drm/virtio: Add prepare and cleanup routines for imported dmabuf obj

When an imported dmabuf obj is used as part of an atomic commit, we
need to pin it as part of prepare and unpin it during cleanup of
the associated FB, to make sure that it does not move until the
commit is completed (and also while it is being used on the Host).

Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Cc: Rob Clark <robdclark@gmail.com>
Cc: Gurchetan Singh <gurchetansingh@chromium.org>
Cc: Chia-I Wu <olvaffe@gmail.com>
Signed-off-by: Vivek Kasireddy <vivek.kasireddy@intel.com>
Tested-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Reviewed-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241126031643.3490496-6-vivek.kasireddy@intel.com

drivers/gpu/drm/virtio/virtgpu_plane.c

@@ -27,6 +27,7 @@
 #include <drm/drm_damage_helper.h>
 #include <drm/drm_fourcc.h>
 #include <drm/drm_gem_atomic_helper.h>
+#include <linux/virtio_dma_buf.h>
 
 #include "virtgpu_drv.h"
 
@@ -259,6 +260,44 @@ static void virtio_gpu_primary_plane_update(struct drm_plane *plane,
 				  rect.y2 - rect.y1);
 }
 
+static int virtio_gpu_prepare_imported_obj(struct drm_plane *plane,
+					   struct drm_plane_state *new_state,
+					   struct drm_gem_object *obj)
+{
+	struct virtio_gpu_device *vgdev = plane->dev->dev_private;
+	struct virtio_gpu_object *bo = gem_to_virtio_gpu_obj(obj);
+	struct dma_buf_attachment *attach = obj->import_attach;
+	struct dma_resv *resv = attach->dmabuf->resv;
+	struct virtio_gpu_mem_entry *ents = NULL;
+	unsigned int nents;
+	int ret;
+
+	dma_resv_lock(resv, NULL);
+
+	ret = dma_buf_pin(attach);
+	if (ret) {
+		dma_resv_unlock(resv);
+		return ret;
+	}
+
+	if (!bo->sgt) {
+		ret = virtgpu_dma_buf_import_sgt(&ents, &nents,
+						 bo, attach);
+		if (ret)
+			goto err;
+
+		virtio_gpu_object_attach(vgdev, bo, ents, nents);
+	}
+
+	dma_resv_unlock(resv);
+	return 0;
+
+err:
+	dma_buf_unpin(attach);
+	dma_resv_unlock(resv);
+	return ret;
+}
+
 static int virtio_gpu_plane_prepare_fb(struct drm_plane *plane,
 				       struct drm_plane_state *new_state)
 {
@@ -267,6 +306,8 @@ static int virtio_gpu_plane_prepare_fb(struct drm_plane *plane,
 	struct virtio_gpu_framebuffer *vgfb;
 	struct virtio_gpu_plane_state *vgplane_st;
 	struct virtio_gpu_object *bo;
+	struct drm_gem_object *obj;
+	int ret;
 
 	if (!new_state->fb)
 		return 0;
@@ -280,7 +321,14 @@ static int virtio_gpu_plane_prepare_fb(struct drm_plane *plane,
 	if (!bo || (plane->type == DRM_PLANE_TYPE_PRIMARY && !bo->guest_blob))
 		return 0;
 
-	if (bo->dumb) {
+	obj = new_state->fb->obj[0];
+	if (obj->import_attach) {
+		ret = virtio_gpu_prepare_imported_obj(plane, new_state, obj);
+		if (ret)
+			return ret;
+	}
+
+	if (bo->dumb || obj->import_attach) {
 		vgplane_st->fence = virtio_gpu_fence_alloc(vgdev,
 						     vgdev->fence_drv.context,
 						     0);
@@ -291,10 +339,21 @@ static int virtio_gpu_plane_prepare_fb(struct drm_plane *plane,
 	return 0;
 }
 
+static void virtio_gpu_cleanup_imported_obj(struct drm_gem_object *obj)
+{
+	struct dma_buf_attachment *attach = obj->import_attach;
+	struct dma_resv *resv = attach->dmabuf->resv;
+
+	dma_resv_lock(resv, NULL);
+	dma_buf_unpin(attach);
+	dma_resv_unlock(resv);
+}
+
 static void virtio_gpu_plane_cleanup_fb(struct drm_plane *plane,
 					struct drm_plane_state *state)
 {
 	struct virtio_gpu_plane_state *vgplane_st;
+	struct drm_gem_object *obj;
 
 	if (!state->fb)
 		return;
@@ -304,6 +363,10 @@ static void virtio_gpu_plane_cleanup_fb(struct drm_plane *plane,
 		dma_fence_put(&vgplane_st->fence->f);
 		vgplane_st->fence = NULL;
 	}
+
+	obj = state->fb->obj[0];
+	if (obj->import_attach)
+		virtio_gpu_cleanup_imported_obj(obj);
 }
 
 static void virtio_gpu_cursor_plane_update(struct drm_plane *plane,