From: Joerg Roedel <jroedel@suse.de>
Date: Thu, 4 Jun 2020 11:19:44 +0200
Subject: iommu: Check for deferred attach in iommu_group_do_dma_attach()
Git-commit: 431275afdc7155415254aef4bd3816a1b8a2ead0
Patch-mainline: v5.8-rc1
References: bsc#1175713

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@redhat.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Tested-by: Jerry Snitselaar <jsnitsel@redhat.com>
Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>
Link: https://lore.kernel.org/r/20200604091944.26402-1-joro@8bytes.org
---
 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..d43120eb1dc5 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(domain, dev))
+		ret = __iommu_attach_device(domain, dev);
+
+	return ret;
 }
 
 static int __iommu_group_dma_attach(struct iommu_group *group)