memory: Helpers to copy/free a MemoryRegionSection

In case one wants to create a permanent copy of a MemoryRegionSections,
one needs access to flatview_ref()/flatview_unref(). Instead of exposing
these, let's just add helpers to copy/free a MemoryRegionSection and
properly adjust references.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Dr. David Alan Gilbert <dgilbert@redhat.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Auger Eric <eric.auger@redhat.com>
Cc: Wei Yang <richard.weiyang@linux.alibaba.com>
Cc: teawater <teawaterz@linux.alibaba.com>
Cc: Marek Kedzierski <mkedzier@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20210413095531.25603-3-david@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>

2 files changed, 47 insertions, 0 deletions

diff --git a/include/exec/memory.h b/include/exec/memory.h
index 6574e46..27a8833 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -1067,6 +1067,26 @@ static inline bool MemoryRegionSection_eq(MemoryRegionSection *a,
 }
 
 /**
+ * memory_region_section_new_copy: Copy a memory region section
+ *
+ * Allocate memory for a new copy, copy the memory region section, and
+ * properly take a reference on all relevant members.
+ *
+ * @s: the #MemoryRegionSection to copy
+ */
+MemoryRegionSection *memory_region_section_new_copy(MemoryRegionSection *s);
+
+/**
+ * memory_region_section_new_copy: Free a copied memory region section
+ *
+ * Free a copy of a memory section created via memory_region_section_new_copy().
+ * properly dropping references on all relevant members.
+ *
+ * @s: the #MemoryRegionSection to copy
+ */
+void memory_region_section_free_copy(MemoryRegionSection *s);
+
+/**
  * memory_region_init: Initialize a memory region
  *
  * The region typically acts as a container for other memory regions.  Use
diff --git a/softmmu/memory.c b/softmmu/memory.c
index d20a9de..cea2f62 100644
--- a/softmmu/memory.c
+++ b/softmmu/memory.c
@@ -2701,6 +2701,33 @@ MemoryRegionSection memory_region_find(MemoryRegion *mr,
     return ret;
 }
 
+MemoryRegionSection *memory_region_section_new_copy(MemoryRegionSection *s)
+{
+    MemoryRegionSection *tmp = g_new(MemoryRegionSection, 1);
+
+    *tmp = *s;
+    if (tmp->mr) {
+        memory_region_ref(tmp->mr);
+    }
+    if (tmp->fv) {
+        bool ret  = flatview_ref(tmp->fv);
+
+        g_assert(ret);
+    }
+    return tmp;
+}
+
+void memory_region_section_free_copy(MemoryRegionSection *s)
+{
+    if (s->fv) {
+        flatview_unref(s->fv);
+    }
+    if (s->mr) {
+        memory_region_unref(s->mr);
+    }
+    g_free(s);
+}
+
 bool memory_region_present(MemoryRegion *container, hwaddr addr)
 {
     MemoryRegion *mr;