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iommu: Fix race condition during default domain allocation

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When two devices with same SID are getting probed concurrently through
iommu_probe_device(), the iommu_domain sometimes is getting allocated more
than once as call to iommu_alloc_default_domain() is not protected for
concurrency. Furthermore, it leads to each device holding a different
iommu_domain pointer, separate IOVA space and only one of the devices'
domain is used for translations from IOMMU. This causes accesses from other
device to fault or see incorrect translations.
Fix this by protecting iommu_alloc_default_domain() call with group->mutex
and let all devices with same SID share same iommu_domain.

Signed-off-by: Ashish Mhetre <amhetre@nvidia.com>
Link: https://lore.kernel.org/r/1628570641-9127-2-git-send-email-amhetre@nvidia.com
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Ashish Mhetre 2021-08-10 10:14:00 +05:30 committed by Will Deacon
parent afefe67e08
commit 211ff31b3d
1 changed files with 2 additions and 0 deletions
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2
drivers/iommu/iommu.c
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@ -273,7 +273,9 @@ int iommu_probe_device(struct device *dev)
* support default domains, so the return value is not yet
* checked.
*/
mutex_lock(&group->mutex);
iommu_alloc_default_domain(group, dev);
mutex_unlock(&group->mutex);
if (group->default_domain) {
ret = __iommu_attach_device(group->default_domain, dev);