AMD/IOMMU: don't free shared IRT multiple times

Calling amd_iommu_free_intremap_table() for every IVRS entry is correct
only in per-device-IRT mode. Use a NULL 2nd argument to indicate that
the shared table should be freed, and call the function exactly once in
shared mode.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
v5: New.

--- a/xen/drivers/passthrough/amd/iommu_init.c
+++ b/xen/drivers/passthrough/amd/iommu_init.c
@@ -1106,6 +1106,15 @@ static void __init amd_iommu_init_cleanu
 {
     struct amd_iommu *iommu, *next;
 
+    /* free interrupt remapping table */
+    if ( amd_iommu_perdev_intremap )
+        iterate_ivrs_entries(amd_iommu_free_intremap_table);
+    else if ( shared_intremap_table )
+        amd_iommu_free_intremap_table(list_first_entry(&amd_iommu_head,
+                                                       struct amd_iommu,
+                                                       list),
+                                      NULL);
+
     /* free amd iommu list */
     list_for_each_entry_safe ( iommu, next, &amd_iommu_head, list )
     {
@@ -1128,9 +1137,6 @@ static void __init amd_iommu_init_cleanu
         xfree(iommu);
     }
 
-    /* free interrupt remapping table */
-    iterate_ivrs_entries(amd_iommu_free_intremap_table);
-
     /* free device table */
     deallocate_device_table(&device_table);
 
--- a/xen/drivers/passthrough/amd/iommu_intr.c
+++ b/xen/drivers/passthrough/amd/iommu_intr.c
@@ -792,14 +792,23 @@ void amd_iommu_read_msi_from_ire(
 int __init amd_iommu_free_intremap_table(
     const struct amd_iommu *iommu, struct ivrs_mappings *ivrs_mapping)
 {
-    void *tb = ivrs_mapping->intremap_table;
+    void **tblp;
 
-    XFREE(ivrs_mapping->intremap_inuse);
+    if ( ivrs_mapping )
+    {
+        XFREE(ivrs_mapping->intremap_inuse);
+        tblp = &ivrs_mapping->intremap_table;
+    }
+    else
+    {
+        XFREE(shared_intremap_inuse);
+        tblp = &shared_intremap_table;
+    }
 
-    if ( tb )
+    if ( *tblp )
     {
-        __free_amd_iommu_tables(tb, intremap_table_order(iommu));
-        ivrs_mapping->intremap_table = NULL;
+        __free_amd_iommu_tables(*tblp, intremap_table_order(iommu));
+        *tblp = NULL;
     }
 
     return 0;