RE: [PATCH v2 1/1] iommu/vt-d: Fix RID2PASID setup failure

[Tian, Kevin]

> From: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> Sent: Wednesday, June 22, 2022 12:41 PM
> 
> The IOMMU driver shares the pasid table for PCI alias devices. When the
> RID2PASID entry of the shared pasid table has been filled by the first
> device, the subsequent devices will encounter the "DMAR: Setup RID2PASID
> failed" failure as the pasid entry has already been marked as present. As
> the result, the IOMMU probing process will be aborted.
> 
> This fixes it by skipping RID2PASID setting if the pasid entry has been
> populated. This works because the IOMMU core ensures that only the same
> IOMMU domain can be attached to all PCI alias devices at the same time.
> Therefore the subsequent devices just try to setup the RID2PASID entry
> with the same domain, which is negligible. This also adds domain validity
> checks for more confidence anyway.
> 
> Fixes: ef848b7e5a6a0 ("iommu/vt-d: Setup pasid entry for RID2PASID
> support")
> Reported-by: Chenyi Qiang <chenyi.qiang@xxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>

Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>