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Date:   Thu,  2 May 2019 09:34:26 +0800
From:   Lu Baolu <>
To:     Joerg Roedel <>,
        David Woodhouse <>
        Zhenyu Wang <>,,,
        Lu Baolu <>,
        Jacob Pan <>
Subject: [PATCH 2/2] iommu/vt-d: Make kernel parameter igfx_off work with vIOMMU

The kernel parameter igfx_off is used by users to disable
DMA remapping for the Intel integrated graphic device. It
was designed for bare metal cases where a dedicated IOMMU
is used for graphic. This doesn't apply to virtual IOMMU
case where an include-all IOMMU is used.  This makes the
kernel parameter work with virtual IOMMU as well.

Cc: Ashok Raj <>
Cc: Jacob Pan <>
Suggested-by: Kevin Tian <>
Fixes: c0771df8d5297 ("intel-iommu: Export a flag indicating that the IOMMU is used for iGFX.")
Signed-off-by: Lu Baolu <>
Tested-by: Zhenyu Wang <>
 drivers/iommu/intel-iommu.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 00ad00193883..e078b13ce3d8 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -3415,9 +3415,12 @@ static int __init init_dmars(void)
 		iommu_identity_mapping |= IDENTMAP_ALL;
-	iommu_identity_mapping |= IDENTMAP_GFX;
+	dmar_map_gfx = 0;
+	if (!dmar_map_gfx)
+		iommu_identity_mapping |= IDENTMAP_GFX;
 	if (iommu_identity_mapping) {

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