[Qemu-devel] [PATCH memory v1 1/1] memory: remove may_overlap property

[Peter Crosthwaite]

In a5e1cbc80e88ed7d73b3fcb46053a3ba167293fc the enforcement of Memory
collisions was disabled. This means that the MemoryRegion map_overlap
state is unused. Remove it completely.

The commit mentions that it should be fixed, but we have been living
happily-every-after since removal of the check so it's probably
unneeded complication.

If we were to repair this, a simpler and more effective check would be
to only assert collisions between same-priority regions. The fact that
colliding memory regions may-overlap is then left as implicit by the
fact that they have different priorities.

Signed-off-by: Peter Crosthwaite <address@hidden>
---

 include/exec/memory.h |  1 -
 memory.c              | 35 -----------------------------------
 2 files changed, 36 deletions(-)

diff --git a/include/exec/memory.h b/include/exec/memory.h
index e2c8e3e..a8e9707 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -158,7 +158,6 @@ struct MemoryRegion {
     MemoryRegion *alias;
     hwaddr alias_offset;
     int32_t priority;
-    bool may_overlap;
     QTAILQ_HEAD(subregions, MemoryRegion) subregions;
     QTAILQ_ENTRY(MemoryRegion) subregions_link;
     QTAILQ_HEAD(coalesced_ranges, CoalescedMemoryRange) coalesced;
diff --git a/memory.c b/memory.c
index 64d7176..be4cf76 100644
--- a/memory.c
+++ b/memory.c
@@ -964,13 +964,6 @@ static void memory_region_get_priority(Object *obj, 
Visitor *v, void *opaque,
     visit_type_int32(v, &value, name, errp);
 }
 
-static bool memory_region_get_may_overlap(Object *obj, Error **errp)
-{
-    MemoryRegion *mr = MEMORY_REGION(obj);
-
-    return mr->may_overlap;
-}
-
 static void memory_region_get_size(Object *obj, Visitor *v, void *opaque,
                                    const char *name, Error **errp)
 {
@@ -1007,10 +1000,6 @@ static void memory_region_initfn(Object *obj)
                         memory_region_get_priority,
                         NULL, /* memory_region_set_priority */
                         NULL, NULL, &error_abort);
-    object_property_add_bool(OBJECT(mr), "may-overlap",
-                             memory_region_get_may_overlap,
-                             NULL, /* memory_region_set_may_overlap */
-                             &error_abort);
     object_property_add(OBJECT(mr), "size", "uint64",
                         memory_region_get_size,
                         NULL, /* memory_region_set_size, */
@@ -1623,7 +1612,6 @@ void memory_region_del_eventfd(MemoryRegion *mr,
 
 static void memory_region_update_container_subregions(MemoryRegion *subregion)
 {
-    hwaddr offset = subregion->addr;
     MemoryRegion *mr = subregion->container;
     MemoryRegion *other;
 
@@ -1631,27 +1619,6 @@ static void 
memory_region_update_container_subregions(MemoryRegion *subregion)
 
     memory_region_ref(subregion);
     QTAILQ_FOREACH(other, &mr->subregions, subregions_link) {
-        if (subregion->may_overlap || other->may_overlap) {
-            continue;
-        }
-        if (int128_ge(int128_make64(offset),
-                      int128_add(int128_make64(other->addr), other->size))
-            || int128_le(int128_add(int128_make64(offset), subregion->size),
-                         int128_make64(other->addr))) {
-            continue;
-        }
-#if 0
-        printf("warning: subregion collision %llx/%llx (%s) "
-               "vs %llx/%llx (%s)\n",
-               (unsigned long long)offset,
-               (unsigned long long)int128_get64(subregion->size),
-               subregion->name,
-               (unsigned long long)other->addr,
-               (unsigned long long)int128_get64(other->size),
-               other->name);
-#endif
-    }
-    QTAILQ_FOREACH(other, &mr->subregions, subregions_link) {
         if (subregion->priority >= other->priority) {
             QTAILQ_INSERT_BEFORE(other, subregion, subregions_link);
             goto done;
@@ -1677,7 +1644,6 @@ void memory_region_add_subregion(MemoryRegion *mr,
                                  hwaddr offset,
                                  MemoryRegion *subregion)
 {
-    subregion->may_overlap = false;
     subregion->priority = 0;
     memory_region_add_subregion_common(mr, offset, subregion);
 }
@@ -1687,7 +1653,6 @@ void memory_region_add_subregion_overlap(MemoryRegion *mr,
                                          MemoryRegion *subregion,
                                          int priority)
 {
-    subregion->may_overlap = true;
     subregion->priority = priority;
     memory_region_add_subregion_common(mr, offset, subregion);
 }
-- 
2.0.1.1.gfbfc394