tests: add unit tests for RamDiscardManager multi-source aggregation

Add various unit tests for the RamDiscardManager multi-source
aggregation functionality.

The test uses a TestRamDiscardSource QOM object that tracks populated
state via a bitmap, similar to RamBlockAttributes implementation.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Link: https://lore.kernel.org/r/20260604-rdm5-v5-10-5768e6a0943d@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>

MAINTAINERS

@@ -3363,6 +3363,8 @@ F: system/memory-internal.h
 F: system/ram-block-attributes.c
 F: system/ram-discard-manager.c
 F: scripts/coccinelle/memory-region-housekeeping.cocci
+F: tests/unit/test-ram-discard-manager.c
+F: tests/unit/test-ram-discard-manager-stubs.c
 
 Memory devices
 M: David Hildenbrand <david@kernel.org>

tests/unit/meson.build

@@ -138,7 +138,13 @@ if have_system
     'test-bufferiszero': [],
     'test-smp-parse': [qom, meson.project_source_root() / 'hw/core/machine-smp.c'],
     'test-vmstate': [migration, io],
-    'test-yank': ['socket-helpers.c', qom, io, chardev]
+    'test-yank': ['socket-helpers.c', qom, io, chardev],
+    'test-ram-discard-manager': [
+      'test-ram-discard-manager.c',
+      'test-ram-discard-manager-stubs.c',
+      meson.project_source_root() / 'system/ram-discard-manager.c',
+      genh, qemuutil, qom
+    ],
   }
   if config_host_data.get('CONFIG_INOTIFY1')
     tests += {'test-util-filemonitor': []}

tests/unit/test-ram-discard-manager-stubs.c

@@ -0,0 +1,48 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#include "qemu/osdep.h"
+#include "qom/object.h"
+#include "glib.h"
+#include "system/memory.h"
+
+RamDiscardManager *memory_region_get_ram_discard_manager(MemoryRegion *mr)
+{
+    return mr->rdm;
+}
+
+int memory_region_add_ram_discard_source(MemoryRegion *mr,
+                                         RamDiscardSource *source)
+{
+    if (!mr->rdm) {
+        mr->rdm = ram_discard_manager_new(mr);
+    }
+    return ram_discard_manager_add_source(mr->rdm, source);
+}
+
+int memory_region_del_ram_discard_source(MemoryRegion *mr,
+                                         RamDiscardSource *source)
+{
+    RamDiscardManager *rdm = mr->rdm;
+
+    if (!rdm) {
+        return 0;
+    }
+
+    return ram_discard_manager_del_source(rdm, source);
+}
+
+uint64_t memory_region_size(const MemoryRegion *mr)
+{
+    return int128_get64(mr->size);
+}
+
+MemoryRegionSection *memory_region_section_new_copy(MemoryRegionSection *s)
+{
+    MemoryRegionSection *copy = g_new(MemoryRegionSection, 1);
+    *copy = *s;
+    return copy;
+}
+
+void memory_region_section_free_copy(MemoryRegionSection *s)
+{
+    g_free(s);
+}