iommu/vt-d: Make kernel parameter igfx_off work with vIOMMU

[ 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@intel.com>
Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>
Suggested-by: Kevin Tian <kevin.tian@intel.com>
Fixes: c0771df8d5297 ("intel-iommu: Export a flag indicating that the IOMMU is used for iGFX.")
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Tested-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index b965561..a2005b8 100644 (file)
--- 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) {