From dda2e71bd0134b226709fe59c2ebe62337a62b60 Mon Sep 17 00:00:00 2001
From: IndecisiveTurtle <47210458+raphaelthegreat@users.noreply.github.com>
Date: Sun, 23 Mar 2025 01:53:43 +0200
Subject: [PATCH] buffer_cache: Fix CopyBuffers bug

---
 src/video_core/buffer_cache/buffer_cache.cpp | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/video_core/buffer_cache/buffer_cache.cpp b/src/video_core/buffer_cache/buffer_cache.cpp
index a53b8004b..69a6363b7 100644
--- a/src/video_core/buffer_cache/buffer_cache.cpp
+++ b/src/video_core/buffer_cache/buffer_cache.cpp
@@ -288,13 +288,17 @@ void BufferCache::CopyBuffer(VAddr dst, VAddr src, u32 num_bytes, bool dst_gds,
         if (src_gds) {
             return gds_buffer;
         }
-        const auto [buffer, offset] = ObtainBuffer(src, num_bytes, false);
-        return *buffer;
+        // Avoid using ObtainBuffer here as that might give us the stream buffer.
+        const BufferId buffer_id = FindBuffer(src, num_bytes);
+        auto& buffer = slot_buffers[buffer_id];
+        SynchronizeBuffer(buffer, src, num_bytes, false);
+        return buffer;
     }();
     auto& dst_buffer = [&] -> const Buffer& {
         if (dst_gds) {
             return gds_buffer;
         }
+        // Prefer using ObtainBuffer here as that will auto-mark the region as GPU modified.
         const auto [buffer, offset] = ObtainBuffer(dst, num_bytes, true);
         return *buffer;
     }();