Commit b4da4e11 authored by Lu Baolu's avatar Lu Baolu Committed by Joerg Roedel
Browse files

iommu/vt-d: Remove commented-out code 



These lines of code were commented out when they were first added in commit
ba395927 ("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: default avatarLu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: default avatarJerry Snitselaar <jsnitsel@redhat.com>
Link: https://lore.kernel.org/r/20230609060514.15154-1-baolu.lu@linux.intel.com


Signed-off-by: default avatarJoerg Roedel <jroedel@suse.de>
parent 3f13f727

drivers/iommu/intel/iommu.c

+1 −9
Original line number Original line Diff line number Diff line
@@ -1312,15 +1312,7 @@ static void __iommu_flush_iotlb(struct intel_iommu *iommu, u16 did, 
			iommu->name, type);

			iommu->name, type);

		return;

		return;

	}

	}

	/* Note: set drain read/write */



#if 0

	/*

	 * This is probably to be super secure.. Looks like we can

	 * ignore it without any impact.

	 */

	if (cap_read_drain(iommu->cap))

		val |= DMA_TLB_READ_DRAIN;

#endif

	if (cap_write_drain(iommu->cap))

	if (cap_write_drain(iommu->cap))

		val |= DMA_TLB_WRITE_DRAIN;

		val |= DMA_TLB_WRITE_DRAIN;