Commit ca77f27a authored by Vivek Kasireddy's avatar Vivek Kasireddy Committed by Dmitry Osipenko
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drm/virtio: Import prime buffers from other devices as guest blobs 



By importing scanout buffers from other devices, we should be able
to use the virtio-gpu driver in KMS only mode. Note that we attach
dynamically and register a move_notify() callback so that we can
let the VMM know of any location changes associated with the backing
store of the imported object by sending detach_backing cmd.

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: default avatarVivek Kasireddy <vivek.kasireddy@intel.com>
Tested-by: default avatarDmitry Osipenko <dmitry.osipenko@collabora.com>
Reviewed-by: default avatarDmitry Osipenko <dmitry.osipenko@collabora.com>
Signed-off-by: default avatarDmitry Osipenko <dmitry.osipenko@collabora.com>
[dmitry.osipenko@collabora.com: added kref check to move_notify]
Link: https://patchwork.freedesktop.org/patch/msgid/20241126031643.3490496-5-vivek.kasireddy@intel.com
parent 2885e575

drivers/gpu/drm/virtio/virtgpu_prime.c

+62 −3
Original line number Diff line number Diff line
@@ -189,14 +189,19 @@ static void virtgpu_dma_buf_free_obj(struct drm_gem_object *obj) 
	struct virtio_gpu_object *bo = gem_to_virtio_gpu_obj(obj);

	struct virtio_gpu_device *vgdev = obj->dev->dev_private;

	struct dma_buf_attachment *attach = obj->import_attach;

	struct dma_resv *resv = attach->dmabuf->resv;



	if (attach) {

		dma_resv_lock(resv, NULL);



		virtio_gpu_detach_object_fenced(bo);



		if (bo->sgt)

			dma_buf_unmap_attachment_unlocked(attach, bo->sgt,

			dma_buf_unmap_attachment(attach, bo->sgt,

						 DMA_BIDIRECTIONAL);



		dma_resv_unlock(resv);



		dma_buf_detach(attach->dmabuf, attach);

		dma_buf_put(attach->dmabuf);

	}
@@ -259,10 +264,39 @@ static int virtgpu_dma_buf_init_obj(struct drm_device *dev, 
	return ret;

}



static const struct drm_gem_object_funcs virtgpu_gem_dma_buf_funcs = {

	.free = virtgpu_dma_buf_free_obj,

};



static void virtgpu_dma_buf_move_notify(struct dma_buf_attachment *attach)

{

	struct drm_gem_object *obj = attach->importer_priv;

	struct virtio_gpu_object *bo = gem_to_virtio_gpu_obj(obj);



	if (bo->created && kref_read(&obj->refcount)) {

		virtio_gpu_detach_object_fenced(bo);



		if (bo->sgt)

			dma_buf_unmap_attachment(attach, bo->sgt,

						 DMA_BIDIRECTIONAL);



		bo->sgt = NULL;

	}

}



static const struct dma_buf_attach_ops virtgpu_dma_buf_attach_ops = {

	.allow_peer2peer = true,

	.move_notify = virtgpu_dma_buf_move_notify

};



struct drm_gem_object *virtgpu_gem_prime_import(struct drm_device *dev,

						struct dma_buf *buf)

{

	struct virtio_gpu_device *vgdev = dev->dev_private;

	struct dma_buf_attachment *attach;

	struct virtio_gpu_object *bo;

	struct drm_gem_object *obj;

	int ret;



	if (buf->ops == &virtgpu_dmabuf_ops.ops) {

		obj = buf->priv;
@@ -276,7 +310,32 @@ struct drm_gem_object *virtgpu_gem_prime_import(struct drm_device *dev, 
		}

	}



	if (!vgdev->has_resource_blob || vgdev->has_virgl_3d)

		return drm_gem_prime_import(dev, buf);



	bo = kzalloc(sizeof(*bo), GFP_KERNEL);

	if (!bo)

		return ERR_PTR(-ENOMEM);



	obj = &bo->base.base;

	obj->funcs = &virtgpu_gem_dma_buf_funcs;

	drm_gem_private_object_init(dev, obj, buf->size);



	attach = dma_buf_dynamic_attach(buf, dev->dev,

					&virtgpu_dma_buf_attach_ops, obj);

	if (IS_ERR(attach)) {

		kfree(bo);

		return ERR_CAST(attach);

	}



	obj->import_attach = attach;

	get_dma_buf(buf);



	ret = virtgpu_dma_buf_init_obj(dev, bo, attach);

	if (ret < 0)

		return ERR_PTR(ret);



	return obj;

}



struct drm_gem_object *virtgpu_gem_prime_import_sg_table(