From bfd3c6b9fa4a1dc78139dd1621d5bea321ffa69d Mon Sep 17 00:00:00 2001
From: Lu Baolu <baolu.lu@linux.intel.com>
Date: Wed, 29 Mar 2023 21:47:20 +0800
Subject: [PATCH] iommu/vt-d: Allow zero SAGAW if second-stage not supported
Git-commit: bfd3c6b9fa4a1dc78139dd1621d5bea321ffa69d
Patch-mainline: v6.3-rc5
References: git-fixes
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: 792fb43ce2c9 ("iommu/vt-d: Enable Intel IOMMU scalable mode by default")
Suggested-by: Raghunathan Srinivasan <raghunathan.srinivasan@intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Signed-off-by: Lu 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: Joerg Roedel <jroedel@suse.de>
Acked-by: Vasant Karasulli <vkarasulli@suse.de>
---
drivers/iommu/intel/dmar.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/iommu/intel/dmar.c b/drivers/iommu/intel/dmar.c
index 6acfe879589c..23828d189c2a 100644
--- a/drivers/iommu/intel/dmar.c
+++ b/drivers/iommu/intel/dmar.c
@@ -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;
--
2.34.1