Fix crashes in dual core mode on a PI_FIFO_RESET

Source/Core/Core/HW/ProcessorInterface.cpp

@@ -18,6 +18,7 @@
 #include "Core/IOS/IOS.h"
 #include "Core/IOS/STM/STM.h"
 #include "Core/PowerPC/PowerPC.h"
+#include "VideoCommon/AsyncRequests.h"
 #include "VideoCommon/Fifo.h"
 
 namespace ProcessorInterface
@@ -108,7 +109,19 @@ void RegisterMMIO(MMIO::Mapping* mmio, u32 base)
                    if ((val & 1) != 0)
                    {
                      GPFifo::ResetGatherPipe();
-                     Fifo::ResetVideoBuffer();
+
+                     // Call Fifo::ResetVideoBuffer() from the video thread. Since that function
+                     // resets various pointers used by the video thread, we can't call it directly
+                     // from the CPU thread, so queue a task to do it instead. In single-core mode,
+                     // AsyncRequests is in passthrough mode, so this will be safely and immediately
+                     // called on the CPU thread.
+
+                     // NOTE: GPFifo::ResetGatherPipe() only affects
+                     // CPU state, so we can call it directly
+
+                     AsyncRequests::Event ev = {};
+                     ev.type = AsyncRequests::Event::FIFO_RESET;
+                     AsyncRequests::GetInstance()->PushEvent(ev);
                    }
                  }));
 

Source/Core/VideoCommon/AsyncRequests.cpp

@@ -158,6 +158,10 @@ void AsyncRequests::HandleEvent(const AsyncRequests::Event& e)
     *e.bbox.data = g_renderer->BBoxRead(e.bbox.index);
     break;
 
+  case Event::FIFO_RESET:
+    Fifo::ResetVideoBuffer();
+    break;
+
   case Event::PERF_QUERY:
     g_perf_query->FlushResults();
     break;

Source/Core/VideoCommon/AsyncRequests.h

@@ -27,6 +27,7 @@ public:
       EFB_PEEK_Z,
       SWAP_EVENT,
       BBOX_READ,
+      FIFO_RESET,
       PERF_QUERY,
       DO_SAVE_STATE,
     } type;
@@ -62,6 +63,10 @@ public:
         u16* data;
       } bbox;
 
+      struct
+      {
+      } fifo_reset;
+
       struct
       {
       } perf_query;