[PATCH 8/9] iommu/vt-d: Drop old iopf ref only after attach succeeds

[Lu Baolu <baolu.lu@linux.intel.com>]

identity_domain_attach_dev() currently removes the old domain’s iopf
reference before programming pass-through. If pass-through setup fails,
attach fails but the old domain is still effectively attached — now
with its IOPF ref already dropped.

This can undercount info->iopf_refcount and may disable iopf queue
handling while the old domain can still issue page requests.

Fix it by removing the old domain’s iopf reference only after
pass-through setup succeeds, matching other attach paths.

Fixes: 236dd58fabd2 ("iommu/vt-d: Fix iopf_refcount leak on RID domain replacement")
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
---
 drivers/iommu/intel/iommu.c | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 1fb9b80f3b5e..e3ec7f3b7826 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -3985,6 +3985,14 @@ static int identity_domain_attach_dev(struct iommu_domain *domain,
 	if (dev_is_real_dma_subdevice(dev))
 		return 0;
 
+	if (sm_supported(iommu))
+		ret = intel_pasid_setup_pass_through(iommu, dev, IOMMU_NO_PASID);
+	else
+		ret = device_setup_pass_through(dev);
+
+	if (ret)
+		return ret;
+
 	/*
 	 * The identity domain has no iopf_handler, so no IOPF reference is
 	 * taken for it.  The reference held by the old domain must still be
@@ -3992,16 +4000,9 @@ static int identity_domain_attach_dev(struct iommu_domain *domain,
 	 * not affect the IOPF reference count.
 	 */
 	iopf_for_domain_remove(old, dev);
+	info->domain_attached = true;
 
-	if (sm_supported(iommu))
-		ret = intel_pasid_setup_pass_through(iommu, dev, IOMMU_NO_PASID);
-	else
-		ret = device_setup_pass_through(dev);
-
-	if (!ret)
-		info->domain_attached = true;
-
-	return ret;
+	return 0;
 }
 
 static int identity_domain_set_dev_pasid(struct iommu_domain *domain,
-- 
2.43.0