[PATCH 2/2] iommu/arm-smmu: Fix race condition during iommu_group creation
From: Ashish Mhetre <hidden>
Date: 2021-06-10 04:17:43
Also in:
linux-iommu, lkml
Subsystem:
arm smmu drivers, iommu subsystem, the rest · Maintainers:
Will Deacon, Joerg Roedel, Linus Torvalds
From: Krishna Reddy <vdumpa@nvidia.com> iommu_group is getting created more than once during asynchronous multiple display heads(devices) probe on Tegra194 SoC. All the display heads share same SID and are expected to be in same iommu_group. As arm_smmu_device_group() is not protecting group creation across devices, it is leading to multiple groups creation across devices with same SID and subsequent IOMMU faults. Fix this by protecting group creation with smmu->stream_map_mutex. Signed-off-by: Krishna Reddy <vdumpa@nvidia.com> --- drivers/iommu/arm/arm-smmu/arm-smmu.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c b/drivers/iommu/arm/arm-smmu/arm-smmu.c
index 6f72c4d..21af179 100644
--- a/drivers/iommu/arm/arm-smmu/arm-smmu.c
+++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c@@ -1458,6 +1458,7 @@ static struct iommu_group *arm_smmu_device_group(struct device *dev) struct iommu_group *group = NULL; int i, idx; + mutex_lock(&smmu->stream_map_mutex); for_each_cfg_sme(cfg, fwspec, i, idx) { if (group && smmu->s2crs[idx].group && group != smmu->s2crs[idx].group)
@@ -1466,8 +1467,10 @@ static struct iommu_group *arm_smmu_device_group(struct device *dev) group = smmu->s2crs[idx].group; } - if (group) + if (group) { + mutex_unlock(&smmu->stream_map_mutex); return iommu_group_ref_get(group); + } if (dev_is_pci(dev)) group = pci_device_group(dev);
@@ -1481,6 +1484,7 @@ static struct iommu_group *arm_smmu_device_group(struct device *dev) for_each_cfg_sme(cfg, fwspec, i, idx) smmu->s2crs[idx].group = group; + mutex_unlock(&smmu->stream_map_mutex); return group; }
--
2.7.4
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