From 4c1d93a322ce2f1567de29a86ebab4d787dca35b Mon Sep 17 00:00:00 2001
From: Stenzek <stenzek@gmail.com>
Date: Wed, 25 Jan 2023 22:02:19 +1000
Subject: [PATCH] VMManager: Defer reset when running

Stops us resetting during the event test, which can leave things in a
pretty messed up state.
---
 pcsx2-qt/QtHost.cpp |  4 ++++
 pcsx2/VMManager.cpp | 19 ++++++++++++++++++-
 pcsx2/VMManager.h   |  1 +
 3 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/pcsx2-qt/QtHost.cpp b/pcsx2-qt/QtHost.cpp
index abdbb94c44..d7169a5550 100644
--- a/pcsx2-qt/QtHost.cpp
+++ b/pcsx2-qt/QtHost.cpp
@@ -429,6 +429,10 @@ void EmuThread::executeVM()
 				VMManager::Execute();
 				continue;
 
+			case VMState::Resetting:
+				VMManager::Reset();
+				continue;
+
 			case VMState::Stopping:
 				destroyVM();
 				m_event_loop->processEvents(QEventLoop::AllEvents);
diff --git a/pcsx2/VMManager.cpp b/pcsx2/VMManager.cpp
index 5f7e49b0a5..e587e521c9 100644
--- a/pcsx2/VMManager.cpp
+++ b/pcsx2/VMManager.cpp
@@ -214,7 +214,7 @@ void VMManager::SetState(VMState state)
 bool VMManager::HasValidVM()
 {
 	const VMState state = s_state.load(std::memory_order_acquire);
-	return (state == VMState::Running || state == VMState::Paused);
+	return (state >= VMState::Running && state <= VMState::Resetting);
 }
 
 std::string VMManager::GetDiscPath()
@@ -1161,6 +1161,19 @@ void VMManager::Shutdown(bool save_resume_state)
 
 void VMManager::Reset()
 {
+	pxAssert(HasValidVM());
+
+	// If we're running, we're probably going to be executing this at event test time,
+	// at vsync, which happens in the middle of event handling. Resetting everything
+	// immediately here is a bad idea (tm), in fact, it breaks some games (e.g. TC:NYC).
+	// So, instead, we tell the rec to exit execution, _then_ reset. Paused is fine here,
+	// since the rec won't be running, so it's safe to immediately reset there.
+	if (s_state.load(std::memory_order_acquire) == VMState::Running)
+	{
+		s_state.store(VMState::Resetting, std::memory_order_release);
+		return;
+	}
+
 #ifdef ENABLE_ACHIEVEMENTS
 	if (!Achievements::OnReset())
 		return;
@@ -1187,6 +1200,10 @@ void VMManager::Reset()
 		g_InputRecording.handleReset();
 		GetMTGS().PresentCurrentFrame();
 	}
+
+	// If we were paused, state won't be resetting, so don't flip back to running.
+	if (s_state.load(std::memory_order_acquire) == VMState::Resetting)
+		s_state.store(VMState::Running, std::memory_order_release);
 }
 
 std::string VMManager::GetSaveStateFileName(const char* game_serial, u32 game_crc, s32 slot)
diff --git a/pcsx2/VMManager.h b/pcsx2/VMManager.h
index 0b9d927ce7..61cb920040 100644
--- a/pcsx2/VMManager.h
+++ b/pcsx2/VMManager.h
@@ -35,6 +35,7 @@ enum class VMState
 	Initializing,
 	Running,
 	Paused,
+	Resetting,
 	Stopping,
 };