[PATCH AUTOSEL 4.9 127/251] iommu/vt-d: Make kernel parameter igfx_off work with vIOMMU

Sasha Levin
2020-01-16T18:08:32Z

From: Lu Baolu <baolu.lu@linux.intel.com>

[ 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>
---
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 25cc6ae87039..5c6e0a9fd2f3 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -3345,9 +3345,12 @@ 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