drm/i915/gvt: Revert "drm/i915/gvt: Fix possible recursive locking issue"

This reverts commit 62d02fd1.

The rwsem recursive trace should not be fixed from kvmgt side by using
a workqueue and it is an issue should be fixed in VFIO. So this one
should be reverted.
Signed-off-by: Chuanxiao Dong <chuanxiao.dong@intel.com>
Cc: Zhenyu Wang <zhenyuw@linux.intel.com>
Cc: stable@vger.kernel.org # v4.10+
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>

drivers/gpu/drm/i915/gvt/gvt.h

@@ -182,9 +182,6 @@ struct intel_vgpu {
 		struct kvm *kvm;
 		struct work_struct release_work;
 		atomic_t released;
-		struct work_struct unpin_work;
-		spinlock_t unpin_lock; /* To protect unpin_list */
-		struct list_head unpin_list;
 	} vdev;
 #endif
 };

drivers/gpu/drm/i915/gvt/kvmgt.c

@@ -78,7 +78,6 @@ struct gvt_dma {
 	struct rb_node node;
 	gfn_t gfn;
 	unsigned long iova;
-	struct list_head list;
 };
 
 static inline bool handle_valid(unsigned long handle)
@@ -167,7 +166,6 @@ static void gvt_cache_add(struct intel_vgpu *vgpu, gfn_t gfn,
 
 	new->gfn = gfn;
 	new->iova = iova;
-	INIT_LIST_HEAD(&new->list);
 
 	mutex_lock(&vgpu->vdev.cache_lock);
 	while (*link) {
@@ -199,52 +197,26 @@ static void __gvt_cache_remove_entry(struct intel_vgpu *vgpu,
 	kfree(entry);
 }
 
-static void intel_vgpu_unpin_work(struct work_struct *work)
+static void gvt_cache_remove(struct intel_vgpu *vgpu, gfn_t gfn)
 {
-	struct intel_vgpu *vgpu = container_of(work, struct intel_vgpu,
-					       vdev.unpin_work);
 	struct device *dev = mdev_dev(vgpu->vdev.mdev);
 	struct gvt_dma *this;
-	unsigned long gfn;
-
-	for (;;) {
-		spin_lock(&vgpu->vdev.unpin_lock);
-		if (list_empty(&vgpu->vdev.unpin_list)) {
-			spin_unlock(&vgpu->vdev.unpin_lock);
-			break;
-		}
-		this = list_first_entry(&vgpu->vdev.unpin_list,
-					struct gvt_dma, list);
-		list_del(&this->list);
-		spin_unlock(&vgpu->vdev.unpin_lock);
-
-		gfn = this->gfn;
-		vfio_unpin_pages(dev, &gfn, 1);
-		kfree(this);
-	}
-}
-
-static bool gvt_cache_mark_remove(struct intel_vgpu *vgpu, gfn_t gfn)
-{
-	struct gvt_dma *this;
+	unsigned long g1;
+	int rc;
 
 	mutex_lock(&vgpu->vdev.cache_lock);
 	this  = __gvt_cache_find(vgpu, gfn);
 	if (!this) {
 		mutex_unlock(&vgpu->vdev.cache_lock);
-		return false;
+		return;
 	}
+
+	g1 = gfn;
 	gvt_dma_unmap_iova(vgpu, this->iova);
-	/* remove this from rb tree */
-	rb_erase(&this->node, &vgpu->vdev.cache);
+	rc = vfio_unpin_pages(dev, &g1, 1);
+	WARN_ON(rc != 1);
+	__gvt_cache_remove_entry(vgpu, this);
 	mutex_unlock(&vgpu->vdev.cache_lock);
-
-	/* put this to the unpin_list */
-	spin_lock(&vgpu->vdev.unpin_lock);
-	list_move_tail(&this->list, &vgpu->vdev.unpin_list);
-	spin_unlock(&vgpu->vdev.unpin_lock);
-
-	return true;
 }
 
 static void gvt_cache_init(struct intel_vgpu *vgpu)
@@ -485,9 +457,6 @@ static int intel_vgpu_create(struct kobject *kobj, struct mdev_device *mdev)
 	}
 
 	INIT_WORK(&vgpu->vdev.release_work, intel_vgpu_release_work);
-	INIT_WORK(&vgpu->vdev.unpin_work, intel_vgpu_unpin_work);
-	spin_lock_init(&vgpu->vdev.unpin_lock);
-	INIT_LIST_HEAD(&vgpu->vdev.unpin_list);
 
 	vgpu->vdev.mdev = mdev;
 	mdev_set_drvdata(mdev, vgpu);
@@ -517,7 +486,6 @@ static int intel_vgpu_iommu_notifier(struct notifier_block *nb,
 	struct intel_vgpu *vgpu = container_of(nb,
 					struct intel_vgpu,
 					vdev.iommu_notifier);
-	bool sched_unmap = false;
 
 	if (action == VFIO_IOMMU_NOTIFY_DMA_UNMAP) {
 		struct vfio_iommu_type1_dma_unmap *unmap = data;
@@ -527,10 +495,7 @@ static int intel_vgpu_iommu_notifier(struct notifier_block *nb,
 		end_gfn = gfn + unmap->size / PAGE_SIZE;
 
 		while (gfn < end_gfn)
-			sched_unmap |= gvt_cache_mark_remove(vgpu, gfn++);
-
-		if (sched_unmap)
-			schedule_work(&vgpu->vdev.unpin_work);
+			gvt_cache_remove(vgpu, gfn++);
 	}
 
 	return NOTIFY_OK;