[Qemu-ppc] [RFC PATCH 01/10] vfio: Remove unneeded union from VFIOContainer

[David Gibson]

Currently the VFIOContainer iommu_data field contains a union with
different information for different host iommu types.  However:
   * It only actually contains information for the x86-like "Type1" iommu
   * Because we have a common listener the Type1 fields are actually used
on all IOMMU types, including the SPAPR TCE type as well
   * There's no tag in the VFIOContainer to tell you which union member is
valid anyway.

In fact we now have a general structure for the listener which is unlikely
to ever need per-iommu-type information, so this patch removes the union.

In a similar way we can unify the setup of the vfio memory listener in
vfio_connect_container() that is currently split across a switch on iommu
type, but is effectively the same in both cases.

The iommu_data.release pointer was only needed as a cleanup function
which would handle potentially different data in the union.  With the
union gone, it too can be removed.

Signed-off-by: David Gibson <address@hidden>
---
 hw/vfio/common.c              | 51 +++++++++++++++++--------------------------
 include/hw/vfio/vfio-common.h | 14 +++---------
 2 files changed, 23 insertions(+), 42 deletions(-)

diff --git a/hw/vfio/common.c b/hw/vfio/common.c
index 6d21311..e3152f6 100644
--- a/hw/vfio/common.c
+++ b/hw/vfio/common.c
@@ -316,7 +316,7 @@ static void vfio_listener_region_add(MemoryListener 
*listener,
                                      MemoryRegionSection *section)
 {
     VFIOContainer *container = container_of(listener, VFIOContainer,
-                                            iommu_data.type1.listener);
+                                            iommu_data.listener);
     hwaddr iova, end;
     Int128 llend;
     void *vaddr;
@@ -406,9 +406,9 @@ static void vfio_listener_region_add(MemoryListener 
*listener,
          * can gracefully fail.  Runtime, there's not much we can do other
          * than throw a hardware error.
          */
-        if (!container->iommu_data.type1.initialized) {
-            if (!container->iommu_data.type1.error) {
-                container->iommu_data.type1.error = ret;
+        if (!container->iommu_data.initialized) {
+            if (!container->iommu_data.error) {
+                container->iommu_data.error = ret;
             }
         } else {
             hw_error("vfio: DMA mapping failed, unable to continue");
@@ -420,7 +420,7 @@ static void vfio_listener_region_del(MemoryListener 
*listener,
                                      MemoryRegionSection *section)
 {
     VFIOContainer *container = container_of(listener, VFIOContainer,
-                                            iommu_data.type1.listener);
+                                            iommu_data.listener);
     hwaddr iova, end;
     int ret;
 
@@ -485,7 +485,7 @@ static const MemoryListener vfio_memory_listener = {
 
 static void vfio_listener_release(VFIOContainer *container)
 {
-    memory_listener_unregister(&container->iommu_data.type1.listener);
+    memory_listener_unregister(&container->iommu_data.listener);
 }
 
 int vfio_mmap_region(Object *obj, VFIORegion *region,
@@ -683,21 +683,6 @@ static int vfio_connect_container(VFIOGroup *group, 
AddressSpace *as)
             ret = -errno;
             goto free_container_exit;
         }
-
-        container->iommu_data.type1.listener = vfio_memory_listener;
-        container->iommu_data.release = vfio_listener_release;
-
-        memory_listener_register(&container->iommu_data.type1.listener,
-                                 container->space->as);
-
-        if (container->iommu_data.type1.error) {
-            ret = container->iommu_data.type1.error;
-            error_report("vfio: memory listener initialization failed for 
container");
-            goto listener_release_exit;
-        }
-
-        container->iommu_data.type1.initialized = true;
-
     } else if (ioctl(fd, VFIO_CHECK_EXTENSION, VFIO_SPAPR_TCE_IOMMU)) {
         ret = ioctl(group->fd, VFIO_GROUP_SET_CONTAINER, &fd);
         if (ret) {
@@ -723,19 +708,25 @@ static int vfio_connect_container(VFIOGroup *group, 
AddressSpace *as)
             ret = -errno;
             goto free_container_exit;
         }
-
-        container->iommu_data.type1.listener = vfio_memory_listener;
-        container->iommu_data.release = vfio_listener_release;
-
-        memory_listener_register(&container->iommu_data.type1.listener,
-                                 container->space->as);
-
     } else {
         error_report("vfio: No available IOMMU models");
         ret = -EINVAL;
         goto free_container_exit;
     }
 
+    container->iommu_data.listener = vfio_memory_listener;
+
+    memory_listener_register(&container->iommu_data.listener,
+                             container->space->as);
+
+    if (container->iommu_data.error) {
+        ret = container->iommu_data.error;
+        error_report("vfio: memory listener initialization failed for 
container");
+        goto listener_release_exit;
+    }
+
+    container->iommu_data.initialized = true;
+
     QLIST_INIT(&container->group_list);
     QLIST_INSERT_HEAD(&space->containers, container, next);
 
@@ -774,9 +765,7 @@ static void vfio_disconnect_container(VFIOGroup *group)
         VFIOAddressSpace *space = container->space;
         VFIOGuestIOMMU *giommu, *tmp;
 
-        if (container->iommu_data.release) {
-            container->iommu_data.release(container);
-        }
+        vfio_listener_release(container);
         QLIST_REMOVE(container, next);
 
         QLIST_FOREACH_SAFE(giommu, &container->giommu_list, giommu_next, tmp) {
diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
index 59a321d..aff18cd 100644
--- a/include/hw/vfio/vfio-common.h
+++ b/include/hw/vfio/vfio-common.h
@@ -64,21 +64,13 @@ typedef struct VFIOAddressSpace {
 
 struct VFIOGroup;
 
-typedef struct VFIOType1 {
-    MemoryListener listener;
-    int error;
-    bool initialized;
-} VFIOType1;
-
 typedef struct VFIOContainer {
     VFIOAddressSpace *space;
     int fd; /* /dev/vfio/vfio, empowered by the attached groups */
     struct {
-        /* enable abstraction to support various iommu backends */
-        union {
-            VFIOType1 type1;
-        };
-        void (*release)(struct VFIOContainer *);
+        MemoryListener listener;
+        int error;
+        bool initialized;
     } iommu_data;
     QLIST_HEAD(, VFIOGuestIOMMU) giommu_list;
     QLIST_HEAD(, VFIOGroup) group_list;
-- 
2.4.3