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

This reverts commit 62d02fd1f807bf5a259a242c483c9fb98a242630.

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>

2 files changed, 10 insertions, 48 deletions

diff --git a/drivers/gpu/drm/i915/gvt/gvt.h b/drivers/gpu/drm/i915/gvt/gvt.h
index 28d817e96e58..3a74e79eac2f 100644
--- a/drivers/gpu/drm/i915/gvt/gvt.h
+++ b/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
 };
diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c
index 75a6e1d8af0d..fd0c85f9ef3c 100644
--- a/drivers/gpu/drm/i915/gvt/kvmgt.c
+++ b/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;