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LuBaolujoergroedel
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iommu/vt-d: Remove commented-out code
These lines of code were commented out when they were first added in commit ba39592 ("Intel IOMMU: Intel IOMMU driver"). We do not want to restore them because the VT-d spec has deprecated the read/write draining hit. VT-d spec (section 11.4.2): " Hardware implementation with Major Version 2 or higher (VER_REG), always performs required drain without software explicitly requesting a drain in IOTLB invalidation. This field is deprecated and hardware will always report it as 1 to maintain backward compatibility with software. " Remove the code to make the code cleaner. Signed-off-by: Lu Baolu <[email protected]> Reviewed-by: Jerry Snitselaar <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Joerg Roedel <[email protected]>
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drivers/iommu/intel/iommu.c

Lines changed: 1 addition & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -1312,15 +1312,7 @@ static void __iommu_flush_iotlb(struct intel_iommu *iommu, u16 did,
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iommu->name, type);
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return;
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}
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/* Note: set drain read/write */
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#if 0
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/*
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* This is probably to be super secure.. Looks like we can
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* ignore it without any impact.
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*/
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if (cap_read_drain(iommu->cap))
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val |= DMA_TLB_READ_DRAIN;
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#endif
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if (cap_write_drain(iommu->cap))
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val |= DMA_TLB_WRITE_DRAIN;
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