memory: add ref/unref calls

Add ref/unref calls at the following places:

- places where memory regions are stashed by a listener and
  used outside the BQL (including in Xen or KVM).

- memory_region_find callsites

- creation of aliases and containers (only the aliased/contained
  region gets a reference to avoid loops)

- around calls to del_subregion/add_subregion, where the region
  could disappear after the first call

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

1 files changed, 6 insertions, 0 deletions

diff --git a/hw/display/exynos4210_fimd.c b/hw/display/exynos4210_fimd.c
index d9088d9594..b520f524f7 100644
--- a/hw/display/exynos4210_fimd.c
+++ b/hw/display/exynos4210_fimd.c
@@ -1126,6 +1126,11 @@ static void fimd_update_memory_section(Exynos4210fimdState *s, unsigned win)
     /* Total number of bytes of virtual screen used by current window */
     w->fb_len = fb_mapped_len = (w->virtpage_width + w->virtpage_offsize) *
             (w->rightbot_y - w->lefttop_y + 1);
+
+    /* TODO: add .exit and unref the region there.  Not needed yet since sysbus
+     * does not support hot-unplug.
+     */
+    memory_region_unref(w->mem_section.mr);
     w->mem_section = memory_region_find(sysbus_address_space(&s->busdev),
             fb_start_addr, w->fb_len);
     assert(w->mem_section.mr);
@@ -1154,6 +1159,7 @@ static void fimd_update_memory_section(Exynos4210fimdState *s, unsigned win)
     return;
 
 error_return:
+    memory_region_unref(w->mem_section.mr);
     w->mem_section.mr = NULL;
     w->mem_section.size = int128_zero();
     w->host_fb_addr = NULL;