IOMMU/x86: drop pointless NULL checks

map_domain_page() et al never fail; no need to check their return values
against NULL, and no need to carry dead printk()s.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>

xen/drivers/passthrough/amd/pci_amd_iommu.c

@@ -566,12 +566,6 @@ static void amd_dump_page_table_level(struct page_info *pg, int level,
         return;
 
     table_vaddr = __map_domain_page(pg);
-    if ( table_vaddr == NULL )
-    {
-        printk("AMD IOMMU failed to map domain page %"PRIpaddr"\n",
-                page_to_maddr(pg));
-        return;
-    }
 
     for ( index = 0; index < PTE_PER_TABLE_SIZE; index++ )
     {

xen/drivers/passthrough/vtd/iommu.c

@@ -2633,12 +2633,6 @@ static void vtd_dump_page_table_level(paddr_t pt_maddr, int level, paddr_t gpa,
         return;
 
     pt_vaddr = map_vtd_domain_page(pt_maddr);
-    if ( pt_vaddr == NULL )
-    {
-        printk(VTDPREFIX " failed to map domain page %"PRIpaddr"\n",
-               pt_maddr);
-        return;
-    }
 
     next_level = level - 1;
     for ( i = 0; i < PTE_NUM; i++ )

xen/drivers/passthrough/vtd/utils.c

@@ -106,11 +106,6 @@ void print_vtd_entries(struct vtd_iommu *iommu, int bus, int devfn, u64 gmfn)
     }
 
     root_entry = (struct root_entry *)map_vtd_domain_page(iommu->root_maddr);
-    if ( root_entry == NULL )
-    {
-        printk("    root_entry == NULL\n");
-        return;
-    }
 
     printk("    root_entry[%02x] = %"PRIx64"\n", bus, root_entry[bus].val);
     if ( !root_present(root_entry[bus]) )
@@ -123,11 +118,6 @@ void print_vtd_entries(struct vtd_iommu *iommu, int bus, int devfn, u64 gmfn)
     val = root_entry[bus].val;
     unmap_vtd_domain_page(root_entry);
     ctxt_entry = map_vtd_domain_page(val);
-    if ( ctxt_entry == NULL )
-    {
-        printk("    ctxt_entry == NULL\n");
-        return;
-    }
 
     val = ctxt_entry[devfn].lo;
     printk("    context[%02x] = %"PRIx64"_%"PRIx64"\n",
@@ -151,11 +141,6 @@ void print_vtd_entries(struct vtd_iommu *iommu, int bus, int devfn, u64 gmfn)
     do
     {
         l = map_vtd_domain_page(val);
-        if ( l == NULL )
-        {
-            printk("    l%u == NULL\n", level);
-            break;
-        }
         l_index = get_level_index(gmfn, level);
         pte.val = l[l_index];
         unmap_vtd_domain_page(l);