Commit ea5ea3d8 authored by David Stevens's avatar David Stevens Committed by Gerd Hoffmann
Browse files

drm/virtio: support mapping exported vram 



Implement virtgpu specific map_dma_buf callback to support mapping
exported vram object dma-bufs. The dma-buf callback is used directly, as
vram objects don't have backing pages and thus can't implement the
drm_gem_object_funcs.get_sg_table callback.

Signed-off-by: default avatarDavid Stevens <stevensd@chromium.org>
Link: http://patchwork.freedesktop.org/patch/msgid/20210813005441.608293-1-stevensd@chromium.org


Signed-off-by: default avatarGerd Hoffmann <kraxel@redhat.com>
parent f492283b

drivers/gpu/drm/virtio/virtgpu_drv.h

+8 −0
Original line number Diff line number Diff line
@@ -26,6 +26,7 @@ 
#ifndef VIRTIO_DRV_H

#define VIRTIO_DRV_H



#include <linux/dma-direction.h>

#include <linux/virtio.h>

#include <linux/virtio_ids.h>

#include <linux/virtio_config.h>
@@ -459,4 +460,11 @@ bool virtio_gpu_is_vram(struct virtio_gpu_object *bo); 
int virtio_gpu_vram_create(struct virtio_gpu_device *vgdev,

			   struct virtio_gpu_object_params *params,

			   struct virtio_gpu_object **bo_ptr);

struct sg_table *virtio_gpu_vram_map_dma_buf(struct virtio_gpu_object *bo,

					     struct device *dev,

					     enum dma_data_direction dir);

void virtio_gpu_vram_unmap_dma_buf(struct device *dev,

				   struct sg_table *sgt,

				   enum dma_data_direction dir);



#endif

drivers/gpu/drm/virtio/virtgpu_prime.c

+30 −2
Original line number Diff line number Diff line
@@ -43,13 +43,41 @@ static int virtgpu_virtio_get_uuid(struct dma_buf *buf, 
	return 0;

}



static struct sg_table *

virtgpu_gem_map_dma_buf(struct dma_buf_attachment *attach,

			enum dma_data_direction dir)

{

	struct drm_gem_object *obj = attach->dmabuf->priv;

	struct virtio_gpu_object *bo = gem_to_virtio_gpu_obj(obj);



	if (virtio_gpu_is_vram(bo))

		return virtio_gpu_vram_map_dma_buf(bo, attach->dev, dir);



	return drm_gem_map_dma_buf(attach, dir);

}



static void virtgpu_gem_unmap_dma_buf(struct dma_buf_attachment *attach,

				      struct sg_table *sgt,

				      enum dma_data_direction dir)

{

	struct drm_gem_object *obj = attach->dmabuf->priv;

	struct virtio_gpu_object *bo = gem_to_virtio_gpu_obj(obj);



	if (virtio_gpu_is_vram(bo)) {

		virtio_gpu_vram_unmap_dma_buf(attach->dev, sgt, dir);

		return;

	}



	drm_gem_unmap_dma_buf(attach, sgt, dir);

}



static const struct virtio_dma_buf_ops virtgpu_dmabuf_ops =  {

	.ops = {

		.cache_sgt_mapping = true,

		.attach = virtio_dma_buf_attach,

		.detach = drm_gem_map_detach,

		.map_dma_buf = drm_gem_map_dma_buf,

		.unmap_dma_buf = drm_gem_unmap_dma_buf,

		.map_dma_buf = virtgpu_gem_map_dma_buf,

		.unmap_dma_buf = virtgpu_gem_unmap_dma_buf,

		.release = drm_gem_dmabuf_release,

		.mmap = drm_gem_dmabuf_mmap,

		.vmap = drm_gem_dmabuf_vmap,

drivers/gpu/drm/virtio/virtgpu_vram.c

+61 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

#include "virtgpu_drv.h"



#include <linux/dma-mapping.h>



static void virtio_gpu_vram_free(struct drm_gem_object *obj)

{

	struct virtio_gpu_object *bo = gem_to_virtio_gpu_obj(obj);
@@ -64,6 +66,65 @@ static int virtio_gpu_vram_mmap(struct drm_gem_object *obj, 
	return ret;

}



struct sg_table *virtio_gpu_vram_map_dma_buf(struct virtio_gpu_object *bo,

					     struct device *dev,

					     enum dma_data_direction dir)

{

	struct virtio_gpu_device *vgdev = bo->base.base.dev->dev_private;

	struct virtio_gpu_object_vram *vram = to_virtio_gpu_vram(bo);

	struct sg_table *sgt;

	dma_addr_t addr;

	int ret;



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

	if (!sgt)

		return ERR_PTR(-ENOMEM);



	if (!(bo->blob_flags & VIRTGPU_BLOB_FLAG_USE_MAPPABLE)) {

		// Virtio devices can access the dma-buf via its UUID. Return a stub

		// sg_table so the dma-buf API still works.

		if (!is_virtio_device(dev) || !vgdev->has_resource_assign_uuid) {

			ret = -EIO;

			goto out;

		}

		return sgt;

	}



	ret = sg_alloc_table(sgt, 1, GFP_KERNEL);

	if (ret)

		goto out;



	addr = dma_map_resource(dev, vram->vram_node.start,

				vram->vram_node.size, dir,

				DMA_ATTR_SKIP_CPU_SYNC);

	ret = dma_mapping_error(dev, addr);

	if (ret)

		goto out;



	sg_set_page(sgt->sgl, NULL, vram->vram_node.size, 0);

	sg_dma_address(sgt->sgl) = addr;

	sg_dma_len(sgt->sgl) = vram->vram_node.size;



	return sgt;

out:

	sg_free_table(sgt);

	kfree(sgt);

	return ERR_PTR(ret);

}



void virtio_gpu_vram_unmap_dma_buf(struct device *dev,

				   struct sg_table *sgt,

				   enum dma_data_direction dir)

{

	if (sgt->nents) {

		dma_unmap_resource(dev, sg_dma_address(sgt->sgl),

				   sg_dma_len(sgt->sgl), dir,

				   DMA_ATTR_SKIP_CPU_SYNC);

	}

	sg_free_table(sgt);

	kfree(sgt);

}



static const struct drm_gem_object_funcs virtio_gpu_vram_funcs = {

	.open = virtio_gpu_gem_object_open,

	.close = virtio_gpu_gem_object_close,