From ae19ab0cff6e59e945f017cce3f2403d4dc45164 Mon Sep 17 00:00:00 2001
From: Sebastian Sumpf <sebastian.sumpf@genode-labs.com>
Date: Wed, 10 May 2023 19:37:29 +0200
Subject: [PATCH] gpu/intel: remove vgpus from schedule before destruction

When a GPU session is destroyed, remove vgpu of session from scheduling
and as possible active vgpu. Otherwise, page faults might occur in case
already destroyed vgpu object is referenced during interrupt handling.

fixes #4881
---
 repos/os/src/drivers/gpu/intel/main.cc | 32 +++++++++++++++++++++-----
 1 file changed, 26 insertions(+), 6 deletions(-)

diff --git a/repos/os/src/drivers/gpu/intel/main.cc b/repos/os/src/drivers/gpu/intel/main.cc
index e5918bfa96..c9fce636a8 100644
--- a/repos/os/src/drivers/gpu/intel/main.cc
+++ b/repos/os/src/drivers/gpu/intel/main.cc
@@ -974,9 +974,14 @@ struct Igd::Device
 
 	Vgpu *_unschedule_current_vgpu()
 	{
+		if (_active_vgpu == nullptr) return nullptr;
+
 		Vgpu *result = nullptr;
 		_vgpu_list.dequeue([&] (Vgpu &head) {
 			result = &head; });
+
+		_active_vgpu = nullptr;
+
 		return result;
 	}
 
@@ -1382,11 +1387,19 @@ struct Igd::Device
 	 */
 	bool vgpu_active(Vgpu const &vgpu) const
 	{
-		bool result = false;
-		_vgpu_list.head([&] (Vgpu const &curr) {
-			result = (&vgpu == &curr);
-		});
-		return result;
+		return _active_vgpu == &vgpu;
+	}
+
+	/**
+	 * Remove VGPU from scheduling list, if it is enqeued
+	 */
+	void vgpu_unschedule(Vgpu &vgpu)
+	{
+		if (vgpu_active(vgpu)) _active_vgpu = nullptr;
+
+		if (vgpu.enqueued())
+			_vgpu_list.remove(vgpu);
+
 	}
 
 	/*******************
@@ -1542,7 +1555,6 @@ struct Igd::Device
 
 		if (user_complete) {
 			_unschedule_current_vgpu();
-			_active_vgpu = nullptr;
 
 			if (notify_gpu) {
 				if (!_notify_complete(notify_gpu)) {
@@ -1874,6 +1886,11 @@ class Gpu::Session_component : public Genode::Session_object<Gpu::Session>
 			return _device.vgpu_active(_vgpu);
 		}
 
+		void vgpu_unschedule()
+		{
+			return _device.vgpu_unschedule(_vgpu);
+		}
+
 		/***************************
 		 ** Gpu session interface **
 		 ***************************/
@@ -2211,6 +2228,9 @@ class Gpu::Root : public Gpu::Root_component
 				Genode::warning("vGPU active, reset device and hope for the best");
 				_device->reset();
 			}
+
+			/* remove from scheduled list */
+			s->vgpu_unschedule();
 			Genode::destroy(md_alloc(), s);
 		}