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authorJoerg Roedel <jroedel@suse.de>2019-02-07 12:59:16 +0100
committerMichael S. Tsirkin <mst@redhat.com>2019-03-06 11:19:15 -0500
commite6d6dd6c875eb3c9b69bb640419405726e6e0bbe (patch)
tree0392d073aef16f875c6772cdda08554d8798a45a /drivers/virtio
parent133d624b1cee16906134e92d5befb843b58bcf31 (diff)
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 <konrad.wilk@oracle.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Joerg Roedel <jroedel@suse.de> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Diffstat (limited to 'drivers/virtio')
-rw-r--r--drivers/virtio/virtio_ring.c11
1 files changed, 11 insertions, 0 deletions
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)
{