[PATCH v3 4/7] drm/i915/gvt: hold reference of VFIO group during opening of vgpu

[Yan Zhao <yan.y.zhao@intel.com>]

hold reference count of the VFIO group for each vgpu at vgpu opening and
release the reference at vgpu releasing.

Signed-off-by: Yan Zhao <yan.y.zhao@intel.com>
---
 drivers/gpu/drm/i915/gvt/gvt.h   |  1 +
 drivers/gpu/drm/i915/gvt/kvmgt.c | 13 +++++++++++++
 2 files changed, 14 insertions(+)

diff --git a/drivers/gpu/drm/i915/gvt/gvt.h b/drivers/gpu/drm/i915/gvt/gvt.h
index 0081b051d3e0..5230ac80b84c 100644
--- a/drivers/gpu/drm/i915/gvt/gvt.h
+++ b/drivers/gpu/drm/i915/gvt/gvt.h
@@ -219,6 +219,7 @@ struct intel_vgpu {
 		struct work_struct release_work;
 		atomic_t released;
 		struct vfio_device *vfio_device;
+		struct vfio_group *vfio_group;
 	} vdev;
 #endif
 
diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c
index bd79a9718cc7..ed4c79cc3e09 100644
--- a/drivers/gpu/drm/i915/gvt/kvmgt.c
+++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
@@ -747,6 +747,7 @@ static int intel_vgpu_open(struct mdev_device *mdev)
 	struct intel_vgpu *vgpu = mdev_get_drvdata(mdev);
 	unsigned long events;
 	int ret;
+	struct vfio_group *vfio_group;
 
 	vgpu->vdev.iommu_notifier.notifier_call = intel_vgpu_iommu_notifier;
 	vgpu->vdev.group_notifier.notifier_call = intel_vgpu_group_notifier;
@@ -769,6 +770,14 @@ static int intel_vgpu_open(struct mdev_device *mdev)
 		goto undo_iommu;
 	}
 
+	vfio_group = vfio_group_get_external_user_from_dev(mdev_dev(mdev));
+	if (IS_ERR_OR_NULL(vfio_group)) {
+		ret = !vfio_group ? -EFAULT : PTR_ERR(vfio_group);
+		gvt_vgpu_err("vfio_group_get_external_user_from_dev failed\n");
+		goto undo_register_group;
+	}
+	vgpu->vdev.vfio_group = vfio_group;
+
 	/* Take a module reference as mdev core doesn't take
 	 * a reference for vendor driver.
 	 */
@@ -785,6 +794,9 @@ static int intel_vgpu_open(struct mdev_device *mdev)
 	return ret;
 
 undo_group:
+	vfio_group_put_external_user(vgpu->vdev.vfio_group);
+
+undo_register_group:
 	vfio_unregister_notifier(mdev_dev(mdev), VFIO_GROUP_NOTIFY,
 					&vgpu->vdev.group_notifier);
 
@@ -834,6 +846,7 @@ static void __intel_vgpu_release(struct intel_vgpu *vgpu)
 	kvmgt_guest_exit(info);
 
 	intel_vgpu_release_msi_eventfd_ctx(vgpu);
+	vfio_group_put_external_user(vgpu->vdev.vfio_group);
 
 	vgpu->vdev.kvm = NULL;
 	vgpu->handle = 0;
-- 
2.17.1