The Documentation/DMA-API-HOWTO.txt states that dma_map_sg returns the numer of the created entries in the DMA address space. However the subsequent calls to dma_sync_sg_for_{device,cpu} and dma_unmap_sg must be called with the original number of entries passed to dma_map_sg. The sg_table->nents in turn holds the result of the dma_map_sg call as stated in include/linux/scatterlist.h. Adapt the code to obey those rules.
Signed-off-by: Marek Szyprowski m.szyprowski@samsung.com --- For more information, see '[PATCH v2 00/21] DRM: fix struct sg_table nents vs. orig_nents misuse' thread: https://lkml.org/lkml/2020/5/4/373 --- drivers/gpu/drm/virtio/virtgpu_object.c | 11 ++++++----- drivers/gpu/drm/virtio/virtgpu_vq.c | 8 ++++---- 2 files changed, 10 insertions(+), 9 deletions(-)
diff --git a/drivers/gpu/drm/virtio/virtgpu_object.c b/drivers/gpu/drm/virtio/virtgpu_object.c index 6ccbd01..12f6bee 100644 --- a/drivers/gpu/drm/virtio/virtgpu_object.c +++ b/drivers/gpu/drm/virtio/virtgpu_object.c @@ -73,7 +73,8 @@ void virtio_gpu_cleanup_object(struct virtio_gpu_object *bo) if (shmem->pages) { if (shmem->mapped) { dma_unmap_sg(vgdev->vdev->dev.parent, - shmem->pages->sgl, shmem->mapped, + shmem->pages->sgl, + shmem->pages->orig_nents, DMA_TO_DEVICE); shmem->mapped = 0; } @@ -157,13 +158,13 @@ static int virtio_gpu_object_shmem_init(struct virtio_gpu_device *vgdev, }
if (use_dma_api) { - shmem->mapped = dma_map_sg(vgdev->vdev->dev.parent, + shmem->pages->nents = dma_map_sg(vgdev->vdev->dev.parent, shmem->pages->sgl, - shmem->pages->nents, + shmem->pages->orig_nents, DMA_TO_DEVICE); - *nents = shmem->mapped; + *nents = shmem->mapped = shmem->pages->nents; } else { - *nents = shmem->pages->nents; + *nents = shmem->pages->orig_nents; }
*ents = kmalloc_array(*nents, sizeof(struct virtio_gpu_mem_entry), diff --git a/drivers/gpu/drm/virtio/virtgpu_vq.c b/drivers/gpu/drm/virtio/virtgpu_vq.c index 9e663a5..661325b 100644 --- a/drivers/gpu/drm/virtio/virtgpu_vq.c +++ b/drivers/gpu/drm/virtio/virtgpu_vq.c @@ -604,8 +604,8 @@ void virtio_gpu_cmd_transfer_to_host_2d(struct virtio_gpu_device *vgdev,
if (use_dma_api) dma_sync_sg_for_device(vgdev->vdev->dev.parent, - shmem->pages->sgl, shmem->pages->nents, - DMA_TO_DEVICE); + shmem->pages->sgl, + shmem->pages->orig_nents, DMA_TO_DEVICE);
cmd_p = virtio_gpu_alloc_cmd(vgdev, &vbuf, sizeof(*cmd_p)); memset(cmd_p, 0, sizeof(*cmd_p)); @@ -1020,8 +1020,8 @@ void virtio_gpu_cmd_transfer_to_host_3d(struct virtio_gpu_device *vgdev,
if (use_dma_api) dma_sync_sg_for_device(vgdev->vdev->dev.parent, - shmem->pages->sgl, shmem->pages->nents, - DMA_TO_DEVICE); + shmem->pages->sgl, + shmem->pages->orig_nents, DMA_TO_DEVICE);
cmd_p = virtio_gpu_alloc_cmd(vgdev, &vbuf, sizeof(*cmd_p)); memset(cmd_p, 0, sizeof(*cmd_p));