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 --- drivers/gpu/drm/virtio/virtgpu_drv.h | 8 ++++ drivers/gpu/drm/virtio/virtgpu_prime.c | 30 ++++++++++++- drivers/gpu/drm/virtio/virtgpu_vram.c | 61 ++++++++++++++++++++++++++ 3 files changed, 97 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.h b/drivers/gpu/drm/virtio/virtgpu_drv.h index d4e610a44e12..0c4810982530 100644 --- a/drivers/gpu/drm/virtio/virtgpu_drv.h +++ b/drivers/gpu/drm/virtio/virtgpu_drv.h @@ -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 diff --git a/drivers/gpu/drm/virtio/virtgpu_prime.c b/drivers/gpu/drm/virtio/virtgpu_prime.c index 807a27a16365..79efc878f508 100644 --- a/drivers/gpu/drm/virtio/virtgpu_prime.c +++ b/drivers/gpu/drm/virtio/virtgpu_prime.c @@ -43,13 +43,39 @@ 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); + else + 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, diff --git a/drivers/gpu/drm/virtio/virtgpu_vram.c b/drivers/gpu/drm/virtio/virtgpu_vram.c index 5cc34e7330fa..6b45b0429fef 100644 --- a/drivers/gpu/drm/virtio/virtgpu_vram.c +++ b/drivers/gpu/drm/virtio/virtgpu_vram.c @@ -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,