-----Original Message----- From: Robin Murphy [mailto:robin.murphy@arm.com] Sent: 12 February 2021 16:39 To: Shameerali Kolothum Thodi shameerali.kolothum.thodi@huawei.com; linux-kernel@vger.kernel.org; iommu@lists.linux-foundation.org Cc: joro@8bytes.org; jean-philippe@linaro.org; will@kernel.org; Zengtao (B) prime.zeng@hisilicon.com; linuxarm@openeuler.org Subject: Re: [PATCH v2] iommu: Check dev->iommu in iommu_dev_xxx functions
On 2021-02-12 14:54, Shameerali Kolothum Thodi wrote:
Hi Robin/Joerg,
-----Original Message----- From: Shameer Kolothum [mailto:shameerali.kolothum.thodi@huawei.com] Sent: 01 February 2021 12:41 To: linux-kernel@vger.kernel.org; iommu@lists.linux-foundation.org Cc: joro@8bytes.org; robin.murphy@arm.com; jean-philippe@linaro.org; will@kernel.org; Zengtao (B) prime.zeng@hisilicon.com; linuxarm@openeuler.org Subject: [Linuxarm] [PATCH v2] iommu: Check dev->iommu in
iommu_dev_xxx
functions
The device iommu probe/attach might have failed leaving dev->iommu to NULL and device drivers may still invoke these functions resulting in a crash in iommu vendor driver code. Hence make sure we check that.
Also added iommu_ops to the "struct dev_iommu" and set it if the dev is successfully associated with an iommu.
Fixes: a3a195929d40 ("iommu: Add APIs for multiple domains per device") Signed-off-by: Shameer Kolothum
shameerali.kolothum.thodi@huawei.com
v1 --> v2: -Added iommu_ops to struct dev_iommu based on the discussion with
Robin.
-Rebased against iommu-tree core branch.
A gentle ping on this...
Is there a convincing justification for maintaining yet another copy of the ops pointer rather than simply dereferencing iommu_dev->ops at point of use?
TBH, nothing I can think of now. That was mainly the way I interpreted your suggestion from the v1. Now it looks like you didn’t mean it :). I am Ok to rework it to dereference it from iommu_dev. Please let me know.
Thanks, Shameer
Robin.
Thanks, Shameer
drivers/iommu/iommu.c | 19 +++++++------------ include/linux/iommu.h | 2 ++ 2 files changed, 9 insertions(+), 12 deletions(-)
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index fd76e2f579fe..6023d0b7c542 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -217,6 +217,7 @@ static int __iommu_probe_device(struct device
*dev,
struct list_head *group_list }
dev->iommu->iommu_dev = iommu_dev;
dev->iommu->ops = iommu_dev->ops;
group = iommu_group_get_for_dev(dev); if (IS_ERR(group)) {
@@ -2865,10 +2866,8 @@
EXPORT_SYMBOL_GPL(iommu_fwspec_add_ids);
*/ int iommu_dev_enable_feature(struct device *dev, enum iommu_dev_features feat) {
- const struct iommu_ops *ops = dev->bus->iommu_ops;
- if (ops && ops->dev_enable_feat)
return ops->dev_enable_feat(dev, feat);
if (dev->iommu && dev->iommu->ops->dev_enable_feat)
return dev->iommu->ops->dev_enable_feat(dev, feat);return -ENODEV; }
@@ -2881,10 +2880,8 @@ EXPORT_SYMBOL_GPL(iommu_dev_enable_feature); */ int iommu_dev_disable_feature(struct device *dev, enum iommu_dev_features feat) {
- const struct iommu_ops *ops = dev->bus->iommu_ops;
- if (ops && ops->dev_disable_feat)
return ops->dev_disable_feat(dev, feat);
if (dev->iommu && dev->iommu->ops->dev_disable_feat)
return dev->iommu->ops->dev_disable_feat(dev, feat);return -EBUSY; }
@@ -2892,10 +2889,8 @@ EXPORT_SYMBOL_GPL(iommu_dev_disable_feature);
bool iommu_dev_feature_enabled(struct device *dev, enum iommu_dev_features feat) {
- const struct iommu_ops *ops = dev->bus->iommu_ops;
- if (ops && ops->dev_feat_enabled)
return ops->dev_feat_enabled(dev, feat);
if (dev->iommu && dev->iommu->ops->dev_feat_enabled)
return dev->iommu->ops->dev_feat_enabled(dev, feat);return false; }
diff --git a/include/linux/iommu.h b/include/linux/iommu.h index 524ffc2ff64f..ff0c76bdfb67 100644 --- a/include/linux/iommu.h +++ b/include/linux/iommu.h @@ -354,6 +354,7 @@ struct iommu_fault_param {
- @fault_param: IOMMU detected device fault reporting data
- @fwspec: IOMMU fwspec data
- @iommu_dev: IOMMU device this device is linked to
- @ops: iommu-ops for talking to the iommu_dev
- @priv: IOMMU Driver private data
- TODO: migrate other per device data pointers under
iommu_dev_data,
e.g. @@ -364,6 +365,7 @@ struct dev_iommu { struct iommu_fault_param *fault_param; struct iommu_fwspec *fwspec; struct iommu_device *iommu_dev;
- const struct iommu_ops *ops; void *priv; };
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