Messages in this thread | | | Date | Wed, 28 Oct 2015 11:06:50 +0900 | From | Joerg Roedel <> | Subject | Re: [PATCH 2/3] virtio_ring: Support DMA APIs |
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Hi Andy,
On Tue, Oct 27, 2015 at 06:17:09PM -0700, Andy Lutomirski wrote: > From: Andy Lutomirski <luto@amacapital.net> > > virtio_ring currently sends the device (usually a hypervisor) > physical addresses of its I/O buffers. This is okay when DMA > addresses and physical addresses are the same thing, but this isn't > always the case. For example, this never works on Xen guests, and > it is likely to fail if a physical "virtio" device ever ends up > behind an IOMMU or swiotlb.
The overall code looks good, but I havn't seen and dma_sync* calls. When swiotlb=force is in use this would break.
> + vq->vring.desc[head].addr = cpu_to_virtio64(_vq->vdev, vring_map_single( > + vq, > + desc, total_sg * sizeof(struct vring_desc), > + DMA_TO_DEVICE));
Nit: I think readability could be improved here by using a temporary variable for the return value of vring_map_single().
Joerg
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