[PATCH 4.4 086/183] iommu/vt-d: Make kernel parameter igfx_off work with vIOMMU

[Greg Kroah-Hartman]

From: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>

[ Upstream commit 5daab58043ee2bca861068e2595564828f3bc663 ]

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 <ashok.raj@xxxxxxxxx>
Cc: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
Suggested-by: Kevin Tian <kevin.tian@xxxxxxxxx>
Fixes: c0771df8d5297 ("intel-iommu: Export a flag indicating that the IOMMU is used for iGFX.")
Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
Tested-by: Zhenyu Wang <zhenyuw@xxxxxxxxxxxxxxx>
Signed-off-by: Joerg Roedel <jroedel@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 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 b965561a41627..a2005b82ec8ff 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -3259,9 +3259,12 @@ static int __init init_dmars(void)
 		iommu_identity_mapping |= IDENTMAP_ALL;
 
 #ifdef CONFIG_INTEL_IOMMU_BROKEN_GFX_WA
-	iommu_identity_mapping |= IDENTMAP_GFX;
+	dmar_map_gfx = 0;
 #endif
 
+	if (!dmar_map_gfx)
+		iommu_identity_mapping |= IDENTMAP_GFX;
+
 	check_tylersburg_isoch();
 
 	if (iommu_identity_mapping) {
-- 
2.20.1