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drm/virtio: support mapping exported vram

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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: David Stevens <stevensd@chromium.org>
Link: http://patchwork.freedesktop.org/patch/msgid/20210813005441.608293-1-stevensd@chromium.org
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
This commit is contained in:
David Stevens
2021-08-13 09:54:41 +09:00
committed by Gerd Hoffmann
parent f492283b15
commit ea5ea3d8a1
3 changed files with 99 additions and 2 deletions
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61
drivers/gpu/drm/virtio/virtgpu_vram.c
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@@ -1,6 +1,8 @@
// 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,