linux-kernel - [PATCH] iommu: Check for deferred attach in iommu_group_do_dma

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Message-Id: <20200604091944.26402-1-joro@8bytes.org>
Date:   Thu,  4 Jun 2020 11:19:44 +0200
From:   Joerg Roedel <joro@...tes.org>
To:     Joerg Roedel <joro@...tes.org>
Cc:     iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        Jerry Snitselaar <jsnitsel@...hat.com>,
        Joerg Roedel <jroedel@...e.de>
Subject: [PATCH] iommu: Check for deferred attach in iommu_group_do_dma_attach()

From: Joerg Roedel <jroedel@...e.de>

The iommu_group_do_dma_attach() must not attach devices which have
deferred_attach set. Otherwise devices could cause IOMMU faults when
re-initialized in a kdump kernel.

Fixes: deac0b3bed26 ("iommu: Split off default domain allocation from group assignment")
Reported-by: Jerry Snitselaar <jsnitsel@...hat.com>
Reviewed-by: Jerry Snitselaar <jsnitsel@...hat.com>
Tested-by: Jerry Snitselaar <jsnitsel@...hat.com>
Signed-off-by: Joerg Roedel <jroedel@...e.de>
---
 drivers/iommu/iommu.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index b5ea203f6c68..5a6d509f72b6 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -1680,8 +1680,12 @@ static void probe_alloc_default_domain(struct bus_type *bus,
 static int iommu_group_do_dma_attach(struct device *dev, void *data)
 {
 	struct iommu_domain *domain = data;
+	int ret = 0;
 
-	return __iommu_attach_device(domain, dev);
+	if (!iommu_is_attach_deferred(group->domain, dev))
+		ret = __iommu_attach_device(group->domain, dev);
+
+	return ret;
 }
 
 static int __iommu_group_dma_attach(struct iommu_group *group)
-- 
2.26.2