Re: [PATCH 01/13] virtio_ring: support per-virtqueue DMA mapping ops

[Kevin Loughlin]

On Tue, Oct 27, 2026 at 2:42 AM Michael S. Tsirkin <mst@xxxxxxxxxx> wrote:
>
> On Tue, Oct 27, 2026 at 02:56:04AM +0000, Kevin Loughlin wrote:
> > Allow individual virtqueues to override the device-wide DMA mapping
> > operations via virtqueue_set_map_ops(). When custom per-virtqueue
> > mapping operations are configured, vring_map_one_sg(), vring_unmap_one(),
> > vring_mapping_error(), and the DMA sync helpers dispatch through
> > vq->map_ops instead of the parent virtio_device DMA API path.
> >
> > Replace vring_map_single() with vring_map_indirect() and
> > vring_unmap_indirect() using the device-level mapping path (vdev->map
> > or dma_map_page_attrs()) so that indirect descriptor tables continue to
> > be DMA-mapped for host VMM access even when a virtqueue overrides buffer
> > mapping via vq->map_ops.
> >
> > Signed-off-by: Kevin Loughlin <kevinloughlin@xxxxxxxxxx>
>
> Please, don't. The automatic mappings inside virtio core are there
> to keep simple things, simple.
>
> Everyone doing something funky with mappings should use the premapped API.

Thanks for suggesting. I will use the premapped API if I end up sending a v2.