From e6d6dd6c875eb3c9b69bb640419405726e6e0bbe Mon Sep 17 00:00:00 2001 From: Joerg Roedel Date: Thu, 7 Feb 2019 12:59:16 +0100 Subject: virtio: Introduce virtio_max_dma_size() This function returns the maximum segment size for a single dma transaction of a virtio device. The possible limit comes from the SWIOTLB implementation in the Linux kernel, that has an upper limit of (currently) 256kb of contiguous memory it can map. Other DMA-API implementations might also have limits. Use the new dma_max_mapping_size() function to determine the maximum mapping size when DMA-API is in use for virtio. Cc: stable@vger.kernel.org Reviewed-by: Konrad Rzeszutek Wilk Reviewed-by: Christoph Hellwig Signed-off-by: Joerg Roedel Signed-off-by: Michael S. Tsirkin --- drivers/virtio/virtio_ring.c | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'drivers/virtio') diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index a0b07c331255..18846afb39da 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -271,6 +271,17 @@ static bool vring_use_dma_api(struct virtio_device *vdev) return false; } +size_t virtio_max_dma_size(struct virtio_device *vdev) +{ + size_t max_segment_size = SIZE_MAX; + + if (vring_use_dma_api(vdev)) + max_segment_size = dma_max_mapping_size(&vdev->dev); + + return max_segment_size; +} +EXPORT_SYMBOL_GPL(virtio_max_dma_size); + static void *vring_alloc_queue(struct virtio_device *vdev, size_t size, dma_addr_t *dma_handle, gfp_t flag) { -- cgit v1.2.3-55-g7522