Commit bfd3c6b9 authored by Lu Baolu's avatar Lu Baolu Committed by Joerg Roedel
Browse files

iommu/vt-d: Allow zero SAGAW if second-stage not supported 



The VT-d spec states (in section 11.4.2) that hardware implementations
reporting second-stage translation support (SSTS) field as Clear also
report the SAGAW field as 0. Fix an inappropriate check in alloc_iommu().

Fixes: 792fb43c ("iommu/vt-d: Enable Intel IOMMU scalable mode by default")
Suggested-by: default avatarRaghunathan Srinivasan <raghunathan.srinivasan@intel.com>
Reviewed-by: default avatarKevin Tian <kevin.tian@intel.com>
Signed-off-by: default avatarJacob Pan <jacob.jun.pan@linux.intel.com>
Signed-off-by: default avatarLu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20230318024824.124542-1-baolu.lu@linux.intel.com
Link: https://lore.kernel.org/r/20230329134721.469447-3-baolu.lu@linux.intel.com


Signed-off-by: default avatarJoerg Roedel <jroedel@suse.de>
parent c7d62452

drivers/iommu/intel/dmar.c

+2 −1
Original line number Diff line number Diff line
@@ -1071,7 +1071,8 @@ static int alloc_iommu(struct dmar_drhd_unit *drhd) 
	}



	err = -EINVAL;

	if (cap_sagaw(iommu->cap) == 0) {

	if (!cap_sagaw(iommu->cap) &&

	    (!ecap_smts(iommu->ecap) || ecap_slts(iommu->ecap))) {

		pr_info("%s: No supported address widths. Not attempting DMA translation.\n",

			iommu->name);

		drhd->ignored = 1;