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    Subject[PATCH 4.14 187/343] iommu/vt-d: Make kernel parameter igfx_off work with vIOMMU
    Date
    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 523d0889c2a4e..4fbd183d973ab 100644
    --- a/drivers/iommu/intel-iommu.c
    +++ b/drivers/iommu/intel-iommu.c
    @@ -3361,9 +3361,12 @@ 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


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