drm/virtio: Ensure framebuffers for dGPU residing in local memory

Leverage shared field in dmabuf attachment to obtained information about
the imported buffers. In atomic check, we must return an error when the
user space is trying to present a framebuffer in system memory on dGPU
backing display.

Tracked-On: OAM-129610
Signed-off-by: Weifeng Liu <weifeng.liu@intel.com>

drivers/gpu/drm/virtio/virtgpu_object.c

@@ -23,6 +23,7 @@
  * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  */
 
+#include <linux/dma-buf.h>
 #include <linux/dma-mapping.h>
 #include <linux/moduleparam.h>
 
@@ -114,8 +115,11 @@ void virtio_gpu_cleanup_object(struct virtio_gpu_object *bo)
 		kfree(vram);
 	}
 
-	if (bo->prime)
+	if (bo->prime) {
 		kfree(bo->ents);
+		if (bo->base.base.import_attach->shared)
+			kfree(bo->base.base.import_attach->shared);
+	}
 
 	virtio_gpu_object_del_restore_list(vgdev, bo);
 }

drivers/gpu/drm/virtio/virtgpu_plane.c

@@ -23,6 +23,8 @@
  * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  */
 
+#include <linux/dma-buf.h>
+
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_damage_helper.h>
 #include <drm/drm_fourcc.h>
@@ -244,6 +246,7 @@ static int virtio_gpu_plane_atomic_check(struct drm_plane *plane,
 										 plane);
 	struct drm_device *dev = plane->dev;
 	struct virtio_gpu_device *vgdev = dev->dev_private;
+	struct virtio_gpu_dmabuf_attach_shared *shared = NULL;
 	bool is_cursor = 1;
 	struct virtio_gpu_output *output = NULL;
 	output = drm_crtc_to_virtio_gpu_output(new_plane_state->crtc);
@@ -264,6 +267,42 @@ static int virtio_gpu_plane_atomic_check(struct drm_plane *plane,
 	if (IS_ERR(crtc_state))
                 return PTR_ERR(crtc_state);
 
+	/* Ensure lmem objects from i915_ag are attached to dGPU backing CRTC */
+	if (vgdev->output_cap_mask & (1lu << drm_crtc_index(new_plane_state->crtc))) {
+		for (int i = 0; i < DRM_FORMAT_MAX_PLANES; ++i) {
+			struct drm_gem_object *obj = new_plane_state->fb->obj[i];
+			if (!obj)
+				break;
+
+			if (!obj->import_attach)
+				return -EINVAL;
+
+			if (obj->import_attach->dmabuf->exporter_type_id
+			    != DMA_BUF_DRIVER_TYPE_ID_I915_BACKPORTS) {
+				drm_dbg(vgdev->ddev, "cannot use non-i915_ag "
+					"buffer for crtc %u, driver name %s\n",
+					drm_crtc_index(new_plane_state->crtc),
+					obj->dev->driver->name);
+				return -EINVAL;
+			}
+
+			shared = obj->import_attach->shared;
+			if (!shared) {
+				drm_dbg(vgdev->ddev, "unsupported i915_ag dmabuf attachment\n");
+				return -EINVAL;
+			}
+			if (shared->version != VIRTIO_GPU_DMABUF_ATTACH_SHARED_CURRENT_VERSION) {
+				drm_dbg(vgdev->ddev, "unsupported i915_ag dmabuf attachment "
+					"version %u\n", shared->version);
+				return -EINVAL;
+			}
+			if (!(shared->shared.v1.flags & VIRTIO_GPU_DMABUF_ATTACH_SHARED_FLAG_LMEM)) {
+				drm_dbg(vgdev->ddev, "not local memory from i915_ag\n");
+				return -EINVAL;
+			}
+		}
+	}
+
 	if(vgdev->has_scaling && (new_plane_state->fb->format->format != DRM_FORMAT_C8)) {
 		min_scale = 1;
 		max_scale = 0x30000-1;

drivers/gpu/drm/virtio/virtgpu_prime.c

@@ -150,6 +150,7 @@ struct drm_gem_object *virtgpu_gem_prime_import(struct drm_device *dev,
 	struct sg_table *sgt;
 	struct device *attach_dev = dev->dev;
 	struct virtio_gpu_device *vgdev = dev->dev_private;
+	struct virtio_gpu_dmabuf_attach_shared *shared = NULL;
 	int ret;
 	bool p2p = false;
 
@@ -180,10 +181,19 @@ struct drm_gem_object *virtgpu_gem_prime_import(struct drm_device *dev,
 	}
 	spin_unlock(&dma_buf->name_lock);
 
-	attach = ____dma_buf_dynamic_attach(dma_buf, attach_dev, NULL, NULL,
-					    p2p);
-	if (IS_ERR(attach))
-		return ERR_CAST(attach);
+	if (dma_buf->exporter_type_id == DMA_BUF_DRIVER_TYPE_ID_I915_BACKPORTS) {
+		shared = kmalloc(sizeof(*shared), GFP_KERNEL);
+		if (!shared)
+			return ERR_PTR(-ENOMEM);
+	}
+
+	attach = ____dma_buf_dynamic_attach(dma_buf, attach_dev,
+					    DMA_BUF_DRIVER_TYPE_ID_VIRTIO_GPU,
+					    shared, NULL, NULL, p2p);
+	if (IS_ERR(attach)) {
+		ret = PTR_ERR(attach);
+		goto fail_shared;
+	}
 
 	get_dma_buf(dma_buf);
 
@@ -210,6 +220,10 @@ struct drm_gem_object *virtgpu_gem_prime_import(struct drm_device *dev,
 	dma_buf_detach(dma_buf, attach);
 	dma_buf_put(dma_buf);
 
+fail_shared:
+	if (shared)
+		kfree(shared);
+
 	return ERR_PTR(ret);
 }