nx2: unmap GPU memory the game frees

nx2:gpu 213 (NormalUnmapGpuMemory4K) and 102 (destroy GPU-accessible
memory) were no-ops, so Eden kept freed memory mapped for the GPU. Title 4
frees its customization-room memory right after saving and reuses it as
ordinary heap; pending GPU->CPU write-backs for the old buffers then landed on
the new objects, and two threads crashed on garbage pointers ~5 s later
(the post-customization freeze).

Unmap the range from every address space (the GMMU unmap drops cached
buffers/images and their pending downloads), keep the registry's mapping
list in step, re-map 211 requests even at the memory's own address, and
drop freed regions from the semaphore mirror table, which every 8 KiB
allocation used to fill for good after 32 entries.

1 files changed, 15 insertions, 2 deletions

diff --git a/src/video_core/nx2.h b/src/video_core/nx2.h
index ef6619df3f..7bbbf14785 100644
--- a/src/video_core/nx2.h
+++ b/src/video_core/nx2.h
@@ -23,19 +23,32 @@ inline std::array<std::atomic<u64>, Nx2MaxSemaphoreRegions> g_nx2_semaphore_regi
 
 inline void Nx2AddSemaphoreRegion(u64 start) {
     for (auto& region : g_nx2_semaphore_regions) {
+        if (region.load() == start) {
+            return;
+        }
+    }
+    for (auto& region : g_nx2_semaphore_regions) {
         u64 expected = 0;
-        if (region.load() == start || region.compare_exchange_strong(expected, start)) {
+        if (region.compare_exchange_strong(expected, start)) {
             return;
         }
     }
 }
 
+/// The region's memory was destroyed: stop mirroring into it.
+inline void Nx2RemoveSemaphoreRegion(u64 start) {
+    for (auto& region : g_nx2_semaphore_regions) {
+        u64 expected = start;
+        region.compare_exchange_strong(expected, 0);
+    }
+}
+
 /// GPU VA in the first page that mirrors a release at `address`, or 0.
 inline u64 Nx2SemaphoreMirror(u64 address) {
     for (const auto& region : g_nx2_semaphore_regions) {
         const u64 start = region.load(std::memory_order_relaxed);
         if (start == 0) {
-            break;
+            continue;
         }
         if (address >= start + 0x1000 && address < start + 0x2000) {
             return address - 0x1000;