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BACKPORT: 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>

Bug: 229173748
(cherry picked from commit 211ff31b3d33b56aa12937e898c9280d07daf0d9)
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Change-Id: Iafd361871c0f06f75f71f7dbd7575b74d9c4253f
This commit is contained in:
Ashish Mhetre 2021-08-10 10:14:00 +05:30 committed by Suren Baghdasaryan
parent 0dcfc2c036
commit 00f2b55cc4
1 changed files with 2 additions and 0 deletions
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2
drivers/iommu/iommu.c
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@ -268,7 +268,9 @@ 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);