vfio: Move iommu specific data to a union

This should help in adding support for other archs.  Create a
structure, add it to the union, populate it with map and unmap
function pointers, each of which take a pointer to your structure
as an argument, register that structure with something that will
call it when there's mappings to change.  If you need to free or
unregister, set the release function.  Map and unmap functions can
use container_of to get to the container and thefore the fd to use
to get to the iommu.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

hw/vfio_pci.c

@@ -1064,7 +1064,8 @@ static bool vfio_listener_skipped_section(MemoryRegionSection *section)
 static void vfio_listener_region_add(MemoryListener *listener,
                                      MemoryRegionSection *section)
 {
-    VFIOContainer *container = container_of(listener, VFIOContainer, listener);
+    VFIOContainer *container = container_of(listener, VFIOContainer,
+                                            iommu_data.listener);
     target_phys_addr_t iova = section->offset_within_address_space;
     ram_addr_t size = section->size;
     void *vaddr;
@@ -1092,7 +1093,8 @@ static void vfio_listener_region_add(MemoryListener *listener,
 static void vfio_listener_region_del(MemoryListener *listener,
                                      MemoryRegionSection *section)
 {
-    VFIOContainer *container = container_of(listener, VFIOContainer, listener);
+    VFIOContainer *container = container_of(listener, VFIOContainer,
+                                            iommu_data.listener);
     target_phys_addr_t iova = section->offset_within_address_space;
     ram_addr_t size = section->size;
     int ret;
@@ -1112,6 +1114,11 @@ static void vfio_listener_region_del(MemoryListener *listener,
     }
 }
 
+static void vfio_listener_release(VFIOContainer *container)
+{
+    memory_listener_unregister(&container->iommu_data.listener);
+}
+
 /*
  * Interrupt setup
  */
@@ -1603,7 +1610,7 @@ static int vfio_connect_container(VFIOGroup *group)
             return -1;
         }
 
-        container->listener = (MemoryListener) {
+        container->iommu_data.listener = (MemoryListener) {
             .begin = vfio_listener_dummy1,
             .commit = vfio_listener_dummy1,
             .region_add = vfio_listener_region_add,
@@ -1617,8 +1624,10 @@ static int vfio_connect_container(VFIOGroup *group)
             .eventfd_add = vfio_listener_dummy3,
             .eventfd_del = vfio_listener_dummy3,
         };
+        container->iommu_data.release = vfio_listener_release;
 
-        memory_listener_register(&container->listener, get_system_memory());
+        memory_listener_register(&container->iommu_data.listener,
+                                 get_system_memory());
 
     } else {
         error_report("vfio: No available IOMMU models\n");
@@ -1649,8 +1658,8 @@ static void vfio_disconnect_container(VFIOGroup *group)
     group->container = NULL;
 
     if (QLIST_EMPTY(&container->group_list)) {
-        if (container->listener.begin) {
-            memory_listener_unregister(&container->listener);
+        if (container->iommu_data.release) {
+            container->iommu_data.release(container);
         }
         QLIST_REMOVE(container, next);
         DPRINTF("vfio_disconnect_container: close container->fd\n");

hw/vfio_pci.h

@@ -56,7 +56,12 @@ struct VFIOGroup;
 
 typedef struct VFIOContainer {
     int fd;
-    MemoryListener listener;
+    struct {
+        union {
+            MemoryListener listener;
+        };
+        void (*release)(struct VFIOContainer *);
+    } iommu_data;
     QLIST_HEAD(, VFIOGroup) group_list;
     QLIST_ENTRY(VFIOContainer) next;
 } VFIOContainer;