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From: Ashish Mhetre <amhetre@nvidia.com>
To: <amhetre@nvidia.com>, <joro@8bytes.org>, <will@kernel.org>,
	<robin.murphy@arm.com>, <vdumpa@nvidia.com>
Cc: <iommu@lists.linux-foundation.org>,
	<linux-kernel@vger.kernel.org>,
	<linux-arm-kernel@lists.infradead.org>
Subject: [PATCH 1/2] iommu: Fix race condition during default domain allocation
Date: Thu, 10 Jun 2021 09:46:53 +0530	[thread overview]
Message-ID: <1623298614-31755-2-git-send-email-amhetre@nvidia.com> (raw)
In-Reply-To: <1623298614-31755-1-git-send-email-amhetre@nvidia.com>

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.

Signed-off-by: Ashish Mhetre <amhetre@nvidia.com>
---
 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);
 
 	if (group->default_domain) {
 		ret = __iommu_attach_device(group->default_domain, dev);
-- 
2.7.4


  reply	other threads:[~2021-06-10  4:17 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-10  4:16 [PATCH 0/2] iommu/arm-smmu: Fix races in iommu domain/group creation Ashish Mhetre
2021-06-10  4:16 ` Ashish Mhetre [this message]
2021-06-11 10:45   ` [PATCH 1/2] iommu: Fix race condition during default domain allocation Will Deacon
2021-06-11 12:49     ` Robin Murphy
2021-06-17  5:51       ` Ashish Mhetre
2021-06-17 17:49         ` Will Deacon
2021-06-11 18:30     ` Krishna Reddy
2021-06-10  4:16 ` [PATCH 2/2] iommu/arm-smmu: Fix race condition during iommu_group creation Ashish Mhetre

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