diff options
Diffstat (limited to 'drivers/virtio')
| -rw-r--r-- | drivers/virtio/virtio_ring.c | 53 |
1 files changed, 53 insertions, 0 deletions
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index 87d7ceeecdbd..8e81b01e0735 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -172,6 +172,9 @@ struct vring_virtqueue { /* Host publishes avail event idx */ bool event; + /* Do DMA mapping by driver */ + bool premapped; + /* Head of free buffer list. */ unsigned int free_head; /* Number we've added since last sync. */ @@ -2061,6 +2064,7 @@ static struct virtqueue *vring_create_virtqueue_packed( vq->packed_ring = true; vq->dma_dev = dma_dev; vq->use_dma_api = vring_use_dma_api(vdev); + vq->premapped = false; vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC) && !context; @@ -2550,6 +2554,7 @@ static struct virtqueue *__vring_new_virtqueue(unsigned int index, #endif vq->dma_dev = dma_dev; vq->use_dma_api = vring_use_dma_api(vdev); + vq->premapped = false; vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC) && !context; @@ -2693,6 +2698,54 @@ int virtqueue_resize(struct virtqueue *_vq, u32 num, } EXPORT_SYMBOL_GPL(virtqueue_resize); +/** + * virtqueue_set_dma_premapped - set the vring premapped mode + * @_vq: the struct virtqueue we're talking about. + * + * Enable the premapped mode of the vq. + * + * The vring in premapped mode does not do dma internally, so the driver must + * do dma mapping in advance. The driver must pass the dma_address through + * dma_address of scatterlist. When the driver got a used buffer from + * the vring, it has to unmap the dma address. + * + * This function must be called immediately after creating the vq, or after vq + * reset, and before adding any buffers to it. + * + * Caller must ensure we don't call this with other virtqueue operations + * at the same time (except where noted). + * + * Returns zero or a negative error. + * 0: success. + * -EINVAL: vring does not use the dma api, so we can not enable premapped mode. + */ +int virtqueue_set_dma_premapped(struct virtqueue *_vq) +{ + struct vring_virtqueue *vq = to_vvq(_vq); + u32 num; + + START_USE(vq); + + num = vq->packed_ring ? vq->packed.vring.num : vq->split.vring.num; + + if (num != vq->vq.num_free) { + END_USE(vq); + return -EINVAL; + } + + if (!vq->use_dma_api) { + END_USE(vq); + return -EINVAL; + } + + vq->premapped = true; + + END_USE(vq); + + return 0; +} +EXPORT_SYMBOL_GPL(virtqueue_set_dma_premapped); + /* Only available for split ring */ struct virtqueue *vring_new_virtqueue(unsigned int index, unsigned int num, |