Commit 304b3bde authored by Lu Baolu's avatar Lu Baolu Committed by Joerg Roedel
Browse files

iommu/vt-d: Remove caching mode check before device TLB flush 



The Caching Mode (CM) of the Intel IOMMU indicates if the hardware
implementation caches not-present or erroneous translation-structure
entries except for the first-stage translation. The caching mode is
irrelevant to the device TLB, therefore there is no need to check it
before a device TLB invalidation operation.

Remove two caching mode checks before device TLB invalidation in the
driver. The removal of these checks doesn't change the driver's behavior
in critical map/unmap paths. Hence, there is no functionality or
performance impact, especially since commit <29b32839> ("iommu/vt-d:
Do not use flush-queue when caching-mode is on") has already disabled
flush-queue for caching mode. Therefore, caching mode will never call
intel_flush_iotlb_all().

Signed-off-by: default avatarLu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: default avatarKevin Tian <kevin.tian@intel.com>
Reviewed-by: default avatarYi Liu <yi.l.liu@intel.com>
Link: https://lore.kernel.org/r/20240415013835.9527-1-baolu.lu@linux.intel.com


Signed-off-by: default avatarJoerg Roedel <jroedel@suse.de>
parent 621b7e54

drivers/iommu/intel/iommu.c

+2 −7
Original line number Diff line number Diff line
@@ -1502,11 +1502,7 @@ static void iommu_flush_iotlb_psi(struct intel_iommu *iommu, 
	else

		__iommu_flush_iotlb_psi(iommu, did, pfn, pages, ih);



	/*

	 * In caching mode, changes of pages from non-present to present require

	 * flush. However, device IOTLB doesn't need to be flushed in this case.

	 */

	if (!cap_caching_mode(iommu->cap) || !map)

	if (!map)

		iommu_flush_dev_iotlb(domain, addr, mask);

}
@@ -1580,7 +1576,6 @@ static void intel_flush_iotlb_all(struct iommu_domain *domain) 
			iommu->flush.flush_iotlb(iommu, did, 0, 0,

						 DMA_TLB_DSI_FLUSH);



		if (!cap_caching_mode(iommu->cap))

		iommu_flush_dev_iotlb(dmar_domain, 0, MAX_AGAW_PFN_WIDTH);

	}