Hi，

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 marke 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.

Two ASPEED devices locate behind one PCIe-PCI bridge and iommu SM, PT mode is enabled.  Most

Interesting thing is the second device is only used by BIOS, and BIOS left it to OS without shutting down,

and it is useless for OS.  Is there practical case multi devices behind PCIe-PCI bridge share the same

PASID entry without any security concern ? these two customer's case is not.

Thanks,

Ethan

Fixes: ef848b7e5a6a0 ("iommu/vt-d: Setup pasid entry for RID2PASID support")
Reported-by: Chenyi Qiang <chenyi.qiang@intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
 drivers/iommu/intel/iommu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 44016594831d..b9966c01a2a2 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -2564,7 +2564,7 @@ static int domain_add_dev_info(struct dmar_domain *domain, struct device *dev)
 			ret = intel_pasid_setup_second_level(iommu, domain,
 					dev, PASID_RID2PASID);
 		spin_unlock_irqrestore(&iommu->lock, flags);
-		if (ret) {
+		if (ret && ret != -EBUSY) {
 			dev_err(dev, "Setup RID2PASID failed\n");
 			dmar_remove_one_dev_info(dev);
 			return ret;

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