[PATCH v2 4/7] iommu/vt-d: Ignore domain parameter in attach_device if device requires identity map

[James Sewart]

If a device requires an identity map then it is not safe to attach a
domain that can remap addresses. Warn the user if this occurs.

Signed-off-by: James Sewart <jamessewart@xxxxxxxxxx>
---
 drivers/iommu/intel-iommu.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 2e00e8708f06..104d36f225a7 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -5101,6 +5101,11 @@ static int intel_iommu_attach_device(struct iommu_domain *domain,
 		}
 	}
 
+	if (iommu_no_mapping(dev)) {
+		dmar_domain = si_domain;
+		dev_warn(dev, "VT-d: Device is required to use identity IOMMU mapping, ignoring domain attached\n");
+	}
+
 	iommu = device_to_iommu(dev, &bus, &devfn);
 	if (!iommu)
 		return -ENODEV;
-- 
2.17.1