diff --git a/xen/drivers/passthrough/amd/pci_amd_iommu.c b/xen/drivers/passthrough/amd/pci_amd_iommu.c
index 70b7475..17c1f6d 100644
--- a/xen/drivers/passthrough/amd/pci_amd_iommu.c
+++ b/xen/drivers/passthrough/amd/pci_amd_iommu.c
@@ -285,6 +285,8 @@ static void __hwdom_init amd_iommu_hwdom_init(struct domain *d)
 
     if ( !iommu_passthrough && !need_iommu(d) )
     {
+        int rc = 0;
+
         /* Set up 1:1 page table for dom0 */
         for ( i = 0; i < max_pdx; i++ )
         {
@@ -295,12 +297,22 @@ static void __hwdom_init amd_iommu_hwdom_init(struct domain *d)
              * a pfn_valid() check would seem desirable here.
              */
             if ( mfn_valid(pfn) )
-                amd_iommu_map_page(d, pfn, pfn, 
-                                   IOMMUF_readable|IOMMUF_writable);
+            {
+                int ret;
+
+                ret = amd_iommu_map_page(d, pfn, pfn,
+                                         IOMMUF_readable|IOMMUF_writable);
+                if ( !rc )
+                    rc = ret;
+            }
 
             if ( !(i & 0xfffff) )
                 process_pending_softirqs();
         }
+
+        if ( rc )
+            AMD_IOMMU_DEBUG("d%d: IOMMU mapping failed: %d\n",
+                            d->domain_id, rc);
     }
 
     for_each_amd_iommu ( iommu )
diff --git a/xen/drivers/passthrough/arm/smmu.c b/xen/drivers/passthrough/arm/smmu.c
index 1ce4ddf..ee5c89d 100644
--- a/xen/drivers/passthrough/arm/smmu.c
+++ b/xen/drivers/passthrough/arm/smmu.c
@@ -2745,8 +2745,8 @@ static void arm_smmu_iommu_domain_teardown(struct domain *d)
 	xfree(xen_domain);
 }
 
-static int arm_smmu_map_page(struct domain *d, unsigned long gfn,
-			     unsigned long mfn, unsigned int flags)
+static int __must_check arm_smmu_map_page(struct domain *d, unsigned long gfn,
+                                          unsigned long mfn, unsigned int flags)
 {
 	p2m_type_t t;
 
diff --git a/xen/drivers/passthrough/vtd/iommu.c b/xen/drivers/passthrough/vtd/iommu.c
index 4844193..e900019 100644
--- a/xen/drivers/passthrough/vtd/iommu.c
+++ b/xen/drivers/passthrough/vtd/iommu.c
@@ -1687,9 +1687,10 @@ static void iommu_domain_teardown(struct domain *d)
     spin_unlock(&hd->arch.mapping_lock);
 }
 
-static int intel_iommu_map_page(
-    struct domain *d, unsigned long gfn, unsigned long mfn,
-    unsigned int flags)
+static int __must_check intel_iommu_map_page(struct domain *d,
+                                             unsigned long gfn,
+                                             unsigned long mfn,
+                                             unsigned int flags)
 {
     struct domain_iommu *hd = dom_iommu(d);
     struct dma_pte *page = NULL, *pte = NULL, old, new = { 0 };
diff --git a/xen/include/asm-x86/hvm/svm/amd-iommu-proto.h b/xen/include/asm-x86/hvm/svm/amd-iommu-proto.h
index 57b6cc1..ac9f036 100644
--- a/xen/include/asm-x86/hvm/svm/amd-iommu-proto.h
+++ b/xen/include/asm-x86/hvm/svm/amd-iommu-proto.h
@@ -51,8 +51,8 @@ int amd_iommu_init(void);
 int amd_iommu_update_ivrs_mapping_acpi(void);
 
 /* mapping functions */
-int amd_iommu_map_page(struct domain *d, unsigned long gfn, unsigned long mfn,
-                       unsigned int flags);
+int __must_check amd_iommu_map_page(struct domain *d, unsigned long gfn,
+                                    unsigned long mfn, unsigned int flags);
 int __must_check amd_iommu_unmap_page(struct domain *d, unsigned long gfn);
 u64 amd_iommu_get_next_table_from_pte(u32 *entry);
 int amd_iommu_reserve_domain_unity_map(struct domain *domain,
diff --git a/xen/include/xen/iommu.h b/xen/include/xen/iommu.h
index 73a7f1e..14041a1 100644
--- a/xen/include/xen/iommu.h
+++ b/xen/include/xen/iommu.h
@@ -166,8 +166,8 @@ struct iommu_ops {
 #endif /* HAS_PCI */
 
     void (*teardown)(struct domain *d);
-    int (*map_page)(struct domain *d, unsigned long gfn, unsigned long mfn,
-                    unsigned int flags);
+    int __must_check (*map_page)(struct domain *d, unsigned long gfn,
+                                 unsigned long mfn, unsigned int flags);
     int __must_check (*unmap_page)(struct domain *d, unsigned long gfn);
     void (*free_page_table)(struct page_info *);
 #ifdef CONFIG_X86
