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....@intel.com>
Cc: Jacob Pan <jacob.jun....@linux.intel.com>
Suggested-by: Kevin Tian <kevin.t...@intel.com>
Fixes: c0771df8d5297 ("intel-iommu: Export a flag indicating that the IOMMU is
used for iGFX.")
Signed-off-by: Lu Baolu <baolu...@linux.intel.com>
Tested-by: Zhenyu Wang <zhen...@linux.intel.com>
---
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;
#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) {
--
2.17.1
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