This is a note to let you know that I've just added the patch titled
iommu/vt-d: Allow zero SAGAW if second-stage not supported
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
iommu-vt-d-allow-zero-sagaw-if-second-stage-not-supp.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 5d3297f3c3a74b4708f7a7987e209514614bfe70
Author: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
Date: Wed Mar 29 21:47:20 2023 +0800
iommu/vt-d: Allow zero SAGAW if second-stage not supported
[ Upstream commit bfd3c6b9fa4a1dc78139dd1621d5bea321ffa69d ]
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@xxxxxxxxx>
Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
Signed-off-by: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20230318024824.124542-1-baolu.lu@xxxxxxxxxxxxxxx
Link: https://lore.kernel.org/r/20230329134721.469447-3-baolu.lu@xxxxxxxxxxxxxxx
Signed-off-by: Joerg Roedel <jroedel@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/iommu/intel/dmar.c b/drivers/iommu/intel/dmar.c
index bff2420fc3e14..7c20083d4a798 100644
--- a/drivers/iommu/intel/dmar.c
+++ b/drivers/iommu/intel/dmar.c
@@ -1080,7 +1080,8 @@ 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;
