Re: [PATCH 1/2] iommu: Fix race condition during default domain allocation
From: Will Deacon <will@kernel.org>
Date: 2021-06-11 10:45:35
Also in:
linux-iommu, lkml
On Thu, Jun 10, 2021 at 09:46:53AM +0530, Ashish Mhetre wrote:
Domain is getting created more than once during asynchronous multiple display heads(devices) probe. All the display heads share same SID and are expected to be in same domain. As iommu_alloc_default_domain() call is not protected, the group->default_domain and group->domain are ending up with different domains and leading to subsequent IOMMU faults. Fix this by protecting iommu_alloc_default_domain() call with group->mutex.
Can you provide some more information about exactly what the h/w configuration is, and the callstack which exhibits the race, please?
quoted hunk ↗ jump to hunk
Signed-off-by: Ashish Mhetre <redacted> --- drivers/iommu/iommu.c | 2 ++ 1 file changed, 2 insertions(+)diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index 808ab70..2700500 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c@@ -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);
It feels wrong to serialise this for everybody just to cater for systems with aliasing SIDs between devices. Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel