iommu/vtd: cleanup MAP_SINGLE_DEVICE and related code

This flag was only used in case cx16 is not available, as those code paths no
longer exist, this flag now does basically nothing.

Signed-off-by: Teddy Astie <teddy.astie@vates.tech>
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Release-Acked-by: Oleksii Kurochko <oleksii.kurochko@gmail.com>

xen/drivers/passthrough/vtd/iommu.c

@@ -1695,15 +1695,9 @@ static int domain_context_mapping(struct domain *domain, u8 devfn,
         break;
     }
 
-    if ( domain != pdev->domain && pdev->domain != dom_io )
-    {
-        if ( pdev->domain->is_dying )
+    if ( domain != pdev->domain && pdev->domain != dom_io &&
+         pdev->domain->is_dying )
         mode |= MAP_OWNER_DYING;
-        else if ( drhd &&
-                  !any_pdev_behind_iommu(pdev->domain, pdev, drhd->iommu) &&
-                  !pdev->phantom_stride )
-            mode |= MAP_SINGLE_DEVICE;
-    }
 
     switch ( pdev->type )
     {

xen/drivers/passthrough/vtd/vtd.h

@@ -28,9 +28,8 @@
  */
 #define MAP_WITH_RMRR         (1u << 0)
 #define MAP_OWNER_DYING       (1u << 1)
-#define MAP_SINGLE_DEVICE     (1u << 2)
-#define MAP_ERROR_RECOVERY    (1u << 3)
-#define UNMAP_ME_PHANTOM_FUNC (1u << 4)
+#define MAP_ERROR_RECOVERY    (1u << 2)
+#define UNMAP_ME_PHANTOM_FUNC (1u << 3)
 
 /* Allow for both IOAPIC and IOSAPIC. */
 #define IO_xAPIC_route_entry IO_APIC_route_entry