[xen stable-4.14] VT-d: don't leak domid mapping on error path

[patchbot@xxxxxxx]

commit fb9177385357bd0856692a6aa9c1513468281ae1
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Fri Jan 7 08:51:27 2022 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri Jan 7 08:51:27 2022 +0100

    VT-d: don't leak domid mapping on error path
    
    While domain_context_mapping() invokes domain_context_unmap() in a sub-
    case of handling DEV_TYPE_PCI when encountering an error, thus avoiding
    a leak, individual calls to domain_context_mapping_one() aren't
    similarly covered. Such a leak might persist until domain destruction.
    Leverage that these cases can be recognized by pdev being non-NULL.
    
    Fixes: dec403cc668f ("VT-d: fix iommu_domid for PCI/PCIx devices 
assignment")
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
    master commit: e6252a51faf42c892eb5fc71f8a2617580832196
    master date: 2021-11-24 11:07:11 +0100
---
 xen/drivers/passthrough/vtd/iommu.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/xen/drivers/passthrough/vtd/iommu.c 
b/xen/drivers/passthrough/vtd/iommu.c
index 59809bba7f..ce3e511ef7 100644
--- a/xen/drivers/passthrough/vtd/iommu.c
+++ b/xen/drivers/passthrough/vtd/iommu.c
@@ -1518,7 +1518,12 @@ int domain_context_mapping_one(
         rc = me_wifi_quirk(domain, bus, devfn, MAP_ME_PHANTOM_FUNC);
 
     if ( rc )
-        domain_context_unmap_one(domain, iommu, bus, devfn);
+    {
+        ret = domain_context_unmap_one(domain, iommu, bus, devfn);
+
+        if ( !ret && pdev && pdev->devfn == devfn )
+            check_cleanup_domid_map(domain, pdev, iommu);
+    }
 
     return rc;
 }
--
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