exec: reintroduce MemoryRegion caching

MemoryRegionCache was reverted to "normal" address_space_* operations
for 2.9, due to lack of support for IOMMUs.  Reinstate the
optimizations, caching only the IOMMU translation at address_cache_init
but not the IOMMU lookup and target AddressSpace translation are not
cached; now that MemoryRegionCache supports IOMMUs, it becomes more widely
applicable too.

The inlined fast path is defined in memory_ldst_cached.inc.h, while the
slow path uses memory_ldst.inc.c as before.  The smaller fast path causes
a little code size reduction in MemoryRegionCache users:

    hw/virtio/virtio.o text size before: 32373
    hw/virtio/virtio.o text size after: 31941

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/memory.c b/memory.c
index e70b64b..fc7f9b7 100644
--- a/memory.c
+++ b/memory.c
@@ -298,7 +298,7 @@ static bool flatview_ref(FlatView *view)
     return atomic_fetch_inc_nonzero(&view->ref) > 0;
 }
 
-static void flatview_unref(FlatView *view)
+void flatview_unref(FlatView *view)
 {
     if (atomic_fetch_dec(&view->ref) == 1) {
         trace_flatview_destroy_rcu(view, view->root);
@@ -822,7 +822,7 @@ static void address_space_add_del_ioeventfds(AddressSpace *as,
     }
 }
 
-static FlatView *address_space_get_flatview(AddressSpace *as)
+FlatView *address_space_get_flatview(AddressSpace *as)
 {
     FlatView *view;