drm/i915/gvt: switch to user vfio_group_pin/upin_pages

substitute vfio_pin_pages() and vfio_unpin_pages() with
vfio_group_pin_pages() and vfio_group_unpin_pages(), so that
it will not go through looking up, checking, referencing,
dereferencing of VFIO group in each call.
Signed-off-by: Yan Zhao <yan.y.zhao@intel.com>
Reviewed-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20200313031151.8042-1-yan.y.zhao@intel.com

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

@@ -152,6 +152,7 @@ static void gvt_unpin_guest_page(struct intel_vgpu *vgpu, unsigned long gfn,
 		unsigned long size)
 {
 	struct drm_i915_private *i915 = vgpu->gvt->gt->i915;
+	struct kvmgt_vdev *vdev = kvmgt_vdev(vgpu);
 	int total_pages;
 	int npage;
 	int ret;
@@ -161,7 +162,7 @@ static void gvt_unpin_guest_page(struct intel_vgpu *vgpu, unsigned long gfn,
 	for (npage = 0; npage < total_pages; npage++) {
 		unsigned long cur_gfn = gfn + npage;
 
-		ret = vfio_unpin_pages(mdev_dev(kvmgt_vdev(vgpu)->mdev), &cur_gfn, 1);
+		ret = vfio_group_unpin_pages(vdev->vfio_group, &cur_gfn, 1);
 		drm_WARN_ON(&i915->drm, ret != 1);
 	}
 }
@@ -170,6 +171,7 @@ static void gvt_unpin_guest_page(struct intel_vgpu *vgpu, unsigned long gfn,
 static int gvt_pin_guest_page(struct intel_vgpu *vgpu, unsigned long gfn,
 		unsigned long size, struct page **page)
 {
+	struct kvmgt_vdev *vdev = kvmgt_vdev(vgpu);
 	unsigned long base_pfn = 0;
 	int total_pages;
 	int npage;
@@ -184,7 +186,7 @@ static int gvt_pin_guest_page(struct intel_vgpu *vgpu, unsigned long gfn,
 		unsigned long cur_gfn = gfn + npage;
 		unsigned long pfn;
 
-		ret = vfio_pin_pages(mdev_dev(kvmgt_vdev(vgpu)->mdev), &cur_gfn, 1,
+		ret = vfio_group_pin_pages(vdev->vfio_group, &cur_gfn, 1,
 					   IOMMU_READ | IOMMU_WRITE, &pfn);
 		if (ret != 1) {
 			gvt_vgpu_err("vfio_pin_pages failed for gfn 0x%lx, ret %d\n",