 14 ++------------
drivers/iommu/mtk_iommu.c | 7 +------
drivers/iommu/mtk_iommu_v1.c | 3 ---
drivers/iommu/sprd-iommu.c | 8 +-------
drivers/iommu/virtio-iommu.c | 3 ---
7 files changed, 5 insertions(+), 42 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 ab160198edd6..cb05d9771192 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -2642,9 +2642,6 @@ static struct iommu_device *arm_smmu_probe_device(struct device *dev)
struct arm_smmu_master *master;
struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);

- if (!fwspec || fwspec->ops != &arm_smmu_ops)
- return ERR_PTR(-ENODEV);
-
if (WARN_ON_ONCE(dev_iommu_priv_get(dev)))
return ERR_PTR(-EBUSY);

diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c b/drivers/iommu/arm/arm-smmu/arm-smmu.c
index 607f06af01b6..235550db0d59 100644
--- a/drivers/iommu/arm/arm-smmu/arm-smmu.c
+++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c
@@ -1118,11 +1118,6 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
struct arm_smmu_device *smmu;
int ret;

- if (!fwspec || fwspec->ops != &arm_smmu_ops) {
- dev_err(dev, "cannot attach to SMMU, is it on the same bus?\n");
- return -ENXIO;
- }
-
/*
* FIXME: The arch/arm DMA API code tries to attach devices to its own
* domains between of_xlate() and probe_device() - we have no way to cope
@@ -1352,10 +1347,8 @@ static struct iommu_device *arm_smmu_probe_device(struct device *dev)
fwspec = dev_iommu_fwspec_get(dev);
if (ret)
goto out_free;
- } else if (fwspec && fwspec->ops == &arm_smmu_ops) {
- smmu = arm_smmu_get_by_fwnode(fwspec->iommu_fwnode);
} else {
- return ERR_PTR(-ENODEV);
+ smmu = arm_smmu_get_by_fwnode(fwspec->iommu_fwnode);
}

ret = -EINVAL;
diff --git a/drivers/iommu/arm/arm-smmu/qcom_iommu.c b/drivers/iommu/arm/arm-smmu/qcom_iommu.c
index d7be3adee426..3fe02720ab29 100644
--- a/drivers/iommu/arm/arm-smmu/qcom_iommu.c
+++ b/drivers/iommu/arm/arm-smmu/qcom_iommu.c
@@ -79,16 +79,6 @@ static struct qcom_iommu_domain *to_qcom_iommu_domain(struct iommu_domain *dom)

static const struct iommu_ops qcom_iommu_ops;

-static struct qcom_iommu_dev * to_iommu(struct device *dev)
-{
- struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
-
- if (!fwspec || fwspec->ops != &qcom_iommu_ops)
- return NULL;
-
- return dev_iommu_priv_get(dev);
-}
-
static struct qcom_iommu_ctx * to_ctx(struct qcom_iommu_domain *d, unsigned asid)
{
struct qcom_iommu_dev *qcom_iommu = d->iommu;
@@ -361,7 +351,7 @@ static void qcom_iommu_domain_free(struct iommu_domain *domain)

static int qcom_iommu_attach_dev(struct iommu_domain *domain, struct device *dev)
{
- struct qcom_iommu_dev *qcom_iommu = to_iommu(dev);
+ struct qcom_iommu_dev *qcom_iommu = dev_iommu_priv_get(dev);
struct qcom_iommu_domain *qcom_domain = to_qcom_iommu_domain(domain);
int ret;

@@ -486,7 +476,7 @@ static bool qcom_iommu_capable(struct device *dev, enum iommu_cap cap)

static struct iommu_device *qcom_iommu_probe_device(struct device *dev)
{
- struct qcom_iommu_dev *qcom_iommu = to_iommu(dev);
+ struct qcom_iommu_dev *qcom_iommu = dev_iommu_priv_get(dev);
struct device_link *link;

if (!qcom_iommu)
diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
index d5a4955910ff..ce19a2a21e2a 100644
--- a/drivers/iommu/mtk_iommu.c
+++ b/drivers/iommu/mtk_iommu.c
@@ -776,16 +776,11 @@ static phys_addr_t mtk_iommu_iova_to_phys(struct iommu_domain *domain,
static struct iommu_device *mtk_iommu_probe_device(struct device *dev)
{
struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
- struct mtk_iommu_data *data;
+ struct mtk_iommu_data *data = dev_iommu_priv_get(dev);
struct device_link *link;
struct device *larbdev;
unsigned int larbid, larbidx, i;

- if (!fwspec || fwspec->ops != &mtk_iommu_ops)
- return ERR_PTR(-ENODEV); /* Not a iommu client device */
-
- data = dev_iommu_priv_get(dev);
-
if (!MTK_IOMMU_IS_TYPE(data->plat_data, MTK_IOMMU_TYPE_MM))
return &data->iommu;

diff --git a/drivers/iommu/mtk_iommu_v1.c b/drivers/iommu/mtk_iommu_v1.c
index 78d0a84c704f..328833823181 100644
--- a/drivers/iommu/mtk_iommu_v1.c
+++ b/drivers/iommu/mtk_iommu_v1.c
@@ -478,9 +478,6 @@ static struct iommu_device *mtk_iommu_v1_probe_device(struct device *dev)
idx++;
}

- if (!fwspec || fwspec->ops != &mtk_iommu_v1_ops)
- return ERR_PTR(-ENODEV); /* Not a iommu client device */
-
data = dev_iommu_priv_get(dev);

/* Link the consumer device with the smi-larb device(supplier) */
diff --git a/drivers/iommu/sprd-iommu.c b/drivers/iommu/sprd-iommu.c
index ae94d74b73f4..85378f7cfd1f 100644
--- a/drivers/iommu/sprd-iommu.c
+++ b/drivers/iommu/sprd-iommu.c
@@ -358,13 +358,7 @@ static phys_addr_t sprd_iommu_iova_to_phys(struct iommu_domain *domain,

static struct iommu_device *sprd_iommu_probe_device(struct device *dev)
{
- struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
- struct sprd_iommu_device *sdev;
-
- if (!fwspec || fwspec->ops != &sprd_iommu_ops)
- return ERR_PTR(-ENODEV);
-
- sdev = dev_iommu_priv_get(dev);
+ struct sprd_iommu_device *sdev = dev_iommu_priv_get(dev);

return &sdev->iommu;
}
diff --git a/drivers/iommu/virtio-iommu.c b/drivers/iommu/virtio-iommu.c
index 5b8fe9bfa9a5..59f1abd6ee53 100644
--- a/drivers/iommu/virtio-iommu.c
+++ b/drivers/iommu/virtio-iommu.c
@@ -945,9 +945,6 @@ static struct iommu_device *viommu_probe_device(struct device *dev)
struct viommu_dev *viommu = NULL;
struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);

- if (!fwspec || fwspec->ops != &viommu_ops)
- return ERR_PTR(-ENODEV);
-
viommu = viommu_get_by_fwnode(fwspec->iommu_fwnode);
if (!viommu)
return ERR_PTR(-ENODEV);
--
2.36.1.dirty